FZRSupport: the FZROnline Archive

Ok, I just synchronized my carbs on my 91 FZR 600. They are even using the DIY tool in the wiki. Now the issue is it revs at 4k and will not idle down. I have messed with the idle adjustment knob with no luck. I can get it to rev higher, but not lower.

I have a V&H full exhaust. Stock air box, stock filter. I have the air/fuel mixture screws at 3 turns out. I am not 100% sure what jets or needles I have.

Any ideas?

Joe



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Shot in the dark but this might work. While it's idling, turn the center screw(in between carbs 2&3) counter clockwise. You should see the idle begin to drop. Give it a blip a few times to purposely unsettle it and see if all that makes a difference.

Hope that helps

I will try that. I am going to run through the sync process again today. Just waiting to give the neighbors time to wake up.

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throttle cable(s) sticky or too tight .......................

I don't think its the cables. I backed the center screw off some, and its back to 1300-1500. I also turned the air/fuel mixture screws back .5 of a turn. I am going to run it down the road in a while. In the mean time, I split my fuel line open off the bottom of the tank. Temp fix with clear vinyl tube.

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Ok, ride done. The high rev problem is fixed. Now there is a bucking problem on take off. I have to slip the clutch to keep it from bucking. Also, at cruising speed (55-65 mph) it has a stumble. Almost like its starving for fuel, but clears up if I open the throttle up. Today was my last chance to ride until the weekend. I plan to tear the carbs apart and make notes on the Jet sizes and needle clips. Anyone else have this issue?

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I can't tell you rpms because my tach needle dances all over the place. I was in 6th gear at 55 to 65 mph while it was happening.

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jsph.mitch wrote:Ok, ride done. The high rev problem is fixed. Now there is a bucking problem on take off. I have to slip the clutch to keep it from bucking. Also, at cruising speed (55-65 mph) it has a stumble. Almost like its starving for fuel, but clears up if I open the throttle up. Today was my last chance to ride until the weekend. I plan to tear the carbs apart and make notes on the Jet sizes and needle clips. Anyone else have this issue?

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JM,
There is not an FZR rider who has not met this problem @some point

Clean the carbs, jet sizes not likely to be problem unless you bought it from some guy on a beach & moved it to the rockies.

then you have to learn to use the "choke" @start up and get the bike quite warm, these bikes hate cold engines.

It's doing all of this throughout a 30-45 minute ride. I am sure its warmed up by then. I am going to pull the carbs completely apart this weekend. Give them a good bath, and note all the jet sizes and needle clips.

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Ok, I was able to get my carbs apart today. My Jet sizes are Main 118, Starter Jet 52.5 I have a Dynojet Needle. The clips are set 3 from the top. The 2 Holes on the diaphragm were not drilled. I took care of that. The Air/fuel screws are 2.5 turns.

Put everything back together. Then bench synced the carbs. I put the bike together, and ran it down the road. It runs rough in the 1/8 - 1/4 throttle. WOT has no issues.

Any ideas?

jsph.mitch wrote:Ok, I was able to get my carbs apart today. My Jet sizes are Main 118, Starter Jet 52.5 I have a Dynojet Needle. The clips are set 3 from the top. The 2 Holes on the diaphragm were not drilled. I took care of that. The Air/fuel screws are 2.5 turns.

Put everything back together. Then bench synced the carbs. I put the bike together, and ran it down the road. It runs rough in the 1/8 - 1/4 throttle. WOT has no issues.

Any ideas?

JM,
yes you have to finish the job.

Bench synching only establishes a base line to work with it DOES NOT take into account, wear OR more importantly manufacturing variances in the carbs.

see:-

viewtopic.php?f=8&t=8422

my last post in that thread ref to poor jetting standards.

To get the engine running in a better fashion it is required you synch the carbs interaction with each other dynamically.

You will require a set of Synch stix or gauges OR if you do not want to buy a set the WIKI has an article on how to make your own tool for about 5 bucks and how to use it.

Once you have done that you will have a bike that runs better and any minor glitches in the rev range can be PROPERLY diagnosed (as opposed to guess work at this stage) and you can go forward.

Time to learn to welcome to FZR tuning

Uh...what he said

It took it out today. She runs good now. Bogs just a little around 50 mph. I am not sure of the rpm. That's my next job.

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Well, back to having problems. I tore the carbs apart, again. When I took the floats out, the valve needle on number 4 carb is deteriorated. It's allowing fuel to just pour into the carb. Does anyone know a cheap place to pick the float needles up?

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[quote="jsph.mitch". Does anyone know a cheap place to pick the float needles up?

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JM,
talk to Allen at The motorcycle General store on the Southern Main Road in Curepe he carries a good stock of carb parts.