Chainsaw Repair

Just saving info I reposted 10 years ago.

This is all 2nd hand info from reading. The redlight saws were rev limited to 12.5k and the little led red light would come on.

This first part is more info on Willards 066 RL.

(((066 Mag Artic red light, with dp muffler serial # is 126316881. This "ARTIC" has the thermostatically controlled heated carb and no heated handles. I didn't bother getting the bulky wrap handle. The heated carb still heats perfectly today.
I bought this saw brand new in the summer of 1992 so I presume its a 1991 model. I did upgrade it about 6mths after I bought it with the newer flywheel and module.
18 years later and a few thousand hrs on it, it still has lots of compression, I never had the cylinder off of it. Only 2nd to my 090AV, my 066 is the toughest saw I ever owned, never broke a crank, bearing, etc.
Willard.)))))

Again all 2nd hand info. So take it for what it is worth. This is just stuff I have heard since I dug up info after getting mine. Even though mine was updated I wanted to know too .



((((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 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 accommodate 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).

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 gimmick 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.

The 066 came in several models. The MR (Mag Rescue) model had a 3/4 wrap, a PNW sprocket side cover and large falling dogs. The early M (magnum) model had a dual port muffler. The Arctic model had a wrap handle heater and a mini alternator in the flywheel (both AL and poly flywheels have a heated handle/carb version). There are also Aussie AUS and Canadian CDN versions of the saws. The Canadian model had a full wrap option. The Australian model came with a high output oil pump. They had light, medium and heavy duty air filter options. They came with an Elasto-start as an option. They also had a variety of carbs, some had a fixed H jet, some with heaters to keep the carbs from icing up.))))))

More info. From a stihl guy out in the PNW

Early 1994 - Thin cylinder base ( Red light etc) changed to "thick base". Base screws changed from M6x20 to M6x25


Mid 1994 - Beefed up crank - Crankshaft BIG end changed from 12 to 13 roller pins from serial number 129 588 002. At the same time, the cylinder base gasket changed to rubber coated Steel (so quit using the junk aftermarket gaskets!).


Early 1995 - OHSA (NOT EPA) forced the dicontinuation of the Dual port Magnum muffler from serial number 131 960 509. HP dropped to 7.2


Mid 1996 - decomp valve fitted on all 066 from serial number 131 960 509


Early 1996 - Poly flywheel installed and crankshaft bearing increased in size from 13.5 to 15mm from serial number 131 917 066

Early 1998 - shrouds and filter box changed from squared to "rounded " type. Limiter caps on carbs and EPA labeling...


Early 2002 - Name changed from 066 to MS660.


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

Just confirmed with Definitive Dave's info that my above 1996 066 is not a 1996 but is a 1997 model....the last year of the flat top.
The 1998's were the start of the EPA round top 066's.
Dave says: 1997_ 064/066 after serial#133459523 first plastic name badge.
Mine has the plastic badge and its serial # is 134989911.

I'm just proud to say I got a keeper here.

Just made the 066 hybrid 3 ounces lighter and alot more compact with a narrower profile.
I stuck a Husqvarna 272XP top handle on it, bolted right up.
At the rate I'm going I'll have her in the 13 lb category, Lol
Here's 2 pics.

That's good to know.  The carry handle on AM660's are weak.  Will have to see if 272 fits.
Shep

I was a mechanic at a Stihl dealership from before the introduction of the 064 to the introduction of the 066. The last run of 064's to come out had the Red Light ignition,Stihl called this "Digital" ignition,it worked fine and did indeed rev limit at 12,500. Some fanatical fallers hated it,so to fix it I had to install the ignition and flywheel from an earlier 064(usually just using used parts). However there was a glitch to the digital ignition,if you installed a non-resistor spark plug the saw would misfire like crazy. Usually in modded work saws I built I would use a 1 step colder plug without the resistor,such as the Bosch WS5F,but when a I modded a brand new Redlight for a customer it misfired and barely ran,a call to Stihl's tech I found out they need a resistor plug,so I put one back in and it was fine.