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Old 11-23-2012   #1
icantdrive55
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Fueling help on CBR600F2

Any old racers/tuners around who might be willing to give me some advice about tuning the carbs on the CBR600? Go to the thread here:

http://www.assfaultjunkies.com/showt...-from-the-dead!!!

Long story short, I've been fiddling with the pilot screw settings thinking that with the aftermarket exhaust, the engine was running a little lean, but based on the popping/farting on closed-throttle deceleration--and the sniff test as well--I'm convinced that at least at low RPM/part throttle, it's too rich. Then as the revs go up, there are a several flat spots at different throttle openings plus the engine feels pretty 'soft' above 9K-10K RPM to redline, and I'd guess that means maybe too lean at WFO, but don't know for sure.

What I'm looking for is any resources to tap for tuning info. I'm not trying to track this thing, so NOT looking for max HP, but would like it to run cleanly around town and show a little more guts on the top end. Still running the stock CV carbs--have no idea if the original owner did any tuning as far as different jets/needles when he swapped the exhaust. I did install new rebuild kits all around, although I didn't replace the slide diaphragms as they appeared in good shape.

Thx for any help!!! Ciao--Bubba
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Old 11-24-2012   #2
Dave Bannister
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Re: Fueling help on CBR600F2

Shim the needles with #5 washers to help mid range

Go up a size or 2 with jetting.... everything was lean in general from the factory
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Old 11-24-2012   #3
Dave Bannister
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Or you could just buy a factory pro or dyno jet kits.. I think usually without changing exhaust they suggest stage 1 kit
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Old 11-24-2012   #4
icantdrive55
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Re: Fueling help on CBR600F2

Dave: Thx for the suggestion. I looked at the DJ kits. Dems is some pricey little pieces!
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Old 11-24-2012   #5
Dave Bannister
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I have an assortment of jets and needles that I just play around with until I find what I want personally but when pulling a bank of 4 carbs I usually want to just get it right and forget about it!

Though if you spring for a set of re-useable air cleaners than pulling and installing those carbs get real easy
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Old 11-27-2012   #6
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Re: Fueling help on CBR600F2

I ran mine mostly witha stock pipe and a K&N in the stock airbox. Factory needles one clip lean. It ran great!

Popping on decel is always lean. With a pipe, up one size on the pilots is needed. You can play with the needles after that. Factory needles are supposed to be stock taper, but the have grooves to move the height, unlike the fixed position on the stock needles.

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Old 11-27-2012   #7
icantdrive55
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Re: Fueling help on CBR600F2

Hmmm, my memory isn't that great anymore, but I don't remember the needles being adjustable or having clips for raising/lowering the needle height. What are you referring to when you mention 'factory' vs 'stock' needles?

As far as mixture goes, I would typically guess the fueling to be lean with aftermarket pipes (this is a whole system with headers/can and almost no baffling) but my nose says rich when idling, and friend who followed me says it smelled way rich from behind. Haven't pulled the plugs yet, but I'm guessing I'm gonna have to do some more dis-assembly to figure things out.
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Old 11-27-2012   #8
Dave Bannister
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Re: Fueling help on CBR600F2

Quote:
Originally Posted by icantdrive55 View Post
Hmmm, my memory isn't that great anymore, but I don't remember the needles being adjustable or having clips for raising/lowering the needle height. What are you referring to when you mention 'factory' vs 'stock' needles?

As far as mixture goes, I would typically guess the fueling to be lean with aftermarket pipes (this is a whole system with headers/can and almost no baffling) but my nose says rich when idling, and friend who followed me says it smelled way rich from behind. Haven't pulled the plugs yet, but I'm guessing I'm gonna have to do some more dis-assembly to figure things out.
Yes I think he meant the brand "Factory" not to be confused with OEM which I'm thinking he referred to Stock = OEM

The smell of richness you are thinking could just be the smell of a poor tuned bike

FYI
Pete raced a F2 in the endurance series with us and he and his partner got around the track as fast if not faster than the rest running basically a stock bike.
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