On the way home, she stopped altogether three times. I could see that the fuel filters were dry so there was no doubt it was fuel starvation. My guess is that when the bike heats up, the rubber fuel hoses soften and then close up where they bend. I think it is both the vacuum pipe to the rear of the fuel tap and one or both of the fuel hoses to the carbs. Each time, after the bike had cooled I could see fuel flow into the filters again and so could do some more miles.
So last night I took it all apart again to take out the fuel filters so the hoses would have an easier route to the carbs. And in doing so I managed to snap one of the t-pieces I'd plumbed in to link the two sides of the system!!! So I had to pull the carbs out too so I could remove the broken stub etc.
Ironically, I could see that the carb throats and inlet rubbers were wet with fuel. It is ironic bearing in mind the problem I was trying to solve was not having enough fuel. That suggests I set the float heights too generously. So I'll be adjusting them by 1 - 2 mm whilst I'm at it.
On the plus side, with the carbs out I could do something else. And so I have a nice new heavy duty lead from the starter solenoid to the starter motor ;-)
2 comments:
Both fuel filters dry? Did running on prime make any difference? Perhaps there's a split in the vacuum pipe. I had one in mine last year.
I couldn't see the innermost filter but it must have been dry too because it went from all four cylinders to none of them running. The vacuum pipe probably kinked when hot and malleable. I used some small-bore fuel pipe and I don't think it was rigid enough. My prime setting is very poor - the fuel just trickles out.
I bought some new pipe and t-pieces at the weekend. I also checked the carb float heights with a Vernier caliper and can see they are about 1mm out by the Haynes spec: they are approx 13.5mm whereas Haynes says 14.5mm. I don't know why I got it wrong first time.
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