65 pan smells gassy when running

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65 pan smells gassy when running


Post by longhorn » Sat Aug 07, 2010 2:19 am

I have an M74B carb on my 65.
Runs pretty good.
Whenever I ride, she smells gassy. Just got in I still smell gassy.
I have had this carb apart, and put back together so many times, I can do it in my sleep.
I recently had the top-end redone. When I put her back together, I lined the cylinders up perfectly with the intake, installed new seals, did a pressure test on the manifold. Everything seems cool to me. She pops when letting off on the gas, otherwise runs pretty good rolling down the road. Starts fine, with a little choke.
I did lose the spring on top of the throttle shaft(my shop is a disaster area), last time I had it apart, but it ran the same as before.
Also you can screw the high idle in almost to the stop, doesn't seem to effect the performance.
What am I missing?
I've owned this bike for years, its always been like this.

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Re: 65 pan smells gassy when running


Post by steve_wood » Sat Aug 07, 2010 1:32 pm

Maybe it's not the carb? Did you check for fuel leaks in the lines and even the tanks themselves?


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Re: 65 pan smells gassy when running


Post by ozwick86 » Sat Aug 07, 2010 1:55 pm

Popping/back firing when letting off the gas could be caused by a lean condition on the carb on the low speed screw. Back the low speed screw out a couple of clicks and try it. Or, there may be a hole in one of your exhaust pipes sucking in the cold air causing the backfire. The throttle shaft spring keeps proper tension on the throttle shaft which will keep the throttle disc from bottoming out causing wear on the shaft bore. Have you also checked your gas cap rubber?

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