Hi nathan_867 the KAV87 is a 140?cc two stroke motor. There was a few different versions, I have one off a Sunbeam it was painted green and was the round barrel finned version.
The motor's were not "loved" in the mower industry as I'm sure others will attest to. They had a few issues of there own; like the crank case covers coming loose and the bolts holding the muffler on coming loose, yet the exhaust cover to get to them being near impossible to get out! Not to mention starting etc. However they are a powerful motor on a mower.
Also once the big end Main bearings wear the crankshaft can be bent and they vibrate. The big end bearing on the conrod are needle rollers (there is 28 of them) and the crankshafts/conrods can tend to get "ripples" in them or the case hardening can flake off as well.
If the crank is bent due to worn mains it can be successfully straightend and be serviceable. I have done a few.......
The ones I have come across have usually had little wear and some have had real bad carbon deposits choking up the exhaust ports.
Having said all that if you have the parts, (change the crankshaft seals too!) it would make a good collector motor mower. I don't think there are many left.
If you have forgotten which way the head goes on I can help you out.
Specs:
KAV 87
Bore 2.500" Stroke 1.770"
2.8 HP @ 2400 RPM
3.4 HP @ 2800
3.9 HP @ 3200
4.2 HP & 3600
6.3ft/lbs @ 3600 RPM
Pic's would be good mate!
Watch out for the Gaskets they ARE ASBESTOS! (The replacements are as well) so keep them damp with WD or oil wrap them up in plastic and discard if you must.... Scrape them off if you need to.
DO-NOT power buff them off!
