pipes running red glowing hot

[SpaceKing]

I always let my bike warm up to the first bar before I ride. The other night I was coming home and noticed the piples were bright red hot, maybe a half minute after firing up the bike. I had it on full throttle, like I say, maybe half a minute. Is this normal? Bike is going in for its 36k service tomorrow.

Thanks for your help

beno

[cjmkerns]

Space,

 

Did you have it on full throttle warming up while stopped?

 

Carl

[USAF1]

"Full throttle" to most of us is getting the RPM's up next to the red line.....so I'm presuming that you really mean that you didn't have the choke on, right? Why are you waiting for the first bar? Most of us have learned that you give it about 30 seconds (if that), and move out. Not necessary to do all that waiting. The pipes are single walled, not double walled, so they'll show the heat a lot quicker. You wanna be careful that the heat doesn't melt the undersides of your panels above the headers....

 

 

Pat

[Mike O]

I always let my bike warm up to the first bar before I ride. The other night I was coming home and noticed the piples were bright red hot, maybe a half minute after firing up the bike. I had it on full throttle, like I say, maybe half a minute. Is this normal? Bike is going in for its 36k service tomorrow.

Thanks for your help

beno

 

I'd say it's the result of your un-necessary warm up procedure. Those pipes should NOT get red hot as minimally they will melt your tupperware. BMW has (at least on the '03 RT) added a sticker to the gas tank warning against what you are doing. Full throttle? At a stand still? Never.

 

Certainly not warmed up to the first bar (hell, my bike doesnt' warm up to the first bar for a couple of miles of riding this time of year.) I would recommend on a cold engine, you start the bike with the "choke" on (on my bike, that raises the RPM's to maybe 1200 or so), and after 15 secs, ride off. Within a minute, turn the "choke" off. Bike should be plenty warmed up to no longer need it.

 

Regards,

 

Mike O

 

P.S. As someone else already pointed out, its not really a choke, but you get the idea...

[BFish]

no need to warm up. start it and go. i'm surprised you haven't melted the tupperware yet.

[Murf]

That's perfectly normal....only you DON'T want to do it ! The most I let it warm up is just to put on the helmet and gloves. Warped tupperware around the pipes is in your future if you let that practice continue.. Set the throttle position lever..(some refer to it as a choke- but it's not) fire it up and head out

[SpaceKing]

Sorry, wrong terminology on the "throttle". I meant the faux "choke" on full. Master Yoda claims that warming up the engine (or any motor really) makes a big difference to is longevity. His comments about this are in his discussion about breaking in the engine:

"Warm Up

Typical advice about an air or oil cooled engine is to start it and drive off, then drive moderately until operating temperature is reached. That's supposed to get the engine to operating temperature most quickly, and thus expand things to their best tolerances. Less wear that way.

 

Crap!!!

 

Tests show that running an engine at about 1250 rpm, with no forward (cooling) motion, warms it up fastest IN A MANNER that produces the LEAST WEAR. This is according to the engine builders for MG and Jaguar, circa 1968.

 

In 1982 I bought two Honda Civic CRX's, for my (ex)wife and myself. We drove the same route to work (a tough mountain commute), except for the last 7 miles. Hers needed an engine rebuild at 80,000 miles. Mine was traded-in at 125,000 miles with no rebuild.

 

Religiously, I warmed my engine up before driving off. She didn't.

 

Whether new, or mature, engines wear less destructively if warmed up properly before normal operation."

 

What do you think?

Beno

[Ken H.]

What do you think?

I think it's 1982 thinking, that's what I think.

 

But it's your bike, your pipes, your plastic. But don't say we didn't warn you!

[313_Matt]

"Warm Up

Typical advice about an air or oil cooled engine is to start it and drive off, then drive moderately until operating temperature is reached. That's supposed to get the engine to operating temperature most quickly, and thus expand things to their best tolerances. Less wear that way.

 

Crap!!!

 

Tests show that running an engine at about 1250 rpm, with no forward (cooling) motion, warms it up fastest IN A MANNER that produces the LEAST WEAR. This is according to the engine builders for MG and Jaguar, circa 1968.

 

In 1982 I bought two Honda Civic CRX's, for my (ex)wife and myself. We drove the same route to work (a tough mountain commute), except for the last 7 miles. Hers needed an engine rebuild at 80,000 miles. Mine was traded-in at 125,000 miles with no rebuild.

 

Religiously, I warmed my engine up before driving off. She didn't.

 

Whether new, or mature, engines wear less destructively if warmed up properly before normal operation."

 

What do you think?

Beno

 

To quote your quote: crap. Who is this guy and where did he come from? Anyone who overhauled a Honda CRX at 80k had much more serious problems than not warming it up. That sounds to me like abuse; i.e. not proper oil changes or exceeding the redline on a regular basis.

