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What RPM for highway =Less Vibration r1200rt


mickeymc

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Ok, You can see that it is my first post here so if the question has been answered please point me to the thread.

 

Here are the specifics. New to me 2007 R1200RT, 15,0000 miles. Getting ready for a trip to the RA Rally so rode 400 miles yesterday. All different roads, two lane to interstate. The previous owner had 12K service done and running synthetic oil. That about all I know.

 

The question is what gear and RPM do most run on interstate. It runs good and smooth up to about 73 mph in 6 gear. Accelerating from there seem to vibrate a good bit and seems like it is under a load for lack of a better term. Maybe like spsrk knock but I was wearing earplugs so maybe/probably not actually spark knock but felt like it in the grips. I have not many mile on the RT1200 although I have 100000+ and a 1150 GS and the GS does not do this.

I was thinking about shifing to 5th gear, is this to fast to run 5 for long periods?

BTW riding 2 up with total weight around 310.

Thanks

 

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Don't be scared to rev the Boxer.

For overtaking and harder riding, 4500 ~ 7000rpm, no problem.

For lazy cruising 3000 ~ 4000rpm.

It does increase the vibes a bit above 4000rpm.

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I ride in the 4K to 5K rpm range. This typically translates to 4th gear when the speed limit is 55, 5th gear for 65, 6th gear above 80.

 

My basic rule is that I should be able to twist the throttle and the bike should accelerate quickly; If it bogs down, or I need to downshift, I am in too high a gear.

 

And, she will happily run all day on interstate in 4th or 5th. Mine just finished a 3000 mile trip, and is running wonderfully.

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I think for your top speed long distance you always want the highest gear you have. This is to reduce your rpms and wear and tear on the engine and get the most speed out of your engine, to get you there.

Unless you are on a slow road.

But for open freeway, I usually am around 80 at about 4100 rpm.

I do vary it from time to time for various reasons, like scenery.

But I never pay much attention to vibration, if valves are ok, and tbi sync is ok.

Motorcycles just vibrate. Particularly boxers, particularly 2 cylinders.

Honda 4s are supposedly real smooth. I know their 2s are, as those were the only Hondas I was interested in.

dc

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Welcome on board. This is the place for things like that.

 

Vibes can occur at any RPM, but are often noticed more in the conditions you mention in you post. Once you get to cruising along things have the chance to be noticed. 3-4k is a good cruise speed and if you encounter a load situation, like passing, or up-hill you may notice the vibe more. It is highly unlikely that you have a serious problem. It is also highly likely that a precise valve adjustment might help.

 

The answer to your question has been posted, but let me assure you that the bike will be very happy in 5th at highway speeds. In-fact it will be happy all the way up to the Rev Limiter, aka Shift Indicator.

 

 

But, the question must be asked if your vibrations are the "normal" vibes associated with a twin cylinder bike or are they the consequence of something else.

 

The traditional remedy is a competent (meaning self-done) valve adjustment followed by a meticulous Throttle Body Synchronization (TBS). That plus the fact that your bike is likely not quite broken-in yet, but getting close.

 

If you are the mechanical sort both the valves and the TBS are easily done and can add a lot of confidence and pride of ownership to your experience. If you are not the sort to do valves etc, then you might want to investigate finding an experienced BMW guy in your part of the world who can show you the ropes.

 

The process can be done in just an hour or two if you have a guide, or a dealer can do it and charge you for the time.

 

If the vibe is not bad, then just ride it.

 

 

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Thanks for the replys so far. I do all my own work. I have had an airhead, still have oilhead and a k bike, never had any work done by dealer so valves tb's no problem, I have read that hexheads do nat adjust TB's at idle inly after the TBs begin to open. I will have to read more on this. Maybe be a break in issue as well. When I told a frien who has a 1200 that it already had synthetic oil he said that seemd a little early. Should I switch back to dino oil for a while?

 

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Morning mickeymc

 

At higher sustained RPM's both of my 1200 hexheads do have a buzz on the handlebar grips & at some narrow RPM bands to the seat & foot pegs.

 

I usually cruise on the hi-way at 4500-5000 RPM's on my RT (a bit higher on my GS). That puts me "well" above the posted speed limits.

 

At that high of an RPM (above 4k) that is well above valve adjustment or TB balance influence so that is your basic BMW boxer buzz.

 

BMW added a (single) secondary balance shaft to the 1200 hexhead boxer. That is both good & bad. Seeing as the primary balance on the BMW boxer is basically in balance as designed then adding a (single) balance shaft has to add a imbalance at some point in the operating range.

That balance shaft offsets some lower & mid RPM rocking couple imbalance but adds a bit of higher frequency disturbance at higher RPM's.

 

If you want to work at it you can lower the rider-felt higher RPM boxer buzz especially in the handlebar grip area. You need to work with handlebar end weight (I originally add a 2nd set of stock bar end weights as a test then finally machined up a set of stainless steel "much larger" bar end weights. That helped the bar buzz a bit. Then went to the later 3 bolt handlebar (semi tuned) attachment by eliminating one bolt & adding thin spacers between the bar & triple tree at the remaining 3 bolts (that softened & tuned the bar frequency response), also added thicker "O" rings between the bars & the triple tree (to seal the water out) as the bars were raised up that thin washer thickness.

