Author Topic: Truth about my clogged tank/petcock caused stop. Friend helped taking bike home  (Read 870 times)

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Online PeWe

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Today I found the real root cause of my stop in spring 2015.  I had just mounted a tank I had derusted with vinegar, then a quick rinse with water- alcohol that removed the water.

Bike stopped after about 10 miles. I was sure it was clogged petcock. A friend helped me to get my bike home on a wagon after his car.  I changed tank to my new tank complteley fresh and clean.

I drained the tank from fuel today. It stopped fllow after a short while. Removed petcock bowl and mesh filter. Still same problem.
I opened the fuel cap and the fuel started to flow.

Fuel cap was clogged, no air supply into tank, not the petcock!!
If I had understood that I could have driven the bike home with fuel cap open.

I hope this will help others. If you think your fuel supply is clogged, open fuel cap, it might help.
« Last Edit: February 06, 2016, 11:43:56 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline turboed13b

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My buddy had the same problem but his tank had the wrong cap on it without a vent but it looked exactly like the stock one. we even drilled a hole in it to try and fix it to which did not work. Bought a used cap with vent and all the problems went away.

He has a clear fuel filter inline to the carbs so troubleshooting was actually pretty easy to do on the side of the road.

Online PeWe

  • Really Old Timer ...
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  • Posts: 15,618
  • Bike almost back to the 70's 2015
I will check the fuel cap air vent. If bad, new fuel cap.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967