 

I do not 'warm up' any of my vehicles. Even at very low temperatures I start up and go.

 

313-Matt

 

ps - MGs and Jaguars in the 60s suffered from many problems. Engine wear was not one of them. You were lucky if the 'Price of Darkness' electrics lasted past two oil changes. How did they keep these cars running long enough to do this test?

[baggerchris]

If that quote was indeed from master Yoda, Who in real life is Dick Frantz, then I would certainly pay attention to what he says. Not only did he practically invent the riding position most of us use, but his knowledge of Beemers is legendary. I would certainly not want to flame him.(or anyone else for that matter) I respect Dick and thank him for the useful knowledge he has imparted.

[rdsmith3]

Well I don't mean to be disrespectful, but what do anecdotes about unreliable British cars, and reliable Honda cars, both with liquid cooled engines, have to do with our air/oil cooled engines? The manual for my bike specifically says DO NOT warm up the engine. Start up and go. That is what I do.

[baggerchris]

You might want to read the complete article which is under M/C FAQ. ON THIS BOARD! It is entitled: "Break in your new RT" It has been here for years, and you are just now questioning it?

[RFW]

I always let my bike warm up to the first bar before I ride. The other night I was coming home and noticed the piples were bright red hot, maybe a half minute after firing up the bike. I had it on full throttle, like I say, maybe half a minute. Is this normal? Bike is going in for its 36k service tomorrow.

Thanks for your help

beno

 

You should NEVER let any motor idle for an extended time! Start it up and let it run only until the oil is circulating nicely (30 seconds or so) then ride off, not exerting the bike until it has gotten a bit warm.

 

I always laught at people who think they are doing their vehicles a favor by idling for an extended period before moving off.

 

In fact, this results in potential damage to the motor. The idea is to get the motor up to temperature as quickly as possible (without straining it). Idling is the worst way possible to do this.

 

What is most dangerous to the motor is that extended idling, with the rich mixture that is unavoidable when the motor is cold, results in raw unvaporized, liquid gasoline droplets, that wash the oil off the cylinder walls. The result of this is metal on metal and increase wear.

 

So in trying to "baby" the motor, you are increasing the potential of damage.

 

As for the red hot pipes, a friends oilhead does this at idle, and he was told that it was normal. Something to do with the retarded spark at idle required for emissions control.

 

Bob.

[bmw_rider]

I can see the next thread already: Why does my tupperware look like it is melted? or is it: Why did my bike go up in flames?

I didn't believe it either until I saw first hand what happens (not my bike) when the 'fast idle' is left on while not moving.

Some people must learn the hard way. I don't mean to flame anyone, but read the manual. For an 1150 it clearly states not to follow the practice you bring up.

[rdsmith3]

You might want to read the complete article which is under M/C FAQ. ON THIS BOARD! It is entitled: "Break in your new RT" It has been here for years, and you are just now questioning it?

 

Again, no disrespect intended, but just because something appears in a FAQ on the internet does not mean it is 100% true. I did read the FAQ. If you want to be precise it states

You should follow the the recommendations of the manufacturer of YOUR vehicle.

 

It also is characterized as an opinion.

 

So my choice is to believe the opinion of someone on the internet (a person whom I have never met) or the recommendation of the manufacturer. I choose to follow the manufacturer's recommendation.

 

Also, FWIW, on my bike there is no temperature gauge of any kind.

[SpaceKing]

If that quote was indeed from master Yoda, Who in real life is Dick Frantz, then I would certainly pay attention to what he says. Not only did he practically invent the riding position most of us use, but his knowledge of Beemers is legendary. I would certainly not want to flame him.(or anyone else for that matter) I respect Dick and thank him for the useful knowledge he has imparted.

 

Well, Chris, that's what I thought. With regards to melting tupperwear, it is 50 degrees out here and less in the winter time, and I am not really worried about that. My main question was, are glowing red pipes normal, particularly after a half a minute of the engine running with a full choke?

Beno

[John in VA]

My startup procedure:

 

- Sit on bike.

 

- Snick to first gear.

 

- Turn ignition key on.

 

- Flip "choke" full on.

 

- Clutch in.

 

- Press starter button.

 

- Blip to 3k once or twice.

 

- Go.

 

 

(Flip choke back at one/two bars.)

[SpaceKing]

You might want to read the complete article which is under M/C FAQ. ON THIS BOARD! It is entitled: "Break in your new RT" It has been here for years, and you are just now questioning it?

