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  #1  
Old 15-07-2018, 11:08 AM
johno74 johno74 is offline
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Default gsxr1100 carbs wont balance

I'd appreciate some help please people:
95 gsxr1100wr with 40mm carbs.
With bike fully warmed and following the carbtune instructions.
Problem is i cannot balance the 4th carb, it shoots off the vacuum scale(i have tried switching the carbtunes around not its not just missing the restrictor in the carbtune tube unfortunately).
I cannot tune the other 3 to this carb because it is off the scale
All four pots are within a hairs breadth of200psi
with the bike running i have sprayed wd40 around carbs looking for an air leak and found nothing.
Carbs have been thoroughly cleaned and treated to a seal kit - exactly the same as before..
Any ideas short of selling bike on appreciated please!
ta
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Old 15-07-2018, 11:43 AM
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Have you checked the carb manifold O rings, sometimes these can shrink overtime causing air leaks.
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Old 15-07-2018, 12:08 PM
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If its off the scale with a high vacuum I'd say that the throttle for that carb is fully closed.
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Old 15-07-2018, 01:45 PM
Tricky-Dicky Tricky-Dicky is offline
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Have you checked valve clearances ? as a tight tappet/shim will cause high vacuum and no amount of carb tweaking will help.
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Old 15-07-2018, 03:41 PM
johno74 johno74 is offline
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Strima: its a new set of o rings and they seem to sit nice but it behaves the same as the old set tbh. Any cunning ways of checking what you suggested?

Harry: fully closed - no throttle hence max vacuum(?)

Tricky - Dicky: would clearances need to be way out or just a bit? just wondering because i did them fairly recently (but i couldv messed it up of course)
thanks all
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Old 15-07-2018, 06:24 PM
johno74 johno74 is offline
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sorry Strima, just reread your message n you said manifold o rings. I suppose i cant check/test without removal and replace or are there any other symptoms that i can look for?
ta
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Old 15-07-2018, 07:44 PM
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You could try the WD40 spray around the area.
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Old 16-07-2018, 05:17 AM
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What about a bent needle valve? or a punctured float?
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Old 16-07-2018, 09:03 AM
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Quote:
Originally Posted by johno74 View Post
Strima: its a new set of o rings and they seem to sit nice but it behaves the same as the old set tbh. Any cunning ways of checking what you suggested?

Harry: fully closed - no throttle hence max vacuum(?)

Tricky - Dicky: would clearances need to be way out or just a bit? just wondering because i did them fairly recently (but i couldv messed it up of course)
thanks all
Yup closed throttle = Max vacuum.

The engine is running on the other cylinder/ carbs. The engine is sucking on the carb which has a closed throttle so no air can get in. Hence high vacuum.

Once the throttle is open the air can enter the engine and the vacuum drops
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Old 16-07-2018, 12:33 PM
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Harry: so id be looking at wrong needle height, punctured diaphragm, bent needle that sort of thing?
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Old 16-07-2018, 03:38 PM
Tricky-Dicky Tricky-Dicky is offline
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The pilot system on CV carbs is separate to the throttle flap and slide, so the pilot airway could be blocked, although that cylinder wouldn't run unless the throttle flap has been set to accommodate this previously, you didn't say whether it was firing on that cylinder or not?
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Old 17-07-2018, 05:35 AM
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A bloody good clear out with an airline might help. aldo drain the tank and give that a good clean out. Dirty fuel might have built up in the tank over time. Sometimes it's something so simple that takes the hardest thing to find....
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Old 17-07-2018, 07:37 PM
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Quote:
Originally Posted by johno74 View Post
Harry: so id be looking at wrong needle height, punctured diaphragm, bent needle that sort of thing?
Nope the high vacuum would be caused by no air getting in so throttle valve closed or as dicky said blocked pilot passage.

Wind open the idle speed on that carb and see if the vacuum drops. If it does you then need to check the reason which might be out of balance carb settings or the idle circuit / pilot air blocked.

Has it got separate air cleaners if it has it could even be that VERY blocked. but as I once found an aerosol lid in one its not impossible.
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Old 20-07-2018, 10:20 AM
Tricky-Dicky Tricky-Dicky is offline
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Any joy with the balancing johno74?
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Old 21-07-2018, 04:57 AM
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You could always put each one on a set of scales and add a washer to each until they all weigh the same, then they'll balance out......Not helping am I?
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