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San Jose dual-spark conversion: Any long-term issues?


Joe Frickin' Friday

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Joe Frickin' Friday

A few years ago San Jose BMW began offering a dual-spark conversion package for the 1100 boxer motor. The modification was said to cure surging and offer slightly more power/efficiency/MPG. Indeed, BMW started doing the same thing straight from the factory not long afterward.

 

Certainly BMW will have done lots of durability testing before coming to market with their design change, but I doubt the same is true for SJ's aftermarket mod. Not a slam against them, it's just that I don't imagine SJ has the facilities to quickly rack up a couple thousand hours each on a dozen test engines.

 

I'm curious to know if anyone has heard of or directly experienced any long-term issues associated with SJ's dual-spark conversion. Any heads cracking at the new plug location, or overheating, or anything weird like that?

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i sent my heads to San Jose, I think in early 2004. so two years now and about 30,000 miles. works great and i have had no problems

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i sent my heads to San Jose, I think in early 2004. so two years now and about 30,000 miles. works great and i have had no problems
But, do thay have one for my 2004. dopeslap.gifdopeslap.gifdopeslap.gifgrin.gif
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Killer's got 10's of thousands on his and still rolling.

 

BarryBeemer also had his done a few years ago, but I don't know how many miles he's got on it.

 

I haven't heard of anyone else having any problems with theirs. I believe the folks at SJ had some inside info on BMW's mod as they were active in the Boxer cup and they've been doing dual spark mods on bikes for many years.

 

I had a few conversations with the head tech there and I was impressed. Leslie's and my bikes are getting up there in mileage and when it comes time for a top end rebuild (or I guess in this case an "outside" rebuild! grin.gif ) I'm giving it serious thought! thumbsup.gif

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Killer's got 10's of thousands on his and still rolling.
70,000 and no problems at all. San Jose have been doing this for a long time, I enjoy going there and talking to them, they seem to be interested and to care about their customers.
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I've got about 40,000 on my SJ dual plug conversion, and I'm very happy with it. clap.gif

 

Pat

 

But did your RT surge and if so did the conversion resolve the problem?

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Power Commander sounds like a cheaper fix for surging, than a dual spark conversion.
True, but the dual spark is not just for surging. I too couldn't justify it just for the better off-idle response, nominal HP increase and the better mileage, but now with Premium in the SoCal area bumping up against $4.00 a gallon and us needing a top end rebuild soon anyway, I'm seriously considering it. With a good tune-up (and pulling that LPB), Maynard never surged much anyway. The TPS on the 1150's which eliminated the need for the 0=0 were less prone to surging problems anyway, though as the miles are piling on I'm starting to notice a wee bit creeping back in at steady low-speed cruising (like through neighborhoods).
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Will the PC improve fuel economy?
In my experience, no. I saw approximately the same mileage before and after a PC installation. The street price of the PC is more like $420, but that still makes for a fairly negligible cost difference. My own personal reasons for going with the PC over dual plugs was a lack of desire to R/R the heads and lose use of the bike for a while and not being sure about how well-engineered the aftermarket dual-plug mod was. The PC is a rather simple plug-in affair, has a very beneficial effect on the driveability of the bike and several collateral benefits as well (some nice maintenance aids, new O2 sensor, etc.) The downsides of the PC are no mileage increase (as seems to be reported by dual-plug owners) and the fact that you likely will raise emissions somewhat, but otherwise the benefits seem similar in that there's more than one way to skin a cat (or in this case light a fuel/air mixture)... dual sparks work, and so does a richer mixture. The price is similar so I guess one can take their pick.
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I've got about 40,000 on my SJ dual plug conversion, and I'm very happy with it. clap.gif

 

Pat

 

But did your RT surge and if so did the conversion resolve the problem?

Based on his signature:

 

--------------------

'02 R1150RT, dual plugs - no surge!

 

I'm guessing he thinks it fixed it. But I'm curious as well. For those that have had the conversion done, did it surge before, and did it fix it?

My understanding was that dual-plugs had nothing to do with surge fixes (logically it doesn't make sense to me that it would, since it's a fuel delivery issue, not a burn issue.) I don't believe surging was cured until the 1200's came out with their new fuel injection system.

Am I missing something here?

 

Regards,

 

Mike O

 

P.S. FWIW, I test rode a dual spark and it surged. Sample of 1; may have been out of tune; who knows.