 

No, I just came across it a few days ago, but I have always warmed up my vehicles, even for a few minutes, seeing that I live in a cold climate. Reading Dick's advice just confirmed that for me. However I am relatively new to oil cooled engines and so this thread is about learning. I realized everybody has an opinion and I am interested in the minutae of operating am oil cooled beemer, as, I suspect, most of us on this board are.

cheers

beno

[SpaceKing]

"As for the red hot pipes, a friends oilhead does this at idle, and he was told that it was normal. Something to do with the retarded spark at idle required for emissions control."

 

Thanks Bob, that's what I was looking for.

cheers

beno

[Joe Frickin' Friday]

I can see the next thread already: Why does my tupperware look like it is melted? or is it: Why did my bike go up in flames?

z

 

"Next" thread? We've seen these threads already! Several times!

[jgrant]

I actually owned a 1984 CRX and it had over 150k when I sold it for a Del Sol and it had no probs and was not broken in using that technique. The point being that I think that Master Yoda has some good things to say and great knowledge but there is more than one way to skin a cat.

 

p.s...I am going to hijack this thread and point out that 1984 was the first year that the CRX was available.

[DavidEBSmith]

As for the red hot pipes, a friends oilhead does this at idle, and he was told that it was normal. Something to do with the retarded spark at idle required for emissions control.

 

 

Ummm, no. If the bike is running at idle (not fast idle or above), it should take an extremely long period of time sitting motionless for the pipes get hot enough to glow red. The pipes will glow red if you're sitting at fast idle or above for a minute or more, or if you've just pulled into a darkened garage after a high-speed run, or if you leave the bike running at idle and go back in the house for a cup of coffee and a dump. But if "normal" means something seen in everyday proper operation of the vehicle, I would say, no.

[RT Pilot]

I own an 04 RT. . .have put about 10000 miles on it in the heat of summer and throughout the winter. I've been caught in stop & go traffic in the summer and watched the temp gauge climb to within two bars of the redline--the tupperware got hot like you'd expect, but has never looked like it was close to melting. I know that it can be done, 'cause I've seen the pics of the damaged bikes--the bikes that I saw with melted plastic were those left on fast idle for more than a couple minutes. I just don't want people to have the misperception that it's easy to melt the tupperware on these bikes--it ain't so--you really have to "F" up to do it; for instance, if you start the bike on fast idle and take a phone call (forgetting the bike for 10+ mintutes) then you're probably gonna have melted tupperware. If you let it idle long enough to see one bar on the temp gauge--you're gonna be OK.

 

FWIW, I fly for a living. . .and the engines I run are air/oil cooled just like our beloved BMWs--the manufacturers of these engines promote a gradual warming of the engine into normal temp ranges before take-off--I believe my RT should be treated with the same respect. . .so for what it's worth, I let my engine warm to one bar on the temp gauge and then I take it easy for the first 2-3 miles before I really "take-off". Haven't melted anything yet. . . .

 

Robster

[Ken H.]

I can see the next thread already: Why does my tupperware look like it is melted? or is it: Why did my bike go up in flames?

z

 

"Next" thread? We've seen these threads already! Several times!

Well yes Mitch, but we DO have new people come to this site, maybe with the same old questions, ones we ourselves may have asked at one point in time.

[SpaceKing]

.so for what it's worth, I let my engine warm to one bar on the temp gauge and then I take it easy for the first 2-3 miles before I really "take-off".

 

 

Thanks Robster, that's my philosophy. We are talking two or three minutes at high idle . . . not breakfast and drip coffee . . .

cheers

Beno

[ShovelStrokeEd]

In point of fact, BMW recommends that you ride off immediatly after starting. You don't have to turn the fast idle off at all, just leave it on till the bike starts showing some temp. They also recommend moderate load until the motor is fully warmed up.

 

Unlike an airplane, which requires at or near maximum power on takeoff, a bike can ride for a mile or so with little demand on the engine. They are really two very different applications despite the similarities in their cooling systems.

[russell_bynum]

You should NEVER let any motor idle for an extended time!

 

So I should be shutting my bike down at red lights?

 

Please.

 

I don't know if it helps the engine to let the bike idle to warm up vs. just driving away gently. I do know that you're not going to hurt anything by letting it warm up.

 

I will say that you shouldn't let it sit for any longer than it needs to on the fast idle or you risk melting the tupperware "fins" that are by the headers.

 

But you can let the bike idle normally (no fast idle) until you max the temp gauge on the RID and you're not going to melt anything.

[russell_bynum]

Thanks Robster, that's my philosophy. We are talking two or three minutes at high idle . . . not breakfast and drip coffee . . .

 

That's fine, except don't do it at high idle.

