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I’ve got a 1966 305 Dream that is garage kept and is ridden weekly. About 2 weeks ago I installed a new carb kit and ever since then the bike has strong gas fumes in my garage. It starts and runs great. Has no fuel or oil leaks and I installed a new gas cap. Any ideas what may be wrong?
 

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Are you turning the petcock off after you ride it?
 

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^^^absolutely as above - and while you're at it, did you check the oil for fuel contamination? it can happen on these older bikes, slight overflow of fuel into the cylinders through an open intake valve and it ends up in the bottom end
 

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In addition to the above your new gas cap could be the culprit.
 

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Can you put the old cap back on and see if that makes a difference?
 

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Do you know the size of jets that came with the new carb kit? Some kits come w/ oversized jets which could cause fumes from running rich. I believe the pw22 carb was designed for 110 size main jet and 35 size slow jet. Also the jet needle from kit may be a different length or shape than the original. I recommend only changing the gaskets and float needle (if needed) in the carb and put the old jets and jet needle back in after cleaning as long as they are not worn or corroded.

Look at your spark plugs for black powdery soot - a sign of running rich. If so look into causes of running rich, such as adjustment of idle air screw and idle throttle stop screw or verifying your carbs are not overflilling with gas. With overfilling you may see gas dripping from the carb, or coming out the overflow drain tube. Or you may smell gas in the oil (change out that oil ASAP if so). Overfilling could be float height incorrect or floats getting hung up on the sides of the chambers and not being alllowed to swing freely Or even a pin-hole in the float that causes it to fill up with gas and sink! You can shake the float next to your ear and perhaps hear the gas sloshing around if it’s a pinhole leak. Could also be a bad float needle or needle seat. The float valves are not 100% effective on these bikes that’s why they say shut off the pet cock whenever the bike is not running.

And of course check that gas cap! ?
 

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Did you buy and install a full gas cap assembly or just part of the assembly?

I ask because... I just replaced my cap gasket this past week because of lingering fumes in my garage. The old gasket was aged, cracked in several places and not sealing well. New one gets two thumbs up, but I could have easily be messed up the install if I wasn’t paying attention to the finer details.
 
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