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2009 Sherco 250 Wont Run Right

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Hi all I hope someone can help me coz im about stumped. Just over a week ago I dropped my bike and it got completely submerged in very muddy water. Obviously I was straight home to clean it all out, ive cleaned the airbox, carb, cylinder and crankcase and exhaust thorouly. Put it all back together and its running like a pig.

It will not start or rev up without choke wether hot or cold and even with choke in it takes gentle persuasion to get the revs up, once it is reving reasonably hard you can knock the choke off and it will run well enough to ride it as long as you keep the revs high. It wont idle at all it just stalls unless the choke is in.

I have tried two different carbs, all the carb settings under the sun, changed the spark plug all with the same result.

What am I missing?? Any help would be greatly appreciated.

If it was running when it went under water, it could be damaged reed valve.

  • Author

It was running when it went under but only for a second coz I have a lanyard kill switch that killed it as soon as I came off. I havnt checked the reed valve tho might be worth a look.

definetly double check the idle jet again , if the bikes not ticking over at low end revs then i recon thats where your problem lies.. like thats a five said .also drain the tank and put fresh fuel in.

i did this on my evo it killed the cdi which on an evo is just over £200

  • Author

Yeh one of first things I did was drain fuel and put fresh in tank. Ive tried two different carbs on it, one with brand new jets in it, with same results. Would it still run if CDI was bust? I did think that the spark didnt seem that strong tho hence why I changed the plug.

It was running when it went under but only for a second coz I have a lanyard kill switch that killed it as soon as I came off. I havnt checked the reed valve tho might be worth a look.

How did you clean out the crankcase and cylinder and not the reeds. I think you trashed the main bearings running it after you thought you cleaned it. Did you remove the cylinder and flush out the mains and rod before you started it? Unfortunately a full rebuild is probably needed. Does it grind while running? Good luck.

  • Author

Yeh I took cylinder off and cleaned the crankcase out but not before trying to start it after giving the airbox and carb a quick clean to try and get it running straight away. I am also begining to think I may have goosed the bearings. I am going to try and replace the crank seals today to see if it is sucking air in through them. Oh and the stator and flywheel are dry and seem fine.

Yes, that sucks. Twice in my life I totally submerged bikes less than 30 days old. Once in a eight foot deep hole!

Voice of experience right there!

  • Author

Well ive changed both crank seals and its still no better. The clutch side crank bearing does sound a little noisy and there is a small amount of play in the stator side but that wouldnt stop it running right would it?

Any more bright ideas? Could it be the cdi?

You haven't said what you found when or if you checked the reed valve petals .

Your original comments stating that it will only idle on choke points to a fuel/mixture issue.

Ignitions can do some weird stuff at times, but not usually like this. That ignition does not know if the choke is on or off!

The initial water issue is a major factor here. Hopefully things are really clean by now after all this tinkering. I would carefully remove the carb and break it over a pyrex or clear plastic collector to see what comes out the bowl. Using a light you may find small debris or water droplets. Clean out the jets again with a fine wire.

You can spray around with carby spray to detect air leaks if carefull with it, try WD40 first.

M2C

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