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Discussion Starter · #1 ·
Hello, I am reviving a 1971 CL175 that was not running and was COVERED with rust when I got it. It had been left out, uncovered, on the coast for 3 years. Once I resolved some of the electrical issues that were preventing it from starting, I was able to get it running. This gave me confidence to start restoring the bike. I stripped everything down to the frame, painted, fixed a number of things, and the bike is finally all back together.

For about a day it was running nicely, idling well too w/o having to give the carbs too much attention. On the second day I went to start it up for my first test drive but then I noticed that fuel was leaking profusely from the left exhaust manifold, and it stopped firing on the left cylinder altogether. I figured the float valve got stuck open, causing the fuel to flood the cylinder. I took off the left carb, cleaned the float valve, main, and pilot jets and put it back together. No luck. I have since tried a number of things trying to diagnose the problem, but no success yet.

So far I have:
- Checked the float height. Good, 21mm
- Checked for leaks in the float. No leaks
- Checked that throttle cables were on correct carbs. Cut outs are facing out towards air boxes
- Checked for spark on the left spark plug. Good

I have also changed the engine oil and there was a lot of fuel mixed in. The carburetors and airboxes are all stock. The carbs haven't been rebuilt, at least not by me. If anyone has any ideas or suggestions as to what might be causing this, it would be much appreciated. Thanks for reading. (Also, here's a before and after picture if you're interested :))

307274


307275
 

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The fuel got into the oil because either the petcock was left on, or the petcock leaks past the shutoff even when turned off and the carbs seeped into the bottom end through an open intake valve. It's a very common problem on our old carburetors, which is why we recommend the fuel be shut off every time the key is turned off. Changing the oil immediately is important to avoid engine damage from fuel-diluted oil, and clearing up the issues with the petcock (if any) should be done as well
 

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Did you change the spark plug,after it was drowned with all that raw fuel?
 

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Discussion Starter · #4 ·
@ancientdad Thanks for the suggestions. About a week ago the petcock was leaking even when in the stop position. I bought a rebuild kit which stopped the leak and have since changed the oil. But I'm still getting a lot of fuel coming out of the exhaust.
The fuel got into the oil because either the petcock was left on, or the petcock leaks past the shutoff even when turned off and the carbs seeped into the bottom end through an open intake valve. It's a very common problem on our old carburetors, which is why we recommend the fuel be shut off every time the key is turned off. Changing the oil immediately is important to avoid engine damage from fuel-diluted oil, and clearing up the issues with the petcock (if any) should be done as well

@mike in idaho I cleaned up the plug and made sure it sparked, it did. Should I still change it?
Did you change the spark plug,after it was drowned with all that raw fuel?

I'm thinking maybe the timing is off on the left cylinder, so even though it's sparking it's not combusting. Could that explain the gas coming out of the exhaust?
 

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Single set of points w/double-ended coil, both cylinders have to fire at the same time. Did you check for spark, with a spare plug snapped onto the left plug wire? Perhaps one carb is flooding, put in a fresh spark plug and start it with the gas turned off and see if it picks up the left cylinder before it runs out of gas.
 

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Discussion Starter · #6 ·
Thanks @mike in idaho. I am getting a spark on the left plug wire. I do recall that when I first started it up, both cylinders were firing. But when the left carb started flooding, the left cylinder stopped firing. Any ideas as to what would cause the carb to flood so much? I have already cleaned the float valve, main, and pilot jets. I'd really prefer to avoid rebuilding the carb unless I have to. From what I've heard the rebuild kits are worse than the original parts.

Single set of points w/double-ended coil, both cylinders have to fire at the same time. Did you check for spark, with a spare plug snapped onto the left plug wire? Perhaps one carb is flooding, put in a fresh spark plug and start it with the gas turned off and see if it picks up the left cylinder before it runs out of gas.
 
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