Lean spot between 6-7000 rpms

[bro.betterley]

Alright my bike runs OK with the y intake in place, but pulls stronger up to 6000rpms without it, then it stumbles and eventualy pulls thru it till redline.

I know the answer is to do a complete kit, and i plan on putting a morley kit in it over the winter (just dont feel like pulling of the carcs when i can ride)

My set up is: Marks 4into2, Stock jets and airbox, K&N airfilter, af 3 turns out, needle shimmed 22 thousands, stock springs ied 3 coils, floats set beteen 16-17 mm

Plugs are a light grey

Any advise, should i try and richen with needles to help the transition between needles and jets, or will that defeat the gain in power i feel in the lower RPMs by removing the y in the first place

 

[dannymax]

Alright my bike runs OK with the y intake in place, but pulls stronger up to 6000rpms without it, then it stumbles and eventualy pulls thru it till redline.

I know the answer is to do a complete kit, and i plan on putting a morley kit in it over the winter (just dont feel like pulling of the carcs when i can ride)

My set up is: Marks 4into2, Stock jets and airbox, K&N airfilter, af 3 turns out, needle shimmed 22 thousands, stock springs ied 3 coils, floats set beteen 16-17 mm

Plugs are a light grey

Any advise, should i try and richen with needles to help the transition between needles and jets, or will that defeat the gain in power i feel in the lower RPMs by removing the y in the first place

I have almost the same set-up, but with unshimmed needles & the 'Y' in place, and the same 6K problem....it isn't noticeable on the road but shows up on the dyno. I think it's a lean issue.

I'm going to shim around .020" - .025" and go up to a 155 main and see what that does.

 

[bro.betterley]

Yea mine ran good needle shimmed Y in place, although i never put it on a dyno, but it pulls noticeably stronger with y removed until just over 6000 rpms

 

[dannymax]

Yea mine ran good needle shimmed Y in place, although i never put it on a dyno, but it pulls noticeably stronger with y removed until just over 6000 rpms

I tried removing the Y and it started breaking up around 4K, it wouldn't run good at all that way.

Did you tie off 3 coils on the springs? Was the difference noticeable?

 

[bro.betterley]

i tied off 3 coils and it made the throtle response better, that and the shim will help your bike, and is probably the difference why mine breaks up at 6 and your at 4000 without "Y"

 

[dannymax]

i tied off 3 coils and it made the throtle response better, that and the shim will help your bike, and is probably the difference why mine breaks up at 6 and your at 4000 without "Y"

Thanks, I'm pulling the rack today for re-jetting, I'll tie off the coils at the same time.

BTW, I lived in Williamsport about a half a million years ago! :hihi:

 

[bro.betterley]

Ive been here for about 10 years

 

[tugla]

dan-o so you think you will increase jets and also add shim on needle? how lean was the bottom end?

 

[dannymax]

dan-o so you think you will increase jets and also add shim on needle? how lean was the bottom end?

Pretty lean Rov, less than 1% on the gauge....whatever that means :confused2:

Maybe I should just re-jet and see what I got, ey?

 

[tugla]

if there was no pop or any issue at the bottom 1000-3000 rpm i might just try a jet chg but your there riding it you will know if a shim will help, you've seen what kind of chg you will get from that. atleast its a fast chg if it has to be done.

 

[tugla]

just a thought, if you had a drill index that you could put the needles into and then slightly emery cloth them all to match and slightly decrease the diameter of them equally and make a nice taper or a step in them could make it richer closer to idle and leave the rest of the profile and let the jet chg take care of the 6-7000 lean area?........ think it will work, i use to make my jets for the hot rods by drilling to what i needed, so why not custom make needle profiles? think we can figure out a good method dan, might be lots of fun seeing what we come up with.

 

[bro.betterley]

Any carb Pro's have some input to my origanal post?

 

[bro.betterley]

tuggla sorry i missed your last post, Im alright in the lower in lean at 6000rpms

 

[tugla]

sounds like jet chg next then eh?

 

[dannymax]

sounds like jet chg next then eh?

Gotta agree with that....I installed some 155's this afternoon and it seems to pull strong straight up to low 8K's.

It may still show slightly on the dyno but I can't feel it in my road tests at all.



I tried removing the Y and she didn't like it at all.

 

[tugla]

glad you got her purring there dan-o. cant wait to get V2 on the dyno, i think i will end up going to a richer jet/leaner needle setting. agian just seat of the pants feel lol

@Bro Butterley, ya for sure id open them up see what you got for jets let us know, think up one number will help ya out, pending on how rich it is already.

 

[bro.betterley]

jets are stock 152

 

[dannymax]

jets are stock 152

155's might do it for you.