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Posted

I ride in Wisconsin, have FMF Gnarly's, K&N pods, +4 timing. I installed 290 mains and it has a very noticable bog at WOT. I went up to 310's and it would backfire at idle and had a worse bog plus backfire at WOT. Am i running too rich. Does backfiring mean a too rich, or too lean condition? I picked up some 270's and 280's, do you think I'm going too lean? Thanks for your thoughts.

Posted

Hey we need to know what your elevation is before we can help.

Also here are my mods

 

Toomey t-5

K&N

LId no snorkel

+4 timing

626 feet above sea level

 

 

NEed ot know all that. THen we can help you.

 

I run 270 mains with a 25 pilot.

 

ALso if u r having bogging problems, i would start wiht the 280's, Its not all about the main jets,

U have to mess wiht the airscrews and needle clip.

 

Heres mine

 

270 mains

25 pilot

air screw - 2 turns out

needle, - dont remember what clip.

Posted

The backfire at idle is caused by a lean condition. Most people run 27.5 pilots in their stock carbs, with FMF pipes. Turn both airscrews back in to 1.5 turns, and see if the backfire problem is taken care of. It might be wise to check everything over for air leaks also, because changing main jets couldn't have caused the lean idle condition, unless something got messed up, like an intake boot, or a gasket.

Posted

my old stocker with similar mods did the same thing-too rich.when u fattened it and it got worse tells u that too.go 280 main-check plug.if its better but crappy-go 270.u gotta listen to the motor and feel what the bike does.theres a thread on here i just read and people say fuck a plug chop-do the ride and feel.i agree-try it.

Posted

well, is it a backfire, or just popping from the exhaust? popping from one side is normal if it's not synced up good, and a little evenly with some pipes.

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