Losing Compression?

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mkunzel

New Member
Jul 11, 2009
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About a week into having my bike up and running it would start to die after 5-10 minutes of running. I checked the plug and it was dark and wet so I changed it and the bike would run again for a day or two and the same problem would persist. I changed the clip on my slide so it would run leaner and the plug no longer gets wet but the bike still dies out after running for a few minutes. I've checked the carb and it does not seem to be flooding and I've switched my CDI with a friend's that was working and the problem persisted. The head bolts are tight, but the exhaust port leaks oily sludge at the bottom because the stock gasket is rather crummy. Everything is stock except the plug which is a Autolite 4093. If anyone has any ideas as to what I can try next it'd be much appreciated, i'm out of ideas. I can provide pictures if that helps too.

Update: I dropped the clip on the slide down two slots and tightened the plug a bit and it runs better but still tugs at high rpms or going up hill.
 
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noobtard

New Member
Apr 25, 2009
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I'd still be pointing my finger at the plug..

the stock plug worked good for a couple weeks.. decided to get a Champion L78C for a spare(because NAPA didn't have any NGK's..)

was bike-less for 3 weeks or so thanks to a sheared rear mounting stud.. (but that's another story)

anyway when I got it back together my bike was running like p00p. had half power or less... the champion plug worked better... for half a block.. then it died and refused to start again.. cleaning both plugs yielded the same results..

I dumped a cap of 2stroke down the plug hole a walked it around with the plug out for a while(my rings still aren't set, yours probably aren't either so, may be worth a try..)

stuck the stock plug back in and rode to Napa.. got a NGK B7HS,B8HS, and a Champion L92YC

stuck the B7HS in.. was a nice ride home... almost all power back.

The Champion L92YC should only be used for slant heads by the way.
I stuck the champion plug in a little later, has been running awesome since.(credit to kermit05 for that plug idea..)

ANYWAY, sorry to make this so long.. but, try a new plug is my bet...
 

mkunzel

New Member
Jul 11, 2009
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I have a slant head and a champion from previous replacement attempts so I will try putting some two stroke in and walking it, should I use synthetic or no? I haven't been able to find a NGK at any of the auto stores around here which is really bothersome. Thanks for the tip!
 

noobtard

New Member
Apr 25, 2009
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what mix have you been running?
In my experience I used 16:1 semi-synthetic for "break in"... only problem was... it never "broke in"....

so, now I've been running 16:1 regular 2 stroke.. rings still haven't set yet.. I'd say I'm up to 600~ or so miles.... 6th gallon of gas I think..(3rd gallon of reg. oil)

still waiting/hoping..

p.s. the Champion L92YC is supposedly a direct replacement for the stock slant head plug.. it's just a tadd bit shorter than the stock plug.. the NGK's etc are Much shorter..
 
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mkunzel

New Member
Jul 11, 2009
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MD
I started out on 16:1 for the first gallon and i've gone two more gallons on 32:1 but I guess i'll switch back.