 

You can still feel a bit of bar/grip buzz at 4200 -5500 RPM's but it is now substantially better than stock.

 

 

Another thing to consider is your bike is still new to you. More than likely you are gripping the hand grips too tightly. As you get more used to the bike you will find that almost no grip pressure is needed on the hand grips to keep the bike on course so a very light hand hold can be used. That in itself will substantially lower the bar buzz influence.

 

 

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Dave_in_TX

During the 140k miles I owned my 07 RT, I seldom used 6th gear below 70mph. Depending on engine load (head winds, etc.), 5th gear was often smoother then 6th. I've cruised for long periods of time at 80mph in 5th. For me, 6th was an overdrive. Two things I did to reduce vibration in the bars were putting grip puppies (closed cell foam tubes) over the handgrips and replacing the stock bar end weights with a much heavier set from HVP.

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Pardon the rookie somewhat-related question. I don't notice any handlebar buzz on my '09 RT, however, I have an extra set of mirrors on the handlebars. I notice a little vibration in those mirrors - not enough to impair their intended purpose, but a little more than the stock mirrors below, which are pretty "still."

 

Would the extra bar-end weights (if I have that right) tend to reduce this mirror vibration?

 

Thanks.

 

John

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Would the extra bar-end weights (if I have that right) tend to reduce this mirror vibration?

 

Afternoon John

 

Maybe! Try it anyhow.

 

On my 1200RT the R/H added (K bike) mirror is dead steady but the L/H still has a bit of buzz to it at 4200-5500 RPMs.

 

 

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Dirtrider,

Thanks for th insight. I do not think gripping the handle bars to tight is a problem, in fact on the interstate with no close by traffic I usually only use three fingers sort of hung over the grip. Probably a bad habbit but that relaxes my arms and allows to lean back an inch or so. On my GS I had to keep my right hand on the frip but now with cruise my right hand can get a rest. This is probably the reason some put bar back to get that extra inch back.

Anyway, at my job I have access to a complete machine shop so I may experiment with different heaver bar weights.

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Early oilheads had 5 speeds.

4th worked well up to max speed, 5th sort of overdrive rarely used unless over 80 or cruising interstate which I rarely did.

Ride it and rev it, hard to cause a problem.

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Morning mickeymc

 

Yes, do play with the bar end weighting.

 

One thing I forgot to mention in the first post; is make sure the bar attaching bolts are tight. I have seen a few 1200 hexheads that had loose bar attaching bolts.

 

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Perhaps original poster's situation is similar to mine ...

 

I've come to my R1200RT following 28 years riding the same '84 R100RS (Airhead).

 

The new bike's redline is 1000 rpm higher and clearly this engine likes to run all the time 1000 rpm higher than I'm used to. A torque monster it ain't ... unlike the Airhead. Also it has another gear, i.e. sixth, that the Airhead didn't have.

 

There seem very few legal speeds anywhere suitable for 6th gear riding the 1200RT. When on a 75 mph legal freeway, I'll get into 6th running maybe 80, but just about everywhere else 5th or lower is it. As one who always practices being in the highest gear possible, this is a difficult transition. Now I always downshift soon as I see rpms below 4K. (That number was 3K on my Airhead.)

 

Oh, and FWIW, my bike had what I consider to be factory-cracked primary spark plug insulators and it indeed suffered misfiring trying to accelerate in a probably too-high gear. Replaced those and simultaneously have adapted to the night/day different engine and I'm enjoying the bike really a lot.

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If you want to work at it you can lower the rider-felt higher RPM boxer buzz especially in the handlebar grip area. You need to work with handlebar end weight (I originally add a 2nd set of stock bar end weights as a test then finally machined up a set of stainless steel "much larger" bar end weights. That helped the bar buzz a bit. Then went to the later 3 bolt handlebar (semi tuned) attachment by eliminating one bolt & adding thin spacers between the bar & triple tree at the remaining 3 bolts (that softened & tuned the bar frequency response), also added thicker "O" rings between the bars & the triple tree (to seal the water out) as the bars were raised up that thin washer thickness.

 

You can still feel a bit of bar/grip buzz at 4200 -5500 RPM's but it is now substantially better than stock.

 

 

DirtRider,

 

I added the heavier bar end weights from Manic Salamander and they changed the vibration a bit but not as much as I would have liked so I am intrigued by your "handlebar tuning" approach. A couple of questions:

 

- Did you actually leave out one of the bolts so that each handlebar is attached by only two?

- Would you get the same effect by using three per side but only tightening two of the bolts? (I can imagine my mental process every time I look down and saw two handlebar bolts missing. :) )

- You mentioned "thicker o-rings" between the bars and the triple tree. I assume you removed the originals and replaced them with the thicker o-rings. Any suggestions for a specific size of o-ring to start with on the tuning?

 

Thanks!

 

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