Proper bar and chain for Still MS 290

[Steven8439]

Hello all, recently my father in law passed down his MS 290 to me. Currently it's running a 20 inch bar and I wanted to go down to a 18 inch bar. I think the 290 will pull a 18 inch bar better than a 20 inch. From what I read it sounds like the MS 290 is a .325 inch pitch by .063" gauge. I bought a Stihl Farm Boss 18 inch bar that is a .325" pitch and 0.063" gauge. It called for a 74 link chain so I bought a matching chain. Well I finally got it today and put it on but for some reason the links don't like to go into the clutch sprocket grooves. I noticed it when I got it on and tried spinning the chain to make sure the chain wasn't too tight. What did I do wrong? Should I of actually gotten a .325" pitch by .050" inch chain? Is 74 links too much even though the Farm Boss bar called for a 74 link chain? Thank you guys.

 

[Mad Professor]

Most likely the drive sprocket pitch does not match. Maybe it's 3/8"?

It should be marked on the rim, or drum, depending on sprocket type.

Post pictures of the drive sprocket, and any numbers on it.

 

[epo]

Maybe it's just that the saw was equipped with a 3/8 bar and chain, not .325? Therefore, the installed drive sprocket will also have a pitch of 3/8'' (0.375) instead of 0.325''.
Then you'll either have to change the sprocket to .325 or look for a guide bar and chain in the 3/8 size.

.325 (7T) rim sprocket kit part number: 1125 007 1001
.325 (8T): 1125 007 1000

.325 (7T) rim sprocket P/N: 0000 642 1236
.325 (8T): 0000 642 1234

.325 (7T) spur sprocket P/N: 1125 640 2005
.325 (8T): 1125 640 2008

 

[Steven8439]

That was the next thing I checked. It said .325". Part number is 1125 160 2900. I also noticed the chain it's currently running on the 20 inch bar has the number 3 on each link where as the new chain I got has the number 6 on each link.

 

[epo]

That was the next thing I checked. It said .325". Part number is 1125 160 2900. I also noticed the chain it's currently running on the 20 inch bar has the number 3 on each link where as the new chain I got has the number 6 on each link.

Looks like a small spline drum...
The chain with the number 3 is 1.3 mm (0.050'') gauge. Chain number 6 is 1.6 mm (0.063'') gauge. The sprocket for them will be the same if the pitches match. The guide bars will be different.

 

[Steven8439]

Dang.. So really I need a 3/8 bar and a 3/8 chain?

 

[epo]

Dang.. So really I need a 3/8 bar and a 3/8 chain?

And what does it say on the mounted rim sprocket: .325 or 3/8?

 

[Mad Professor]

That was the next thing I checked. It said .325". Part number is 1125 160 2900. I also noticed the chain it's currently running on the 20 inch bar has the number 3 on each link where as the new chain I got has the number 6 on each link.

The cutters and drive links are marked to denote pitch and gauge.

Dang.. So really I need a 3/8 bar and a 3/8 chain?

Does it have a rim or spur drive sprocket? Rims are easy to switch 3/8--->0.325, just buy a rim. Drums you need to switch the whole drum assy. Either/or to 0.325" and your new bar/chain should fit.

 

[Steven8439]

 

[Steven8439]

Couldn't find any other numbers other than the part number.

 

[epo]

Couldn't find any other numbers other than the part number.

Maybe check on this 20'' guide bar. There should be a marking there, too. If it's 3/8, try looking for the .325 rim sprockets that part numbers I gave earlier. You have a choice of 7 pin and 8 pin. It seems that they should fit the drum that is currently installed.

 

[Steven8439]

Alright, I'll get it figured out. Thank you for all the replies guys!