Carb woes

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davephipps
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Carb woes

Post by davephipps »

OK, I just replaced my ripped diapragm and am trying to set up my carbs. I've been foloowing the factorypro site and this one http://www.iwt.com.au/mikunicarb.htm
Everything works fine except for 1/8 to 1/4 throttle openings. the bike stutters and loses power when taking off.
107.5 main
Flots set at 22 mm from carb body
needle clip on 2nd from top.
fuel/air screw
2 turns way lean surges and stutters rough idle
2.5 turns but less surging. Need 1/2 throttle to get going( 4k RPM)
3 no surging but still not idling or taking off well
3.5 almost dies off the line. Smooth idle
4 can barely get the bike going. Smooth idle.
BTW these are franken carbs. Factory pro springs and needles with stock jets.
Trying to get this working without spending money. Wi9fe is leary about me and bike parts :whistle
FZR600 1992
CB550F 1974
GL1000 1978
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Luke-a-Tron
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Re: Carb woes

Post by Luke-a-Tron »

I think the taper of the needle and the stock jets are going to be a problem. If your exhaust and intake are stock you're probably going to have a hard time in the range where the needle first starts moving. That's probably right about the beginning of the power band so like 4k to 6k. Is that where it's stumbling?
davephipps
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Re: Carb woes

Post by davephipps »

Nope it's in the 1k to 3k range at 1/8 to 1/4 throttle opening. From what I've read that's the slow jet and mixture screw range.
At 4k it turns back into a screamer :thumbsup: that's usually 1/2 throttle opening.
FZR600 1992
CB550F 1974
GL1000 1978
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ragedigital
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Re: Carb woes

Post by ragedigital »

Why do you have the jet needle at #2? I would set that back to #3 or #4.

Are you having problems at other throttle areas when you do that?
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davephipps
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Re: Carb woes

Post by davephipps »

I seem to be running too rich whem I go to position #3. At least that's what my fouled plugs say..
I'm thinking it might be time for a good carb cleaning. Even with everything set lean the plugs are fouling.
I'm going to clean them this weekend and try again. I'll post an update this weekend.

Forgot to mention I'm running stock air filter and a D&D full system.
FZR600 1992
CB550F 1974
GL1000 1978
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ragedigital
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Re: Carb woes

Post by ragedigital »

Were you just pulling the plugs after iding or did you do a "plug chop"?

A "plug chop" is when you run the bike at a certain throttle position or when you feel a stutter or problem, hold that throttle positon, pull in the clutch quickly and shut off the bike.

If you don't do it this way, then it doesn't really matter too much what your plugs look like. It would probably just mean tht you're rich at idle or no throttle.
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davephipps
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Re: Carb woes

Post by davephipps »

OK, I dismantled the cabs and cleaned every inch with carb cleaner and compressed air. Also, just to be on the safe side I gave the battery a fresh charge, changed air filter, and installed new plugs. It's running at low RPMS now , with just a slight hesitation. I'l try dialing in the carbs a bit more tomorrow.
FZR600 1992
CB550F 1974
GL1000 1978
davephipps
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Joined: Mon May 12, 2008 10:50 am
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Re: Carb woes

Post by davephipps »

Could the people out there running Factory pro setups tell me what thier float height settings are.
Also what is the stock setting?
I'm looking for a good startting point for the carb dialing in.
FZR600 1992
CB550F 1974
GL1000 1978
Lil Freek
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Re: Carb woes

Post by Lil Freek »

Hmm... did you ever get this figured out?

I'm having the same problem with mine... lots of hesitation under 4000rpm, even after having the carbs jetted and re-inspected.
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