'72 kaw cut out

Joined
Nov 7, 2001
Messages
397
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#1
I was at an AHRMA race this weekend, and I finished moto 1, but the bike died in Moto 2. It started running sluggish, then got gradually worse, then it just bogged and died. Maybe about 30 seconds between when I noticed it wasnt responding as it should and when it died. OF course it was the last lap, about 30 yards from the flag.

Previously, I had a problem with the floats sinking, and it flooded, but when that happened it was like lights out right away and of course alot of leaking gas out of the carb cover.( I put new floats on after that one) This time it was more like it ran out of gas.

Here is my theory, and I want to see if any of you think it might be right. I tore down the carb, and she was clean. THe new floats were fine. No dirt in the valve, or in the fuel filter.

I have this aftermarket plastic tank on it that I got on Ebay. It was NOS, but did not come with a cap. I got one of those universal gas caps, the automotive type that fits well. But, the cap is not vented. DUring the break after Moto 1, I took the cap off to check the gas level, and it hissed at me pretty good, Im not sure at that time whether it was sucking air in, or blowing it off but it made me think its air tight for sure.

I am wondering if enough gas drained out of the tank during the race to create a vacuum large enough to restrict the flow of gas down to the carb. I know that the proper cap for this tank was indeed vented because I had one like it years ago. It sure acted like it ran out of gas, I thought the gas inlet was clogged.

I am going to drill out the cap and put some sort of fitting on it so it can vent in any case.

Thanks,
Neil
 
Joined
Nov 7, 2001
Messages
397
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2
#2
oh yeah, it fired as soon as I pushed it off the track and I rode it back to the truck just fine.
 
Joined
Sep 21, 2003
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#3
i have had the same problem with my 72 kawasaki f6. the problem was that the gas filter clogged from rust that accumulated in the tank. i just had to gun it 3 mins for the gas to slowly catch up. i platcit coated my tank and got a new filter. its runs great now.