internal leak in Keihin?

Joined
Jan 28, 2001
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#1
I have a friend that bought a well abused KTM 300exc (1997). The bike's jetting was set up way off from the factory specs and still ran poorly (bad bog from over rich condition and wouldn't rev out). I reset jetting to stock and adjusted for the altitude and it ran fine but started to load up after a couple of minutes. I took apart and found the float hieght set way too low but readjusted to stock even thought that probably will aggravate the condition. Bike ran the same but when the gas was shut off the bike would stop loading up and run perfect when the gas level in the bowl was in the normal range. I can't see anything wrong with the float valve or float (plastic) but the gas doesnt run out of the overflow hoses like a high float level would suggest and when I set the float height way low the bike won't start from lack of fuel. I'm assuming fuel is running down into the engine but wondered if others have had this same problem. I hate to have the guy buy a new carb but I have a feeling the float and needle aren't they problem so I hate to replace those itmes and then still have to buy a carb. Any ideas?
 

lips

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Joined
Apr 6, 2001
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#2
Sounds like the float may be bad. I'm not sure what material your float is made from. Some floats are hollow plastic and some are a solid foam block.

If it is hollow plastic, it may have a pin hole causing the float to fill up with gas (which makes it heavier) and causes it to sink. If is sinks the chamber will fill up with additonal gas and cause it to load up.

If it is a foam block. Sometimes these things actually will absorb gas and have the same effect.

It is probably not too expensive to just replace the float so that you have eliminated this as a potential cause.

If turning off the gas temporarily corrects the problem, it very well may be the float.

Don