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Carbs are spitting at me

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knocker
Nova Slayer



Joined: 31 Jul 2008
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PostPosted: 14:47 - 04 May 2009    Post subject: Carbs are spitting at me Reply with quote
Attempting to balance up the carbs on my divvy as it has had a really lumpy tickover for quite a while, got the airbox off andstarted it up and i've noticed that the carb on cylinder 4 every so often will spit fuel out at me and the vacum will drop to zero, this in part explains my crap tickover.

Anyone know the reason it's doing this? The carbs didn't seem too bad balance wise so I am starting to suspect that maybe the coils are starting to go seeing as they're 40k + miles old but i would like to know what causes the carb to belch like it is doing.
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dynamec
L Plate Warrior



Joined: 04 May 2009
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PostPosted: 17:40 - 04 May 2009    Post subject: spitting carbs Reply with quote
one thing I could see would be an inlet valve that is not shutting correctly. causing a reverse flow on the compression stroke.
you could try a compression test or a leakdown test on that particular cylinder.
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Noxious89123
World Chat Champion



Joined: 10 Jun 2007
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PostPosted: 18:01 - 04 May 2009    Post subject: Reply with quote
Out of curiosity; What's a leakdown test?
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Blue_SV650S
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Joined: 27 Nov 2008
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PostPosted: 18:45 - 04 May 2009    Post subject: Re: spitting carbs Reply with quote
dynamec wrote:
one thing I could see would be an inlet valve that is not shutting correctly. causing a reverse flow on the compression stroke.
you could try a compression test or a leakdown test on that particular cylinder.


Yep agree with dynamec, sounds like a leaking valve.

When was the last time you checked the valve clearances? Thinking
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knocker
Nova Slayer



Joined: 31 Jul 2008
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PostPosted: 19:19 - 04 May 2009    Post subject: Reply with quote
can;t say i've ever checked them but it is something i've been meaning to do for a while but never got round to it.

Looks like it's time to dig the feeler gauges out Smile
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Blue_SV650S
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Joined: 27 Nov 2008
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PostPosted: 19:21 - 04 May 2009    Post subject: Reply with quote
knocker wrote:
can;t say i've ever checked them but it is something i've been meaning to do for a while but never got round to it.

Looks like it's time to dig the feeler gauges out Smile


Yep, first thing I'd do is check the clearances!! Thumbs Up

Does the bike run worse when hot than when cold? Is it a bit of a sod to start when hot? These are other symptoms of clearances that are too tight/non existent!! Wink
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