066 questions

[Tucker943]

Aloha,
I picked this very clean, fully functional 066 up for $50 a bit back. It started high idling and winding down slow on me when I let off the throttle. So I threw it on the bench. I first had the dealer check the carb settings. Looked good. The problem exists after its good and warmed up. Anyhow, today I went poking around to find an air leak. Couldn't find one so I'm going to vacuum test it. Anyhow while I was digging around in the saw I noticed 2 things.
First, should I cut this baffle out? Of course ill have it tuned if I do.

Second, looking down into the intake boot into the cylinder, it appears on the lower side that its been smoothed out with a dremel where the boot meets the cylinder? Is that normal or has someone toyed with the saw? That shiny ring on the bottom down at the end of the boot tunnel is what I'm referring to.

 

[Al Smith]

What you're looking at is the intake stub on the cylinder .It's part of the cylinder .

A vacuum leak after the thing has ran a bit is indicative of a seal leak .Most likely the clutch side .

That thing in the muffler is the baffle cage .If you remove it it will run better after a carb retune .It will also get a lot louder .

 

[Tucker943]

My question is, do all those intake stubs have polished dremel marks on the lower side? It doesn't go all the way around, and is the work of a human hand.

 

[Al Smith]

Probably not .

 

[Tucker943]

Looking down the bore of that intake boot, I am referring to the silver crescent shape you see. That's the reflection of the dremelled area.

 

[sawinredneck]

Minimal polishing is done at the factory, knocking off the sharp edges really, so anything that appears that way, it's probably not original!
As for the muffler, unless you plan to port it just put on the dual port cover, adjust and be happy. If you port it, some more airflow will help. But the 066 isn't really choked up to start with!

 

[SkwerI]

I disagree with Andy on the muffler. Stihl has been using that internal box/ baffle on their mufflers for 15 years and it really reduces airflow and power. I've removed that internal box on several mufflers and widened the external outlet hole as well. Carefully pull the screen on the side, make that outlet hole bigger and then replace the screen.

 

[Tucker943]

Ya I've always been under the idea that letting the saw breath better is a bonus regardless of any porting or bumping the compression. I just never toyed with removing a baffle before. It seemed like a good idea to cut it out, but I figured I would put it on the table for input.

 

[woodworkingboy]

The only problem I have ever had with removing a baffle, is when the outer shell outlet is opened up too much, or the cumulative total opening of more than one outlet, then I couldn't get a decent idle without the chain moving. That was the case on an 038 that had a removable inner baffle plate. With the baffle in it was fine. You have to be careful about opening things up too much and losing the needed back pressure.

 

[Tucker943]

So remove it or no? I know about back pressure in 4 stroke engines, but not totally clear on how much in 2 strokes. I can't see it being worth having in there. That thing does nothing but create exhaust turbulence.

 

[woodworkingboy]

I have drilled a number of holes through a baffle and it worked fine. I would consider how much of a hole is getting left by completely removing the baffle. Completely removing it looks like what you are going to have left there is a very open can, and your muffler exit looks pretty large. Hard on the ears and the back pressure concern. I think my tendency would be to drill three vertically spaced 3/8" holes through the baffle, just my gut feeling about it.

 

[sawinredneck]

85% of the exhaust port seems to be the favorable number for most muffler mods.

 

[Cut4fun]

If you got the time and energy I would remove the inter baffle in the back. If not I would drill holes all over it at least. Open the side exhaust outlet to the size of the deflector. The OEM dual port cover flows perfect from testing even on woods ported saws. Also could make your own DP cover out of standard cover.

 

[Cut4fun]

Just showing a 034 outlet before and after.

 

[woodworkingboy]

At least in Kevin's, the exhaust bounces off the front of the muffler before exiting out the side. My 034 is a straight shot out the front with the baffle drilled out. Loud isn't the word for it. Powerful too. Bouncing off the front seems to help give the needed back pressure.

 

[HolmenTree]

Your partly right Jay. Frontal barrier to the exhaust port flow is a good thing. The dual exhaust outlet from the factory with the 2nd outlet is in the center of the front half of the muffler so it needs the baffle covering the exhaust port.

Now to clear up a fallacy that the first 066s had no baffle in the muffler is pure B.S. and I know where it came from.....A.S.??

Here is some pics of my 20 year old 066 [1st year] dual port exhaust outlet and a newer mid 1990s 066 [poly flywheel, decomp] Both have the baffle inside the muffler.
Also a picture of the inside of the intake manifold and cylinder intake spigot. Not a great pic but look close and you can see the 2 ribs on the floor of the intake port.
So Chris if the ribs are gone on your cylinder then its been modified. Just one feature Stihl built in to identify modding.

 

[HolmenTree]

Adding to my last post , from looking close at your photo of your intake Chris it has been modified. The ribs should go over the ridge and touch the rubber intake manifold as my photo shows. Your ridge was rounded off seeing the ribs are now gone, even though the ribs on the floor haven't been touched.

 

[Tucker943]

Hmmmmmm. I don't know how I feel about that. Maybe I don't like the idea that an unknown person monkeyed with it. I do think the saw is hardly used. The fins on the cylinder are still as gray as the day it wae new, and the muffler cover is still brass/blue colored, not tinted black and rusty.

 

[Tucker943]

The top end my be newish.

Muffler cover has that original tint I referred to.

It was unusually clean in this area. The dust you see is mostly crappy I knocked into there.

Metal flywheel. So it must be an older saw? I believe this saw is lightly used. I really do.

 

[SkwerI]

Chris, could it possibly be a saw that was seized due to running straight gas or something? Someone tried to rebuild it with a new piston and cylinder along with some performance tweaks, but couldn't nail down the air leak? Therefore it got sold cheap. I would be looking at it as a seized, rebuilt saw as opposed to a brand new one. That might help you hone in on the problem(s).

 

[HolmenTree]

Wish I could help you Chris, I just can't diagnose something over the net without the saw in my own hands.
Get it properly pressure tested for leaks and go from there.
Even though it has some dremil work [who knows whats inside] it could still be a very reliable saw.

 

[Tucker943]

It got bought at an auction by a wealthy man and his groundskeeper used it to trim bushes. No lie. Got sold to me as non running. They didn't know how to start it. It runs great otherwise. I bought it from the wealthy man and it still had the auction tag on it. Ill test it this week.