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1988 CR250 Hard Starting - Won't Stay Running

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Need a little hep.

 

I bought a 1988 CR250 a few years ago, I'm pretty sure it was raced. Always started hard, but ran pretty good once I got it started. It was too aggravating to start so I did the following;

 

New Rings - Compression is now approx 140 PSI

New stock reeds

New NGK stock spark plug

Stock jets

Fresh gas - 32:1

AIr screw 2 turns out.

Kill switch has been removed

New tranny oil

New clutch

 

It's now still difficult to start, but now it will only run for about 20 seconds and dies, no matter what I do with the throttle. In order to get it started again I have to wait about 5 minutes, then it will start again for about 20 seconds and die. If I try to start it again right away, it won't fire. Wait about five minutes and it starts again. I thought I might have weak spark, it doesn't look blue when it sparks. I bought an inline spark plug tester from Harbor Freight, and it indicates good spark. Not sure what to do next. Any next steps in troubleshooting would be greatly appreciated.

 

Thanks

Chris

 

 

 

 

 

 

 

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Sounds like you having a bit of trouble. I was looking on Youtube and there a ton of guys who have bikes from the '80s and they go through a starting technique which I thought was stupid. Give that a go. Type in for example "how to start a 1985 cr500". If that doesn't work you could try taking it in to a shop. 

When I had my CR250 it was very difficult to start if it sat for more than about a week. Try looking in the bottom end to see if there are any problems going on cause mine needed a new bottom end. 

 

Good luck.  :ride:

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Thanks for the reply. Are there any other ways to determine if there are bottom end issues besides a pressure test?

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Need a little hep.

 

I bought a 1988 CR250 a few years ago, I'm pretty sure it was raced. Always started hard, but ran pretty good once I got it started. It was too aggravating to start so I did the following;

 

New Rings - Compression is now approx 140 PSI

New stock reeds

New NGK stock spark plug

Stock jets

Fresh gas - 32:1

AIr screw 2 turns out.

Kill switch has been removed

New tranny oil

New clutch

 

It's now still difficult to start, but now it will only run for about 20 seconds and dies, no matter what I do with the throttle. In order to get it started again I have to wait about 5 minutes, then it will start again for about 20 seconds and die. If I try to start it again right away, it won't fire. Wait about five minutes and it starts again. I thought I might have weak spark, it doesn't look blue when it sparks. I bought an inline spark plug tester from Harbor Freight, and it indicates good spark. Not sure what to do next. Any next steps in troubleshooting would be greatly appreciated.

 

Thanks

Chris

 

I own a 1988 CR250 and it starts like any other 250cc 2 stroke engine, which is to say nothing like yours.

To me it sounds like you have a air leak someplace and a pressure test is really the only way to definitively test for air leaks. The previous jetting, was it richer or leaner than the current stock jetting?

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