bogging and backfiring

[Anonymous]

bogging and backfiring

Ok guys, so I installed new "O" rings on the induction tubes (the old ones were flat and there was gas under them), and got tighter clamps on em, but the bogging and backfiring persists. Still no idea whats causing the problem. Anyone got any ideas?

Chris

[frosty5011]

Chris,

Don't really know what to tell you. Any idea when carbs were cleaned last? Are you running bike with or without fuel filter?........Doesn't take much to start clogging jets. You said you checked floats.......so, we know that they're not stuck, but how about the float heighth? The backfiring during the letting go of the gas could also be due to leak in the exhaust system (perhaps where the pipes attach to the headers).

If it were my bike, I would probably give the carbs a good cleaning. While I had them off, I would have checked/replaced the o-rings under manifold (which you already did). Then during reassembly/reattachment, I would ensure good fuel flow to the carbs (making sure that there are no crimped fuel lines and/or vent lines). Then, after running - I'd check plug colors to see whether mixture screws need any adjustment. If all that didn't work, then I'd start looking at the electrical system.

Wishing you the best of luck, hopefully someone else will have more insight.

[earlfor]

Re: bogging and backfiring

What color is the center ceramic on your spark plugs ? If you are running lean, it will be very light, if rich, it will be much darker. Which is it?
When you are riding the bike, what rpm does this symptom start at and what rpm does it end at? Do you have the stock aircleaner box (with lid) and element in the box? Do you have stock exhaust pipes? Do you know what your idle air screw and fuel pilot screws are set to?

Now that we have the "O" ring question solved (the first step) I need to know what the situation is with the air intakes on both sides of the carbs (the airbox and exhaust system) Thats why my further questions. Everything works together as a system and you cannot step into the middle without knowing what is happening at both ends.

Earl

Ok guys, so I installed new "O" rings on the induction tubes (the old ones were flat and there was gas under them), and got tighter clamps on em, but the bogging and backfiring persists. Still no idea whats causing the problem. Anyone got any ideas?

Chris

[Anonymous]

bogging and backfiring

The carbs were cleaned about 2 weeks ago, and its behavior hasn't changed since then. No fuel filter (just the one in the tank). Dunno about the float height, I have no specs as far as that goes, but there is no fuel coming out of the overflow tubes. The exhaust is pretty blown out, each pipe has a hole near the end, the manifold side seems fine, bolts are nice and tight. Mixture screws are at factory setting, and fuel is flowing to the carbs (petcock is operating properly). Spark plugs are very light brown. The bike idles fine at 1k RPM, any additional throttle makes it bog down. I quick flick of the throttle then letting go will increase the RPM's to about 1750-2000 RPM, if I hit the throttle right when it peaks at 1750-2000 RPM, it will rev up like normal. The bog is much worse when the engine is under load (in gear). The air box is stock but has no filter. I have put foam in there to see if it helped but had no effect. As I said before, the bike runs great once I get it opened up but low RPM's are just bogging. Thanks for any help fellas.

[frosty5011]

Chris,

Again, I'm just guessing here, but trying to get a GS engine running perfect without a proper air filter can be a very tricky affair.

[earlfor]

Re: bogging and backfiring

Its likely having no air filter is your problem and you need the restriction.
To check this theory, try taking some duct tape and taping over 1/2 of the opening on your airbox and take a test ride. Let me know if this makes any difference.

Earl

The air box is stock but has no filter. I have put foam in there to see if it helped but had no effect. As I said before, the bike runs great once I get it opened up but low RPM's are just bogging. Thanks for any help fellas.