Fuel starvation - fuel tap issue?

[jdwoodbury]

Hey folks,

So had my VTR for 3yrs but only just got round to getting it back on the road recently, its had a full carb rebuild and pulled great on the dyno. Went to take the bike home the other day but conked out 5mins down the road. Assumed the fuel tap was turned off, or vacuum not put back on but all looks ok. So I called AA for recovery, when they arrived they looked at the same things as me, fiddled with the fuel tap (on and off again)....and hey presto bike was brought back to life. Odd I did the same things 5mins before any nothing!

So does this sound like I need to get the fuel tap repaired? I noticed when the bike start to have problems it was only running on the front cylinder, fiddled with the tap and now running ok. I am off on a big trip (TT) in a few months so want to make sure its not going to break down on me again.

JD

[Pete.L]

Hi JD,
Sounds like it could be. The diaphragm in the pet rock perishing is quite common but before you do pull it apart, make sure you have the vacuum pipe on the correct spigot on the fuel tap. Second most common thing is people popping the pipe onto the wrong spigot after removing the tank.
I would also check the fuel pipe hasn't been pinched and is restricting the fuel flow. Another quick easy one is "vapour lock". If the petrol cap isn't allowing air into the tank it can also cause fuel starvation. Open the cap ,if it happens again, and listen for a sucking sound. Other than that, I'd make sure your vacuum hoses are in good nick and don't have any splits or cracks.

Welcome aboard!

Pete.l

[jdwoodbury]

Thanks Pete, I have checked the vacuum is connected correctly...all looks good. It was odd that no fuel was getting through then a wiggle of the fuel tap seemed to work.

[AMCQ46]

the running only on the front cylinder is what happens when the flow of fuel from the tank drops as the rear float bowl sits higher so it runs out of gas first.

Pete has coverd all the suggestions I would have made.

A) diaphragm failing
B) vacumn lock

both of these have happened to me with the same symptoms

[jdwoodbury]

I have ordered an OEM part from Japan (eBay), so hopefully that provides a long term fix.