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Discussion Starter #1
UPDATE:
Okay, I've had very little time to play with this, but while I was sitting in the garage smoking a cigarrette, I noteced that one of the O-Rings on my float assembly was bad, on all the carbs. The problem is I don't know what it feeds. The O-Ring on the gas feed is fine, but there's another tube heading up towards the engine side of the carbs. Not only is the O-Ring bad on this, but it feeds into the float assembly to a small hole that would normally be submerged in gasoline, and that hole is clogged. Can anybody tell me what this is all about, and how it might affect performance?

OLD MESSAGE:
Hi guys,

Just joined - very cool forum. I just upgraded from an '86 VFR750F to an '89 GSXR 750. The bike had been sitting for 5 years. I cleaned the carbs, and got it on the road. It ran great for a couple of weeks, then it started doing some strange pulsing. I found that the plugs were fouled. I cleaned them and adjusted the pilot screws to run it a little bit lean at idle. It ran great for a day and then it started running rough again, with a little bit of pulsing, and it wouldn't idle. The plugs were fouled again. I cleaned them, andit improved a little bit, but not much. I've played with the pilot screws and they're making very little difference. I've run it at idle for a while, with clean plugs and the pilot screws leaned full out, and it still fouls the plugs. It's got a K&N pipe on it. I've checked all the electronics, and they pass with flying colors. It's got plenty of compression, etc. It's only got 5000 miles on it and the engine is strong - I think it has to be a carburetor problem.

Any thoughts would be appreciated. I've taken it to a mechanic, and he's just as confused as me.

[ 10-03-2002, 07:23 PM: Message edited by: boxcar99 ]
 

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Tough call without seeing the plugs. You need to be sure about what is fouling them. Sooty black or grey crap is from too much fuel, and shiny black is from oil. If the idle screws don't make much difference then the floats may need adjustment. If the fuel level in the bowl is too high, the idle screw won't be able to lean out the mixture enough. You should be able to lean out the engine enough with the idle mixture scres to make it stall.
 

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If at-all possible, test the ignition coils by replacing them with a "known-good" set. My `89 1100 had the *exact* same symptoms and I nearly had a psychotic-break before I finally found that the ignition coils/wires/plugs were bad. Mine tested good on winding resistance, but as soon as I replaced the coils, the problems all went away... and I hadda restore the carbs back to the original settings.
 

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Did you check your tank for rust? It could cause your carbs to act up.

 

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I agree check you coils, but it sounds like a carb problem check for varnish due to its long sit. Clean the carbs, completely drain and change the fuel in the tank. While the tank is empty pull the petcock and check the screen. Change the filters if it has any. Change the air fliter (to a K&N prefered) Pull the float bowls (all of them do not just check one) and check for sedament and grit. Make sure the float shut off valves work while the bowls are off.
Bones
 

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Discussion Starter #6
Thank you all very much. I've been working too much, so I haven't torn back into them, but I will try all of these suggestions. My buddy has a frankenstein gsxr 750 stored at my house, so I'll yank his coils, maybe his carbs too, and try them. Then I'll check the floats and needles.

Thanks for your time.
Corey
 
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