[peterbulgar]

Your pipes are trying to tell you something, namely don't run the bike stationary at fast idle until the temperature reaches the first bar. The temperature gauge indicates your oil temperature, and that is the last thing to get warm except your tires.

 

Richard Frantz is something of a legend on this and other BMW forums. Without contradicting his wisdom, I'd like to deconstruct his article and point out a few areas where a different interpretation might be called for:

1) Given a choice between following what BMW says in the 2005 owner's manual or what MG and Jaguar said back in 1968, I'll choose BMW.

2) It's unclear whether the Rolls-Royce and Pratt & Whitney reference was about warming up or breaking in. Either way, see #1 above. In addition if it was about warming up: An aircraft needs full power to take off - you can't "ride moderately for a couple of miles" like you can on a bike or car.

3) Dr. Frantz's wife did not warm up her Honda before setting off a "tough mountain commute." Could it be that the "tough mountain commute" meant that she was using a heavy throttle before the engine was warm. This sounds like a special circumstance. For the record my 1987 Honda has 220K miles with no rebuild, and I follow Honda's warm up recommmendation, which is the same as BMW's.

4) Dr. Frantz's V-45 Sabre has 225K miles on it. I would suggest that the fact that he never revs it beyond 7K RPM, and that it's a famously robust and water-cooled engine has more to do with it's long life than his warm-up procedure.

5) The break-in procedure that Dr. Frantz outlines is very conservative, although it is closer to BMW's own recommendations than the "ride it like you stole it" philosophy that seems to be popular with a few members of this and other BMW forums.

 

Fast idle on my Oilhead is a lot higher than the 1250 RPM that Dr. Frantz recommends as a warm-up. I'm heading down the street less than 30 seconds after starting the bike, and I turn off the fast idle at the stop sign at the end of the block. I ride moderately for the first couple of miles, and don't go over 4000-4500 RPM for the first 10 miles. The freeway is a mile from where I work, so I stay in the slow lane for the first couple of miles when I go home at night. If I were taking off in a piston-engined plane where I'd need to use full power, or heading for the starting line of a race track where I'd need to red-line the engine before the first turn, I'd definitely find a way to have the engine at normal operating temperature before setting off. Riding my motorcycle in above freezing temperature on the street where I can use moderate throttle and relatively low RPMs for a few miles after starting out, I follow the owner's manual.

peter '73 R75/5, '04 R1150RA

[RT Pilot]

We're talking about the same thing--I think most of us agree, but we're expressing it in different ways. Suffice it to say that a warm-up phase is necessary for the engine, whether it's a minute on fast-idle and take off to easy riding, or just taking off and taking it easy for a few miles--we're splitting hairs here--but we're BMW riders. . .that's what we do!!

 

The airplane engine comparison is accurate--I'm doing the same thing every morning with my airplane. I let it warm up a little (into the normal temp range) and then I'm off to work. This is usually accomplished by the time I make it to the runway and run through the checklist. I DO ask for 100% power for about the first 60 seconds of flight and then it gets throttled back to climb-power (or less) for the remainder of the flight. Airplanes are usually run at 75% power or less in cruise flight--that's 5550 RPMs on my RT, a point that I exceed often. How is this different then the warm-up and take-off for the Boxer?? It isn't. . except airplane oil is cheaper than BMW oil. . .go figure!

 

 

By the way. . .I just want to express my gratitude for everyone on this board who contributes their knowledge. I'm also fairly new to BMWs (1 year), and I've learned much from everyone that posts here. Thanks!!

 

Robster

[MotoBoy]

There's one other difference: due to prop action, your plane has a continuous airflow over the cylinders, even if e.g. you've got cowl flaps closed for warm-up ... so it takes longer to get everything up to normal operating temp. The bike while sitting still on "fast idle" has no airflow, so you will get more (and more localized) heating. Once in a "cruise" regime of course, your plane is running somewhere between maybe 65% and 80% power, and your bike more like 20% to 30%. That's why you'll be re-closing cowl flaps after takeoff power is reduced and why the oil flow valve in your bike will be throttling back oil flow to the oil heat exchanger. Each is designed for this.

 

I'm no expert, and because of that, I try to operate the machinery just as advised in the pilot operating handbook or the BMW Owner's manual. I have no doubt at all that the engineers who did the design and test / certification work have given all of this some pretty extensive thought. And I conclude, rightly or wrongly, that they know more about the topic than I do.

[subvet]

The FINAL answer on this issue is here

[peterbulgar]

As is often the case on this forum, the thread has wandered far from the original post, but it is still interesting. Just another comment/observation before it goes away: I think that the coolant in a liquid-cooled engine warms up a lot faster (and operates at a more constant temperature) than the oil in an air/oil-cooled engine. Robster, is your airplane engine liquid-cooled or air-cooled?

