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Old 05-02-2014, 06:26 PM
Theon Theon is offline
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Join Date: Jan 2014
Location: FNQ Australia
Posts: 1,440
Default Re: 4 stroking

Hi compression and slant head made my motor run too hot.
Slant head and 40mm stroke is bad combination.
Not hard to do a squish test.
Also if your primary compression is not enough for final compression, may also cause 4 stroking.
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Old 05-02-2014, 09:54 PM
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maniac57 maniac57 is offline
Old, Fat, and still faster than you
Join Date: Oct 2011
Location: memphis Tn
Posts: 4,486
Default Re: 4 stroking

I had the exact same problem with a brand new motor. No other signs of air leak besides overheating. Plug looked fine, ran fine for ten minutes at a time, then refused to shut off and began dieseling.
Turned out to be a bad crank seal that had been installed improperly.
Look for the air leak.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.
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Old 05-04-2014, 04:54 PM
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rogergendron1 rogergendron1 is offline
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Join Date: Sep 2013
Location: woburn ma
Posts: 882
Default Re: 4 stroking

i wont run ANY stock head no matter how its modded... well not unless you plan to weld huge cooling fins to it lol !!! especialy one with no squish band and shaved down for higher comp ratio !

i run damn near 13:1 comp at close to 9,00o rpms and my bike runs like a champ ! its all in the carburation and tunning and oil mix......

i run a puch 70cc high comp head and a thin .4 mm head gasket on a decked jug with a close squish clearance, balanced and lightened top end (wrist pin and trimmed piston) with a larger 16mm bore intake intake and a 16mm carb......... no reed conversion....

and trust me with the higher comp you will want it running a tit bit rich, you see a piston port 2 stroke should break into a light four stroke on a flat with no load on the motor but snap right back into a crisp 2 stroke when the throttle is cracked. that is the proper tune for a piston port 2 stroke. also if you plan to turn higher rpms or higher comp you may want to go with a LEANER MIX,that means more oil in the gas and run a larger jet... 32:1 is leaner than 100:1 and requires a larger main. 100:1 is a rich mix 32:1 is a lean mix most people think its the other way around but its not .... adding more oil LEANS OUT YOUR MIX !

ohh and the best plugs i have found for high comp is the nkg b6hix and nkg br6hs and champion l86c ... the nkg r type is a resistor plug and will help if you get interfearance with your speedo, the nkg b6hix is a great iridium plug and should be used with high comp heads and the best plug for the stock head i found to be the champion plug
here to stay and compleatly insane ! deal with it lol

Last edited by rogergendron1; 05-04-2014 at 05:02 PM.
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