Building a 290/390

[MasterMech]

I'm just waiting for the opportune moment to put the bearings in the toaster oven so I can get rollin on this build.
Seems like there isn't enough time during the week for me to do much with saws.
I'd rather hang out with the family.
Maybe tonight I'll fire up the oven when the wife goes to bed

Yep, I work on the honey-dos mostly during the day and when she goes to bed, I call that "second shift."

 

[paragonbuilder]

Yep, I work on the honey-dos mostly during the day and when she goes to bed, I call that "second shift."

My wife won't go to bed without me... I'll take it as a good thing with 19 years approaching.


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[idiotwithasaw]

$6 a bearing, cheap insurance I think. When you checked the bearings were they lubed or did you clean them with brake clean. lube can hide a rough bearing, just because it isn't catching doesn't mean it's good.

 

[MustangMike]

Thanks, I'll check them more thoroughly as I go along, but so far they seem to be VG, and I would rather keep used OEM then go new AM.

 

[Adirondackstihl]

Thanks, I'll check them more thoroughly as I go along, but so far they seem to be VG, and I would rather keep used OEM and go new AM.

Manufacturers use a wide range of bearings when it comes to crank bearings.

NTN & slacker are most prevalent although there are others.
FWIW, I paid $8 for sealed NTN bearings here.
I just popped the seals out with a pick

 

[Lightning Performance]

LOL; this thread has to be killing someone

More than likely

Hey great thread ya got goin..... I have a ms290 and when she does, I want to make it a 390.....do you guys always rebuild using OEM parts..... Have any of you ever tried buying the whole engine assembly?????

Don't buy any leftovers from Bailey's

$6 a bearing, cheap insurance I think. When you checked the bearings were they lubed or did you clean them with brake clean. lube can hide a rough bearing, just because it isn't catching doesn't mean it's good.

That's damn good advice!

Thanks, I'll check them more thoroughly as I go along, but so far they seem to be VG, and I would rather keep used OEM than go new AM.

Me to

Bread and butter 290 brake handles are on sale for seven bucks here. Thank Bruce not me.

 

[Adirondackstihl]

So I had some time on Sat AM before I started to put a new roof on the garage and I managed to get the bearings on the crank.
The way I heated the bearings was probably a little different than most, but I did it outside......in a disposable cooking tray with regular 5w-30.......on the BBQ grill.

Worked perfectly!!

 

[MustangMike]

Holy crap, that don't look anything like what I'm used to seeing!!!!

I'm trying to wrap my head around how those transfers work! I'm ascared of this!

 

[Onan18]

Holy crap, that don't look anything like what I'm used to seeing!!!!

I'm trying to wrap my head around how those transfers work! I'm ascared of this!

Open port my friend, they actually run pretty well, have a nice fat torque curve. The Husqvarna 51, 55, and 257 are also open port although not a clamshell.

 

[Adirondackstihl]

 

[Adirondackstihl]

Gonna let it sit overnight, then press & vac test it tomorrow before I go any further. That includes leaving the rear bar stud out until then.

 

[Canadian farm boy]

I haven't had the privilege of rebuilding a clam shell saw yet.
I'm just curious how hard it is to get the piston with the rings installed into the cylinder?
It doesn't look like the normal plastic ring compressor would work

 

[Adirondackstihl]

I haven't had the privilege of rebuilding a clam shell saw yet.
I'm just curious how hard it is to get the piston with the rings installed into the cylinder?
It doesn't look like the normal plastic ring compressor would work

You're right Mike, it doesn't work.
Patience, a small screwdriver & finesse is your friend here.

 

[Onan18]

Stihl actually makes a ring compressor for the 1127 series, I have one somewhere, works really well.

 

[Adirondackstihl]

Stihl actually makes a ring compressor for the 1127 series, I have one somewhere, works really well.

Yup
Funky lookin thing

 

[MustangMike]

Jeremy, thanks for the excellent pics, very helpful. But, I have a question, do you use sealer on the base, or just gaskets?

 

[MustangMike]

Has anyone ever tried to play with the upper portion of those transfers??? The boxy look of them just seems like it does not facilitate a smooth flow of the mix.

 

[angelo c]

I haven't had the privilege of rebuilding a clam shell saw yet.
I'm just curious how hard it is to get the piston with the rings installed into the cylinder?
It doesn't look like the normal plastic ring compressor would work

no need for any special tools. You just wiggle it in...together with the rings on. no xhit.

Stihl actually makes a ring compressor for the 1127 series, I have one somewhere, works really well.

see above. Ive done about 10 clams so far and never needed a tool. and Im just about spastic with my manual dexterity.

stone serious. Lube the cyl and piston and don't use a screw driver or anything just wiggle the piston assembly into the cyl.
you'll laugh once its in and say huh ? WTF was all that about. must have been a lucky shot....but it aint.

edit. just remembered there is a slight "taper" that allows the "wiggle" way.

 

[angelo c]

Jeremy, thanks for the excellent pics, very helpful. But, I have a question, do you use sealer on the base, or just gaskets?

I seal the entire case and around the bearing pockets as well. there are a few "spots" that look like they may be tough to get at to seal near the bearing pockets but a qtip or some other implement will get it in.
there are no "gaskets" per se.
clam is different then pro.

 

[MustangMike]

Thanks for that Angelo, I can see this is going to be much different than anything I've done before.

Would putting the cylinder in a vice with the spark plug facing down facilitate the build on these things? I'm trying to work this out in my mind before I actually get there.