 

Also, unless you have a police bike, our oilheads do not have a cooling fan behind the oil radiator, whereas all modern liquid-cooled bikes have cooling fans. This doesn't affect warming up, but it does make a difference if you get stuck in a traffic jam in the summer - and my bike (a Roadster) doesn't have a temperature gauge.

peter '73 R75/5, '04 R1150RA

[Pilgrim]

. . . The manual for my bike specifically says DO NOT warm up the engine. Start up and go. That is what I do.

 

I suspect that BMW recommends the immediate ride-off because they know that if you let if you try to warm it up it will melt the plastic, and for no other reason.

 

Here's why a warmup particularly matters, and why I think BMW has done us all a disservice with its advice.

 

BMWs and Harleys both construct their crankcase/cylinder/head stack in the same way.

 

Those parts are aluminum. The head bolts are steel. The bolts run through the head down through the cylinder, then they screw into the crankcase.

 

Aluminum expands more, and more rapidly than steel.

 

What this means to BMW (and Harley riders on post-1984 models) is this: you do not achieve full clamping pressure on the head gasket and cylinder base gasket until heat has caused the head and cylinder to expand against the restraining force of the head bolt, which does not expand as much as the head and cylinder.

 

Many of you who have looked at the base of your cylinders may have noticed a seepage of oil there, more or less of it depending on how you operate the bike when it is cool. Take off with more than just a modicum of throttle and you will force oil out through that gap as the crankcase pressures rise and fall with the pumping action of the pistons going up and down.

 

Harley riders who whack the throttle open before the warmup is complete may even notice a puff of combustion gases from between the head and cylinder.

 

Harley does not recommend an immediate ride-off despite the fact that the motors have very strong similarities of construction. There's a reason for that.

 

Pilgrim

[RFW]

In point of fact, BMW recommends that you ride off immediatly after starting.

 

....as does nearly every car manufacturer as well. An engine should warm up as a result of a few blocks of gentle driving, not extended idling which at the very least causes excessive oil dilution, and at worst excessive wear on pistons/rings that get exposed to raw (condensed or poorly atomized) gas.

 

Bob.

[Steve_Witmer]

Beno:

 

I'll chime in here and suggest that following Dick's suggestion for a brief warm-up will almost certainly do no harm to your RT (as long as you don't have the fast idle set). It may be beneficial, but on the other hand, I'm not convinced that the data upon which he relies would support the conclusion that warm up helps achieve longer engine life in the context of modern engine designs and modern oils (especially synthetic).

 

Regardless of the expertise of MG and Jaguar engineers in 1968, engines back then were built to far less precise tolerances and oil had poorer flow qualities at low temperatures and offered less engine protection generally than modern oils. So for a 1968 Jaguar engine running on 1968 oil, a warm up might have been much more important to engine life.

 

I've never owned any vehicle of any kind that needed an engine rebuild until way past 100,000 miles. There was only one of those and that vehicle (a Honda Civic) had been run hard and had a two speed semi-automatic transmission that caused the motor to rev awfully high.

 

I had one old car that just wouldn't run well (in cold weather)unless you warmed it up. I've never warmed up the others except on really cold days to get the heat going for the kids. All of my current vehicles (except the RT and it will be there in another couple years) have well over 100K and they don't burn any noticeable oil and show no signs of needing internal engine work for many years to come.

 

I use regular Dino oil in the Ford Explorer and Synthetic in the RT and the other car.

 

I feel comfortable with regular oil changes and reasonable driving until the engine is warmed up (to prevent oil starvation until the oil warms up and flows better) as protection against engine wear.

 

If you start an automobile an average of twice daily and warm it up for 5 minutes each time, you will run the engine about an extra 1200 hours over the course of 20 years, thus burning about an extra 600 gallons of gasoline (assuming fuel consumption at idle of 1/2 gallon per hour -- many vehicles use more). If we all do that it's a lot of unnecessary pollution. At $2.50/gallon you save enough on fuel to pay for an engine rebuild after 20 years if one is needed.

 

My advice - FWIW - don't warm up and save some $$ on gas.

[RFW]

You should NEVER let any motor idle for an extended time!

 

So I should be shutting my bike down at red lights?

 

Please.

 

I don't know if it helps the engine to let the bike idle to warm up vs. just driving away gently. I do know that you're not going to hurt anything by letting it warm up.

 

Sorry, I should have said "cold engine". A cold engine suffers from poor gas atomization, which results in oil film dilution. This is anything but good for the motor.

 

Your opinion that it won't hurt anything by letting the motor idle to warm up is not shared by a large number of manufacturers. Over the years, I have read comments from several manufacturers stating that one should not let a cold engine idle to warm up, and it is better for the engine to drive right off after a few seconds to get the oil circulating.

