Trying to find 6 tooth sprockets for stihl

[over9k]

Hey guys, new to the forum and registered literally just to make this post after an entire afternoon on google got me nowhere.

I have an ms170 and a ms391. They both come with spur sprockets from factory, the 170 is a 6 tooth, the 391 is a 7 tooth. I'm wanting to convert both of them to a rim sprocket setup as both gears are due for replacement and it seems silly not to.

I can find kits to convert the 391 to a 7 tooth rim sprocket but I cannot find any 6 tooth ones. I can also find kits to convert the 170 to a rim sprocket, but again, cannot find any 6 tooth ones. I'd even be ok with a 6 tooth spur sprocket on the 391, but that doesn't seem to exist either.

The 170 is a picco chain, the 391 is a 3/8. I KNOW I've seen such items mentioned, but I can't for the life of me find where or anyone that sells them.


Long story short, I want both to be 6 tooth and ideally 6 tooth rim gears but I'll settle for spur if that's the only thing available but I can only find 6 tooth factory replacement spur sprockets for the 170 and cannot find EITHER type in a 6 tooth for the 391.

Anyone able to assist?

 

[cscltd]

I don’t think there is enough of a diameter on spline to allow a 6 tooth to work as there Is 2 parts to rim sprocket and drive links would hit spline. rim sprocket require more overall larger diameter or material needed for 2 parts as opposed to 1 part (spur)-

 

[over9k]

Well if they can do a 6 tooth picco spur sprocket then surely they could do a 6 tooth 3/8 one?

 

[user 122190]

Well if they can do a 6 tooth picco spur sprocket then surely they could do a 6 tooth 3/8 one?

Rim vs Spur?

When I was changing from a spur to a rim on my ms290, I found Oregon was the best source of info on what is available. Basically if they don't offer/sell it, then it don't exist. YMMV.

 

[over9k]

Rim vs Spur?

When I was changing from a spur to a rim on my ms290, I found Oregon was the best source of info on what is available. Basically if they don't offer/sell it, then it don't exist. YMMV.

I'd prefer rim but if spur is all that's available then I'd take that.

Will check oregon now.

 

[Mad Professor]

Well if they can do a 6 tooth picco spur sprocket then surely they could do a 6 tooth 3/8 one?

Chain chassis is different on picco

 

[user 122190]

I'd prefer rim but if spur is all that's available then I'd take that.

Will check oregon now.

Rim vs. Spur meant if it is available in spur it does not mean that it is available in rim, nor is it even possible to get in a rim. I'm no expert but 6 spoke rim is something that might be impossible. But what do I know?

 

[SAWMIKAZE]

You won't find a 6 tooth rim sprocket for that saw, it doesn't exist.

 

[over9k]

Ok. What about 6 tooth spur for the 391?

 

[67L36Driver]

Ok. What about 6 tooth spur for the 391?

Why on gods green earth would you want Slower chain speed?

 

[over9k]

Torque. I am cutting dry australian hardwood which is unbelievably hard/dense. As far as I know, it's the hardest/densest wood in the world.

 

[cscltd]

Use could change ms391 to .325 and use 7 tooth which is smaller diameter than 7tooth 3/8 (not much smaller but would effect chain speed slightly slower and also smaller kerf. Or use 3/8 semi skip chain which may cause saw not to bog as much?
You could also contact those guys that make racing sprockets and see if they can make one.
Also perfect excuse to big a bigger saw.

 

[over9k]

Yeah semiskip chain was going to be my next option if 6 tooth sprockets didn't exist.

 

[user 122190]

Use could change ms391 to .325 and use 7 tooth which is smaller diameter than 7tooth 3/8 (not much smaller but would effect chain speed slightly slower and also smaller kerf. Or use 3/8 semi skip chain which may cause saw not to bog as much?
You could also contact those guys that make racing sprockets and see if they can make one.
Also perfect excuse to big a bigger saw.

And it would be a good one. Most here just like saws, or have money to burn, etc.

 

[Dennisthemenace]

Hey guys, new to the forum and registered literally just to make this post after an entire afternoon on google got me nowhere.

I have an ms170 and a ms391. They both come with spur sprockets from factory, the 170 is a 6 tooth, the 391 is a 7 tooth. I'm wanting to convert both of them to a rim sprocket setup as both gears are due for replacement and it seems silly not to.

I can find kits to convert the 391 to a 7 tooth rim sprocket but I cannot find any 6 tooth ones. I can also find kits to convert the 170 to a rim sprocket, but again, cannot find any 6 tooth ones. I'd even be ok with a 6 tooth spur sprocket on the 391, but that doesn't seem to exist either.

The 170 is a picco chain, the 391 is a 3/8. I KNOW I've seen such items mentioned, but I can't for the life of me find where or anyone that sells them.


Long story short, I want both to be 6 tooth and ideally 6 tooth rim gears but I'll settle for spur if that's the only thing available but I can only find 6 tooth factory replacement spur sprockets for the 170 and cannot find EITHER type in a 6 tooth for the 391.

Anyone able to assist?

Buy a bigger saw, for hard dry Oz wood a 170 is for pruning the missus's garden and a 391 is OK for limbing and 10 inch trunks, bigger than that try a 462

 

[ericm979]

How long a bar are you running on the 391?

 

[user 122190]

Torque. I am cutting dry australian hardwood which is unbelievably hard/dense. As far as I know, it's the hardest/densest wood in the world.

Buy a bigger saw, for hard dry Oz wood a 170 is for pruning the missus's garden and a 391 is OK for limbing and 10 inch trunks, bigger than that try a 462

I'm thinking even a 661. This is an opportunity to really splurge on a new saw and be fully justified.

 

[user 122190]

Torque. I am cutting dry australian hardwood which is unbelievably hard/dense. As far as I know, it's the hardest/densest wood in the world.

Is that how torque works? Slower chain speed doesn't mean that the engine will dig deeper and find power to move the chain. In fact it might even be detrimental if the chain gets grabby in the wood -- the engine might just bog out on you. If you want a big torque engine you have to buy it. I know first hand the 880 is a torque monster, but I can't speak to other saws.

 

[over9k]

Is that how torque works? Slower chain speed doesn't mean that the engine will dig deeper and find power to move the chain. In fact it might even be detrimental if the chain gets grabby in the wood -- the engine might just bog out on you. If you want a big torque engine you have to buy it. I know first hand the 880 is a torque monster, but I can't speak to other saws.

Er, yes? It's a simple question of leverage. A sprocket is a lever.

Whilst I appreciate the "just buy a bigger saw" comments, we're talking orders of magnitude different cost. A sprocket and/or semiskip chain is about $50. A new saw is 2000.

 

[drf255]

I don’t think there is enough of a diameter on spline to allow a 6 tooth to work as there Is 2 parts to rim sprocket and drive links would hit spline. rim sprocket require more overall larger diameter or material needed for 2 parts as opposed to 1 part (spur)-

Here lies your answer. It doesn’t exist because it can’t be made to work. The MS170 is so underpowered it needs the 6T spur. Interestingly enough, some spur sprockets are interchangeable between models, but I don’t think a 170 and 391 are. A 170 6T spur actually fits only an 026, I only know this because I bought a used one that came that way.