1979 CR 390 - Engine re-build

My good mate's 1979 CR 390 came to a grinding halt at Farleigh castle last year and I've been asked to strip her down to find out why ?

Basically the gearbox has sh1t itself....see pics, but I've found a few odd bits that I would like to share that I've not seen before. The piston has two rings for a start, but the main issue is the crank half shaft isn't a mail thread, which is what I was expecting to see. I've not looked at one of these for years and I'm not sure if the Motorplat hasn't been changed as well.

The old man is coming down at the weekend to give me a hand but I thought I'd ask the fellow Husky experts for their opinion.

Not seen this type of motoplat before...is this an update from the original ? Also not plane shaft end..?

5th - 6th Gear well and truely shagged...!!!

one possible culprit for the gearbox crapping itself. The circlip holding gear 411 (6th) in place wasn't properly located allowing gear to lift.

Twin ring piston..

Its interesting how that c-clip came out of its groove. Those suckers are pretty stout and when they are in, its permanent.
It may be better to consider picking up a complete transmission. I scanned Ebay this morning and found this '81 250 CR transmission that someone is auctioning off. It has a blown 1st gear but Tritrophy in Oregon may have one on hand. Here is the link:
http://www.ebay.com/itm/1981-HUSQVA...Parts_Accessories&hash=item3f14755dbf&vxp=mtr
Husky transmissions are pretty interchangable with other models and years as long as they are six speed. In other words, the case holes are the same for the CR, WR, and OR. They changed the countershaft to more serrations in '81, but I'm pretty sure the entire transmission will fit into a '79 case.

Twin ring on my Wiseco too. Small W in an oval underside on wrist pin casting.

Thanks for the input chaps.

The piston issue is the last of my mates problems at the moment. However, the Wisco piston has a couple of quite big washer / spacers to pack out the small end of the conrod (if that makes sense)

With respect to the motoplat....the guy who did the mod, did a brilliant job of loctite (ing) it one...stuck like sh1t to a blanket. My only real issue is that he used a torx cap head screw with a washer to hold the mag on...? As a result the cap head screw and the mag have made a nice trepanning mark on the mag cover.

Does anyone have any thoughts on the Motoplat ? I've never seen one like that on a Husky ?

I'm seeing the piston being a minor issue at the moment. As for spacing washers either side of little end, I'm just having some made up in ally bronze for mine as we speak, needs 0.3mm min clearance. If you PM me the dimensions when you finally get back to the top end I'll m/c some up for you. Good luck with the rest !

Cheers for that mate....I don't need spacers, I was just questioning the use of them. Without measuring them I say they were a couple of mm each side ?

Probably will be that thick. Check the clearance on re-assembly. You probably know they control the float on the big end ? Worth checking when rebuilding, don't suppose you have checked big end/ crank/mains yet...?

Only checked mains play by hand (not measured)...no great drama's with that.

No takers on the Magneto I.D ?