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My understanding was that dual-plugs had nothing to do with surge fixes (logically it doesn't make sense to me that it would, since it's a fuel delivery issue, not a burn issue.)
It is kind of a burn issue actually, in that lean surge is caused by occasional lack of ignition due to an excessively lean mixture. Two sparks have a higher chance of getting the lean mixture to light than one and will reduce the number of misfires, reducing surging and increasing mileage. Richening the mixture has a similar effect in driveability improvement in that it also makes ignition more reliable, but usually won't increase mileage much (unless the engine was running really lean) since any efficiency gain as a result of greater ignition reliability tends to be offset by the fact that a richer mixture requires more fuel. (Of course, how much mileage is affected by either change is dependent on a number of factors and isn't easy to predict, and an important equation to remember in any of these discussions is: actual mileage gain = reported mileage gain * 0.5 wink.gif)
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My understanding was that dual-plugs had nothing to do with surge fixes (logically it doesn't make sense to me that it would, since it's a fuel delivery issue, not a burn issue.)
It is kind of a burn issue actually, in that lean surge is caused by occasional lack of ignition due to an excessively lean mixture. Two sparks have a higher chance of getting the lean mixture to light than one and will reduce the number of misfires, reducing surging and increasing mileage. Richening the mixture has a similar effect in driveability improvement in that it also makes ignition more reliable, but usually won't increase mileage much (unless the engine was running really lean) since any efficiency gain as a result of greater ignition reliability tends to be offset by the fact that a richer mixture requires more fuel. (Of course, how much mileage is affected by either change is dependent on a number of factors and isn't easy to predict, and an important equation to remember in any of these discussions is: actual mileage gain = reported mileage gain * 0.5 wink.gif)
hmmmm...so why did BMW change the fuel injection system on the 1200's if dual spark fixed the surging?(yea, it was to make it easier to add cruise wink.gif). And why did MCN say that the surging was finally fixed after the 1200's were introduced? (could it be that as BMW claimed, the dual spark was for emissions reasons and not surging as we have all been speculating for so long?). I don't mean to raise the 'surging' thing all over again, and value everyone's opinion, but we've heard so many times certain things fix the surge (if its present) which is quickly countered by someone else suggesting its a waste of money. It strikes me that there is imperical evidence (hp gains, and mileage gains) that a dual spark might be worth the money for that improvement. But I don't get the same sense it really fixed the surge. Without proper test environment and a before/after results, it seems we have a lot of anecdotal "seat of the pants" evidence only (which is fine but everybody's seat is different).

 

But there are far wiser mechanics on this board than I and quite frankly I'm thrilled I've learned how to tune out the surge. (I believe Mitch's original question wasn't about surging anyway.) I'll drop off the 'surge' discussion and listend for the experts to chime in.

 

Regards,

 

Mike O

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Without proper test environment and a before/after results, it seems we have a lot of anecdotal "seat of the pants" evidence only (which is fine but everybody's seat is different).
I couldn't agree more Mike, and please note that I wasn't at all trying to claim that dual-plugging the oilheads will necessarily fix surging, just that there was a logical basis for it possibly doing so in some cases, that's all.

 

I would assume that anyone wishing to do a dual-plug mod is at least partially trying to address surging or some kind of driveability issue as I doubt it couple possibly be very cost-effective on a fuel-saving basis alone.

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Joe Frickin' Friday
I would assume that anyone wishing to do a dual-plug mod is at least partially trying to address surging or some kind of driveability issue...

 

Nope. I'm just bored.

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ProductUser

FWIW -- my '04 dual spark 1150 R surges -- albeit very little. It has surged pretty hard in the early days; but addressing a number of known issues, that presumably cause surging, has reduced the surge to a minimum.

 

Just my .02

 

Tony

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ShovelStrokeEd

More anecdotal stuff on the surge thing and dual sparks in general.

 

'94 R1100RS - Never surged when new, at about 8K miles I installed a chip and and exhaust system from RB Racing, no not the elephant dildo they sell now, just a cat eliminator and a can. Never surged after that. It has been down for a couple of years cause I'm too lazy to put it back together but it has about 19K on it and it never surged.

