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Cr250 Won't Start

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I have a 1988 CR250 fresh after a top end rebuilt. I started the bike a couple of times and rode it around and then a week later it wouldn't go. I changed the reed valve and cleaned the carb and I also put an air filter in it. It has a fresh plug with good spark. The timing is fixed on the timing plate. I have tried all of the tricks like tipping it on its side and heat the plug up and nothing. Does anyone have an idea what's going on?

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I have a 1988 CR250 fresh after a top end rebuilt. I started the bike a couple of times and rode it around and then a week later it wouldn't go. I changed the reed valve and cleaned the carb and I also put an air filter in it. It has a fresh plug with good spark. The timing is fixed on the timing plate. I have tried all of the tricks like tipping it on its side and heat the plug up and nothing. Does anyone have an idea what's going on?

A 2-stroke will run a little richer after a re-build, maybe you fouled a plug.  Sometimes a plug can spark but still be fouled, is plug brand new ?

 

Here's a technique I use to start my big bores, works for smaller bikes too, see if this will get it started...

 

Turn the gas on, full choke, no throttle.  Get on the bike and put in first gear.  Now roll the bike back & forth swiftly,

(till you feel the compression resistance each way), do it at least 10 times.  Doing this puts a fuel charge in the cylinder.

Set the piston to TDC (top dead center) by using the kicker.  Give er a good kick & see what happens !!

Edited by Throttle5

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Did you repack your can by chance? I had one with a fresh top not start because I had to much packing in there.

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also try fresh fuel.

 

another trick is spray a bit(dont use too much) of starter fluid into the carb and see if it starts.

 

check the colour of the spark, it should be a nice blue.

 

and depending on how many hours you ride repack the silencer every 2 years, costs about $20. but it is worth it to know it is not going to be a issue... also keeps the sound level down a bit.

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shathappens1.gifI was wondering about the rebuild, is everything installed correctly, did you time your hpp valve correctly? does the crank roll? you messed with your reed valve, did you install the reeds correctly? Loctite the screws on said reed block..people think a rebuild is simple on a single cyl bike,,,,one last thing, did you break it in correctly, the junk man has a video of correct measuring and rebuilding, go check it out!

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When we sent the cylinder to be bored the guy we sent it to told us not to fool with the hpp valve, he said that it has to me timed correctly so I think he did the job(he owns a boring business and races a 2 stroke bike). The crank rolls and I'm pretty sure everything is together right. We got a clymer service manual and made sure the transmission moved correctly I did not loctite the screws in I will do that. I also will repack the can

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On my cr250 I have an fmf powercore the cheap $100 can and I can get neither the end cap or the pipe that hooks into the gnarly. It has given me nothing but trouble. Does anyone have a solution?

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Im trying to repack it

Shouldn't have to remove the end cap.  Just keep on tugging on the end with the pipe, it should come out eventually.  :smashpc:

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When cold full choke NO throttle.  Any throttle at all and my CR will not start when cold.

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When cold full choke NO throttle.  Any throttle at all and my CR will not start when cold.

also, slow kick it 3 or 4 times to prime it a bit then a good kick, if it farts a few more slow then a good kick.

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Well I repacked the can and what do you know it started, so turn it off and see if it wasn't lucky and it goes yet again but then I get it outside to take it for a spin and... Nothing

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