My IPL shows #18 for all models except #2 below, and #19 for the MS440-D. Someone else will have to say which saw that is - I'm clueless.
OK. Yup. I see it now. Cat stands for catalytic converter. Thank you.
That is about .0015" on each side of the diameter (.003"total). Crankshaft stubs are normally heat treated to harden them (case hardening?). I know that the hardening doesn't go very deep. Some others here might be able to contribute more. The telltale is that the drum may rock back and forth too much. Check for this with the new OEM bearing and new OEM drum.
If you don't have a CAT muffler either seal should work. The CAT seal is likely a different material that will survive higher temperatures.
I'm replacing the sprocket. I don't know how much life the chain and bar have left - probably not much, considering all the evidence of abuse. I'll see once I get it rebuilt and running.
A chain that has been ruined by a worn sprocket will quickly ruin a new sprocket.
The main issue is chain stretch which will cause an uneven distribution of load on the sprocket. There is no easy way to check this other than to measure the distance between an odd number of rivets and compare with the chain pitch specification. For bicycle chains (1/2" pitch) the wear limit is 0.125" over 1 foot of chain (1% stretch).
The main thing to check on the bar is the width of the groove (gauge). It should be no more than about .004" larger than the marked gauge to keep the chain from flopping side to side.
I've never used one in a 440, but I have used a lot of oregon clutch drums and never have had any issues with them.
As good as, if it’s not actually oem
Thank you!
