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46cc rep polini motor hot up help

1565 Views 5 Replies 5 Participants Last post by  nesikachad
if got a rep polini 46cc with pollini blue crank . gen pollini flywheel .19mm gen dellorto .pollini green reeds ports have just been cleaned up and exaust port a little bigger .set squish to .54 if thats wrong sorry i 4 get exactly what it was . what else can be done .iam in sydney so been lookn 4 some1 that does good port work ?any input would be gratefull tar
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Reset the squish to .042", when the cylinder gets hot it expands... I do my portwork myself with a dremel tool.... there are tutorials available.... theres also a guy on here that does porting, but you would have to send your cylinder head and piston. He also taper bores carbs I believe.
Need to find someone there, cause shipping prices kill everything now days.
Sam, Boosted306 don't do water cooled cylinders.
"Quench height" as its known in other racing circles is the space between the piston crown and the quench ring on the cylinder head.

In the work I've done with methanol/nitromethane powered engines (aviation purposes) the best performance I found was with a quench ring set at 10% of the bore's diameter. This is the width of the ring or it's "thickness".

The quench height I had best success with was .5mm (.018") with a relief angle of 1/2 degree. Keeping the transition edge from ring to chamber helped with throttle response. Breaking the edge slightly is supposedly good for a little more max power but I never noticed it.

Hope it helps.

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