Bike Problems - Carb or exhaust popping out of 1 cylinder

[Mikesblackbird]

I just got back from an 1800 mile trip and halfway into the trip my 97 carbed bird would pop on the decel. It sounded like it came from the carb or the right tailpipe but I am not sure. While cruising in 6th at 85-90 mph, it ran great but as soon as I let off the throttle I would get a few pops, then a few more when accelerating again. Beyond that accelerating and cruising is fine.

I changed the plugs about 2500 miles ago and added a K&N filter and up until this point the bike has been running great. On the ride I picked up a can of carb/injector cleaner and added it to the gas, but no change.

A mechanic that I was riding was thought possibly a stuck float. Any help would be appreciated.

[redxxrdr]

Backfires can come from air leaking into the exhaust. Loose joint at a slip on, or a cracked or loose manifold could cause it. Nice, hot, unburned gas, just looking for some oxygen.

If it runs good, I would check for leaks first. 2500 miles should be enough for you to pull the plugs and see if one cylinder is running rich.

[Mikesblackbird]

Backfires can come from air leaking into the exhaust. Loose joint at a slip on, or a cracked or loose manifold could cause it. Nice, hot, unburned gas, just looking for some oxygen.

If it runs good, I would check for leaks first. 2500 miles should be enough for you to pull the plugs and see if one cylinder is running rich.

Ok. I pulled the plugs and they look fine. The exhaust is tight. Since I have the K&N should I add a Stage 1 Dynojet kit?

Thanks for the help.

[TURK]

Do you have stock exhaust of aftermarket if the exhaust is not stock you could have a lean pop and you should rejet.I have a dyno jet kit in mine and love it

ps stop riding your mechanic its not nice

[Graham]

[attachmentid=1240] :icon_clap: I agree with Redxxrdr with exhaust leaks' otherwise check the aircleaner is fitted properly without any leaks.

Also check all carb balance or injection mixtures are properly adjusted (not really sure about FI models).

My FI 2003 model ran rough and had a lumpy idle and a new CCT resolved 1/2 dozen issues.

[Mikesblackbird]

Do you have stock exhaust of aftermarket if the exhaust is not stock you could have a lean pop and you should rejet.I have a dyno jet kit in mine and love it

ps stop riding your mechanic its not nice

I have a stock exhaust. I guess I need to check for intake leaks and synch the carbs.

Err...that should have been the mechanic I was riding with....where is the grammar checker on this site???

Thanks.

[attachmentid=1240] :icon_clap: I agree with Redxxrdr with exhaust leaks' otherwise check the aircleaner is fitted properly without any leaks.

Also check all carb balance or injection mixtures are properly adjusted (not really sure about FI models).

My FI 2003 model ran rough and had a lumpy idle and a new CCT resolved 1/2 dozen issues.

I do notice a little sound coming from the engine and think that it is the clutch basket making noise. I think I'll change the CCT as well. Thanks.

[Pete in PA]

PAIR valve malfunction? Get the block off kit.

Also richen up the pilot screws by backing them out to 3 turns.

[Mikesblackbird]

PAIR valve malfunction? Get the block off kit.

Also richen up the pilot screws by backing them out to 3 turns.

Pete - thanks for the tip. I have the Haynes manual and see the section on the PAIR and reed valve system. Where do I get the block off kit, or is this something you just fab on your own to disconnect and plug it?

Also, I read somewhere on this forum that you drilled your stock pipes. If so, how did you do it and did that require turning the pilot screws out to 3?

Thanks.

[Red J]

Pete - thanks for the tip. I have the Haynes manual and see the section on the PAIR and reed valve system. Where do I get the block off kit, or is this something you just fab on your own to disconnect and plug it?

Either. You can remove the PAIR system by just capping off the airbox nipple and the two reed covers in the valve cover. Or you can spend 40 USD on my kit that replaces the reed covers with an anodized aluminum plate and the cap for the airbox. Both do the same job, one's a little cleaner for top end (plugs, valve adjust) servicing. PM me if you want a kit, I have them in stock.

[Pete in PA]

PAIR valve malfunction? Get the block off kit.

Also richen up the pilot screws by backing them out to 3 turns.

Pete - thanks for the tip. I have the Haynes manual and see the section on the PAIR and reed valve system. Where do I get the block off kit, or is this something you just fab on your own to disconnect and plug it?

Also, I read somewhere on this forum that you drilled your stock pipes. If so, how did you do it and did that require turning the pilot screws out to 3?

Thanks.

I just installed Red J's block off plates, Nice. :icon_clap: well worth the $40. I had mine blocked with silicone for years.

I didn't drill my pipes so much as punch holes through them. I had a threaded piece of stock I sharpened and hammered several holes in the inner baffle (about a foot into the outlet use a flashlight and you'll see where I mean) Punch a few holes and listen and tune to taste remembering that you can't go back.

