Very high idle
- BarMan
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Very high idle
14 Jun 2007 12:54
ok guys this is what my problem is.... bikes starts with 5000 rpm idle with idle screw all the way out. even with the throttle cable disconnected. already put liquid gasket on the outside and insides of carb boots. with the pods off it what i see is the vacuum diaphrams are sitting down almost all the way and fuel is spitting out around the needle. when i cover the carbs individually with my hand, the idle goes down to 3000 on everyone of them. Please tell me what to look for!! Ask me questions if you need to know anything else
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- wiredgeorge
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Re: Very high idle
15 Jun 2007 05:44
First, I would replace the carb holders... never put goop on the inside as it is likely to be sucked into the engine as it dries and flakes.
Second, take the carbs off. Look at the throttle butterflies. The butterflies MUST all be able to shut completely. Sounds like they are not shutting. Toooooo much air may be getting in when the throttle is shut. If they can completely shut, then the air is getting in some other way. You may have already figured that out since you have attempted to seal your carb holders. Since you have NOW bought new carb holders, the only other thing that can leak that bad is the vacuum plugs or a leak in the emissions hoses connected to the carbs or even the vacuum line to the petcock.
When you CHOKE the carbs by sticking your hand over the intake venturi you are reducing the amount of air getting into the venturis. The excess air is causing the high idle. To recap, it can ONLY be from the throttle butterflies staying ajar slightly (doesn't take much) OR an airleak from the carb holders or vacuum plug areas...
I lean towards the butterflies because usually, if you completely leave one vacuum cap off, it won't cause the idle to go to 5K... maybe 2500 rpms... so it has to be happening on multiple cylinders. The only other thing that can hang the idle is having long carb holder screws interfere with the sync mechanisms and hold the carb's throttle plates open. I have cut off the 5mm screws on my carb holders on my carb test bikes just for this reason... they tend to interfere on BS34s.
Second, take the carbs off. Look at the throttle butterflies. The butterflies MUST all be able to shut completely. Sounds like they are not shutting. Toooooo much air may be getting in when the throttle is shut. If they can completely shut, then the air is getting in some other way. You may have already figured that out since you have attempted to seal your carb holders. Since you have NOW bought new carb holders, the only other thing that can leak that bad is the vacuum plugs or a leak in the emissions hoses connected to the carbs or even the vacuum line to the petcock.
When you CHOKE the carbs by sticking your hand over the intake venturi you are reducing the amount of air getting into the venturis. The excess air is causing the high idle. To recap, it can ONLY be from the throttle butterflies staying ajar slightly (doesn't take much) OR an airleak from the carb holders or vacuum plug areas...
I lean towards the butterflies because usually, if you completely leave one vacuum cap off, it won't cause the idle to go to 5K... maybe 2500 rpms... so it has to be happening on multiple cylinders. The only other thing that can hang the idle is having long carb holder screws interfere with the sync mechanisms and hold the carb's throttle plates open. I have cut off the 5mm screws on my carb holders on my carb test bikes just for this reason... they tend to interfere on BS34s.
wiredgeorge Motorcycle Carburetors
Mico TX
www.wgcarbs.com
Too many bikes to list!
Mico TX
www.wgcarbs.com
Too many bikes to list!
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- kzwolfsr
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Re: Very high idle
19 Jun 2007 10:35
I now see why there is only 1 reply here, WG has covered it all!
1979 KZ SR650, stock candy persimmon red and crossover pipes
1981 KZ 1000LTD with non stock and more comfortable handle bars and 4 into one V&H
Original man of the Caribbean
1981 KZ 1000LTD with non stock and more comfortable handle bars and 4 into one V&H
Original man of the Caribbean
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- Snakebyte
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