please help!

[tom_bish]

This is not nova related but im sure someone can help with this problem.. its been driving me mad! :tard:

Ive got a CR 125 1990 motocross bike and it stopped running a while back.. i found that the bottom end bearings had gone because there was slight up and down movement in the flywheel which was kicking the timing out. I replaced these and rebuilt the engine and it fired up second kick and it ran fine with no problems at all!.. but after taking it out for a ride it wouldnt start again! After checking over the engine i noticed that the nut had come off the flywheel and the flywheel had come loose.. i knew this was because i hadnt done the nut up too tight because the thread on the crank was a bit dodgy and i didnt want to strip it.. silly me. The nut must have bounced around in the casing and shaved a small amount from the small sensor on the flywheel.. At first i didnt think this would matter too much so i put the flywheel bak on to see if it would start.. and it didnt! Thinking now it must be the sensor that was the problem i took the flywheel off and had the sensor built back up with weld and filed to its original shape. I then put the flywheel back on and this time used a new nut with locktight and did it up using an air gun.. Bike still does not start? It will chuff every so often indicating an ignition but just wont fire up. There is a fat blue spark and the spark plug is getting wet.

Ive tried moving the stator plate behind the flywheel to different positions to adjust the timing but there is only 2mm movement. Also the magentic sensor on the stator plate which piks up the sensor on the flywheel can be moved into and out from the flywheel. How vital is this gap?
How vital is the sensor on the flywheel? Is repairing it with weld ok? :confused:

[tom_bish]

Forgot to mention that i forced some fuel through the carb past the slider kicked the bike over a few times (about 5) and then it JUST started.. but it picked up really slow.
however it wont start normally.

[craig0120]

strip and rebuild carb, check reed valve

[pul16v]

if its sparking mate theres no probs with fixng the sensor with weld the only thing i can think off from your discription is the wood ruff key that locates the fly wheel in place is it still intact as ive had bikes b4 that would start when this was sheard off and they still spark as well
why did you move the stator plate ?

phil

[tom_bish]

Ive stripped and rebuilt the carb. I was speaking to a mate last nite and he said that the float might need adjusting as it needs to cut off the fuel at about halfway up.. and u can do this by bending the tab on the float. The reed valve seems fine and the woodruff key is fine.

I was thinking that because the sensor on the flywheel has been damaged and repaired it has kicked the timing out? I imagine that the timing has to be exact as even the slightest movement up and down when the main bearings had gone meant that it wouldnt start.

I moved the stator plate just as an experiment to see if it would start. There are timing marks but it does not start when these are lined up.

I think ill try adjusting the float first and if that dosn't work there is an undamaged second hand flywheel on ebay for ?35.. would it be worth getting?

[DIY*VALVER84]

simple point...are the piston rings,piston,cylinder wall,bearings,gudgeon pin and con rod all intact i had the same problem as you on a 98 rm 250 that was down to needing the cylinder wall replating. had this done,battered the bike senseless it broke again so i went out and bought a spankers kx250 instead.