 

Warming up an engine by driving gently results in it warming up a lot faster (which is obviously good) and also avoids a lot of the problem of raw gas washing the oil film off cylinder walls since the combustion process is hotter and the greater velocity of the air/gas mixture results in less fallout of gasoline droplets.

 

By the way, if you lived in Switzerland, you would be expected to shut off your motor at a red light!

 

Bob.

[RFW]

What this means to BMW (and Harley riders on post-1984 models) is this: you do not achieve full clamping pressure on the head gasket and cylinder base gasket until heat has caused the head and cylinder to expand against the restraining force of the head bolt, which does not expand as much as the head and cylinder.

 

This effect is basically irrelivant.

 

If you work out the math, you can see that the contribution of the differential heating of the head stud/cylinder, is extremely minor as compared to the preload due to the bolt/nut torque stretching the studs. After all, it's not like the head gasket is on the hairy edge of sealing. The actual clamping force is several times what is required for sealing.

 

Bob.

[SpaceKing]

My advice - FWIW - don't warm up and save some $$ on gas.

 

Well there is that . . . I do notice I don't get anywhere near the gas mileage that most people on this forum do . . .

 

It's been a great discussion boys, thanks for all the feedback, relevant and not. Once again I am a lot richer coming out of this issue than getting into it. I am constantly amazed at the wealth of knowledge (and opinion ) of the members of this forum.

Cheers to everyone who responded.

I'm goin' for a ride . . .

Beno

[BFish]

2 add'l comments-

-your tupperware will met eventually if it sits with red pipes

-this thread evoked more emotion than any oil changing/level questions we've had lately. i like it.

[Pilgrim]

What this means to BMW (and Harley riders on post-1984 models) is this: you do not achieve full clamping pressure on the head gasket and cylinder base gasket until heat has caused the head and cylinder to expand against the restraining force of the head bolt, which does not expand as much as the head and cylinder.

 

This effect is basically irrelivant.

 

If you work out the math, you can see that the contribution of the differential heating of the head stud/cylinder, is extremely minor as compared to the preload due to the bolt/nut torque stretching the studs. After all, it's not like the head gasket is on the hairy edge of sealing. The actual clamping force is several times what is required for sealing.

 

Bob.

 

You are mistaken, Bob; the effect is far from irrelevant and a Harley engineer will tell you that - as one told me at Sturgis about 1987. In those days you'd still find HD engineers there and at other rallys available to answer questions.

 

Witness the fact that the headbolt torques for an old shovelhead (which bolts the heads to the cylinders at the joint) is far beyond what it is for an Evolution or TwinCam engine. An Evo calls for 38 to 42 lbs/ft of twist, while the shovelhead demands 65 to 70 lbs/ft per the book and some knowledgeable people add ten lbs/ft more. I have been told (but don't know for a fact) that at 38 lbs/ft the headbolts are very lightly loaded, nearly unstretched.

 

Aside from what the Harley engineer told me, every Harley wrench I've known since the Evo came out in 1984 has said that if you don't do a pretty good warmup you absolutely will get base gasket leaks and will eventually blow a head gasket if you hammer the throttle before the engine has run five to ten minutes. I have had personal experience with both of those problems, and both arose while I still subscribed to the "ride it off gently" theory.

 

A close friend who built engines measured heat penetration to the exterior parts and found that on a summer day in Seattle it took 20 minutes of cruise for the temps to stabilize.

 

The layman's version of warmup for an Evo engine now is let it run until the head is too warm to lay the back of your hand on, then ride off gently another five minutes or so.

 

My experience in this respect is largely with Harleys and I have no information from BMW on the subject (beyond their "ride it now" position), but I have seen enough leaky base gaskets on BMWs to believe it is the case there, too.

 

Pilgrim

[RFW]

[quote

You are mistaken, Bob; the effect is far from irrelevant and a Harley engineer will tell you that - as one told me at Sturgis about 1987. In those days you'd still find HD engineers there and at other rallys available to answer questions.

 

Witness the fact that the headbolt torques for an old shovelhead (which bolts the heads to the cylinders at the joint) is far beyond what it is for an Evolution or TwinCam engine. An Evo calls for 38 to 42 lbs/ft of twist, while the shovelhead demands 65 to 70 lbs/ft per the book and some knowledgeable people add ten lbs/ft more.

I hardly consider consider old Harleys as the paragon of engineering. Anyway, there are far too many other variables between an old shovelhead and an oilhead to draw any meaningful conclusions here. Just because a BMW has a leaky base gasket, does not mean it has anything to do with head stud relaxation. In fact, considering the far greater combustion pressures on the head gasket, I cannot see how it would maintain its integrity, while the lightly loaded base gasket fails (having only the much lower oil pump pressure to seal against, and even that is as I recall sealed by a separate O-ring that requres no force at all other than that needed to make the cylinder base contact the block).

