WR390 rebuild/questions

Isn't that location of that Mark is close to where the opening of the skirt on the piston is? That's a machining mark the more I look at it. See the other mating mark to the left of it. They cut a circular clearance for the piston skirt so they clear the rear and front in the block and the cutter just touched the sides a tad.

Remember to do the leak down test after the engine is reassembled with new seals and gaskets to make sure nothing is leaking.

I learned the hard way about doing the on the bench leak down test. We had a 125cc honda where the PO was prying off the cylinder and it mushroomed the material in the base gasket area enough to cause an air leak. The leak down test showed why it was running lean. It pays to recheck to make sure it's right. I use a fork pump to do the leak down test.

I think that it is a machined grove for clearance, but the cut in the groves is what had me thinking, could just be from a cutter though.
I definatly will be doing a leak down test once i get it together, im not willing to take any chances after getting all the work done.
From what i could find i think i will be able to make the case asembly tool and i can make the case separator, but it looks like im going to have to buy a flywheel tool unfortunately. There is a shop down the road that sell gas gas and occasionally husqvarnas and the do work on bikes so im going to run down there soon and see if they have anything that would work.

I might have just got really lucky, i was talking to my father about the puller i need for the flywheel and he suggested i give my uncle a call. Now my uncle back in the day used to be big into hill climbing (he used a bsa) but mainly he built and raced drag snowmobiles, so he has a lot of old tools and such around still. I gave him a call and said he would call me back after he looked through his garage. After a bit i got a call back and he didn't have one but he said he has a friend was a motorcycle mechanic and a huge dirtbike guy, he also did a lot of engine building for race bikes (he did the engine work for my uncle) and things like that and still occasionally will do work if its a bike he is into and its the right person. So i gave him a call and from the measurements we took it looks like he has not only one but two and that if it fits i can have one. He said it was for a bultaco but from the measurements they are the same. After talking for a bit he said he wanted me to bring the bike over and that he is going to keep looking and see what else he can find that i could use. Hopefully the tools he has will work for my bike but either way at least i have another good person whose brain i can pick.

i can believe it, probably a puller thats shared as they both used a motoplat and maybe femsa? have him check the timing, some of these ol timers get a kick out of younger generations liking this stuff..they are thee brains to pick!

Yea after talking to him it sounds like they might share the same motoplant, i will find out for sure when i get to his place.
Also before i split the case does the transmission need to be in a specific gear? I haven't seen it mentoned in my manual and i want to be sure if he wants to split the case.

Went out and meet my uncles friend at his place and the puller he had is the right one so i got really lucky today. I ended up talking to him for a couple hours. Turns out he raced flat track and sold bultacos, and he have me some ghood advice for working on these old bikes. One of the coolest parts was when he took me into the back of his shop and showed me a old 250 yamaha dirtbike but he droped a mild built xs650 motor in it, aparently it is good for around 115mph and it was one of two he built.
I hopefully will have the case apart tonight when im out of work.

they gotta!!! be in 4th when you go to put it all back and make sure you kickstarter is timed right cuz its all goin to hell when you pull the shaft out to put the new seal in but we'll get you though it its not that bad

Ok i noticed it had to go together in a gear but i wanted to make sure it didnt have to come apart in one.
I got the flywheel off and the case split. Everything looks good inside.

The only thing i wasnt sure on was that there seems to be a broken piece on my mag,

and the inside of the flywheel is getting rough,

Im not really worried though because it all works and i have good spark.

match your transfers to the barrel while its in bits(after you open the transfers to match the gasket shape) Husky were pretty good getting it right but its worth checking, makes them smoother.

Well i know its been a few years and i haven't posted in a long time but i could use some advice. I finally have gotten time to put the bike back together and she runs great, but it doesn't want to go above second gear i'm not sure what could have been put together wrong. The only manual i have is for the 360 which in my manual the transmission is different. Does anyone have any idea what i could have done wrong on assembly, with the case split it seemed like it would go through all the gears right but from 1st to 2nd it doesn't want to go right to 2nd it wants to stop in neutral and then go to second after a second click it goes to 2nd, but doesn't seem to want to go past 2nd.

You have to setup the transmission in fourth gear as it is a six speed non primary kick engine. There is a view in the workshop manual that must be heeded as that is the biggest problem to manifest the assembly of the engine. Always verify the shifting prior to putting the rest of the engine together.

Do not feel stupid as it has happened to me and a few others having to split the cases 2 or 3 times before getting the shifting correct. One tip to live by is to use gasket cement to pin the gasket on the left centercase and lightly grease the side of the gasket. This allows you to split the cases anytime without ruining the centercase gasket.

Im curious as to the intake ports on a 390. Mine is a 78 OR. When i had the motor rebuilt, I noticed the intake ports were large rectangular. It looked to me like factory. Now I've seen a couple pics posted of a CR and now a WR cylinder showing the intake ports that are L shaped, mirroring each other. Are my intake ports a rectangular shape because its an OR? ...or has it been carved out...

On the 2nd pic, that blemish on the Motoplat is just a chip of the potting and as long as you do not see components , coils, or cracks it will not be a problem. I would take some 5 minute epoxy and build it up in case the potting is thin there. Motoplats are worth that little extra attention.