CBR 600F 1987 - 1990 CBR 600F Forum

Carbs overflowing gas

Old 07-10-2014, 08:45 AM
heresolong's Avatar
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Default Carbs overflowing gas

My CBR belonged to my sister in law and sat for quite a few years. I got it running again but it always leaked a little gas out of the carbs (seemed to be coming out of that brown tube that runs across the top of the carbs which I thought was an air pipe). Then it got worse. Now it just dumps out of there. I have to put a bucket under the bike in order to crank it. Part of the problem is that I haven't ridden it much (haven't got it registered) and part of the problem is that I am a Harley mechanic and these Keihin carbs are somewhat different from the ones that used to come on Harleys.

Any idea why gas would dump out this way, what might be clogged to force the gas up and over, and if there is a quick fix.
Old 07-10-2014, 10:15 AM
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Probably just deteriorated o-rings in the T-couplings (the brown tube). Take the carb battery off the bike (can be really tight and you might break the boots while doing so but if they do rip they were due for change anyway)

Then detach the carbs from each other by unscrewing the nuts from the rods that run through all the carbs, unscrew anything that holds the carbs together like choke linkage etc. and pull them apart. Now you can get to the o-rings. Notice what goes where, and remember that if the carbs are taken apart you need to perform a carb sync afterwards.

Once you've got the carbs on the table it would be a good idea to drop a few coins on them and swap all the gaskets and give the jets and vacuum slides a good clean so you don't find yourself in there again the next weekend specially since the bike has stood for some time.

Disclaimer: this is based on knowledge of the F2 and the 1000f hurricane assuming the f1 is somewhat similar.

Last edited by Mattson; 07-10-2014 at 10:18 AM.
Old 07-10-2014, 10:38 AM
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Most likely a stuck float if it's coming out the overflow tubes, you could try blocking it so it fills the bowl, or what worked for me last time was tapping on the bowls with a screw driver(engine running). But you might need pull the carbs and clean your bowls, needles and floats if the bikes been sitting around for a while.

If not it's probably what mattson said, the o-rings between the carbs tend to deteriorate over time.

Last edited by RedBaron; 07-10-2014 at 10:43 AM.
Old 08-23-2014, 11:22 PM
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Check the floats, needles and seats. If the bike stood for a bit the carbs will be full of ****e for sure. Sometimes the tapping of the float bowls works. Sometimes not lol. Never hurts to try though! Also, if the carbs are out, swap the JIS (Phillips) screws in the float bowls to Allen headed fasteners. No more cammed out screws!
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