KTM 620 LC4 mysteries

Hello, I love this blog and the forum is a great idea, good work. I’ve got a 1995 KTM 620 that I’ve been trying to find a repair manual for, so I can adjust the valves and maybe do some top-end repair work some day. The manual isn’t available anywhere! I’ve tried hours of searching the internets, ebay, local dealers, forums, etc. I realize this bike is ancient by dual-sport standards and is now becoming “obscure”, but I’ve seen some other KTM-related posts on here so I thought I’d ask. Also: what do you think about using synthetic oil for this bike? I’m familiar with the arguments about friction modifiers and so forth, but I’m also noticing a lot more seepage coming out of the motor now that I’ve tried using synthetic on this old Katoom. Were those gaskets too old for synthetic oil’s super slipperiness? Thanks!

Hey Cap` thanks for the positive comments!

I don’t have a manual handy for the early LC4 motors, but there is plenty of information floating around out there. If you are just looking for valve clearance specs and cylinder measurements I’m sure I could dig them up. Are you riding a Duke model? Or one of the SX models?

As for oil – If the bike hasn’t used synthetics from the start I would avoid them. The seeping you noted is extremely common when switching and older bike to synthetic oils. Synthetics are able to make their way through microscopic holes in the gaskets that dino oils can’t. If I was you I would just switch back to dino oil and call it done. Keeping the oil and oil filter clean are far more important than selecting between dino and synthetic. Use dino, change it frequently, ride happy!


Evan Fell

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