project weedbike started a good few years ago as a bmx powered by a weedeater motor, the pullstart died and that was the end of that.
we now have a 66cc ht motor
stripped it down the day it arrived and began "fixing"
new bearings and seals for the crank
new bearings for the output shaft
some spacers to keep the little end needle roller in place
lubrication holes to crank bearings
matched the crankcase to the trasfer ports
in all our haste to strip the motor when it arrived we failed to notice that at BDC the piston covers half of the transfers and exhaust port, a semi-simple fix: a 4mm ally spacer under the jug and the piston crown is now tangent to the exhaust port at BDC, no gasket, 5min epoxy to seal jug to crankcase.
raising the jug changes port timing, the inlet side of the piston skirt needed trimming and the exhaust port needed to be raised
transfers: i could not get my dremel slinky attachment in there so i scraped them smooth with a piece of sharpened HSS.
176deg exhaust
133deg tranfer
155 deg inlet
the head was a failure, had it welded like Foureasy did, but the welding had bubbles. so we made a button style cc that will be held in by the old head.
60%squish
more to follow in the new year,
busy designing the tuned pipe now.
we now have a 66cc ht motor
stripped it down the day it arrived and began "fixing"
new bearings and seals for the crank
new bearings for the output shaft
some spacers to keep the little end needle roller in place
lubrication holes to crank bearings
matched the crankcase to the trasfer ports
in all our haste to strip the motor when it arrived we failed to notice that at BDC the piston covers half of the transfers and exhaust port, a semi-simple fix: a 4mm ally spacer under the jug and the piston crown is now tangent to the exhaust port at BDC, no gasket, 5min epoxy to seal jug to crankcase.
raising the jug changes port timing, the inlet side of the piston skirt needed trimming and the exhaust port needed to be raised
transfers: i could not get my dremel slinky attachment in there so i scraped them smooth with a piece of sharpened HSS.
176deg exhaust
133deg tranfer
155 deg inlet
the head was a failure, had it welded like Foureasy did, but the welding had bubbles. so we made a button style cc that will be held in by the old head.
60%squish
more to follow in the new year,
busy designing the tuned pipe now.
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