# Stihl 066 ?



## JOHN BOY (Sep 15, 2013)

Alright . need a little help here guys . I may be going to look at a stihl 066 for 200.00 bucks the guy says it runs strong and is in good shape .  Says its very hard to start , anything i need to look for besides clogged air filter , a tired plug and old gas.


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## NH_Wood (Sep 15, 2013)

View piston/cylinder as best you can and definitely a compression test. Cheers!


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## StihlHead (Sep 15, 2013)

Pull the muffler and look inside. Pull the plug and look in from the other side. Also pull the side cover, chain and rim and tug/rattle on the shaft and feel for *any* play. Bearings tend to go out on those, and they are really expensive to replace (you also have to split the cases to replace the bearings which takes special tools). The early model 066s had aluminum flywheels and they tended to overspin from too much inertia. For that reason, the original ones had "red light" limited coils in them. Later models have composit flywheels and different coils.

Hard to start can be because of bad rings or scored P&C, a bad coil, bad low end seals, or a bad tune. Or it can be something as simple as bad gas, a fouled plug, a clogged AF, a clogged muffler screen (same effect as clogged AF), or something subtle like as a cracked impulse or gas line.

For $200 it is worth it in parts alone, if it runs or not.


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## Ashful (Sep 15, 2013)

StihlHead said:


> Pull the muffler and look inside. Pull the plug and look in from the other side. Also pull the side cover, chain and rim and tug/rattle on the shaft and feel for *any* play. Bearings tend to go out on those, and they are really expensive to replace (you have to split the cases which takes special tools).


Isn't that a early/late model issue on that saw?

MS660 shows around here at $1100.  Vintage 066's in good used condition with B&C seem to go around $500, at least in my neck of the woods.


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## StihlHead (Sep 15, 2013)

Joful said:


> Isn't that a early/late model issue on that saw?
> 
> MS660 shows around here at $1100.  Vintage 066's in good used condition with B&C seem to go around $500, at least in my neck of the woods.


 
They changed the bearings/crankcases and added the light poly flywheel midway through the 066 production runs. They also had several different coils. All 4 of the different ignitions on the 064 and 3 of the 7 different ignitions on the 066 models had an AL flywheel.


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## Ashful (Sep 15, 2013)

Yeah... thought so.  I remember the ignition being a big ticket item, when I was researching my own 064 purchase.  Some of them were more flakey than others, and some are very expensive / hard to find today.

I've heard debate on whether the heavy/light flywheel is preferred, but thought the bearing failure was more prone with the heavy flywheel.


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## StihlHead (Sep 16, 2013)

I had a metal flywheel on my red light limited coil really early model 066 that had bad bearings. It also had a different coil than stock, and was rewired to bypass the limiter. Which is what I believe caused the bearings to go bad. They (the 066 bearings) are supposed to be more bullet proof than the 044, but I have had the opposite experience myself. At any rate, the 066 I have now is a later model with the poly flywheel and a different timed coil, as well as different style bearings (non-shielded phenolic cage style vs. shielded style). I have a Stihl white paper on the different 064 and 066 models by what ignitions they have. Its complicated.

As for the 066 changes:

In early 1994 the cylinder base was changed to a "thick base" and the base bolts made larger. In mid 1994 the crankshaft big end changed from 12 to 13 roller pins. They also changed the cylinder base gasket to rubber coated steel. In early 1995 OHSA required pulling the dual port 'Magnum' muffler in the US (not in Canada) and the power dropped to 7.2 HP from 7.8 HP. In mid 1996 a decomp valve was added and later that year a poly flywheel replaced the aluminum one along with a different coil. At that time the flywheel side crankshaft seal was made larger and the bearings were changed to a different type. Also the case was changed to accommodate the new seal and flywheel (case was made wider). In 1998 limiter tabs were added to the carb for EPA requirements, the air filter box was rounded off and the rated HP dropped to 7.0. In 2002 the name was changed to MS660 from 066, but they did not get flippy caps like most of the other MS renumbered saws.

Basically you cannot swap a later model poly flywheel into an AL flywheel case because it is too narrow. But seemingly you can get 0.8 more HP from a later 066/600 by adding a CDN DP muffler and cutting the limiter tabs in the carb.


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## mikefrommaine (Sep 16, 2013)

JOHN BOY said:


> Says its very hard to start




The plastic piece that connects the master control lever to the choke/carb can wear out. When that happens the mcl won't stay in the third position (high idle) It  slips down to run when you bump it off choke. 

If the saw burps on full choke. Put it into the run position and hold the throttle when you drop start it. Make sure the brake is on.


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## Foragefarmer (Sep 16, 2013)

mikefrommaine said:


> The plastic piece that connects the master control lever to the choke/carb can wear out. When that happens the mcl won't stay in the third position (high idle) It  slips down to run when you bump it off choke.
> 
> If the saw burps on full choke. Put it into the run position and hold the throttle when you drop start it. Make sure the brake is on.




I am having that problem with my 028. I have to be very ginger with it in order to get it into high idle from choke.


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