MS660 Port Timings

[Canadian farm boy]

Forgive me for my ignorance, but; what is the purpose of the intake epoxy? I've heard guys talk about it but I've never seen it applied so thanks for the pic.

Sometimes after cutting the cylinder base the intake port timing ends up lower(to much duration) then desired and JB weld is put in the intake port to help bring it back up to a desired height.
Another reason for JB in an intake port is that you can use it to reshape the port. Kinda like bondo on a dented fender.

 

[Deets066]

Now in the hardwood here, RPM is not king.
Faster usually just cuts slower.
The timber is so dense, more revs and bigger sprockets just see the chain skipping through without cutting properly.
I have tried lots of different combinations and have settled on a "less is more" approach to porting, aiming at direction and flow, with numbers around the 102/122/78 mark.
I find when I take the intake too low, I loose power band with the saw going great with revs, but becoming easier to bog when revs drop.

It's not just about the intake. I think a 660 is a saw that needs more velocity in the charge. It's a popular saw to epoxy the intake, mostly because you usually need to drop the jug a long ways to get a good low exhaust. But this usually kills velocity by also having a low intake. Raising the intake helps with case compression.

I believe you could make a good runner if you had means to tighten case volume other than the epoxy and keep the low intake if you run a larger carb and boot.

That's my 2 cents though.

 

[TreeLife]

It's not just about the intake. I think a 660 is a saw that needs more velocity in the charge. It's a popular saw to epoxy the intake, mostly because you usually need to drop the jug a long ways to get a good low exhaust. But this usually kills velocity by also having a low intake. Raising the intake helps with case compression.

I believe you could make a good runner if you had means to tighten case volume other than the epoxy and keep the low intake if you run a larger carb and boot.

That's my 2 cents though.
View attachment 85501

Full circle crank...

 

[Deets066]

Full circle crank...

There are a few ways, that is one

 

[Brewz]

It's not just about the intake. I think a 660 is a saw that needs more velocity in the charge. It's a popular saw to epoxy the intake, mostly because you usually need to drop the jug a long ways to get a good low exhaust. But this usually kills velocity by also having a low intake. Raising the intake helps with case compression.

I believe you could make a good runner if you had means to tighten case volume other than the epoxy and keep the low intake if you run a larger carb and boot.

That's my 2 cents though.
View attachment 85501

Deets has why I'm doing it.
I had to raise the upper transfers by almost 10 degrees which doesn't leave much time for case compression with a really low intake.

This cylinder will be lowered about .015 to set squish at .020 with a gasket delete so once the uppers are raised about 10* I will need to put that back on the intake to maintain case compression.
Less case compression means less velocity up the transfers

 

[Brewz]

Tony, you did not provide us with the squish on some of the cylinders, but assuming that it is good, on the Cross MMWS I would just raise the exhaust a bit and leave the rest of it as is (unless you also want to widen the ports a bit).

I have 2 Cross MMWS cylinders running at the moment. One has #s similar to your KS, the other is similar to your Cross. The cylinder with 104 Ex has more compression and is harder to pull over. It runs very well, but so does the one with higher Exhaust, So I would likely raise it to about 100.

The cross cylinder has .025 squish with gasket
The Hyway has .040 squish with gasket
The Huztl has .055 squish with gasket
The KS..... I can't remember

I have the cross cylinder on a Huztl kit saw with a .015 gasket with squish at .020 and it's really strong.
Not checked compression but it's got lots.
Only thing I did to the kit was replace the Chinese piston with a meteor and check the port chamfers after the last one hung a ring when starting to test run.

 

[MustangMike]

Looks good Tony, what were your #s after the gasket?

 

[Brewz]

The Hyway cylinder and cross cylinder have chambers almost identical to the OEM cylinders.
The cross looks a touch tighter.

Hyway:

Cross:


The Huztl cylinder has a wide flat band and a small chamber and should make a lot of compression with just .015 off the base to set squish at .020.

I plan to take it to 97/121/76 and test it, then lower the intake to 80 and see if it gains anything.

 

[Brewz]

Looks good Tony, what were your #s after the gasket?

About 103/121/81ish from memory
I only gave it a quick check but it all came up about a degree with the .015 gasket.
Maybe only half a degree on the intake.
It should pick up well with a bit of run time

 

[MustangMike]

Those #s should work well.

 

[Brewz]

It's good but it doesn't feel as free as I would like.
Maybe that exhaust needs to come up to around 100 like you said.

Will be interesting to see how the other cylinders with the higher exhausts run once I raise the uppers and intake

 

[smokey7]

Very interested on your style of mods and porting. I probably woukd have filled the intake the same way as you with the piston. In my mind it would be the best way for a true area by the port. I have always cone overboard when building skis tunnle porting cases and what not. I have never had epoxie come loose with proper prep. How did you prep the area for filling? Very nice job so far.

 

[Brewz]

I ground the surface back with a course burr to hive a nice rough surface then degreased it

 

[smokey7]

I like to degrease first. Im sure as long as it was clean it should stick good.

 

[Brewz]

It was clean, new out of the box

 

[dustinwilt68]

Wondering if anyone has the bearing number for the PTO side on a 064/066, I know the flywheel side is 6203, looking to buy bulk in Nachi or SKF maybe

 

[mdavlee]

The other side has the lip for the seal doesn't it? Only place to get is oem.

 

[dustinwilt68]

Thanks Mike, I was afraid of that.lol

 

[dustinwilt68]

And yes it has the lip for the seal.

 

[dustinwilt68]

Maybe I can buy some from Dave in bulk next trip out there, I have used his AM bearings on these with good success so far, I just want to keep a few sets on the shelf, instead of ordering each time I need them.