So, rode the bike to the garage on Thursday, went fine, sailed through its mot, when I went to leave it wouldn't run. Now this isn't the first time this has happened, allow me to explain....

Its a 1988 Kawasaki ZX400G Jap Import
Its just finished a 3 month strip down and rebuild
Bike runs fine until the temp gauge gets to half way (it never goes further than that, never over heats)
Then it will cut out, and the only way you can start it is on full throttle (but the revs never go above 1200) You also need to keep it on full throttle to stop it cutting out (release the throttle, bike dies)

Now, I have two thought. Either its something to do with the bike getting up to temperature - maybe something expands and blocks fuel or air.
Or, it could just be a coincidence that it runs for teh length of time it takes to get warm and be unrelated to the temperature of the bike. For instance, if fuel runs out in the float bowls after 10 minutes of riding, the bike will be up to temp but the carbs have run dry

After its been left for a few hours (usually overnight) it starts up with no problems

Now, I'm fairly new to biking but pretty handy with a spanner so anything you could offer as advice or suggestions to check I would be very grateful

Thanks

check you carb settings, check if the choke work propertly ( come back fully ), check the main's and pilot jets.

it's sound like you bike it's extremly rich and thats why you need full trotle to keep it running because when you full trottle the butterfly its all open and allow your engine to breath, check the colour of your spark plugs when this happens


sorry about my poor english.

Someone had the same problem at bruntingthorpe - was it laminator? Had the bimota. Check with him.

That got hot just about started on full throttle but didn't rev at all, cooled down and ran like normal. Never seen anything like it.

Yeah the Bim YB7 has the same issue. Before Bruntingthorpe it went for a fueling dyno run so I'm confident the mixture and carbs are ok. I think it's a fuel delivery problem from the tank to the carbs when it's hot. Either vapourising or trapped pipe, it's very tight under the tank. I've lent my tank and airbox to the other YB7 owner so I can't run it at present.

I don't know but it could be the same for you. I was thinking of running the engine with the tank on, until it's hot and has trouble starting, and time how long it takes. Then leave it for a day to let it cool and be at the same point it was at the beginning of test. The next time I start it I plan on removing the tank and setting up a dummy fuel tank. Start and run up to temperature and see if the problem persists and if it does did it happen at the same time as before.

Fitting a different fuel delivery system could eliminate the tank, fuel tap, pipes, etc.

If the bike runs fine with the tank on and hot, but only warming up on tickover then it could be fuel flow, thus emptying the float bowls when the engine needs more fuel when on throttle.

It could also be electrickery!