79 CR 250 rebuild

I started working on the 79 CR 250 I picked up at mid-Ohio in July. The engine is locked up. After soaking it in the frame with PB blaster for 1 month it still would not budge. So I took it out of the frame and pulled the head. Luckily the bottom end was free so I was able to lift the cylinder and begin soaking the piston from the bottom. Tried freeing it with a 1x1 and a deadblow hammer to no avail. Then took a metal bar attached it to the studs and put a socket between it and the piston. Cranked it down pretty tight and wailed on it with a framing hammer till it moved. Soaked it some more and pressed it out with the same jig my increasing the height of the sockets as the piston moved down the stroke. Pressed the piston pin out earlier today. Shop manual has been ordered.

I will be splitting the cases in the next few weeks. This will be my first time doing a bottom end and tranny. My intent with this rebuild is to do as much as possible (exclusive of machining work) myself including rebuilding the rear shocks. Thanking you guys in advance for advice and answering what may be some dumb questions. My goal is to have it ready for Mid Ohio in 2018.

there are always hidden issues...but looks like a good bike! with a splitter and crank puller you can handle the cases no problem. plenty here to give any info you could need!

nice job getting that stuck slug out

Hahahah, The old piston stuck in the barrel trick. That's a very nice ride, Squid your gonna love it. If you need something just holler. these folk got me thru mine and it works now.

justintendo
I see in a previous thread you use the Tusk Crank Puller..Since their adapters are not left threaded I'm assuming you use the 25mm flywheel nut to pull the ignition side??....what did you use on the drive gear (left side) to pull the crank since that nut on my 79 is 32 mm and probably wont fit in the puller or did their "adapters" fit?....or will i have to heat the left side case, freeze the crank and install the left side first then pull the right side?

thanks
Bob

The flywheel is being as stubborn as the piston...been soaking it in PB blaster, heating with heat gun, and wacking the puller with the hammer for 2 days now...

Patience, and a long breaker bar. Puller all the way in, hook in the flywheel, lots of PB and crank it. I had to make my own 3 bolt puller for the sprocket on this new 450 and I still had to cook it with a map torch. You will win, easy and lots o pressure.

afraid i'm going to strip the puller...FYI Marty Strauss at Paradise Cycle in reynoldsville pa can machine your tapered counter shaft to take a splined sprocket...he did it for my 72 CR.

If you have an air chisel? But put a flat hammer bit in it instead chisel.
Rap it few times by puller threads and crank end. Usually sends a shock thru it to release it.

Kinda same theory getting two rusty pipe threads apart from a union.

I do same on primary gear. A rat a tat tat! Bingo!

See the hammer end bit?

If it's a husky brand puller you'll probably strip the flywheel first. Your fear is of breaking it, It was made to take that pressure! Aftermarket I'm not so sure. Also If you can while heated blow compress air directly on the shaft thru the observation holes to cool it. That's a delicate balance heat and cool. But repeated cycles will help. If you don't have compressed air I have used ice water and a straw. Also try tipping the flywheel on the taper using a 2x4 and mallet on the 4 corners (HAHAHA) of the flywheel. You don't have to kill it, just nudging. If YOU feel it's too much let it sit overnight again. Fresh start in the morning. I'm going to keep this 5 speed for the first motor. It is really excellent and will give the buyer the option of 5 speed and originality or 6 speed and lots of pull away. Good luck. And Failure is NOT an Option!

Any luck Squid?

not yet...taking it to a friend next week with an impact gun...he may have a little heftier puller also..the one I have would work fine if it wasn't stuck but I don't trust it on this one.....will let it soak in PB Blaster in the meantime...Got to get my KTM ready to race on Sunday..

Where you headed Sunday?

This is the type of thing I like my 12V battery/impact driver for. Enough power to jar a lot of things loose, not so much power that it breaks everything it touches.
Good Luck!

also need the correct husky " mangle " to put the cases back together unless anyone knows another way .

Use spacers and the nuts on the cranks to pull them through

There's never any dumb questions here at the Café. That's why I love this site.

ECEA enduro at Michaux State Forrest near Gettysburg PA

Have an awesome time. I'm not an AMA member, but will join soon. When I lived out west as a kid we raced the desert without a club, and we had no fear.