R1100rt back firing

[jnslatky]

When I let off the throttle on my R1100rt it back fires, what would cause this. I read that it could be an exhaust pipe leak or is it something else?

[Hoorenga]

I'm not even close to being a mechanic but mine would do it on occasion, especially as I was going down hill and backed off on the throttle. It turned out to be related to the surge problem I was also experiencing. I did the CAT plug removal fix and both the surging and the backfiring went away. Runs great now.

Doug

[Andy VH]

First off, its not back-firing like everyone says it is. It is a lean fuel-air mix popping condition when off-throttle coasting down. The momentum of the bike coasting down actually "pushes" the engine to keep pumping. Because the engine is pumping all this air in, against a closed throttle, it runs lean, and "pops' out the exhaust when it has built up enough fuel in the mix.

Proof of this is, next time you hear the popping on decel, pull in the clutch and the popping will stop immediately. With the clutch pulled in, the bike isn't "pushing" the engine to pump more air than the closed throttle can provide fuel to balance.

Its done this way to produce low emissions, and all the popping does no harm at all to the engine. But a way to solve the popping is to add a bit more fuel to the closed throttle mix. However, on most of today's bikes that means spending a bunch of bucks on expensive fuel/air mix modifications. On your bike however, you might be able to use a different color-coded CAT-Code plug (relay) in the electrical panel, which will "fatten" up the fuel mix just a bit. The service manager at your dealer may be able to tell you which inexpensive (less than $20) CAT-Code plug to use for your vintage R1100. Mine does not even have one. because the very early R1100s did not have one. But the later ones did ok with the PINK plug.

[kgadley01]

What year is your bike? mine is a 99 and the CAT plug in relay is (or was) Yellow. remove it, remove #5 fuse for 10 seconds then replace the fuse only. Ride Happy!!! no backfireing, no surging...

[jnslatky]

My bike is a 98, so I am replacing the cat plug relay in the fuse and electrical box. The dealer will let me know what color I should replace it with. If I am understanding you correctly. Hope this fixes my surging problem also.

Thanks alot for your help, Jim