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1971 CL450 float bowl stand pipe

Cracky

New Member
Joined
Feb 19, 2023
Total Posts
5
Total likes
4
Location
Barre, VT USA
Hello. I'm looking for information regarding the height of the standpipe from the float bowl sealing surface to the top. I've been having carb overflow issues into the engine. The fuel isn't coming out of the stand pipe( either one) as I believe it should giving proper float height adjustment. When I removed them today I measured the stand pipe height and found one at 5.59mm and the other at 7.83mm that seems like a big difference( 2.24mm) but I'm not sure which one is correct(strange that they are off by that much). I've cleaned the carbs in an ultrasonic tank several times gone through the passages relentlessly installed new carb kits from Scrambler cycle to include needle and seats new floats from CMSL adjusted to what I believe is correct at 20 mm. Yet they continue to dump into the engine. Thoughts? Maybe the new needle and seat are junk. I do try close the shut off valve at the tank every time but these aftermarket shut off valves are just not dependable. If any one has a set they could measure it would be appreciated. Thanks.




needle and seats are junk.
float bowl 1a.jpgFloat bowl 1.jpgFloat bowl 2.jpgFloat bowl 2a.jpg
 
It isn't so much a drain to prevent overflow into the engine, so much as a vent to let the bowl fill be letting air out of the chamber. If the float valve is sticking open, the fuel flow is greater than that little pipe can handle. In any case, the fuel level will reach the height of the pilot/idle circuit at the carb throat before that of that pipe, and flow into the engine.

Do you have a service manual? If so, make a float height gauge according to the drawing there, from thin sheet metal or a hard plastic sheet, and use it to verify that the valves close at that level by holding the floats up with the gauge and opening the petcock. Also, make sure the floats actually float.

floattool20.jpg
 
Thanks for the clarification I’ll get a manual and make the jig then check the needle and seats for fuel shut off.
 
Just to close the loop on the float bowl stand pipe thread. I made the tool and set the floats with the new scramble cycle needle valve and seats turned on the gas...no difference gas still bypassing the needle valve. Polished and reinstalled factory needle valve seats and what ever the bike came with for needle valves, re-installed and fuel no longer bypasses the closed needle valves. So live and learn. Now if I could just get the right cylinder to fire maybe I could take it for a ride!!!
 
Many years ago, maybe 20, I found a source of float valve needles with Viton tips; never had a problem with leaking valves since, as they don't wear the same. Something to look for, anyway. I think mine came from New Zealand, via eBay.
 
Yes wish I had the knowledge to source the correct ones with the Viton, but for now everything is holding. After chasing down ignition problems to bad condenser after bad condenser I"think" I can say the bike is fixed. I did ended up going with Jay100 Apr 7th's post for the McMaster advancer springs. That seemed to have cleared the hanging idle after the bike gets hot. Love this forum.
 
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