The 3 turns out on the pilot screws can be done to a box stock XX. The factory has it real lean on the pilot circuit to pass emissions. Will also improve starting,idleing, and throttle response.

[Mikesblackbird]

PAIR valve malfunction? Get the block off kit.

Also richen up the pilot screws by backing them out to 3 turns.

Pete - thanks for the tip. I have the Haynes manual and see the section on the PAIR and reed valve system. Where do I get the block off kit, or is this something you just fab on your own to disconnect and plug it?

Also, I read somewhere on this forum that you drilled your stock pipes. If so, how did you do it and did that require turning the pilot screws out to 3?

Thanks.

I just installed Red J's block off plates, Nice. :icon_clap: well worth the $40. I had mine blocked with silicone for years.

I didn't drill my pipes so much as punch holes through them. I had a threaded piece of stock I sharpened and hammered several holes in the inner baffle (about a foot into the outlet use a flashlight and you'll see where I mean) Punch a few holes and listen and tune to taste remembering that you can't go back.

The 3 turns out on the pilot screws can be done to a box stock XX. The factory has it real lean on the pilot circuit to pass emissions. Will also improve starting,idleing, and throttle response.

PM forthcoming to Red J.

Thanks Pete. I assume that your mileage did not suffer too severely after the above mod and that the performance improved.

[Guest rockmeupto125]

It was noted on another site, so I figured someone here would advance this. No one has, so I'll reiterate.

Put the stock air filter back in. You made a modification, and then it started to not work right. Go back to safe ground. You know how it ran with the stock air filter.

Don't continue to build on an off-level foundation by adding a jetting kit. You can't fix problems by hopping things up. Go back to baseline, and spend the time to either remove the problem, or understand it thoroughly.

[Red J]

I read thru this thread again, and I must agree with Joe.

I'd put the stock filter back on and see how it does.

Still there, I'd pull the carbs and clean them out.

Still there, I'm not sure what I'd do.

If it's popping out of the carb, then I'd damn sure get that rectified.

A stock bike shouldn't need pair system disabled, other than to clean up the top end or if the user wants to dynotune with a wideband O2 to see if the bike has lean spots. You may want one, and that's fine, but you shouldn't have a NEED for one.

I'll still sell you a kit if you want it, but I think there may be some other issue at hand here.

J.

[Mikesblackbird]

I read thru this thread again, and I must agree with Joe.

I'd put the stock filter back on and see how it does.

Still there, I'd pull the carbs and clean them out.

Still there, I'm not sure what I'd do.

If it's popping out of the carb, then I'd damn sure get that rectified.

A stock bike shouldn't need pair system disabled, other than to clean up the top end or if the user wants to dynotune with a wideband O2 to see if the bike has lean spots. You may want one, and that's fine, but you shouldn't have a NEED for one.

I'll still sell you a kit if you want it, but I think there may be some other issue at hand here.

J.

Thanks for the great advice. I just went outside to clean the bike up after the trip and I started the engine and warmed it up. Sounds as though there is a "hissing"/"sucking" sound at idle. I know it wasn't there before the trip. The bike ran great after putting in the K&N and changing the plugs in late winter/early spring. Maybe something came loose at the higher speeds/rpms on the way down. I do remember the bike running a little rough a few hours into the trip, and at a lower rpm and I thought it was the heat so I increased the idle. Since I ride with earplugs I never noticed it. I guess I'll tear into it in the next few days and see if a vacuum hose is loose, cracked, etc.

I'll get back to you with the results. I appreciate the advice.

Mike

[TechnoGecko]

I read thru this thread again, and I must agree with Joe.

I'd put the stock filter back on and see how it does.

Still there, I'd pull the carbs and clean them out.

Still there, I'm not sure what I'd do.

If it's popping out of the carb, then I'd damn sure get that rectified.

A stock bike shouldn't need pair system disabled, other than to clean up the top end or if the user wants to dynotune with a wideband O2 to see if the bike has lean spots. You may want one, and that's fine, but you shouldn't have a NEED for one.

I'll still sell you a kit if you want it, but I think there may be some other issue at hand here.

J.

Thanks for the great advice. I just went outside to clean the bike up after the trip and I started the engine and warmed it up. Sounds as though there is a "hissing"/"sucking" sound at idle. I know it wasn't there before the trip. The bike ran great after putting in the K&N and changing the plugs in late winter/early spring. Maybe something came loose at the higher speeds/rpms on the way down. I do remember the bike running a little rough a few hours into the trip, and at a lower rpm and I thought it was the heat so I increased the idle. Since I ride with earplugs I never noticed it. I guess I'll tear into it in the next few days and see if a vacuum hose is loose, cracked, etc.

I'll get back to you with the results. I appreciate the advice.

Mike

Vac hose, exahust leak, carb leak, or a PAIR system leak. I dont have a PAIR system on my bike, so I can't say for sure, but if I remember correctly PAIR pulses air to help with emissions and could cause that sound as well.