zxr air lock problem

[slopster]

I recently sold a zxr250a and the new owner has had a bit of trouble with the bike suddenly dieing after a while and not starting again for 5min then running again fine. He's not very mechanically inclined so I've offered to have a look at it for him but I've got to go up to Whangrei so I want to get it sorted the first time. I got him to ride with the cap open and he said it was ok like that so I'm guessing its to do with the breather pipe being blocked. Is this a common thing on these bikes and exactly where is the pipe located. Best ways to clean it? I was thinking a bit of 16guage wire and compressed air maybe some carb cleaner.

Is there anything else that would cause it, I'm pretty sure the carbs are good cos I cleaned them out before I sold it and would imagine that fuel line or filter problems would be gradual and effect performance rather then bringing the show to a grinding halt.

[Oakie]

I have that problem on my CB400. Diagnosed as an overflow/breather block and all I've been able to do to try to fix it so far is fit a drinking straw over the top of the breather hole in the rim of the cap and blow.
What I have figured out though is that it happens only when the bike is left in the sun for more than 20 minutes (depending on the heat in the sun). In the sun, the fuel expands in the tank creating pressure which has nowhere to go but does force down into the fuel tap thereby screwing up the whole vacuum thing in the tap and stopping the fuel from flowing. Simple fix is to leave the bike parked in the shade. Failing that, just open the cap for a short time before starting the engine and it should be fine.

[FROSTY]

I recently sold a zxr250a and the new owner has had a bit of trouble with the bike suddenly dieing after a while and not starting again for 5min then running again fine---- I'm pretty sure the carbs are good cos I cleaned them out before I sold it and would imagine that fuel line or filter problems would be gradual and effect performance rather then bringing the show to a grinding halt.
You answered ya own question.
Betcha anything when ya cleaned the carbs out you twisted or kinked the breather line for the tank.

[slopster]

You answered ya own question.
Betcha anything when ya cleaned the carbs out you twisted or kinked the breather line for the tank.

Possible. I don't actually remember there being a breather line there to kink I think that the breather might have just been an internal pipe exiting under the tank. I do remember the fuel and vacuum line were on the short side and easy to kink. I guess if I come prepared to put longer fuel and vacuum line on and unblock/unkink the breather that should cover all my bases. Might as well replace the fuel filter while I'm at it. Can anyone think of anything else?

Hopefully that will get the guy off my back. Fair enough though I guess I'd be a bit worried if I'd payed good money for a bike and had it cut out on me on the side of the road.

[FROSTY]

Give the guy a yeodle and ask him to try running the bike on prime.
That'll tell you if maybee the vacume line is blocked or disconnected
Then if still not fixed tell him to ride the bike till it cuts out and listen for a hissing noise from the petrol cap.If it does hiss then all he has to do is unblock the fuel cap vent. You can do that sometimes with just an airgun from the tubes top of tank