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350 2 stroke motor (basically) from new. (for the gearheads)

m in sc

Well-known member
Feb 2, 2021
Rockhill, SC
this is for the gearheads.

this is a 73 RD350 bottom end ive had for a long time, and it was just a spare. for one of my bikes, i wanted to do a full bore refresh with everything new, including ALL hardware, crank (banshee style), clutch basket (billet), etc. This motor had maybe 1500 mile son it before a previous owner a long time ago melted down the LH cylinder. there is zero wear in the transmission but even that got all new bearings etc. I bought this motor in a batch sale of motors, were 7 in total probably around 2015. This had been sitting in a bike outside and was so caked with mud on the underside you couldnt even see the lower webbing.

why? I have a set of cylinders out being ported by one of the last great engine tuners from the 70s (as a favor) and will be in the 75-80 rwhp range with this setup. Im currently around 72 at the crank with current motor.

Time to go big or go home (stock these had about 34 at the rear wheel).

post initial cleanup at home. this is 2 hours of scrubbing and lots of really nasty chemicals:

new billet clutch basket and cush drive

some of the new hardware.

picking up cases from vapor blasting on my 72 T500 ( i did bring them there on the trail)

back from the cleaning.

transmission, shift drum and a forks etc in.

underside, all the nuts are black stainless.

topside: again, all new stainless hardware.

Brand new crank. not nos, brand new. runout was almost perfect, well under spec. one spot just tipped the dial gauge at 0.0005" on my truing stand (yes that's the correct # of zeroes) for a split second (about 20 degrees of rotation).

earlier this month i also did a hydraulic clutch slave cyl upgrade (had an old aprilia one that was getting long in the tooth, i put it on back in -8 or so? to this one, and made a new adapter. this is all 100% reversible bolt in.

this is the recipient. This project will be 20 next february. Ist still running riding great now as it is.

Last edited:


Active member
Jun 4, 2022
Beautiful work, looks like a real fun project. It'll be rewarding when it's dyno'd and you see those RWHP numbers happen. Even more rewarding to ride it!