250x wont run after getting hot

[kilrfx]

So i have an 87 250x that fires right up and runs great for about 10 - 15 mins. As the bikes gets hot it starts to pop and back fire and then it dies. If i let it cool down it fires right back up and does the same thing.

Anyone have a similar issue or know what is wrong with my 250x?

Any help would be greatly appreciated.

Brett

[smr]

when it dies do you have spark?

if you do then I would say check valve clerance.

if you don't I would say it's your coil.

[sm00th026]

Yeah, It sound's like a coil.

[kilrfx]

Coil and CDI have both been replaced. It gets sparks when this happens. Tested the stator and it is within resistance specs of the manual.

Not sure but maybe it is fuel somehow?

Brett

[sm00th026]

Um, What's the compression when hot?

[audioworks04]

Fuel isnt going to do anything different with a warm engine over a non warmed up one. Is your fuel old? Are you running atleast 91 octane? Are your valves in spec? Is it burning oil through the rings or valve seals? Are you sure the cdi is good, it is a pretty common thing to go bad on these.

[smr]

So your still getting spark. That rules out all electrical.

Check your valve clearance. Your valves could be a little to tight. Then when the motor gets hot the are not opening up all the way.

[Maddog300EX]

Originally posted by smr
So your still getting spark. That rules out all electrical.

Check your valve clearance. Your valves could be a little to tight. Then when the motor gets hot the are not opening up all the way.

I think you have it backwards but don't Quote me on it.
All things get bigger/swell when thy get hot.
So if his Valves are to tight when it's hot thy will not close all the ways..
This may result in low compression and preventing it from running after it's hot.

I have a similar issue on my 300EX.
But it is do to my Valves being to loose.
It's hard to start and to keep running but runs great about 10 - 15 min as the bikes gets hot.

[smr]

Maddog300EX....thanks....boy did I say that wrong.

[Maddog300EX]

we all have days like that.
I hope i didn't offend you smr just trying to help
and explain what bad valve clearance can do.

kilrfx keep us updated

Valve Clearance for your 87 250x is
Intake and Exhaust
0.10 mm +- 0.02 mm (0.004 in +- 0.0008 in)
you will need a feeler gauge for this or
you can get bye with a American Dollar bill
According to the U.S. Treasury thy are .0043 inches. thick

[smr]

didn't offend me man. I just typed it wrong, glad you picked up on it or I would have looked stupid.

Maddog300ex has given you good advice. You can also cut a sliver out of a coke can fold it over once....used that many time at the races..

keep us updated.

[kilrfx]

First off thank you all so much for your responses and help with this.

It looks like it was the valves being too tight. I was able to finally get the covers off today and get her to TDC. Put the feeler gauge on the exhaust valves and they were right on.

Went to check the intake valves and couldn't get the feeler gauge even close to fitting. Lossened everything up made some adjustments and it seems to have fixed my problem.

I need to get back in there tomorrow and tighten them up some as they are wicked loud now. Hopefully I can quiet them down a little and not go back to my old problem.

Once again I can't thank you all enough for your help. Hopefully I will be able to get out this weekend and ride for more than 15 mins.

Brett

[Maddog300EX]

Nice we are happy you will be back out having fun on it..
I my self will be going out tomorrow in Athol MA
I see your From MA as well.
You never know we may one day meat up on the trails till then be safe and have fun.

Fell free to Subscribe to my Youtube Channel @ youtube.com/user/captinsnot
I try to post a video every time i go out and will have a new video up bye 10pm EDT 5-10-2012
one day ill get a Helmet-Cam so i don't have to stop and pull out my phone lol
Yes all my videos are from my phone in 1080P

[smr]

glad we was able to help...have fun and ride safe.