Rim drive sprocket on Homelite 240

[dpress]

For my sins I have just bought another Homelite saw, a 1989 240 SL (10635B) to add to my very small collection. It was cheap, and having taken it apart today, I can see why....! There is a list of things to do, but before I make too much of a start I would appreciate some advice about the type of clutch sprocket which is fitted. This saw, unlike my other 3, is fitted with a .325 7 tooth rim drive sprocket. I have not seen one 'in the flesh' before and am trying to understand how it works. 

Am I right in thinking that the actual sprocket part is allowed to float on the small splines of the clutch drum to ensure the chain line is always straight? Also, should a large thrust washer be fitted on the outside of it to ensure there is no chance it could come off the clutch drum under any circumstances? Unfortunately I can't find such a set up on the Ipl's for the 240/245, but if anyone can set me straight please do. I am likely to want to change the actual sprocket - would any .325 7 tooth item work, or are they specific to the make of clutch drum (mine is an Oregon marked 38003)

The saw is also fitted with the wrong chain guide bar - it has a 16" Ryobi item fitted which does not have the correct slot for the 240 style chain adjuster, along with a 66 D/L Oregon chain marked '20'. As I understand it this is the correct size .325 chain. I have seen an Oregon bar for sale that is the correct fitment for a 240 but the information indicates a 65 D/L chain would be needed, but I am wondering, given it has an extra tooth on the sprocket up from the standard 6 tooth, if the 66 D/L chain might do, just to get up and running? The chain is almost new (although rusty) so it would be a shame to bin it if I can avoid it.

Any and all advice welcome - I am sure there will be other questions along the way.

Many thanks, Steve

[sweepleader]

"Am I right in thinking that the actual sprocket part is allowed to float on the small splines of the clutch drum to ensure the chain line is always straight?" Yes.

I have never heard of a rim coming off, the chain will keep it aligned.

The spline size is an option on the rims, if it fits it works. It does need to be matched to the chain but several sizes will fit the same splines so chains can be changed without changing the clutch. The sprocket nose on the bar still has to match the chain. The chain pitch does not matter to a roller nose bar.


I believe the rim system is Oregon's design although others make them now. The second page of this .pdf does not want to upload, it shows the various sizes. The whole thing is at:

www.treestuff.com/content/pdf/RimSproxFB0601.pdf

[onlyhomelites]

Rim installations should have a washer large enough to at least block the splines. As sweepleader said, the chain will keep it aligned, but the washer is the insurance policy.

[dpress]

Thanks for the info both. I will find a good size washer to add to the end of the crank. The Oregon PDF was particularly useful thanks - I now have the correct part number for a replacement rim. Back to the garage to play some more!

Steve