3/8 lo pro rim sprocket

[Caloren]

I keep hearing that you can't run 3/8 lo pro chain on a standard 3/8 rim sprocket and I don't understand why. I have layed the lo pro chain over standard 3/8 chain and the rivet spacing is the same. I have draped both chains over the 3/8 rim sprocket and they both rotate fine, the only difference I can see is that the drive links don't go as deep into the sprocket with the lo pro chain. Can someone explain this to me?
Loren

[dougand3]

I'm guessing here - never tried to run 3/8 Lo Pro on Reg 3/8...Drivers are so much smaller/shorter (height) on Lo Pro. They may not grab the teeth on Reg 3/8 sprocket properly. I can envision chain jumping. Check the size and shape differences.

 

[Caloren]

Doug, That is the only thing I could see also. Was wondering if that was the case, I know that Oregon doesn't list any lo pro rims.

[ladylake]

 
Quite a few 40cc and smaller saws come with a 6 tooth sprocket( and they cut faster with a 6 tooth vs a 7 tooth), I don't think they make a 6 tooth rim sprocket.  Steve

[SawTroll]

Running lo-pro on a regular 3/8" sprocket is like running will a well past wore out sprocket. The reason is that a lo-pro chain needs a larger diameter sprocket, to compensate that the chassis of the chain is lower.

As the pitch is .366 on both, the rivets need to run at the same diameter around the sprocket, not the botton of the chassis (or the cutters).

[HolmenTree]

To add to what SawTroll just explained.
Compare the sprocket nose teeth between  a 3/8 lo pro bar and a standard 3/8 bar. You will notice the lo pro teeth are wider and rounded at the tips, that's  what meshes with the lo pro drive links. The 3/8 standard bar nose teeth are more pointed to properly  fit their bigger drive links.
Same goes comparing the differences  of spur drive sprockets between the two.
Spinning by hand a lo pro 3/8 chain on a standard 3/8 bar and rim sprocket may seem like it meshes together ok , but under engine power pulling through  a log the chain starts to ride up the sprocket  teeth.

Surprisingly  the better pitch  sprockets to mesh with a 3/8 lo pro over standard 3/8.........is .404

[Caloren]

Thanks guys! I understand it a little better now. Need a new sprocket for my MS170 and was wanting to use a rim sprocket but couldn't find one. Guess I'll stick with the spur.

[SawTroll]

Thanks guys! I understand it a little better now. Need a new sprocket for my MS170 and was wanting to use a rim sprocket but couldn't find one. Guess I'll stick with the spur.

I believe you have to, with that saw.

[joe_indi]

Thanks guys! I understand it a little better now. Need a new sprocket for my MS170 and was wanting to use a rim sprocket but couldn't find one. Guess I'll stick with the spur.

I use the 3/8" Picco 7 teeth rim sprocket kit available as an option for the 210/230/250 saws. It is a straight fit for a 170 or 180 Part No.1123 007 1030.
While you are at it you might like the optional bumper spike of the 210/230/250 Part No.1123 664 0501. You will need two D5X16 screws to fix it (Part No.9075 478 4115).
I have all those on my 180. I have also opened up the muffler ports on it and it is a mite sized "pro" rocket.

[Caloren]

Thank you, Joe! I already have the bumper spikes; I know a lot of people don't like them, but they are useful occasionally, especially when cutting something that I have no business cutting with that small a saw!  ;D
I'll see about getting the parts you recommend, thanks for the part numbers.
Loren 

[HolmenTree]

Thanks guys! I understand it a little better now. Need a new sprocket for my MS170 and was wanting to use a rim sprocket but couldn't find one. Guess I'll stick with the spur.

I use the 3/8" Picco 7 teeth rim sprocket kit available as an option for the 210/230/250 saws. It is a straight fit for a 170 or 180 Part No.1123 007 1030.
While you are at it you might like the optional bumper spike of the 210/230/250 Part No.1123 664 0501. You will need two D5X16 screws to fix it (Part No.9075 478 4115)
I have all those on my 180. I have also opened up the muffler ports on it and it is a mite sized "pro"
rocket.

Thanks Joe, you're  a wealth of information!
I'll  keep those part numbers  in a safe place where I  won't  lose them.

[SawTroll]

Thanks guys! I understand it a little better now. Need a new sprocket for my MS170 and was wanting to use a rim sprocket but couldn't find one. Guess I'll stick with the spur.

I use the 3/8" Picco 7 teeth rim sprocket kit available as an option for the 210/230/250 saws. It is a straight fit for a 170 or 180 Part No.1123 007 1030.
While you are at it you might like the optional bumper spike of the 210/230/250 Part No.1123 664 0501. You will need two D5X16 screws to fix it (Part No.9075 478 4115).
I have all those on my 180. I have also opened up the muffler ports on it and it is a mite sized "pro" rocket.

I would think a 7-pin is a bit much on a 180 though, and any dawgs on such a small saw sounds a bit silly to me....

[ladylake]

 
Hate to admit it but troll is right, a 170 or 180 will saw with a 7 tooth but will be quite a bit faster with a 6 tooth. Even a 40cc saw likes a 6 tooth 3/8 lp  to saw the fastest. Steve

[HolmenTree]

But as Joe mentioned in his post he did a muffler mod on those little Stihls changing them far from ordinary.

[SawTroll]

But as Joe mentioned in his post he did a muffler mod on those little Stihls changing them far from ordinary.

Well, there is only one way to find out how it works, I guess! 

[ladylake]

 
A MS170 or 180 would have to make at least a 100% increase in power to take advantage of a 7 pin 3/8 LP setup.  I've tried that with 40 cc saws that cut twice as fast as a 170 and they cut faster with the 6 tooth by quite a bit.  Steve

[HolmenTree]

I suggest operators  who run 170/180 Stihls (and even the larger 40cc saws)  cutting larger diameter wood and not up on good chain maintenance, should stick with the factory 6T spur sprocket. .........if that's the case.
Top priority  is proper  chain tension running spur sprockets.  Derailing chains with this setup damages alot of chain drive links.
Something  the luxury  of running 7T rim sprockets prevents.

[SawTroll]

 
A MS170 or 180 would have to make at least a 100% increase in power to take advantage of a 7 pin 3/8 LP setup.  I've tried that with 40 cc saws that cut twice as fast as a 170 and they cut faster with the 6 tooth by quite a bit.  Steve

At least I can't imagine that just a muffler mod will do the trick, for general use.

[ladylake]

 
Any MS170 or 180 will cut faster with a 6 tooth, muff modded or not.  Steve

[HolmenTree]

 
Any MS170 or 180 will cut faster with a 6 tooth, muff modded or not.  Steve

Cookie cutting ? Or limbing and brushing what an operator  intended theses little saws for on his back 40 on the weekend.

[joe_indi]

 :D :D This is one of the lesser work that a 180 is put to over here. Usually they are cutting rubber wood alongside the MS460s and 461s.https://youtu.be/q-xI5ykmtLM


My 180 I got it with a broken engine pan in exchange for 2 saw chains.It had completed nearly 3 years as its owner's sole cutting tool.

Well, there is only one way to find out how it works, I guess! 

Well, a couple of years ago, when the Picco Chisel chain (63PS) was introduced I did upload a video on Youtube. I could lay my hands only on a loop of PS3 because no 63PS was available, and, it is still not available here.
But, this video has my 180 with the 7T rim sprocket, opened up muffler running the 63PS3 on a 12" bar. The wood it is cutting is Jack which is pretty hard, a bit more than teak and is used in house building for its long lasting property.
https://youtu.be/IGopVRElc0o