Chainsaw Repair

Various Accumulation Of 066 Notes

Lot's of ignition changes and carbs over the years...

How much is it spiting out the carb, most saws will do this some.

Is it a flat top 066 or round top 066?

Flat top 066, you use the blue foam in filter

Round top 066 or 660 has a black plastic shield for this

If by 'redeye' you mean the older 066 versions with a LED and ignition modules with speed limiters, machines with serial number with end digits 31067164 onwards had the ignition modules without  speed limiters or the LED.
To change the ignition module of a previous 066 to the newer version, the flywheel too has to be changed.If I read it right, for a short period a flywheel with two slots for the woodruf was available. Probably to suit both ignition modules.
Part number of the flywheel has not been changed.
So, in case you want to replace a red eye module you must also change the flywheel.
 
Carbs became leaner burn from jet size 72 to 64 from serial number end digits  31067138 onwards.


This is the info on a 1994 bulletin.

But according to a bulletin of 1996, the crankshaft was beefed up.
A bigger big end bearing.
Flywheel end was made thicker so that a newer M10 flywheel nut replaced the previous M8 nut.
Flywheel oil seal seat diameter was increased to 15mm from 13.5mm (probable reason for that extra oil seal in the gasket kit).
Polymer flywheel with metal hub.
and...
A change of the Ignition module again!!

So, Redeye module had part number            1122 400 1303
1994 post Redeye module had part number  1122 400 1311
1996 onwards module had part number        0000 400 1303
And the current module has part number       1122 400 1314
The current parts list also shows a module with part number 1122 400 1307 as being available for the 066.

There is a lot of confusion over the 066 'red eye' or 'red light' model saws. Also a lot of confused between the Red Light 066 and the similar limited non red light 064. Even in what has been posted here. You can run an early model 066 red light with the aluminum flywheel with one of the later aluminum flywheel unlimited coils. All the US 066 AL flywheel models should only have one key in the flywheel. I had an AL flywheel on my Red Light 066, and I still have the later Iida coil model from it. It ran fine. The limited coils were commonly pulled and replaced with unlimited ones to run better. This was because the red light coil module would fade out over time and limit downward on RPM's (like 12.5k down to 10k RPM). The non-limiting coils do not have the extra wire and LED lead though. Some 066 red lights were Magnums (mine was), meaning they had the dual port muffler for increasing the 7.3 HP 'regular' 066 to 7.8 HP.

I have the Stihl 066/064 factory ignition module tech sheet that lists the 6 most common aluminum and poly flywheels (there are a whole series of them) as well as all the matched coils. However, there were 9 options in all. There were at least two later models of AL flywheels on non-red-eye 066 before they flipped to polymer in 1996. The red light 066 was only made for a short period of time. They were only made on a very early flat top 066; there was no later model 066 using them. There was an RPM rev limiter in the coil and an LED lead running from the coil to an LED light at the side of the saw. The light lit up when the rev limit was reached and the coil was cutting out. This was so that you could tune the carb H screw to lean it out just until it was cutting out, and the LED light was flashing. For that reason these saws had engines that were fairly bullet-proof; it was nearly impossible to score the engine with the limiter in them. Only straight gassing did them in. Or the bearings went out, as was the case with mine. The swapped out red light and later models of 066 with the AL flywheel and unlimited coil had a common problem with spinning the flywheel side of the crankshaft off because of over revving. So Stihl made the flywheel side of the crank thicker in 1996 and replaced the aluminum with a poly flywheel. They also changed the ignition modules to advance the timing at high revs on the later poly coils. The AL flywheel coils are straight-line timed ignitions; they do not have an advance curve in them like the poly modules do. The CDIC coils also had a timing retard in them at low speed for easier starting.

In the above post, the 1303 module was in the 064, and not the 066. The red light 066 coil module was a Prufrex CDIC, Stihl PN: 1122 400 1307 (similar to the 064 module, but it has the LED lead). It was changed to an Iida unlimited coil module, Stihl PN: 0000 400 1300, in 1993 and retained the AL flywheel. That was changed to an Iida unlimited coil module, Stihl PN: 1122 400 1311, in 1994. The 0000 400 1300 coil is a generic coil and is still used in some of the new larger Stihl saws. The 064 also had a CDIC coil put in them from 1989, but there was no red light limiter LED. Note that only the 064 AL flywheels have two key slots. This is to accomadate different types of ignition; one was for electronic ignition, and the other was for analog points and condenser ignitions. On these flywheels, B stands for Bosch (old points) and P stands for Prufrex (new electronic).

Clear as mud? I figured all this crap out when I tried to restore my Red Light 066 to original condition. However the bearings were shot and so expensive to replace that I wound up parting most if it out.

I believe that the clutch side case bearings are different on the early model 066 (and more expensive). That is from memory from pricing the beargings at a better Stihl shop in Cottage Grove last summer. The flywheel side case bearings are all the same.

In my IPL for the 066 and the 660, its shows the same bearings for both sides, old and new. But I think that is for the later 066 and on.  Can ya explain dat one to me? I don't understand that one for sure eh I know that the cranks are different on the poly flywheel models, and the IPL shows a different crank from Feb. '96 and on. The cases are also slightly different between these, and the flywheel side bearing seals are different as well.

Red Light 066 models had more aggressive porting than later model 066s. They had more power than the new MS660 has. The standard red light 066 had 7.3 HP, and the Mag (DP muffler) had 7.8 HP. The new MS 660 has 7.0 HP.

Quick history of the 066:

Early models from early '91 to late '92 had the 'red light' LED and limiter coil with AL flywheel.

     Loggers figured out the limiter and swapped in the non-limiter coil. Stihl figured out what was being done and came out with the non-limted coil model.
     Original red light saws with limiters were bullet proof and immune from air leaks and lean scoring as well as flywheel sheer (both good).
     Problem with the limiter coils fading in time and rev limits lowering to near 10k from the original 12.5k (bad).

Later-early model 066 from late '92 to early '96 had the non-limiter coil with the AL flywheel. The LED was removed (a weird gimmik at best).

     Problem with this saw was that if they were revved high and sunk into a wood cut and bogged down, the inertia of the AL flywheel sheared off
     the crankshaft, and self-destructed the flywheel, saw case, crank, or all of them (not good).

Late model 066 from '96 and on were updated with a beefier crank and a polymer flywheel which is a lot lighter, and not prone to sheer from built up inertia. The poly flywheel also had a different ignition coil that had an advanced ignition curve at the top end. The decomp button was added at some point, with the humped top.

The late model 066 was made obsolete with the MS660, but they remained essentially the same saw.