WR250F 2004 - Engine stops running as if seized

First post.

I have a 2004 Yamaha WR250F, I have only owned it for 3 months and entered my first ever race in the UK after 27 Years away from Motorcycles.

The bike was prepared for the race with tips from the internet modifying radiators, using sand tyres, new brake pads, coolant, oil, straps for pulling the bike out, high pressure radiator cap etc. The only thing I didn't change was the clutch. Guess what let go during the race, Grrr the clutch.

I got stuck in a rut full of water and burnt the clutch out getting out.

Back home I cleaned the bike down, and found that the electric start wouldn't work. Kick start was fine and bike run ok. Left it a week went back to the garage to strip the clutch down. I warmed the bike up to get the oil flowing and the bike just stopped a couple of minutes in. I went to thumb the starter (which for some reason was working now) and nothing. I then tried to kick start the bike and it was solid. I couldn't believe that the bike appeared to be seized.

I took off the cap on the ignition cover and put a socket on the flywheel nut and the engine turned fine. I moved the kick start and this now moves freely.

Ok so I tried the starter again and it eventually kicked over and ran, it only ran for a minute or so and stuck again. The kick start was again stiff and would not move as if seized. The electric starter won't move either. I again turned the flywheel nut and it moves freely.

I think either the starter is sticking or some how the damaged clutch is causing the engine to stall and stick.

Your advice would be appreciated before I proceed any further.

Delboy

Just guessing based on your description that maybe you got some water into the engine and didn't get it out after your race. I'd pull and inspect the spark plug for signs of water or rust etc. I'd also drain and inspect the engine oil closely for metal and /or water. If that doesn't yield the clues you need, and the engine still won't turn, then it's probably time to start digging into the engine itself.

You might get better advice on details of engine diagnosis in a forum for your bike though. This forum is for the WR250R dual-sport and WR250X supermoto bikes. They have different engines than the WRF bikes. (No kick starters on our bikes either.)

The reason that the clutch has burnt out is that I was stuck in a deep rut full of water. I didn't consider that I may have gotten water into the engine. It run for a couple of minutes before it just stopped.

I don't want to start it again until I have a good idea of what is causing it.

I appreciate this is a forum for a different bike, however it looks so similar I thought that I may get some good answers from you guys.

Thank you for time, it is really appreciated.

Delboy

First question that comes to mind is:
What's the condition of the engine oil, and is there enough of it??

Dismantle the Clutch. I reckon that's where you'll find bits of broken clutch plate locking the basket.

Either that or there are chunks of burnt fibre clutch plates blocking oilways and maybe the strainer.

It's very possible that your bike has seized due to obstructed oil circulation. I believe it's always unwise to run any engine after burning the clutch. I don't know where your oil strainer is, but draining the oil as suggested above and taking the clutch cover off (you have to do it anyway) might reveal some answers.

Hope the damage isn't too bad - it might only be the broken plate, like Elm said.

Thanks for the replies they are very much appreciated. I have spoken to a number of mechanic friends at work and the majority point to the clutch or clutch basket as the potential culprit.

I only ran the bike to drain the oil, otherwise this issue may not have occurred? I won't have time to look at the clutch until the weekend and will let you know what I find.

Drained the oil today which seemed a little low. Took the clutch and basket out. No broken parts but very brown/burnt. I will attach a picture when I work out how.

Kick start moves freely and nothing sticking. I am fairly confident that this is just a clutch issue so will buy new clutch and fit. Not sure about the condition of the clutch basket and carrier so will check those with a mechanic.

Delboy

I hate to be the bearer of bad news but...
My buddys yz450f did the same thing your describing when the crank was shot.
It ran fine until up to temp then seized solid until it cooled off.

I doubt it's the clutch, it wouldn't seize the motor when hot then work after it cooled, all a bad clutch would do is slip or be locked up so you couldn't use the clutch lever. If a piece of fiber or metal was jamming the clutch so the motor couldn't turn over it wouldn't unjam when cooled off.

I have found it strange and after taking the clutch out haven't found and parts to Cause it to jam.

Not the diagnosis anyone wants to hear but if that's the case that is what I will have to deal with unfortunately.

Thanks for the feedback.

Delboy