 

'04 1150GS Adv. Dual spark from the factory. Towards the end of its life at 60K+ miles it had never surged and it didn't get much in the way of spark plug maintenance. I think I changed them once at about 36K miles. Valves and synch done at roughly 6-7K intervals. It is gone from my stable now.

 

'02 R1100SBX. Single spark, never surged when stock, changed chip and exhaust at about 15K miles, 52K on it at present and doesn't surge.

 

The GS got the best fuel milage of the bunch around town. All of them got about the same at the considerable time I spend at freeway speeds. I can't say that the GS, in the mildest state of tune of them all, could attribute its better around town milage to the dual plug heads. The difference was only in the neighborhood of 1-2 mpg.

 

Another factor just might be the way I ride. I don't troll along at low RPM, anywhere. Even when riding "in town" I tend to keep the revs in the 4K RPM range or above so the entire surging issue might be there and I just never knew it. I have always held the opinion that if the motor is unhappy at a particular RPM range, shift.

 

FWIW, the Blackbird will troll along quite happily at 2000 RPM although the wateer pump doesn't work very well at that low an engine speed and it will get hot pretty quickly. I have seen 230 degrees on the water temp indicator but Honda says so long as you are below 270, you are OK. I know it is a different beast but, the technology is similar in that mine is a 2001. Of course, no O2 sensor or cat which I believe to be the prime culprits in the surging issue. Nothing wrong with the cat, just the mixture needed to keep it lit up.

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Adding a second spark plug does not guaranty loss of surging.

 

Proper valve lash adjustment does.

 

 

 

I'm almost afraid to reply to this.....

 

 

 

 

You are saying proper valve lash adjustment will cure surging.. confused.gif

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Yes. A TB sync helps a bit but valve lash is THE way to cure surging. Also, I prefer Autolite 3923 plugs. Better starts, better MPG and less detonation (I ride a '01 GS...single plug. This model is noted for detonation in Houston heat).

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More anecdotal stuff on the surge thing and dual sparks in general.

 

'94 R1100RS - Never surged when new, at about 8K miles I installed a chip and and exhaust system from RB Racing, no not the elephant dildo they sell now, just a cat eliminator and a can. Never surged after that. It has been down for a couple of years cause I'm too lazy to put it back together but it has about 19K on it and it never surged.

 

'04 1150GS Adv. Dual spark from the factory. Towards the end of its life at 60K+ miles it had never surged and it didn't get much in the way of spark plug maintenance. I think I changed them once at about 36K miles. Valves and synch done at roughly 6-7K intervals. It is gone from my stable now.

 

'02 R1100SBX. Single spark, never surged when stock, changed chip and exhaust at about 15K miles, 52K on it at present and doesn't surge.

 

The GS got the best fuel milage of the bunch around town. All of them got about the same at the considerable time I spend at freeway speeds. I can't say that the GS, in the mildest state of tune of them all, could attribute its better around town milage to the dual plug heads. The difference was only in the neighborhood of 1-2 mpg.

 

Another factor just might be the way I ride. I don't troll along at low RPM, anywhere. Even when riding "in town" I tend to keep the revs in the 4K RPM range or above so the entire surging issue might be there and I just never knew it. I have always held the opinion that if the motor is unhappy at a particular RPM range, shift.

 

FWIW, the Blackbird will troll along quite happily at 2000 RPM although the wateer pump doesn't work very well at that low an engine speed and it will get hot pretty quickly. I have seen 230 degrees on the water temp indicator but Honda says so long as you are below 270, you are OK. I know it is a different beast but, the technology is similar in that mine is a 2001. Of course, no O2 sensor or cat which I believe to be the prime culprits in the surging issue. Nothing wrong with the cat, just the mixture needed to keep it lit up.

 

My '01 GS with OE exhaust DOES NOT SURGE even when tooling around in 2nd or 3rd gear at 1800 - 2500 RPM.

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ShovelStrokeEd

Dennis,

Makes sense, as surging, as generally defined here, happens at around 3K RPM in 3rd gear, and very light throttle openings. I won't dispute the fact that valve adjustment can be a contributor to surging, or throttle body synchronization for that matter.

