Swapping chain bars?

[Franny K]

In 0.325 pitch pretty much anything from Oregon in 0.063 is also available in 0.050 and there is also the 95 class narrow kerf. The more recent Stihl 0.325 picth 0.050 gauge chain is essentially narrow kerf as the Stihl 0.063 is still the heavier chassis. I think the bushings and holes in the drive links are the same diameter but the width at the bushings is now different.

I would think the .325 by 0.050 that came with it is an improvement over the 0.063 stuff they came with in years past. If you get into a 72 drive link bar you will likely find a good choice of chain loops in Nk or normal. NK is for up to 55cc and normal is up to 62cc and an ms251 is 45cc. Either modify a brand x bar or get a universal mount NK one like Baileys sells. Could just get 72dl loops and remove 4 links or have done for you to be able to compare to your spare mentioned above.

 

[Franny K]

On my 261 I run an 18'' bar with .063 chain and a 20'' Light 04 bar with .050. It all works fine.

That is the smallest saw the put the medium sized 3003 bar on. The ms251 is the largest saw they put the small mount 3005 bar on. You do verify the sprocket is compatible with either. I suspect the ms251 comes stock with a spur 7 tooth and the mini spline drum to run the same sprockets you do is an extra that you may still have to go to the ms241 parts sheet to find.

 

[Captain Bruce]

Sorry if this has been answered already. Just bought a Stihl MS251 with an 18" .050" guide bar. Can I also use a .063 gauge bar (and .063 chain of course)? It seems like there are a lot more chains available with the thicker bar. Are the sprockets the same for both of these chains?
Thank you.

The sprocket drum, or rim sprocket, will be clearly marked as to the pitch. .325 OR .375/3/8" They determine the choices you have, not the guide bar.

 

[Partnerguy]

Hello, I'll borrow this thread for a question.

I have a Partner P842 which I got from my grandpa. I'm looking to buy a new chain + bar for it. I'm looking for something with quality since the saw is very dear to me.

The thing is I can't seem to find anything that fits??
My current chain and bar is a 18" (45cm), the chain has 28 teeth, 56 drive links with 3/8" pitch (19mm/2 = 9.5mm) and has "50R" and "WM" stamped on it.
My sprocket is a 6 nose.

The thing is I really want a 18" and not a 16" to be true to the original one.
Any ideas on what I should buy?

Thanks in advance!
PG

 

[spuldup]

Hello, I'll borrow this thread for a question.

I have a Partner P842 which I got from my grandpa. I'm looking to buy a new chain + bar for it. I'm looking for something with quality since the saw is very dear to me.

The thing is I can't seem to find anything that fits??
My current chain and bar is a 18" (45cm), the chain has 28 teeth, 56 drive links with 3/8" pitch (19mm/2 = 9.5mm) and has "50R" and "WM" stamped on it.
My sprocket is a 6 nose.

The thing is I really want a 18" and not a 16" to be true to the original one.
Any ideas on what I should buy?

Thanks in advance!
PG

Get out your calipers and compare it to the bar mounts here: https://www.lawnmowerpros.com/chainsaw/chainsaw-guide-bar-mount-chart.asp

Pics online look a lot like D009 or K095.

56 links would be a 16" chain. I assume you want 18"? Looks like that is 62 on this saw.

 

[Partnerguy]

Get out your calipers and compare it to the bar mounts here: https://www.lawnmowerpros.com/chainsaw/chainsaw-guide-bar-mount-chart.asp

Pics online look a lot like D009 or K095.

56 links would be a 16" chain. I assume you want 18"? Looks like that is 62 on this saw.

Thank you so much for your reply! Very helpful links!

I just realized that I measured the whole guide bar and not from the saw base to the tip. Maybe it's 16 inch after all then, I'll have to measure later at home?
That would explain why I can't find anything... Just saw this

Does it matter how many "noses" I have on my sprocket though? It shouldn't as long as my pitch is correct? Right?

 

[spuldup]

Thank you so much for your reply! Very helpful links!

I just realized that I measured the whole guide bar and not from the saw base to the tip. Maybe it's 16 inch after all then, I'll have to measure later at home?
That would explain why I can't find anything... Just saw this

Does it matter how many "noses" I have on my sprocket though? It shouldn't as long as my pitch is correct? Right?

Yes the noses (teeth) are the driving gear of the chain. More teeth equals faster chain speed, but more load on the engine. A 42 cc saw should be running a 6 or 7 tooth sprocket. If you are going to 18" I would keep the 6 tooth. If chain speed seems slow and the powerhead is happy, you can toss a 7T on.

Skål!

 

[Partnerguy]

Yes the noses (teeth) are the driving gear of the chain. More teeth equals faster chain speed, but more load on the engine. A 42 cc saw should be running a 6 or 7 tooth sprocket. If you are going to 18" I would keep the 6 tooth. If chain speed seems slow and the powerhead is happy, you can toss a 7T on.

Skål!

View attachment 1121496

Thank you again for the useful reply. Much appreciated!
I have now ordered I think it'll be marvelous!

Until next time!