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Discussion Starter · #1 ·
Experts,

So the bike is done and has gone through a bunch of short, 3 mile test rides...and all has been good, even in the 105 deg heat in August. So I was getting ready for its inspection and noticed a small leak from the left bowl drain, and what looked like another small leak around the power valve area...but only when on the side stand (which admittedly is leaning too much). No leaks when on the center stand.

So I wrestled the carbs out again today, took off the bowls and the power valve and checked everything. All looked good, except maybe the o-ring for the power valve stem was pinched a bit. Fixed that. The o-ring on the left side drain screw is also old and needs to be replaced.

Set the carbs up for a bench test and when full of fuel and level, no leaks at all regardless of throttle position. But when I simulate the side stand lean angle it leaks from the left drain, and if I go past 45 deg lean angle it leaks from both drains. Is this normal behavior under these extreme lean angles, or do I need to adjust the floats in the carbs?

Any advice appreciated. Thanks.
 

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1983 cx650c
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It sounds like either float levels are off or float needles aren't seating properly. The plastic floats can be replaced or adjusted according to all reports, check forum for procedure. I got aftermarket floats and needles that were not exact duplicates of original parts. The rubber tips of float needles do get hard or worn and cause seating problems. By "power valve" I'm assuming you mean air cut off valve. It would not contribute to carb leakage.
 

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The float needles they are the same length as original are k&l brand. I have a bag of needles that are shorter that came with carb kits. I reused the original floats and found needles of original length to stop the leaking I had when rebuilding the carbs on the cx650.
 

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Try this.

Get a length of clear 4 mm hose.

With bike on centrestand attach a length to the drain nipple of each carb.

Open petcock and while holding the clear line up the side of the carb open the fuel drain screw a couple of turns.

The float bowl fuel level will show in the hose and should be about 2 mm between the carb to bowl joint.
 

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If the bike is starting, idling, and running correctly, I would not change the float height to resolve a leak. Changing the float height will affect your lean/rich condition which will affect performance.

CXPHREAK's method is appropriate if carbs are on the bike. If the carbs are still off, check float height by gradually tilting the carbs until the floats barely touch the float valve plunger, then measure the height. Do not simply turn the carbs upside down as the weight of the float will depress the plunger more than normal operation and give a bad reading of float height.
 
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Discussion Starter · #7 ·
UPDATE...did the CXPHREAK check on my level test setup and the level was just below the joint (2mm-ish), so put the carbs back in and all is well. No leaks and rode around for 15 mins...and let it idle on the kick stand. All is good now. But all was good before until this latest drip...

We'll see what happens when I head out for inspection again this week.
 
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