Is this carb related??

[71xs1]

I have a 81 with short open pipes and pods. As far as I know carbs are stock. They were cleaned well( soaked and all passages air blown) My issue is the bike backfires at idle and deceleration. It also seems to run out of steam at top end. Was thinking this is because of needing more fuel. Any help would be greatly appreciated!
Thanks in advance

 

[5twins]

Are the carbs re-jetted? They need to be re-jetted to match the mods you have. If you have the stock '81 carbs then they would be the BS34s. These were E.P.A. mandated and set up pretty lean from the factory. If your bike was an earlier model with some of the earlier BS38 carbs, you might get away with some minor mods and not have to re-jet. The E.P.A. wasn't meddling yet with the carb sets on those earlier models. Pretty much any mod to a BS34 equipped bike requires some carb changes.

 

[71xs1]

Not sure if it is early or not. Has little rubber plugs over pilot jets. Bike runs well just backfires and doesn't run out on top end. Thanks for reply

 

[figure8]

I ran a similar set up once upon a time. Look at the carb guide and figure out what carbs you have. Those little black plugs do need to be there, sounds like bs34's. If the jets weren't upped, they need to be.

 

[5twins]

Rubber plugs over the pilots would make the carbs BS34s, probably the originals. Check the jet sizes you have in there now as they may have been switched already (although it doesn't sound like it). No sense buying sizes you may already have. Stock for those carbs is a #42.5 pilot and a #132.5 main. Usual routine for mods like yours is one up on the pilots and 2 or 3 up on the mains. That would be a #45 pilot and 137.5 & 140 mains. Install the 45 pilots and the 137.5 mains, then test. Swap the 140 mains in then test to see if they are better (or worse). There's no exact recipe here. The pilot is usually what works but for the best main, you'll just need to experiment and see.

 

[fredintoon]

Hi 71xs1,
short open pipes and the wrong pods will make the bike a swine to tune.
Shove some kinda baffled muffs on it and check you got unipods, all other pods are worse.
Now check if by any chance the carbs still have the EPA-mandated plugs over the slow running needles.
If so the carbs low speed circuits have never been cleaned from new.

 

[71xs1]

I appreciate all the replies!! Thanks I'm not sure of pilot jet(or whichever jet is under the rubber plugs) but if I remember right when I cleaned the carbs the main was a 135 so I'll check again and get some other jets and put the stock mufflers on and try that. Thanks again!