A forum for owners of Yamaha TTR250 trail and enduro bikes!

TTRfan wrote:

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Check petrol is getting through into the carb in case the petrol tap is blocked (happened to me the other day) or the float valve is sticking by undoing the carb float bowl drain screw. Does petrol flow out quickly?

If not, see if its flowing from the pipe that goes into the carb to eliminate the petrol tap. If it is flowing there then tap the side of the float bowl sharply a few times with the blunt end of a screwdriver to free up the float valve.

However, the fact that it doesn't fire on the starter fluid indicates a compression or ignition problem.

Brian

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 Definitely check the fuel first, pull out the spark plug and check that it's not shorting out with a bit of carbon across the gap

Put the cap back on the plug and hit the starter button with the plug earthed against the motor, You should see a strong spark, if no spark you have a short somewhere or a dead coil

Then do as Brian says and check the compression

Put the plug back in and turn over by hand with the kick start, you should have a far bit of resistance there

If there's no compression there you had better find yourself a workshop manual and go through the troubleshooting section

Good Luck

BMSteve

Thanks everyone.

Confirmed strong spark and fuel is making it to the carb.  My next step is to pull the carb out and do a full cleaning.

Why did Yamaha have to make getting the carb out such a pain?  My Honda XR was literally 3 bolts and it easily pulled from the side.  One practically has to disassemble the Great Wall of China to get the TTR carb out. Sigh.

Jell wrote:

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Thanks everyone.

Confirmed strong spark and fuel is making it to the carb.  My next step is to pull the carb out and do a full cleaning.

Why did Yamaha have to make getting the carb out such a pain?  One practically has to disassemble the Great Wall of China to get the TTR carb out. Sigh.

 

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 If you are getting nice bright blue spark and have tried starter fluid I highly doubt that cleaning the carb will help, unless it has water in the cylinder or carb or it is flooding with fuel, although it won't hurt to try. I would suggest to do a compression test cold and hot. If you cannot start it to get the engine hot, run boiling hot water (from the kettle or boiled on the stove) over the engine until it gets hot. If you get vastly lower readings when the engine is cold, the rings will need doing. If it stays at the same low reading, the valves will need work. If you don't have a compression tester, you can try using your finger over the spark plug hole while pressing the start button. It should blast your finger away from the spark plug hole. If you can hold your finger on it or it seems weak, either the valves or rings will need doing.

I feel for you about the carb but once you get the hang of it is a 10-15 minute job (depending on whether the tools want to go walk-about lol). Not quite as quick as my WR400 though. All you have to do on it is loosen the clamps, take the fuel hose off and pull it out.

Jarrah