 

Another point is that to my knowledge, the shovelhead cylinder is cast iron with essentially the identical thermal expansion coefficient as the steel studs. This negates most of the theory that the differential expansion coefficient between Aluminum and steel is responsible for stud relaxation. OK, the head may be aluminum, but its effective length compared to the barrel's effective length is a minor contributor. Most of what is left is the differing temperatures between stud and barrel/head, and that doesn't amount to much of an effect.

 

To throw some rough numbers at the Harley example, if one assumes a 20cm (~8 inch) barrel and stud length (I'm approximating an iron-barreled shovelhead here), and a barrel that heats to 150°C (~300°F), with the stud not heating at all, the total increase in barrel length compared to the stud length is a mere 0.363mm (or 14 thousanths of an inch). This assumes a typical cast iron coefficient of thermal expansion of 12.1um/m. This also assumes the unrealistically conservative assumption that the barrel has reached full operating temperature, and the studs remain totally cold.

 

When the head is torqued down, the stud stretch is FAR more than 14 thousandths of an inch, so the decrease in force caused by heating of the barrel is only a small proportion of total head clamping force.

 

Bob.

[cjmkerns]

Space,

 

If you have a '68 water cooled engine from either MG or Jaguar in your RT, I would certainly follow thier recomendations. But that darn air/oil cooled motor BMW put in them (with plastic bodywork 1.5 inches from the headers) comes with the factory recomendation of no warmup and conservative operation 'til warm. Kinda like Master Yoda said.

 

PS if those red pipes didn't melt any plastic all should be well for now. But if you continue the warmup routine you will likely see the plastic start to buckle just above the headers where the 2 screws are.

 

Regards,

 

Carl

[grizzly660fan]

I found this to be an interesting thread. I am no exptert but add this to the discussion.

 

is it possible that the late sixties early seventies warm up was less due to heating the engine and more to do with getting everything set up for the old carb? remember the old manual chokes on cars? pump gas pedal twice then start. the car needed a period of time for that choke to go back to normal or the car would run rough and maybe even stall.

 

just a thought?

 

Garry

[too old to care]

I found this to be an interesting thread. I am no exptert but add this to the discussion.

 

is it possible that the late sixties early seventies warm up was less due to heating the engine and more to do with getting everything set up for the old carb? remember the old manual chokes on cars? pump gas pedal twice then start. the car needed a period of time for that choke to go back to normal or the car would run rough and maybe even stall.

 

just a thought?

 

Garry

 

I also remember running straight weight oil in my old bikes (new back then). Between straight 40 weight and leaky carbs, you could hardly ride the bike until it was totally warmed up. Good call Garry.

[313_Matt]

SpaceKing, attributed to Master Yoda

Crap!!!

 

313-Matt

To quote your quote: crap.

 

baggerchris

If that quote was indeed from master Yoda, Who in real life is Dick Frantz, then I would certainly pay attention to what he says. Not only did he practically invent the riding position most of us use, but his knowledge of Beemers is legendary. I would certainly not want to flame him.(or anyone else for that matter) I respect Dick and thank him for the useful knowledge he has imparted.

 

No disrespect to Dick Frantz, or anyone else was intended. I apologize if my post came off as disrespect.

 

313-Matt

[RFW]

I found this to be an interesting thread. I am no exptert but add this to the discussion.

 

is it possible that the late sixties early seventies warm up was less due to heating the engine and more to do with getting everything set up for the old carb? remember the old manual chokes on cars? pump gas pedal twice then start. the car needed a period of time for that choke to go back to normal or the car would run rough and maybe even stall.

 

just a thought?

 

Garry

 

Good point. It seems to me that the entire reason that people started "warming up" their cars, was because (as you intimate) the damn thing was semi-undriveable back then unless you did! Nowadays, this problem does not exst.

 

Bob.

[Pilgrim]

[quote

You are mistaken, Bob; the effect is far from irrelevant and a Harley engineer will tell you that - as one told me at Sturgis about 1987. In those days you'd still find HD engineers there and at other rallys available to answer questions.

 

Witness the fact that the headbolt torques for an old shovelhead (which bolts the heads to the cylinders at the joint) is far beyond what it is for an Evolution or TwinCam engine. An Evo calls for 38 to 42 lbs/ft of twist, while the shovelhead demands 65 to 70 lbs/ft per the book and some knowledgeable people add ten lbs/ft more.

