1981 250R resto-mod

[81300R]

Wanted to start a build thread on my project.

I picked this bike up in tucson AZ. Was told it had a rebuilt 300. They tried to use a polaris piston in it, which was the wrong compression height. Needless to say it didnt run right.

I decided to take the motor down and have the crank rebuilt. I did quite a bit of research and found a shop out in California that had a 300R Wossner 77mm piston, the only one left from a batch they had made. The 300 has some mild port work, and (the only one ive ever seen) a S&S Headers expansion chamber.

After pulling the motor i stripped it to the frame and gave it a fresh coat of red. I cut the swinger apart and stretched it 3”.

New seat cover, new plastic, PWK38.

Planning to powdercoat much of the parts. Not going for show, but a nice rider. Trying to recreate an early race bike. I love the look of the Selvy 250R.

[81300R]

[81300R]

Played around with some powder. Ive got Candy gold coming for the swinger and triples.

One of the best tools ive purchased has been a Redline powdercoating gun!!

[Footy]

Looks good! First time I have ever seen a supertrapp on a 2 stroke.

[81300R]

Looks good! First time I have ever seen a supertrapp on a 2 stroke.

Thanks, it was something i had on the shelf for an XT600 i used to own.

Blasted and put the base coat of chrome on the swinger and triples.

[81300R]

It was pretty difficult to get an even coating of the translucent candy gold. Had to go pretty thick. Came out ok i think.

[81300R]

Fitting some parts while i wait to get my crank and 300 cylinder back from the machine shop.

[sjsst41]

Looks good ! It’s amazing how much time goes into these projects when you have to do something to each & every part, but satisfying when it all starts to come together.

[81300R]

Looks good ! It’s amazing how much time goes into these projects when you have to do something to each & every part, but satisfying when it all starts to come together.

I wasn’t planning on going quite this deep but every thing i took apart was trashed


The shock was leaking a bit of oil around the bladder, cleaned it up and with a bit of grease around the sealing surface it held a nitrogen charge again, until the hose blew. Substituted a 10,000 psi rated grease gun whip for that.

Forks stripped down for seals, of course all the teflons are trashed as well. Wheel bearings shot. Brakes missing. Polaris piston in a worn out 76.5 bore. Crank bearings toast. List goes on!

[81300R]

Found that a sprocket for a XL175 uses the same bolt pattern. JT sells a 38T under 30 bucks.

Put the brake together.

[81300R]

Repaired a few cracks in the front wheel, mounted the sprocket and shock reservoir, and got the bottom end put together.

[atc300r]

Man I'm loving this build.

[81300R]

Rebuilt the forks and port matched the intake and exhaust adapters.

Had some major issues with the paint i used. Taking way too long to dry. Giving it some heat..







not me images

[81300R]

Paint is finally setting….Bottom end in. Top end on. Single shim out of a FL350 headgasket for a bit more compression. A bit more port matching to do on the intake. Paint fish eyed on the head so ill have to redo that.

Fun seeing it come back together.

[81300R]

Got it fired up. Funny enough it still isn’t running properly. Sounds like a rev limiter past 1/4 or so throttle. I assume a CDI issue. If anyone has one i could try it would be greatly appreciated!