So, I'm thinking about getting an 8 pin sprocket for my Dolkita 7900 since it normally wears a 20" bar. I might even try an 8 pin on my 550xp since I'm putting a 13" bar on it and see how it does. My question, are rim sprockets universal? Looking at Baileys I only see "Oregon Power Mate" and Stihl rim sprockets. Are they all interchangeable among brands as long as I get the right pitch for my chain? Do I need to go to a dealership instead? Where can I get what I need?
large husky/dolmar/stihl use 7 or 8 pin rims. These all interchanged as wells as the 404 rim. These have a large spine hub. smaller saws like the 550, 346, 036, 026 use a mini rim. to the best of my knowledge, they are only available in 3/8x7, .325x7, .325x8 and I think someone makes a 9. they are about the diameter of a quarter, and the center is only about 1/2" diameter. The large rims use about a 3/4-7/8 diameter. I have not seen an 8T small rim in 3/8. I would try one if I found one on the 550. if you have .325, then by all means get a 8T for it. I run a 3/8 8T rim on all my 70cc and larger saw with a 24" bar or less. The 7T only goes on when I get into long bars. my ported 066/660 runs a 8T with a 36" but normally like on my 7900 I would switch to a 7 for the 28:" bars.
I replace mine every 2 years with the same size. No idea about different sizes for different applications. PS: Like the new avatar
If s saw is strong enough to pull a larger rim, it will significantly increase chain speed. Think about a 7 tooth as 4.11 gears in a truck. Very strong power out of the hole or tq for pulling heavy loads but it tops out at 65-75MPH. Now the same truck with 3.55 gears won't be as strong pulling heavily loads and will work harder doing it but it will do 100-120MPH. Same thing with rim sprockets. A 7t will have more torque for longer bars and be able to lean on it more. But. The 8T will cut A LOT faster if you let the saw do the cutting and not force it and the saw has the power to pull the large rim. If you stand or lean on it the 8t will bog easier. It's simply torque multiplication
Awesome, thanks for the replies. So really there's only 2 spline sizes, a large and small. Sounds easy enough!
No. You just have to have the sane chain size rim as the bar and chain. Meaning 3/8 rim for 3/8 chain. .325 rim for .325 chain. I think stihl has a micro rim also in the baby cc saws. Can't remember though
A standard 3/8 large spline 8 tooth rim is what your after. That same rim will fit numerous saws. I have several that I have bought. Some were a cheap no name, others are Oregon branded. But both are inexpensive and easy to replace. But as SquareFile noted, unless your running a small bar? Then benefits from a 7t outweigh the 8t. We ran a few tests at the last GTG and even a large saw in 20" wood (which is pretty small), liked the 7t better.
8t on modded saws shine. Maybe. It so much on stock saws but there is a reason racers run 9, 10 and 11 tooth custom rims for the chain speed, but the saw has to have the power to spin it. My 372 with an 8t in 20" wood is two seconds quicker per cut that the same bar, same wood with a 7t rim. Stihl rims are much harder and last longer than oregon or other softer "cheap" brands. They also cost a buck or two more.
Both these saws were mod'd (70 cc and 80 cc machines) in a 20" Cant. With some very good chain. In a 10" Cant yeah, the 8t shines. But in 20" wood, it was slower. I have the times somewhere. . An actual piped race saw? That is designed for 1-3 cuts? Yeah, that 8, 9, or 10 tooth rim will help. But they are not cutting 20" wood.
Rims are easy, unless you're into rare or vintage gear, there are only three main sizes to worry about. Stihl "mini" spline, standard/Oregon small spline, and standard large spline which is common across many saws 60cc+ from all manufacturers. Stihl mini is avail in 3/8 Picco 7 or 8T, .325 7 or 8T, and 3/8 Std. 7T. Found on all pro saw's (except top handles) in the 50cc class and some early 1125 series units. (034/36) They also generally made conversion kits available for most of their homeowner saws. Small spline is generally found on non-Stihl equipment or Stihl saws that have had an Aftermarket clutch drum installed. Same sizes as Stihl Mini except for the Picco. Large spline is available in many chain pitch/tooth combinations and is nearly universal on pro saw's over 60-70cc.
