Got 4 Timber Bears... What's the deal?

[E-Ride]

Hey there,

I just picked up a chainsaw lot that had 2 Mac 10-10s 3 Timber Bear 610s and 1 TB Pro Mac 650.

Is there any difference between these 4 TB saws except that the PM650 has a decompression valve? They have been sitting for years, so I am going to get carb kits and put new fuel hoses on.

I cleaned the 650s carburetor and it fires but dies instantly. The sparkplug is getting soaked with fuel. Can't wait to get these parts in. Hopefully they show up before Thanksgiving.

Any help is greatly appreciated
E-Ride

 

[heimannm]

There were many different models based on the 600 Series chassis, PM610, PM605, PM650. PM655, PM645, Eager Beaver 3.4, Eager Beaver 3.7, Timber Bear, Brown Timber Bear, Super PM610, SE3420, SE3720, PM5700-20, several Montgomery Wards models, and the 690 cut off saw just to get the ball rolling. Parts are all quite interchangeable so a saw that has both Timber Bear and PM650 labels is probably put together from parts.

Many believe that the early PM650 models with the compression release had the best porting but I have never tried to verify that by comparison. Later models had the "Q" port and no compression release, in fact the only saws I have ever seen with the compression release are the PM650 version. The IPL's that I have looked at also indicate the early PM650 saws were the only ones with the DSP (compression release).





In early 1984 they switched from thick rings to thin rings on the PM610, and all of the larger bore models after that had the thin rings (94132).



The 3.4 or 57cc models had only thick rings.

While they called them 3.4 and 3.7 In3 the actual difference in displacement was somewhat less. The smaller were 1.810" bore and the bigger were 1.840" bore so they were more like 3.52 and 3.64 In3 respectively.

In general they are somewhat heavy for the displacement, rather bulky (many refer to them and cinderblocks due to the shape), oilers can be temperamental, but the saws seem to be almost indestructible and are capable of cutting a lot of wood.







Mark