Question on Backfiring?

[grumpyone]

Have a question on backfiring on our r1100r 1996; We just replaced the cable on the throttle (single cable) and we cleaned out the throttle bodies with cleaner and then twin max sync. on the throttle bodies.
Everything reads good on th twin max, and idol is at @ 1050 so to my guesstimate things are good ; But when you are idoling the bike on the centerstand and flip the throttle up to about 35 or 45 and let off it backfires. Dont know if this would be normal as the motion is definately not normal to do or if maybe it is a indication something is out of whack? It does not do it all the time just part of the time and only when you throttle it hard and let off real fast. I can find nothing else wrong with the machine that would cause this freeke thing??
One other thing on the BBS the o ring?? can you get the O ring or do you have to order the screw to get new orings??? I find none on the fisch and the BMW dealer in Denver showed nothing???
Thanks for the info
Jim and Esther

[aaaaaa]

Does it do it while you're riding also? Are the TB's clamped securely to the intake? Are the big brass screws clean. Are the o rings good?
robert

[grumpyone]

Have not been able to notice it riding it just under no load on the shop floor.
The throttle bodies are tight and the BBS s are cleaned but the Orings are questinable that are on the BBS. Are the prone to effect the running or just there to keep the screw from moving on its own?? Can you get just the O ring on the BBS somewhere? We can not find them except as a screw with an o ring.??
Jim and Esther

[ArthurKnowles]

You can buy the O-rings from Bing for about $2 each. Only place I found them.

As for the backfiring, I don't recall mine doing that at idle, but it will under load if I do not return the throttle to a completely closed position. As far as I know all R1100s will do this. It's easy to hold a bit of throttle instead of completely closing it. It is also posible that the throttle may be sticking or misadjusted and not returning to a completely closed position.

Just a thought for you, but if your throttle is not adjusted properly, your TPS may provide an incorrect reading and couls cause the backfiring to occur as well.

I suppose it is also possible that an improper state of tune or components could cause it as well. You know, the basics like air filter (clogged), spark plugs, valves, CCP (wrong or missing), or anything that could affect the fuel air mixture.

If it were me, I'd start with the basics (like the throttle cable/TPS) and hope someone with more experiance could provide more specific information to help. More information from you may help the experts help you.

[grumpyone]

Thanks we will order some tomorrow morning. I been going crazy trying to figure them out. I have an o ring kit but not finding the right one in there.
The backfire I think sounds like what you have as common problem and not to be worried about. I only have it once in a while doing the flip of the throttle and all other things show things are good like the twin max. Wont worrie about that. Cant fix it if it ant broke. :scratch
Thanks again for the info on Bing.
Jim and Esther

[ArthurKnowles]

If it only happens occasionally then it is probably not something to worry about. New o rings couldn't hurt either. I found that my o ring kit didn't have the right ones either. Luckily my originals were in good condition.