1996 R850R hesitation as you roll on the throttle

[kmkahuna]

Although I've read a lot of posts about the legendary hesistation issue with these bikes and the 1100, but I haven't come across anything that seems to address the two issues I have. If anyone can help, I'd appreciate it!

1996 R850R, salvaged bike, 2 brothers exhaust with a power commander installed by former owner. The rest of the bike is stock.

First issue is a random, intermittent problem; the bike stutters and burbles as you roll on power when you first start it up. Then, after the bike heats up, it is less noticable, but it will still happen slightly on the road, at interstate speed...that hesitation that makes it risky to pass people, etc.
I have since pulled the fuel filter and replaced it, and replaced the air filter. I have been putting Chevron premium in it consistently, and still get the hesistation, but there doesn't seem to be any rhyme/reason for it anymore...I can go 200 miles with nothing, then it starts up again.

Second issue seems to be serious; it is a sharp, immediate hesistation that seems to come from the drive shaft or transmission when under a load. First time it happened I thought I broke something, but now I've gotten used to it. Again, I can't tie the issue to any specific instance, other than I'm accelerating and it is as if the teeth on a gear miss for half a second..

Thanks, everyone!

Kurt K
San Diego, CA

 

[norton]

To answer the second question first it does sound like you have a gear box shift fork issue. Does it feel as though it skips a beat and resumes fine for the particular gear? The typical symptoms are skipping once per gear/shift and not again until you up or down shift. It usually starts in 2nd gear or 3rd gear. Although this is not catastrophic, it will not get better on its own and probably will get worse and it can affect the shift drum. Other signs are a gold metallic sheen in the gearbox oil, this is the shift fork getting ground down. If the gear box oil is chocolate brown then you have a bearing issue and you need to address it immediately.

The cure is replacing the shift forks, and machining the shift dogs.
http://www.largiader.com/tech/oiltrans/

It's difficult to diagnose the throttle issues with the Power Commander and the non-OEM muffler. If you can start at the basics, valve adjustment and TB sync and remove the two items and get a base line, that would be good. If you had a stock bike I would guess that it is a TB sync, but there are just too many unknowns. With the PC on the bike it could be set up too lean.

 

[kmkahuna]

Thanks, Norton

Appreciate the feedback. Your explanation about the shift forks sounds like what's happening to the bike.
I'll start on the basics with the throttle issue now..
Cheers, and thanks again.

 

[kmkahuna]

2003 thread on Techlusion R259

http://forums.bmwmoa.org/showthread.php?t=760

My bust: I have a techlusion R259 on the bike, not a PC. Great thread above that I wanted to post here for my memory, as well as others who might have a the R259 on thier bikes.
Any advice out there on where to get the handy-dandy TB synch tool?

 

[TheRoss]

There is a thread sopmewhere, maybe on ibmwr, that is a pictoral on how to make a carb stick. Or you could buy one through any dealer for something like $80.

I am unfamiliar with your bike model, but the 2 things that came to mind were..... does your bike require you to reset the TPS after the battery is disconnected? If so you might try that. And..... you might try unplugging the Power Commander. You should be able to unplug it and replug the original stuff without removing the thing completely, if the PO kept the original plugs in there. The PC should plug into the injector, the TPC, and should have its own O2 sensor. That was the solution for my Dakar when it stopped running.