Unlocking a motor

[tony27]

I have a CZ sidepipe coming which I've been told is locked up, has been sitting a long time so I don't know exactly how bad but knowing CZ bearings I assume rings stuck to the cylinder is the most likely reason
What is the best product to soak the cylinder in to slowly work on freeing things up?
Once the cylinder is free I'll be replacing every bearing in the motor, depending on condition of the bore I may get away with rings for a 360 which are available unlike I suspect pistons

[TT5 Matt]

wd40 worked well on a xt500 swingarm pivo.t bolt after giving a spray every time I walked past it for a month.with your motor after soaking cut a piece of timberto act as a spacer  that will allow you to use the head/head studs to help break the locked/rusted piston rings by tightening the head down evenly

[tony27]

That sounds gentler than beating on the end of a lump of wood

[TT5 Matt]

true less stress on everything

[PeterC]

"Penetrene" was the Go to product for unlocking bearings and bushings etc, Perhaps old School compared with WD40 but was before the one can does everything scenario. I still use it when I want to unlock something, particularly when "rusted"

[Oldfart]

brake fluid a kero mixed at 50% ratio

[fred99999au]

Yep, Penetrene is the ducks nuts.

Had a top shock mount for a DT250F well rusted in. Sprayed it day after day for a few weeks, some gentle percussive maintenance and the parts were separated and somewhat reusable.

[bazza]

kero/brake fluid @ 50/50

[OverTheHill]

Where'd ya find one of those Tony. Not too local i hope or i'll be kicking myself lol--again.

[tony27]

Steve Gallichan picked it up amongst a package of 4 bikes & parts, he kept the Maicos & gave me first option on this 1 as he already has a 360 sidepipe that he's restored. Needs to get a twinpipe now so he has all the stages of CZ evolution
Going to take a far amount of time & money to get it race ready but I never thought I'd get my hands on 1



Already have the correct shape front guard & a JOK radial head coming for it, the biggest expense will probably be the getting the forks rechromed.
May have to see what parts I can come back from the CZ worlds with next year depending on how far along the rebuild is at the time

[80-85 husky]

the yanks have a product called pb blaster oe such which they swear by for unlocking frozen locked pistons etc. there are some truly horrendous "unlocking motors" posts on cafe husky!!

[OverTheHill]

Amazing what's still around if ya can find them. Who replaced the Jerkoff with a Mikuni--sacrilege!!. & the days of forward mounting shock experiments [koni's for tony?]. With the back up high compared to original she'll be keen on tank slapping. Na, all good & lucky you. was it an NZ find or did Steve import a container load. Has one of those plastic guards with a terrible arc--i had a bundle of blue ones i cut & pulled around then braced at the side cut. Looks like it's gusseted at the shock mount. Did similar to my 360 a lifetime ago but only braced it simply with a bit of flat in a straight line & during the day thought it's getting lower & was spreading out sideways lol. Anyway--stop woffling.

[tony27]

Was found in Auckland I think but has a south island history, sounds like Paul Doecke knows who raced it back when Paul won the New Zealand title in 69 or 70

[tony27]

Motor freed up amazingly easily, only had the kero/brake fluid mix in the cylinder for a couple of days.
After washing the motor with degreaser & the water blaster I loosened off the head & cylinder base nuts, top of the piston was fairly clean & the head has no signs of damage at all. Out of curiousity I tapped the top of the piston with a dead blow hammer (no room to swing it) & thought I saw movement so I kept going.

This is what I found. Piston is in good condition but fitted backwards, somehow the rings hadn't snagged the exhaust ports

Bore within spec & only in need of a hone but new rings may not be available

[tony27]

I need to get the rings out in 1 piece now, the place who have rings only go to 80.75mm & I need 81mm. If I can get the rings free & measure the gap it will help me decide on what size motor I'll have
Any suggestions on what to soak the piston in that will soften any carbon etc without damaging either part?

I split the cases to find 50 year old Czech bearings & a gearbox with most gears looking great so apart from a rod kit it shouldn't require much that I don't already have to rebuild the botton end