Lash in drivetrain causing a jerk

[carquestman1]

I just bought a used R1100RT and I love the bike but have one small problem. I noticed that after decellerating under compresson and then giving it throttle that most of the time I get a clunk or jerk. Once it clunks it is fine until the next time I let off into a curve or down a hill. Then I get the clunk again. On flat long streatches of road it runs fine. Is there a problem with the drive shaft or slip yoke and is this common?

[4wheeldog]

There is some lash in the driveline with all the shafties. It is hard to know if what you are experiencing is normal or excessive. You need an opinion from someone familiar with similar bikes with your bike in front of them.

By the way, I have it on good authority that driveline slack does not cause jerks. My wife swears that testosterone is almost always the cause.

[carquestman1]

It's more than just a little noise of slight clunk. It's a pretty violent hickup and it doesn't do it all the time. I might just be getting to picky in my old age but I've owned two other shaft drive Hondas with nothing like this. However I did read a post that the fuel injectors shut off during decelleration and it can amplify the lash. My other bikes were carburated. I will try leaving the choke on to keep some gas flowing and see if that is the culprat.

[Stan Walker]

It's more than just a little noise of slight clunk. It's a pretty violent hickup and it doesn't do it all the time

 

It shouldn't do that. Perhaps have a more "BMW" experienced rider check it out to see if it is a real problem.

 

Lot's of 1100 riders read on the internet that a "0=0" procedure would make there bike "better". And, in some cases it was true. BUT, only if you did it correctly. Many tried, and most finally suceeded, but some did not and some strange problems are the results. The transition from idle to slightly off idle can be affected by how the TPS is adjusted. Also a good throttle body sync can help smooth it out.

 

But, shifting technique is important too, and that will only come with practice on this bike.

 

You didn't say anything about what gears this happens in, what rpm were you shifting at, etc. A little more info would be beneficial to providing a little better answer.

 

At 91,000 miles my 1150 shifts nicely, no big clunks, no false neutrals, as long as I don't get sloppy. About as good as BMW tranny's ever get.

 

Stan

[carquestman1]

Well, it does it in any gear or RPM range. It doesn't do it right off idle though and thats what bothers me. I went riding today up to Mt St Helens. Lots of up and down and twistys. If I left the choke on and it wouldn't do it, but it also wouldn't slow on compression. Thats what makes it happen. While slowing on compression I can fell a little jerk but not as soon as it goes to compression but after it has already began to slow. And when I get back in the throttle it doesn't do it right away either instead it waits five to seven seconds while under power and then hickups. It almost feels like the whole transmission may be moving a little like you would feel with bad mounts. I really don't think it is a drivabilty problem and it shifts smoothly into every gear. I am leaning towards u-joint or CV problem (I don't know if it has a ujoint or a cv joint) or maybe even a final drive issue. I've put 2000 miles on the bike since I got it and it hasn't got any worse but it does do it everytime on hard compresson and acceleration so I am going to keep asking around and possibly take it to the dealer which is two hours away. Any other suggestions would be greatly apprieciated.

[Stan Walker]

And when I get back in the throttle it doesn't do it right away either instead it waits five to seven seconds while under power and then hickups.

 

Dosn't sound like drive train lash, sounds more like bad tranny dogs. That has been an issue for some bikes. I would get it checked and if that's what it is all I can say is ouch.... not cheap, but not something that has to be fixed today either. Ship the tranny off to Bruno over the winter and it will come back better than new according to all reports.

 

Maybe some of the smarter guys will speak up, I've had no experience with tranny problems, yet.

 

Stan