 

Bob, perhaps I just don't follow your syntax, but it appears that you misunderstand how shovelheads and evolutions are put together. Or perhaps I just don't understand how you presented your argument. So I'm going to go through here piece at a time, for I have the feeling you don't get it. But maybe you do, and I don't, but I can't tell that from what you wrote.

 

I hardly consider consider old Harleys as the paragon of engineering. Irrelevant since we aren't talking about Harley engineering.

 

Anyway, there are far too many other variables between an old shovelhead and an oilhead to draw any meaningful conclusions here. Just because a BMW has a leaky base gasket, does not mean it has anything to do with head stud relaxation. Maybe; maybe not. That's what we are discussing here. In fact, considering the far greater combustion pressures on the head gasket, I cannot see how it Which "it", Evo, or oilhead? would maintain its integrity, while the lightly loaded base gasket fails (having only the much lower oil pump pressure to seal against, and even that is as I recall sealed by a separate O-ring that requres no force at all other than that needed to make the cylinder base contact the block). In Evo-engined Harleys there is a base gasket, not an O-ring. What I describe is not a failure of the base gasket; what I mean is that it is common to find that the cylinder, when the engine is cold, will lift slightly off the base gasket due to combustion pressure acting on the piston also lifting the head/cylinder stack, and the air in the crankcase being compressed by the fall of the pistons nearly together. Yes, crankcase pressure is vented, but not completely adequately. I was not speaking of any pressure created by the oil pump. The Twin Cam engine dealt with the issue by using an O-ring in that location.

 

Another point is that to my knowledge, the shovelhead cylinder is cast iron with essentially the identical thermal expansion coefficient as the steel studs. This negates most of the theory that the differential expansion coefficient between Aluminum and steel is responsible for stud relaxation. OK, the head may be aluminum, but its effective length compared to the barrel's effective length is a minor contributor. Most of what is left is the differing temperatures between stud and barrel/head, and that doesn't amount to much of an effect. Confused I am with your statement. Yes, the cylinders are steel and the head aluminum in a shovelhead, but there are no long studs, as found on an Evo engine, that run from the heads to the crankcase. Instead, "ears" on the top of the cylinder bolt to the head, and "ears" on the bottom bolt to the crankcase. Thus, as you note, there is no differential expansion anywhere (that amounts to anything). All the clamping pressure on the gaskets in a shovelhead must be exerted by torquing the head and base bolts to a high number. Assuming that the required gasket clamping pressure is more or less the same for both shovelhead and Evo (a fair assumption) the the difference between the two torque values (65 lbs/ft for a shovel; 38 for an Evo) must be made up somewhere if clamping pressure is to remain more or less the same. That "somewhere" is in thermal expansion of the aluminum Evolution cylinder.

 

To throw some rough numbers at the Harley example, if one assumes a 20cm (~8 inch) barrel and stud length (I'm approximating an iron-barreled shovelhead here), and a barrel that heats to 150°C (~300°F), with the stud not heating at all, the total increase in barrel length compared to the stud length is a mere 0.363mm (or 14 thousanths of an inch). This assumes a typical cast iron coefficient of thermal expansion of 12.1um/m. This also assumes the unrealistically conservative assumption that the barrel has reached full operating temperature, and the studs remain totally cold. I think you've missed the boat on what you are calculating here. You must compare the expanded length of an aluminum cylinder to the expanded length of the steel through-stud in the Evo to arrive at a valid length differential. 8" is a reasonable number to use for cylinder height.

 

When the head is torqued down, the stud stretch is FAR more than 14 thousandths of an inch Are you saying that 38 lbs/ft of torque will stretch an Evo head bolt 14 thou? Is that from an engineering handbook? I've never seen an actual value for that torque turned into stretch, but that's interesting if accurate, so the decrease in force caused by heating of the barrel is only a small proportion of total head clamping force. I'm not describing any decrease in force brought about by heating. I contend that the clamping force on the gasket is increased as the aluminum cylinder heats up and expands inside the lesser expansion of the steel head bolts. `

 

Bob.

 

So, Bob, if it seems that I still don't follow your rebuttal, please explain further.

 

But I must say aforehand that explanations of why this bumblebee can't fly will ring pretty hollow in the face of the fact that he does. If you don't warm up a modern Harley you're going to have gasket problems and Harley thinks it's because the cylinders need to expand.

 

Pilgrim

 

EDIT: Just for the sake of maintaining clarity of position, let me say that I am not arguing for a warmup to enhance driveability or any other factor than gasket integrity. Fuel injection, and modern engine tolerances and oils pretty well negate the need for one. The commonality of construction between Harley engines and BMW engines seems to call for it as good practice, though, except that plastic on the R11XXRT series precludes it.