So I've recently come into the possesion of an old model(non injection) Kawasaki KSR. It goes really well, the only problem is that sometimes when riding along the engine just starts to splutter and dies. The previous owner gave me the solution, which is just open the petrol cap to let the air out and start it up again. It works every time. I was told that something was probably removed from the bike causing this problem.

So any ideas what this is? Why does removing the petrol/fuel cap solve this problem and what is the permanent fix?

Sounds like a venting issue. As in the tank creates a vaccum and does not feed the carb. Unfortunately I don't know the KSR well enough to recommend a fix but it may have the wrong cap especially if you don't need to use the ignition key or have to use a different key.

Yep tank venting. Also happened to a CBR 150. Go to Kawasaki either let them sort it or buy a new gas cap.

So do I need some kind of tank vent tube breather or just replace the fuel cap? I've seen online actual tubes where some say it's in the cap itself.

So do I need some kind of tank vent tube breather or just replace the fuel cap? I've seen online actual tubes where some say it's in the cap itself.

Mac I dont know for sure but do not recall seeing KSR's with vented caps eh?

If not their gas tanks may be like the Ninja's

Look on the left side of tank for two tubes

Not the fuel line ...These would go to a square box ( carbon canister )

Those would be the venting system & may need to be checked or even just opened

as canister may be clogged & try let hoses just hang free...ride it & see if it clears the problem

Sorry I meant to add that my Honda has a vent tube but the power went off as I was typing and the... What mania says...

Problem solved!

Thanks everyone, It's very intermittent so not a big problem, I'll bring it to Kawasaki tomorrow, at least i now have an idea of what's causing it, so I can point it out to them.

Thanks for the reminder, just went out and took the cap off the breather tube on my bike. Probably hasn't been done in 50,000km. A very small drop of what looked to be thin oil dropped out.