Huztl MS660

[davhul]

I'm going to shoot for
.80mm when I do it and taper it smooth.when you pull it out you'll see what it moves and see how it works. It moves the gear that the worm gear touches back and forth.

 

[davhul]

I'm sure there's a thread on it but I haven't searched. I ordered one for my 2nd 660. And modding the next. Was about $8-10 at dealer 1128 640 4802

 

[emanaresi]

I just measured squish without a base gasket and it measured 15 thousandths. Is that too tight? DO I need to run the gasket? If so, that'll take it up to about 30 thousandths...

 

[Johnnybar]

The HO parts list shows the adjuster screw and the piston replacing the originals. If you don't replace the piston with the HO version, that I am guessing has a more aggressive cam on the end of the pinion gear, or file the original deeper on the low side, I'm stumped on how it will increase output much. It looks like the original unmodified piston will just move back and forth the same amount in a slightly different position after the adjuster screw is modified. What will happen if I file the cam a little deeper on the low side where the arrow is so that the piston travels a longer stroke?

 

[Johnnybar]

I just measured squish without a base gasket and it measured 15 thousandths. Is that too tight? DO I need to run the gasket? If so, that'll take it up to about 30 thousandths...

I built to .020" squish. You can use 1184 with some aftermarket gasket material that is your choice of thickness to dial in the squish you desire. I seem to remember some guy using paper to tweek squish.

 

[davhul]

From my understating just the bolt has to be upgraded. I'm going to see if I can find it again in some of my literature and make sure. @blsnelling might be able to add some input

 

[Johnnybar]

From my understating just the bolt has to be upgraded. I'm going to see if I can find it again in some of my literature and make sure. @blsnelling might be able to add some input

That would be great because filing that piston's cam looks challenging.

 

[Johnnybar]

here's one that just did the adjuster:

I finally got fed up with not getting enough oil to the B/C when cutting really hard wood so i called Mike at Midwest Stihl and asked if there were any other oilers that would fit and he said no. He said I would have to build a bigger one or mod the one I have, so I started tearing it apart. He said I could trim some off the head of the adjuster so i could turn it a little further. I looked at the inner end of the adjuster and figured out where it would have to sit to give the oiler piston/rotor maximum travel, and grouond the head to that angle. I also took a couple thousandths off the inner end peg just to make sure it had all the travel it could get. Put it back together and put 200 revs on the drum by hand and the oil port/slot were full of oil!!!! It couldn't do that before!!!!

 

[Johnnybar]

Not all 660s have an HO oiler. The wrap models do, as well as those sold in Australia. All you really need is the piston and control bolt.

Evidently, to get max output both are needed but it sounds like the adjuster only will help. Here is a pic of the HO piston...looks like a steeper cam than my stock.

 

[Johnnybar]

Couple minutes with a Dremel and safe edge files:


PS, The piston travel now looks 30% - 50% more but it's hard to tell on such a small part.

 

[Johnnybar]

Now that the adjuster cam is shiny from the filing, I can tell exactly how the parts engage each other and how the mod works along with it's limitations. The adjuster cam engages the small round flat above the pistons cam and its purpose is to limit or allow full return of the piston depending on its setting. I now have at least .010" clearance between the adjuster cam and the piston flat at the max setting meaning it can travel as far as the piston cam will allow and to get more oil will require an HO piston or modding the original to a deeper cam. I'll try the adjuster mod only and see how it does on a 42" milling bar.

 

[emanaresi]

thanks! that is great info. Let us know how it goes.

I have 2 more questions:

-did anyone have trouble with the bearing for the clutch drum? I had a really hard time putting it on, it seems like it is too big, or maybe the clutch drum is made too small. My old saws they come apart easily, but they are well broken in, so I can't say if this is ok or not.

-The oil pump clutch that goes behind the main chain clutch, I think it goes with the dome facing out towards (so it cups over the oil pump sort of). Is that right?

 

[Johnnybar]

thanks! that is great info. Let us know how it goes.

I have 2 more questions:

-did anyone have trouble with the bearing for the clutch drum? I had a really hard time putting it on, it seems like it is too big, or maybe the clutch drum is made too small. My old saws they come apart easily, but they are well broken in, so I can't say if this is ok or not.

-The oil pump clutch that goes behind the main chain clutch, I think it goes with the dome facing out towards (so it cups over the oil pump sort of). Is that right?

1. My bearing was a very snug fit...almost no drum clearance. It had to be in perfect alignment to seat it. Always a chance you have an under-spec drum. If so, wrap some emery paper around slotted dowel and polish it up a bit with a drill or a dremel with a small flap wheel. Clean thoroughly afterward and lube it well before assembly.
2. I think you mean the oil pump cover washer and yes it goes hump up or out toward the clutch.

 

[mdavlee]

About how much smaller is the cam on the HO bolt?

.4mm

 

[davhul]

Your grinding looks good. That's good to know both can be replaced to get the max. That might only be needed for milling like you or just the bolt could be good enough for you. I put a oem upgrade bolt in my 460 last week and I'm going to try it tomorrow. If I use 1:1 with the fuel that's what I want. My early 064 has 2 turns of adjustment and it will dump oil.

 

[Johnnybar]

Your grinding looks good. That's good to know both can be replaced to get the max. That might only be needed for milling like you or just the bolt could be good enough for you. I put a oem upgrade bolt in my 460 last week and I'm going to try it tomorrow. If I use 1:1 with the fuel that's what I want. My early 064 has 2 turns of adjustment and it will dump oil.

1:1 fuel to bar oil is a whole bunch of oil! Might need that much for long bar milling but if you need that much the information I've seen says to use an aux oiler for two reasons. 1. The extra oil goes directly to the work side of the bar. 2. That much extra oil coming from the powerhead oiler gets most of the surplus slung off at the nose and doesn't saturate the cutting side as intended.

 

[davhul]

It used 3/4 a tank before. When I cut dry pine or large white oak is when I would turn it up. I even play with a 36" on it sometime. It's far from stock

 

[dswensen]

thanks! that is great info. Let us know how it goes.

I have 2 more questions:

-did anyone have trouble with the bearing for the clutch drum? I had a really hard time putting it on, it seems like it is too big, or maybe the clutch drum is made too small. My old saws they come apart easily, but they are well broken in, so I can't say if this is ok or not.

-The oil pump clutch that goes behind the main chain clutch, I think it goes with the dome facing out towards (so it cups over the oil pump sort of). Is that right?

Yes to #1. I had to increase the ID of my clutch drum a few thousandths with a Dremel to make it work. Mine wasn't the bearing, I tried an OEM bearing and had the same issue. The problem was ZERO clearance. I added the measured OD of the crank shaft to 2X the measured OD of a bearing roller and got EXACTLY the ID of the clutch drum. Won't work - it needs just a few thousandths extra to make it all fit.

 

[Definitive Dave]

This one aint a Huztl
The third cut is my favorite from this practice run for Saturday

 

[Johnnybar]

It used 3/4 a tank before. When I cut dry pine or large white oak is when I would turn it up. I even play with a 36" on it sometime. It's far from stock

Oh, you mean 1 tank : 1 tank? That would be about 2.3 : 1 by volume so that makes more sense.