MS660 Port Timings

[GoBigBlue1984]

I just bought some OEM bearings for some 064's/066's. They were 16.99 for the PTO side proprietary bearing. But hell, even the standard 6203 OEM bearing is 14.99.
They are smoother than Nachi though. And I've used lots of Nachi bearings. At $4 bucks per bearing its hard to pass up.

 

[Nutball]

A big bore kit I got for a chinese 660 I'm assembling looks like 90, 115, 94 with 51 deg of free porting, and visibly no measurable squish unless I can get paper in there. All this without the base gasket. What do y'all make of that? I guess I'll need lots of epoxy. I'm looking for torque, so I don't stress out the chinese parts with rpm.

 

[cus_deluxe]

Sounds like you have a paperweight. 51 degrees of freeporting with the stock exhaust at 90?

 

[cus_deluxe]

That exhaust port must be

 

[Fruecrue]

A big bore kit I got for a chinese 660 I'm assembling looks like 90, 115, 94 with 51 deg of free porting, and visibly no measurable squish unless I can get paper in there. All this without the base gasket. What do y'all make of that? I guess I'll need lots of epoxy. I'm looking for torque, so I don't stress out the chinese parts with rpm.

That’s terrible.

 

[Mastermind]

That’s terrible.

Par for the course with this BB kit nonsense.

 

[Fruecrue]

Par for the course with this BB kit nonsense.

 

[Wonkydonkey]

Sure you don’t mean 5* FP (free portin), if you do mean 5* and use a gasket that may get the squish you want and less FP

But maybe recheck your numbers first

 

[Nutball]

 

[Wonkydonkey]

I can’t like that..

 

[Mastermind]

View attachment 165058

The perfect representation of Chinese garbage.

 

[MustangMike]

The New West Big Bore kits for the MS 440 needed a lot of work, but at least they were useable! Got a couple of them to run very well.

 

[Nutball]

I checked it another 5 times, I may have not been measuring from exact tdC. 94,119,85 is how it looks now without the gasket, the gasket needs to be enlarged slightly because the piston hits it and stops.

I guess this will be a high rpm saw, it was to be my personal casual race saw anyway. I guess I'll build a torquey 660 too for hardwood.

Still no squish, how bad is that? Is a squish band really that important? I assume it slows the burn rate reducing detonation and increasing torque, so not having one will...what? Still work for high rpm?

 

[Fruecrue]

What do you mean no squish?

 

[Wonkydonkey]

Yes the gasket has had to be inlarged for some peeps in the passed, unless you got a std 54mm gasket.

In my first post I said if you a gasket, it may well reduce the free portin and give you the squish you want, iirc, there are two gaskets, one thick and a thinner one.

You never know you may need both. Which could give you the squish you need (20thou) and it will change those port timings a bit more...

So sort the squish and then do the timings, but you need to be sure about tdc.

There are many ways to work it out, it’s just not worth telling you how to suck eggs, until you tell me how you suck eggs first

Btw... do you know how to get the correct measurements in checking squish. I only ask because. If you don’t, and you get it wrong. Well the results are not so good if the piston hits the top...

And only asking all this, cos I’m being nice, and would not want your saw to be ruined.

 

[Nutball]

The flat ring in the top of the cylinder is what I'm talking about. The crank will turn past TDC with a .004 thick piece of paper stuck through the spark plug hole to the cylinder wall, and I can feel it touch the paper. 2 pieces (.008") takes some pressure to pass TDC, 3 layers will not let it pass. Visually the piston touches the top of the cylinder. My only issue I guess is that the exhaust height will be even higher with the gasket. I need to get a lathe sometime, I'm saving up for one, looking at a mill combo from Grizzly if the reviews are good.

 

[Fruecrue]

You can cut or sand band by hand.

 

[Wonkydonkey]

Ave a read of this thread

http://opeforum.com/threads/measuring-squish-on-my-ms200t.7275/


It will help a bit.

And I get the feeling, your better of sending the cylinder to someone for them to work there magic on it, or get them to buy one and put the majic into it.

 

[Nutball]

Thanks, I'll sand the head.

And see if JB Weld will hold up in the exhaust port to plug the free port area.

 

[Wonkydonkey]

I could be wrong but I don’t think You should jb the exhaust.


But hopefully someone with more brains than me will chime in