1978 WR250 17 inch wheel and other questions

Take the springs out and measure the stroke of the fork. A WR fork will travel about 10.4", CR/XC almost 12"'

Also the MM (1979) and up frame's triple clamp height is a few inches higher than the ML so the forks need to be longer to start with.

I would say that the frame looks to be 1978 OR as the cradle looks rectangular compared to the the semi tear drop of the normal 1978 ML frames.
jimspac, Friday at 8:08 AM House Keeping
Interesting. Yes it is rectangular and has the extra rail unlike the CR's. It seemed to have many of the bits of a WR, including the 17 inch rear wheel, but who knows. For some reason I thought the '78 OR had removable steering bearing cups? The subject bike has permanent cups. Was the 2066 motor used on both OR and WR?

Swingarm bolt is out, that took some work, several cycles of heat and penetrating oil were required. Engine on the bench, I scraped a ton of crud from it which revealed a crack in the case in one of the mounting holes, so that will need to be welded up. For the first time, my case splitter failed me, and would not split this case. The bolts that hold the splitter arms to the case flex too much and despite gentle heating and rubber mallet love taps it will not budge. Going to fabricate something from a rigid plate that will not flex, unless anyone has other ideas. The rigid plate style seems to be what the factory used back in the day.

Rear loop straightened out fairly well. It was bent down and to the side, but nothing some clamps, wood blocks and gentle heat could not cure:

excellent

Get one of these.

https://www.rockymountainatvmc.com/p/731/17167/Tusk-Crankcase-Splitter

Inexpensive at $70 and it is an exact copy of the Honda case splitting service tool, it will work on any engine vintage or modern.

while you are at it, get the tusk "crank puller" as well, so you can reassemble. the tusk stuff works

That's the one I have used many times, but would not split these. That may signal another issue like the crank rusted into the bearing or bent crank, but I did not want to crank any harder on the tusk setup. It was making the bolts tilt inward a bit rather than perpendicular to the case. A rigid plate against against the face may allow for more force. And yes all case screws are out.

something is wrong then for sure...with all screws out, you are in three of the ignition cover holes?

Yes, it was fully into three holes. I did get it apart finally using a plate of steel with a hole in the middle to get a three jaw puller on (cant take credit for this, I saw it on an old CH post). I was able to screw the plate tight to the case in all four ignition holes with this set up. I then used some heat on the crank and a shot of freeze off and it finally came loose. Right side crank was rusted onto the bearing pretty good. Good news is trans looked good and was still bathed in oil, but the autopsy revealed that this engine died because it ingested some water and dirt. Crank cavity was filled with it as was the crank web. And the right side case appears to have had a fix where the shift drum sits in its hole....hate to see that sh*t, never have confidence in those type of fixes. I'll heat the cases tonight and pull all the bearings to see if it was JB weld, or a properly welded fix. Might make sense for me to source a new right side case as that is the side that has a partial crack in the motor mount area.

smart move I rekon, hard to enjoy riding waiting for the weak link to break....

Cleaned the cases last night only to find more horror....rot at the bottom of the crank cavity. Left side is probably salvageable, right side would require some artful welding and then planing down the face, but I have a feeling once I sandblast the surface to prep for weld, I would find more deterioration. I put an ad up on here and Marks Vintage for some cases, hopefully something comes through. Here's is a pic before it was thoroughly cleaned, you can see the chip, and when I cleaned it a good 2-3 inches of the lip was rotted.

sadly, this can happen a decent amount with magnesium.

250 cases are pretty easy to find, usually many sets on eBay at any time reasonably priced. I for sure would not waste any time trying to fix those.

Here are some cases.

http://www.ebay.com/itm/1976-Husqva...ash=item4b0ccbdb6e:g:pJUAAOSwal5YNM1a&vxp=mtr

http://www.ebay.com/itm/1977-HUSQVA...ash=item1c4631f4d1:g:FuYAAOSwnDZUFf7r&vxp=mtr

http://www.ebay.com/itm/1981-Genuin...ash=item33c3f67d72:g:~PEAAOSwoBtW11DT&vxp=mtr



Heck, here is several whole engines for $400.

http://www.ebay.com/itm/1978-HUSQVA...ash=item4d4cc45dab:g:TmwAAOSw-CpYASLR&vxp=mtr

http://www.ebay.com/itm/1978-1979-H...ash=item3f6963ce29:g:ggsAAOSwgZ1XvOFt&vxp=mtr

I did not think pre 78 cases would work? Different part numbers and some, like those from the 76 seem to have an extra hole in the right side? What am I missing there? In any event a member came up with a set for $50 and confirmed no rot.

I don't think an 81 would work either - appears to have larger countershaft hole?

On my OR frame I salvaged the bearing cups for another frame I am building on. I had to cut through a weld bead to remove them

If the 2066 # is for a 250wr or OR. I had already checked to find the 1978 250WR and OR used the same engine, including transmission.

Thanks Jim, If you think that is an OR frame, then I would not doubt you, but I'm going for the WR build.

I'm delayed yet again. After welding on a new kstand bracket, I discovered the bearing bore in the swingarm is elongated on one side and does not properly hold the bearings. Sourced what appears to be a good one (who the f knows on ebay) and will have to cut the new bracket off and reweld.