carb setup help

[mhewitt]

Ok so I haven't had much time to ride lately but I finally got my new motor broken in, now it was running a little lean so I went up to a 45 pilot jet a 178 main and on the third clip on the needle. Seems to run pretty good but when you hold it at half throttle you can hear some popping in the exhaust, is this still signs of a lean condition? Should I bump it up to 180 main or is there some other way to know whats causing this?

[mhewitt]

I've heard about wot shutdowns or something but not real clear on what to do

[chronicsmoke]

Year, Carb, Elevation?

[mhewitt]

07 , not sure of elevation but I'm n eastern Nc pretty close to the coast so I would say around sea level. Oem carb with hrc needle and leak jet and screw turned 2 times out. Acc pump set to hrc specs. Motor is stroked n bored to 497cc's using hrc full exhaust no airbox lid. Uni filter. Crf head (big valve) wit hotcams stage 2. Stock comp piston.

[DnB_racing]

you might want to play with your clip location some, but taper has a bigger effect on half throttle then clip position

the hrc needle has kinda a small taper for a big bore, I would think more of around 2 3/4 to a 3 degree taper would suit the way your motor is setup better then the hrc, which I belive is under a 2 degree taper

[flint250trx]

i just did mine with a hrc needle on the 3rd clip stock piolit jet and a 185 main jet. fuel screw 2 1/2 turns out.

good luck

[mhewitt]

Flint, whats your engine setup?

[flint250trx]

stage 2 cam stock piston, full nmotions exhaust, knn fliter with no lid, running hrc needle stock piolit, 185 main 2.5 turns out on fuel screw. runs like a top

[mhewitt]

ok so i pulled the spark plug out to check it and from where ive been riding under half throttle every time i ride the plug was pitch black with smut so im thinkin the pilot is a lil rich but the top half of the throttle is lean so i went down one position on the needle and put stock pilot jet back in thinkin it would balance out. only rode it once tonight with this setup but seemed better on the top side but now lean on the bottom too. would pop on decel now no matter what the throttle position and popping and breaking up at full throttle in high gears. should i move it one more position down on needle, or move it back up one and put the 145 pilot back in but go up from 178 to 180 main?

[DnB_racing]

dont do more then one adjustment at a time, get your WOT set,then try air fuel screw, see what that does for the the decel popping, by adjusting the a/f it will tell you what to do with the pilot,the needle jet is more of a half throttle circuit,

I kinda think you need a different taper then the HRC, but with the right jets and adjustments, you might get it close enough

Take one step at a time!! it sounds like your over whelming yourself with all the circuits at the same time.Ive done the same thing many times

step back and just start eliminating one throttle position at a time

[Ruf Racing]

Originally posted by DnB_racing
Take one step at a time!! Step back and just start eliminating one throttle position at a time

^^ Agreed ^^ :macho

[mhewitt]

ok ive been workin on it and everything is runnin nice except for full throttle. so i have now gone from a 178,180,182,185, and now am on a 188 i just installed today and at full throttle it still breaks up and feels like im hitting a rev limiter. i can back off to 3/4 throttle and it clears right up. could it really be that much fuel needed? i woulda thought by 185 i woulda been good but thats not the case. am i missing something?

[DnB_racing]

Originally posted by mhewitt
ok ive been workin on it and everything is runnin nice except for full throttle. so i have now gone from a 178,180,182,185, and now am on a 188 i just installed today and at full throttle it still breaks up and feels like im hitting a rev limiter. i can back off to 3/4 throttle and it clears right up. could it really be that much fuel needed? i woulda thought by 185 i woulda been good but thats not the case. am i missing something? if its 4 stroking like hitting a false rev limit usually means too rich,
a lean condition is more like its breaking up, and popping