1979 WR 250

more of a difference than you think!

Try the WR arm. It makes a nice bike.

Question, I’m seeing a lot of late 70’s heads that are drilled I’m guessing for compression releases. Are they orginal factory or done by the owners? I know the early to mid 70’s square heads had compression releases.

My drilled head is clearly an owner job. Although decently well done, one of the fins is slightly broken, and the access area for the plug appears milled, not molded, which I believe it would be if from the factory.

I drop the crank, cylinder, new piston (71.0) and new rod with a machinist tomorrow. He also disagrees with the PO's statement about "good compression".

As far as swing arms go, my intent wasn't to change, I just bought the OR thinking it was interchangeable, and then discovered otherwise (though it is sound, and did come with a few good add-ons, prompting me to consider the change). I think I've got a line on a passable WR swing arm.

Need a swing arm eBay?

They have a nice spark plug threaded adapter for the 10mm compression release too.

I purchased a counterbore with a long pilot so I can drill the pilot hole then machine down through the fins and make a flat counterbored area so the compression adapter will seal. Or just drill it for a 10mm threaded hole to fit the compression release. Depending on how much room I have between the pipe and head. I want a professional looking job when it’s done.

eBay? We're debating compatibility and almost all of the swingarms are listed as "CR/WR/OR" and look like they were removed from their donor bike with a hammer. I'm looking to other sources first.

As for the compression release on the 250, maybe in a few years, I can still kick over 400's though.

Save your wear and tear on your knees now. Don’t push it like I did. If my knees get and worse they will put my feet where my knees are. Just call me stumpy. Lmao. A little crazy glue.? Lol

No really to anything possible to make it kick start easier now. I was a tough guy picking up 400lb parts by hand. One day I carried 40 guide rails that weighed 265lb each.

They both affect geometry. The different shock mount affects geometry because with the same length shock the rear of the bike will sit lower than with the stock swing arm and you will have less travel. The secret is to use a WR swing arm with longer than stock shocks, this jacks up the rear end, changes the effective steering rake, and slightly increases rear travel. Going with a CR swing arm and WR shocks is the wrong direction.

yes, I belief it effects both also. Very minor but think of a radius motion, your swinger moves in a radius motion not vertical as it travels up and down. Just a thought the 79 250 is not known for its awesome gobbs of horse power with the shorter of the two swing arms you may have a slight advantage of pulling the front end off the ground when need be arrives in a hurry.

You guys seem to be losing perspective on the fact that I prefer to use the WR swing arm and

nobody said I would use the WR shock if I used the OR swing arm.
Regardless, my preference is for the WR arm, just waiting for one source or another to come through with one that is serviceable.

Check it out, hone marks at the correct angle!

New question for you guys to fixate on. Anyone know where I can get this type of rubber damper? There are 4 holes drilled down through all of the fins, then these were pushed (or maybe pulled) through. Engine guy said he thought they looked fairly model specific, so I thought I might see if others have the same ones and know where to get replacements:

Don't know about factory replacements but you can probably find proper diameter rubber stock from Mcmaster Carr or Grainger.

I was looking on McMaster, didn't spend a hugely long time might try again. Grainger is a good call too I have one close enough to make a long lunch of it...

The honing stone marks should be closer together when using chrome rings which require more oil. The closer cross hatch allows more oil. Castiron rings require a faster cross hatch. The grit of the honing stones matters too. My small bore engine hone comes with a 280grit max. My 250cc and up engine honing stones come with 500grit stones.

When using a gear driven engine hone to make the bore so it’s not tapered you go slower on the tighter end of the cylinder. This way the bore taper won’t be there.

Just trying to give tips not to flame anyone.

My old man taught me that there are some things you just don't do on your own. Maybe you don't know how, maybe it's just really important to get right, maybe even you just don't like doing it. For these things you find someone who REALLY knows what they are doing. The guy I went to has been working on these things since they were new. Not saying I doubt your wisdom, Bill, just saying I trust the guy I went to.

I been honing cylinders, boring cylinders and rebuilding engines for many decades. There’s a different cross hatch pattern for cast iron rings and chrome rings. Same as different bore clearances for cast pistons and forged pistons. I got into boring and honing cylinders for dirtbikes because it’s hard to find a automotive machine shop that will touch a dirtbike cylinder. I had a sunning gear driven adjustable hone since I was a teenager. It was my dads. It was finally wornout. I replaced it with two new lisle gear driven adjustable hones. I know what I’m doing. I’m a class A machine erector/builder. There isn’t one thing that you touch during the day that I built the machine to make that part. I built CNC machines accurate to the millionths, lathes with chucks from 36” to 144”, assembly involves fitting bearings to their bores sometimes honing. I assembled 155mm howitzers for the US Army. I built CNC machines that manufactured the m1 Abrams upper and lower turret ball bearing. I built a CNC machine to manufacture the main engine rotor for the m1 Abrams tank. I build chuckers that manufacture discs for disc brakes for every brake manufacturer in the world. I helped spec out the steel for the Disney tower of terror. My last job was a lead engineering tech for one of the top ten engineering groups in the country. I worked in the r&d lab, failure analysis why tings break. Tested new product development.

Now your telling me I can’t hone a cylinder? Your kidding me right? Kidding.

For chrome rings you want a tighter cross hatch this gives the rings more oil in the grooves. Otherwise the chrome rings will take longer to break in.

Everytime I sent my work out to be done they screwed it up. I had to fix it. Now with labor so expensive it’s cheaper to even buy the tools I need and do it myself. Right now I need a press for doing bearing replacements in the cases. I’m going to build one. I even make my own tools. I needed a tube socket for doing Honda forks, I made my own husky case disassembly and assembly tools. Stupid me I sold them with parts when I gave up riding. I do what ever it takes to get the job don’t right. There is no way to do it other than the right way. I accept nothing less.

If you have a good guy in a machine shop consider yourself lucky. In today’s times I went to rebuild a starter for my small block Chevy. I had a small machine shop I turned the armature myself. The guy in the parts store wanted me to buy a rebuilt started for $50 when I only needed a $1.50 set of brushes which he didn’t have. There are no real mechanics anymore only remove and replace mechanics. We’re a dying breed of do it yourselfers.

And yet, you get even the most basic of mechanical principles wrong, all the time. If your posts were not littered with errors people might put more weight in them. I'm not trying to be rude or insulting, just stating the obvious.

I’m like trump I’m a target no matter what I say. The perfect man was crucified don’t forget that.

Bill, I've got great respect for your background and skill. I also know that I don't have the skill to machine or hone a cylinder. If you were near me I'd hire you in a heartbeat and take your advice. You're not, and so i went with a local guy who has been in the business since before I was born. I'm not about to go back to him and tell him he demand a new hone job based off of your analysis of one poorly lit photo. If a bike can run with a rounded out smooth cylinder, or after ball-honed by a yahoo with a drill, the way some end up, I'm sure it'll run even if the professional hone job is not ideal. If it somehow fouls the cylinder out, I'll tell you that you told me so....

Eric your guy did ok.