Paul TigerB6
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| posted on 11/3/09 at 07:14 PM |
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Bike carbs issue
Well i had a pretty decent day down at a fellow lister's trying out the bike carbs now they are respaced (as well as doing a few other jobs on
the car. Had an issue with the carbs though which i think i know whats going on but a bit of confirmation would be handy before i strip the (GSXR600)
carbs tomorrow.
Switching on the bike fuel pump resulted in fuel pi$$ing out all over the place so we quickly switched off. A quick check showed fuel coming out of
the air vents at the top of the carbs on two of the four, and also a fountain of fuel being forced out of the main air jet with a slight dribble
coming from the pilot air jet. After sitting in fuel for an hour, one of the carbs seems to have sorted itself (they have been left standing for 1
year plus!!).
Eventually got the car started after blocking up the air vent on the carb to stop the worst of the fuel leak and found it was only running on 2
cylinders (the two that correspond to the leaky carbs). Spark is there so it seems to be a fuel issue.
My initial thoughts are the float valves have stuck due to reside and lack of use. This would cause the fuel to overfill on the leaky carbs and be
forced up the air vent and out of the pilot air jet and main jet. Sound reasonable?? Not too sure whats up with the other carbs as they have fuel in
the float chamber (checked by backing off a screw on the cover) but maybe its related to the leaky ones, or maybe just a blockage.
Any thoughts as to what to check, besides stripping all of the float mechanisms and examining for a damaged float??
Ta
Paul
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RichardK
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| posted on 11/3/09 at 07:21 PM |
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I would have thought they would need the jets re drilling anyway, so you would have the float bowls off to do that.
Rich
Gallery updated 11/01/2011
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mistergrumpy
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| posted on 11/3/09 at 07:51 PM |
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I'd go for crap in the float mechanisms Paul. Whip them off and check under the float needle for grit and whip the main jet out and give it a
clean too.
I used some Wynns carb cleaner (I swear by Wynns, great products) and it sorted all my problems out. I was quite amazed as there wasn't a
massive deal of dust/grit but it made all the difference.
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will121
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| posted on 11/3/09 at 09:08 PM |
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what fuel pump/pressure are you running? if the mororbike fuel pump the float valves next look
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snapper
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| posted on 11/3/09 at 09:26 PM |
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First fire up of my bike carbs resulted in the same pi55ing out of fuel and as a car man i paniced, my fellow kit car mate who also bikes said
"no problem, just use a squezey bottle for the fuel feed and run the car until the carbs settle" It worked, then i set the fuel pressure
to about 2 psi and all has been well.
Still need to sort the jetting as i am overfuelling
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Paul TigerB6
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| posted on 11/3/09 at 10:02 PM |
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Pump is a Yamaha Fazer and was slowing down after i temporarily blocked up the air vents, so that should be fine.
Jets are brand new and shouldnt be too far off being 150's (standard Pinto). The float valves actually seemed to be ok when i had the covers off
but guess finger pressure and float pressure are two different matters. I'll whizz the covers off again tomorrow and strip the float mechanisms
and try soaking the parts in some Wynn's carb cleaner as suggested - think i have some somewhere here. I think this time i'll go and get
the compressor and blast them through with the air line - did have a quick look at them and all seemed clear. Expected maybe a bit of varnish but
thought a few hours soak in fresh fuel would sort them - seemed to work with one carb!!
I would leave them settle but for the fuel pi$$ing out of the air vents........ its right about the main loom connected to the starter motor too!!
Cheers for the suggestions anyway
[Edited on 11/3/09 by Paul TigerB6]
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BenB
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| posted on 11/3/09 at 11:17 PM |
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Run the fuel pump until the fuel comes pissing out of the vents. Leave it for 24-48hrs for the petrol in the float valve chambers to dissolve the
crud. Then disconnect the pump electrical supply and run the float valves dry, then try reconnecting the fuel pump and see what happens.
With a bit of luck leaving them full of petrol will dissolve the crud and running them dry will move the float needles and remove the nasty stuff....
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Paul TigerB6
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| posted on 11/3/09 at 11:25 PM |
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Thanks for the suggestion Ben. Will do that if cleaning the float mechanisms doesnt cure the problem in the morning. The issue i have is i am 25 miles
from the car and didnt have access to the manual (its on my laptop) at the time so brought the carbs back home with me to sort them (only 5 weeks to
SVA). I do have the fuel pump here now too (to make a bracket for it) so can always test it here using a jerry can as a fuel tank, and drip tray.
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iscmatt
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| posted on 11/3/09 at 11:32 PM |
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Just to add i had the same problems. Fuel peeing out the 'air vents', rang bogg bros, they suggested it was the seals had dried up and so
fuel was able to get around them, left it 24 hours, allowing the seals to soak with the fuel in the carbs, and never had a problem since. You may find
yours is the same and so no further work required
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tendoshingan
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| posted on 12/3/09 at 10:16 AM |
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Have you checked to make sure you have connected the fuel line properly.
I had a similar problem, then realised I had connected the fuel to the air inlet. 
Hence fuel coming out. I know of a few people who have also done this.
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Paul TigerB6
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| posted on 12/3/09 at 10:18 AM |
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quote:
Originally posted by tendoshingan
Have you checked to make sure you have connected the fuel line properly.
Yep - definately connected the fuel supply to the fuel inlet pipe and had the car running (badly on 2 cylinders). 
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MikeRJ
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| posted on 12/3/09 at 10:24 AM |
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quote:
Originally posted by mistergrumpy
I'd go for crap in the float mechanisms Paul.
How often do you have to do that then?
The oldies are the best!
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Paul TigerB6
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| posted on 17/3/09 at 09:23 PM |
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Well i got around to stripping down the GSXR 600 bike carbs yesterday and very quickly found the problem. The floats have a small metal tag on them
which actvates a small plunger in the float valve and this tag is held in place by a small wire retainer. Someone in the past hadnt put the tag
through the retaining wire and so the float wasnt activating the float valve properly on 2 of the 4 carbs - instead it just pushed against the wire!!
Such a simple fix but boy did it cause a heck of a fuel leak!!
Anyway, stripped the carbs right down and cleaned everything in sight with the Wynns as suggested so hopefully tomorrow will see the Pinto running on
4 cylinders.
Thanks for all the help chaps.
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