Dominant saw V4 371 build

[Marshy]

Other option is to have the squish band turned...

 

[Funky sawman]

Not an option for me, 5 dollars to me might as well be 500

 

[Dub11]

Found my issue with the ring......no issue. When I tightened cylinder down with that after market gasket I used two screws on opposite corners, the piston didnt hit. Then I found if I tightened all 4 corners then i have contact. Best case scenario is a factory gasket that's .020 and I end up with .010 squish which is scary tight

I've heard tail of factory jugs having squish bands out of wack.

Have you tried the oem piston so see if it makes contact?

If you did and I missed that sorry lol.

 

[Ronie]

You could make you own gasket if you have some 1/32 gasket material, it's a little more than .030.

 

[mettee]

I stuck a .010 feeler gauge on each side of the jug to space cylinder away from crankcase and tightened the jug down, at this thickness the piston just barely kissed the squish band. So I must need a .030 gasket?

Again, take an old piston and put some paper on it and sand out .010, whatever it is so you get .020.

You got this

 

[Funky sawman]

You could make you own gasket if you have some 1/32 gasket material, it's a little more than .030.

What's that gonna do to port timing, it just sounds to me like a good way to throw off numbers. The dominate piston is about .030 taller from pin to crown without counting the popup. Then include the cut intake skirt and exhaust cut that gives more ex duration, man alot of stuff going on here that is above my head

 

[Funky sawman]

All I have is a new piston

 

[mettee]

All I have is a new piston

You have any other piston that's the same diameter? Wood mandrel like Scott uses could be made on the cheap.

 

[Funky sawman]

Nope no other pistons. All my saw stuff is gone, literally all I have is files, piston stop, feeler gauges, bar wrench, spare chains and sprockets, then this 372 with one fact new piston and a dominate saw piston, yep folks that's it

 

[P.M.P.]

You have any other piston that's the same diameter? Wood mandrel like Scott uses could be made on the cheap.

I was going to suggest this.

 

[Funky sawman]

I should have just bought a new ms462rcm and been done with it, but I wanted a project to ease my mind, and no better project than the popular 372 chassis, which I've rebuilt over a hundred of them in my years as a tech. They said it would be easy..... yes that's what I thought lol

 

[Funky sawman]

So what's it take to get/make wood mandrel?

 

[huskihl]

I’d send this piston back for a refund and either run the stock one or get one of DDave’s. Never heard of crown height being that far off

 

[mettee]

Looks like 50mm or 1.96"

 

[Stevetheboatguy]

Probably take it a week to get there but I can send you a 50mm piston to clean up the chamber. I wouldn't run it and it may be for a xt but to stick some sandpaper on it will work.


Steven

 

[Funky sawman]

Yea, I dont really feel comfortable modifying the jug. Mainly due to the fact if this dominate saw piston doesn't work out and I need to go to a factory piston, then my squish will be too big. I think I'm just gonna try, again try to send piston back. I'm not sure what kind of return policy they have in place for something that has been run for 5 minutes

 

[Funky sawman]

Still have atleast .030 squish with fact piston and no base gasket. Checked by stacking cut pieces of feeler gauges lol

 

[Funky sawman]

Ok so after exhaustive measuring, a .016 gasket puts me at ground zero with ring installed on the dominate piston using either cylinder head. So if I use 1/32 gasket that should be in the ball park of .014 to .016 squish . Plausible or no go guys?

 

[Funky sawman]

Stock gasket would put me at .004 squish. I will have to contact dominate about that one

 

[drf256]

I think you’ll need to try the solder method for squish. Your method is probably flawed and making you run in circles.

I’d be glad to mail you out a few feet of .026 and .033 solder. I actually use a drill to turn my saws over and check squish, I find it to be more accurate than rocking the flywheel back and forth at TDC.

You can stack gaskets if needed with a little sealant. I also have brass shim stock here in various thicknesses I can send you some of.