350x cylinder on 300ex lower??

[michigan rider]

is it possible to put a 350x cylinder on a 300ex bottom end and 300ex head? from what ive found the case would have to be bored and the stroke is different, so would a 350x rod work on the 300ex crank?

i know i could just put a 350x motor in the 300 frame, but i want to keep the electric start and the reverse.

[bradley300]

the motors are quite a bit different, i doubt it would work

[440exnacsracer]

you would at least have to trim the case for the larger cylinder sleeve, seems like too much work

[michigan rider]

yea i have all the tools to do that, trying to find out if the cylinder will fit on the studs, if i can use the 300ex head, and if a 350x rod and timing chain would work

[dork]

i've heard of it being done. the 350 rod is 131mm long and the 300 is 123mm, and the big end bearing and wrist pin is larger, so it wouldn't fit on the 300 crank. a stock 350 piston would give you 337cc. the 350x head is 1/2 inch taller from base gasket to head gasket surfaces, but the stud holes are in the same location. the timing chain cutout is longer on the 350 as well so it wouldn't seal all the way to the 300 head, so you'd need to use the 350 head as well.

[michigan rider]

.......ok then so i need a 350 cylinder, piston, and head
that means the 350 piston will fit on the 300 rod?
and when put together the piston will be 8mm below the head due to the shorter rod length, if so can i mill almost 8mm off the cylinder to gain some compression back?
finally what would i do for the timing chain, use one from a 350?
thanks

[400exdad]

dork: Man of few posts but great info. :)

[ajaxs]

I'm looking to do this with a 12:1 82mm set up from a 350x. was wondering if that extra 8 or so mm with the shorter stroke bring my compression ratio down to 11:1?

[dork]

How're you going to fit the piston? Providing you could, advertised compression would be about 11.6:1 when done. In reality, you'll be closer to 10.5 or lower when using stock thickness gaskets.

82x82x68x.7854=359cc in 350x

displacement/(compression ratio-1)=compression space
359/11=32.6cc

82mm piston in 300ex=346cc

(displacement+compression space)/compression space=compression ratio
(346+32.6)/32.6=11.6