engine just quick

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blak__jak

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I've got one for you guys. I was running my m/t yesterday and the motor just shut down. at first I thought the plug had given up because there were no odd sounds or anything. it just quick. anyway after checking it out I've got spark and the compression seems normal. it turns over smoothly and I even went so far as to change the carburetor out with a known good one and I've done everything to insure it's not flooded but still can't even get it to pop. I do have a killer bee but it's making all the right beeps and as I said I've checked for spark and that's not the problem. what next? any ideas!!
 
it's not so wet as to be flooded but some fuel is present. even so I did try a little fuel in plug hole already with no luck. I've tried quick start also and it didn't fire at all that way ether. it's got me stumped so far. guess i'll be tearing this thing apart if I don't get any fresh ideas. thing is like I said it turns over fine and the compression seems ok so I hate to tear it apart if I don't need to.
 
Hi try your head bolts.. If loose the head lifts and you loose comp and spark,It happen to me last week.
 
haven't checked the head bolts but compression seems normal. will check them though momentarily and let you know.
 
larryo said:
Hi try your head bolts.. If loose the head lifts and you loose comp and spark,It happen to me last week.
Click to expand...
+1 on the head bolts.also check to see if the head gasket is sticking out of the back of the head...
 
just checked. head bolts are tight and no signs of leakage or head gasket damage and as mentioned compression seems ok. ????
 
that's actually the first thing I did since when it died that's what I thought was wrong. I've had a plug give up in the past with the same symptoms and was sure that was the problem but not this time.
 
I don't think a air leak is the problem since I changed the carburetor and gaskets to no avail but thanks for any feedback.
 
Also have you tried to start it without the kill switch hooked up? I know you said that you have it set up fine its just that when I am trying to find a problem that I just can not get I like to just start all over from start and see if that me be the problem or not.
 
I didn't check the coil gap or try it without kill switch because I had spark and what seems like a good amount, not weak or yellow but white and enough to give me a good jolt when holding the plug wire wrong.
 
If everything is as it should be, fuel, compression and spark it should run, technically. However, I guess it is possible the flywheel could of sheared the Woodruff key and in turn, a loss in timing. It happened on my CR500 and 125 bikes.
 
well it's been a couple weeks now and I've tried every thing I could think of and i'm still stumped. I checked the gap on the coil now and actually changed out the coil with the one off my d/r. still nothing. I guess it's down to taking it apart. I don't know what else to do. like I've said before I've got spark, compression, fuel and not an excess. I've changed the plug. I've changed the carb. I thought by now I knew a little about these engines but this thing is really puzzling me.
 
well finally got around to taking it apart today and though it did seem to have normal compression it couldn't have. I don't have the right adapter to fit this engine for my compression gauge so I was just going by the way the motor felt when turning it over and by putting my finger over the spark plug hole. i'd say now that this is not the way to judge compression on these little motors because when I got it apart I found that one of the retaining clips from the wrist pin had came loose and destroyed the head. anyway problem found and soon to be resolved. just wanted to kinda close this thread because I know how I hate it when people leave ya hang'in
 
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