that pic is clever, can't really make out the intake runner, what is this thing turbo?

imo or estimation its not a burn pattern but it could be a carbon pattern caused by deposits heading out towards the exh valve at higher temps which leaves the trace, nothing to do with timing but interesting question.

 

whats this out of? its weird cause the intake and exhaust valves look like there really close in size which is unusual. but yeah that carbon trail is strange idk if thats normal or indicative of timing issues

 

Its a head from a gx200 clone. It burned a head gasket so I took it off and was amazed there was no reversion (I did a lot of work to it but it was all "best guess"). It gets my gocart up to about 70 pretty quickly and about an hour of hard running per gallon. Ported and milled head, ported carb, cam, header are about all the mods so far. Am considering advancing the timing about 4 degrees. It was running a little rich but I swapped the jets so it should be close to spot on now.

 

Btw before this head gasket the only problem I had was having to replace the pull cord every other month. With about 11:1 compression it strains it pretty well. The aluminum block chinese knock off has impressed me. Spent 80 bucks on a new core engine when I started and I can't seem to kill it.