 

My opinion, for what it is worth, is that the main cause lies with the O2 sensor and the Motronic programming. At part throttle, the O2 sensor feedback is designed to keep the mixture in very close proximity to stochiometry to keep the converter "lit". The sensor on the 11xx series is really a primative beast, it only really has two states, too rich, too lean. The Motronic adjusts mixture in response to those signals. You should easily see the potential for those signals to get out of phase with ECU response at certain combinations of load/throttle position. Remember, there is a finite reponse time and the O2 sensor is acting post facto. Now add a slightly lazy sensor response and it is easy to see the system getting confused. You can now have long (relative term) periods of too lean (power drops below that needed to maintain speed) followed by too rich (power restored and bike lurches forward).

 

The above also explains why some bikes do it and some don't. Sensor response when new may be within narrow enough limits to prevent this but, add a few K miles and that response may well change. Given, as well, that O2 sensors are probably not individually tested but batch tested by the manufacturer and it is not too far fetched that a couple will make it to the shipping department that are out of spec.

 

Just my humble opinion of course. I have no direct experience in programming closed loop EFI systems. I have done some open loop EFI systems and getting that particular range, low throttle opening low load is quite tricky as you must balance the need for steady state operation against the need for smooth transitions out of same. Surely with your experience in robotics, you have run into instability within closed loop systems before.

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I believe that the problem is even simpler. Catalytic converters work most efficiently when the A/F ratio is exactly at stoichiometric (14.7:1) and thus this is the mixture that the stock Motronic aims for. The trouble is that this mixture is much leaner than optimum for performance and driveability and can result in poor throttle response and lean misfires (with resultant lean surge), especially in a large displacement twin (large bore makes it harder to keep the mixture lit, and only two cylinders moving the crank mean nothing to smooth out misfires as is the case with engines with 4 or more cylinders.) BMW took on a pretty tough task in running a 1100/1150cc twin on the ragged lean edge (necessitated by employing a cat converter) and using a very crude fuel injection system didn't help. It's not at all surprising that many of these engines exhibit lean surge even in a relatively good state of tune.

 

About the only thing you can do to positively cure the problem is run the engine a little richer (with a Power Commander or Techlusion) or try techniques such as dual plugs (two sparks have a better change at lighting the mixture and keeping it lit.) The few stock bikes that don't surge are probably running on the rich side of production tolerance, perhaps for reasons similar to what Ed suggested.

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See the late Rob Lentini's "Zero = Zero" tech write-up. Adding a second plug will not cure surging. Also, head work that removes the dimpled surface in the intake runners in the heads will reduce vortices thereby disrupting mixing. This leads to excess emmisions. Polished intake runners will provide more power due to additional air and fuel reaching the combustion chambers but, likely not worth the expense in my opinion.

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I was thinking of doing this conversion next winter when the roads are covered in snow. I have 2 questions:

 

1. I have always had a detonation problem in the warmer weather, I assume due to carbon build-up. Would a more thorough burn after the conversion help to prevent this?

 

2. I have BMW cylinder head protectors on my bike. Will they have to be scrapped because the bottom bracket would interfere with the second spark plug?

 

Thanks.

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Joe Frickin' Friday
1. I have always had a detonation problem in the warmer weather, I assume due to carbon build-up. Would a more thorough burn after the conversion help to prevent this?

 

Not a more thorough burn - but a faster burn. Detonation resistance is a time thing as well as a temperature thing; if you can burn the entire mixture via normal deflagration before any unburned portion has a chance to transition to detonation, then everything's cool. Dual-spark plugs provides two flame fronts, significantly speeding up combustion.

 

Can't say what it would do for carbon build-up, but I definitely expect the dual-spark mod to reduce detonation.

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ShovelStrokeEd

In re detonation, what Mitch said.

 

As to the valve cover protectors, nothing a little creative work with a Dremel tool won't cure.

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TWEETY BYRD

I did the head,Staintune system and power commander and the bike finaly runs well.

For a better running twin you need to ride my rc 51. bob clap.gif

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Adding a second plug will not cure surging.
I say you are absolutely wrong and I have a bike that proved it. Had the valves adjusted at several dealers, did it myself, did it at tech days with some very picky people, still surged. Had the SJ dual plugs installed, no surging, again many valve adjustments following that and still no surging.
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Dual plugs are often used in engine applications employing a large bore and a lean mixture to both reduce the tendency for detonation and to make ignition more reliable. Much depends on the engine design but dual plugs most definitely have the potential to help reduce lean surge. Why do you think BMW added this feature, just for the heck of it..?

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