Greg, I have the same problem with the filler cap leaking when the tank is filled and I move the bike so that the petrol slops around. I have tried filler caps with 1 and 2 holes, neither worked so I don't put as much fuel in now. It would be great if someone had a solution to this one.
Al.
Rebuilt engine seizedFuel filler leakage.Are you using the new style rubber gasket or do you still have the original cork washer in place?
I drilled the extra hole in both my CB and CL and always FILL the tanks to get max range, especially important with the CL as the small tank is only good for about 100 miles max and reserve is VERY small! Neither really have a problem with leakage even when full, it could be some minor damage to your tank in the filler area which is stopping the washer sealing properly or it could be the internal spring in the filler cap has weakened over the years. With care you can get the filler cap apart so if the tank neck looks OK it might be worth either trying another cap of having a look inside the one you have. That style of cap was used on lots of models over quite a lot of years so getting hold of another cap shouldn't be difficult. Hi Dennis,
Further investigation did reveal a dip on the sealing area so I got a piece of ally tube 54mm dia out of the bin and faced it up on my little lathe, then I put it onto the sealing area to see what needed to be done. It was about .5mm dip so I gently lifted it with a piece of 20mm ally bar, this looked like it was working but I was scared of damaging the tank and stopped. I then put the ally tube on the sealing face and VERY carefully tapped it then put the cap back, it seems to have worked as when I shake the bike no leaks. I have to stress it's scary doing it as paint is damaged so easily and from now on will be checking before paint. Cheers Al. Leaking fillersI think this is quite common with older tanks, particularly any that have been 'stored' badly or have been kicking about for years with no cap in place. Obviously the filler cap protects the critical area which forms the seal. Doesn't need much of a ding to cause a leak.
I spoke too soon, after 200 miles of problem free running I have a problem. The bike will not pull more than 5000revs. I was planning to change the oil after 200 miles so I effectively did a full service, checked the timing, checked tappers, stripped the carbs and filled the tank up with fuel as it was getting a bit low.
No difference. I checked the plugs and one cylinder is running really weak. All previous checks had shown good plug colour. My next thought was a head gasket failure ( it has been on and off a few times!) as there was a bit of oil around but could not be sure whether it had come from the plug area. So I checked the compression and it seems even across the 2 cylinders. The only thing I have found is that the fuel level in the float bowl of the carb feeding the weak running cylinder was lower than the other one but still a fair amount of fuel in there. A bit frustrating! Greg
I struggled to find a reason for the latest problem and to be honest I worked on other stuff for a while as I was getting a bit fed up!
in the end all I found was a bit of burning on the points but my suspicion is that maybe the carb to head connection had loosened off and leaked air though I can not be sure. I rebuilt the carbs again, checked float heights etc and it now seems OK though only done about 60 miles so far. I think over the winter I might look at how the head to carb fitting can be improved. Greg
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