Help! My GSX-R250 won't start.

[Unforgiven]

I need help!

My bikes dead!

It wont start, it just turns over and backfires every 15 seconds or so.
Ive pulled the air box off and sprayed some carb cleaner in and changed the spark plugs, the old ones wernt too bad.

It has spark and seems to be getting fuel.

The big problem is I need it going this weekend.

Any ideas?

Its a 1990 GSXR 250

[T.W.R]

Did you check which leads went to which plugs when you changed the plugs ?? sounds like you've mixed the leads up

[NighthawkNZ:Me]

Did you check which leads went to which plugs when you changed the plugs ?? sounds like you've mixed the leads up

was going to suggest that...

[Grub]

And if it's not that then it sounds like the ignition timing has slipped or a bit has broken

[Unforgiven]

Leads are all in the right place. It was doing it before I changed the plugs. It could be timing but I dont have a timing light (or know how to set the timing on it). Anyone local that could come over and have a look? its a bit late I know, Ive been working on it all day. I took it down to Maunder Suzuki earlier and they said to try plugs and clean the carb. It runs ok and starts once warmed up, but now it wont start at all.

[Ixion]

What do you mean "it runs ok and starts once warmed up but now won't start"?

You need to be a lot more specific. Do you mean that until now it has been fine, starting OK (hot or cold) etc (for how long?) , but now , suddenly, has started misbehaving? Did it stop when running? At high revs? or idling? Or just not start one morning? If so was it running OK immediately before (how long since you last roide it? Is it kept under cover?) ? Or do you mean that it has been reluctant to start when cold for some time (since when?) but now won't start at all? They are all quite different issues. You need to PRECISELY state what is wrong and the COMPLETE history of the problem.

If you just say "it won't start" my diagnosis would be that your engine has been stolen. Be specific.

(If it won't start how did you take it down to Maunder Suzuki?)

[T.W.R]

Leads are all in the right place. It was doing it before I changed the plugs. It could be timing but I dont have a timing light (or know how to set the timing on it).

The ignition is digital on a 90' GSX-R250, so no timing as such, so check to see if the pulser/pick-up coil hasn't worked loose & the gap between it & the rotor is set properly.

[Unforgiven]

It has been running badly for a couple of weeks, cutting out under load. I ran it low on gas, so it may have picked up some crap from the bottom of the tank. I ran some fuel injector cleaner in the fuel, which helped. In the last couple of days it has been hard to start, when it finally did I rode straight to Maunders. Unfortunatly it wouldnt play up while it was hot. It did have a slight misfire while it was running.

[Unforgiven]

The ignition is digital on a 90' GSX-R250, so no timing as such, so check to see if the pulser/pick-up coil hasn't worked loose & the gap between it & the rotor is set properly.

How do I check that? I havnt spent much time working on bikes. mostly on diesel trucks and injected cars.

[Ixion]

Strip carbs and fuel tap (and any filters) , and a cupfull of meths in the tank. CAREFULLY and THROUGHLY clean the carb jets. Does this model have a fuel pump or is it gravity feed?

[BAD DAD]

Not familiar with your model of bike but if it DOES have carbs are they the type that have rubber diaphrams? Had a problem a few years ago which turned out to be a minute tear in the diaphram of one carb. Sorry if this has no relevance to your situation.

[jonbuoy]

If you can get to the carbys you could spray some CRC 5-56 into the inlet - needs to be directly into them - where you can see the throttle slide, while you crank it if you get a decent spray down their throats it will fire on the CRC, least you will know if its a fuel or ignition problem.

[T.W.R]

How do I check that? I havnt spent much time working on bikes. mostly on diesel trucks and injected cars.

not 100% sure on a gixxer250 but by rights it should be under a small cover R/H side of the engine at the end of the crankshaft. Under the cover should be a rotor disc with a tang on it and the pulser coil should be off to one side slightly. the gap shouldn't be any more than .5mm

[Unforgiven]

Ill check the rotor disc in the morning. Ive had the fuel tap out and the filters and cleaned them. Its gravity feed, no pump. Ive tried engine start into the carbs, no success. I havnt pulled the carbs off yet, but I might have to.

[Ixion]

Fuel comes out the far end of the hose when you turn the tap on ? Lots of it?

EDIT. I assume that when it IS running it runs OK? As in no rattling noises, normal amount of power etc?