Topic: Do I need to remove carbon deposits from head?

[zabzob]

As asked, do I need to do this? There's quite a bit of build up, because I was burning a lot of oil. I've got new pistons and rings in and am getting ready to put the head back on. Does all that carbon have to be removed, or will it kind of burn off on its own once it's not burning all that oil?

[Jarrett_Honda]

I would remove it. Carbon build up can affect proformance. This is one of the things petroleum companies try to fight by engineering their fuels to break down the deposits. 

[PeWe]

Are valves and their seats OK? Good idea to inspect when you have everything apart. Remove valve springs easy done with correct tool that is rather cheap.
CB750 can have burnt ex valves, seats and maybe bad guides too. You'll see when removing the springs and wiggle the valve when it is 8-10 mm out of completely closed. It should not move much sideways. I think max is 0.1mm.

I recently found a really nice CB750 K6 head on eBay.Looked like a low miler.
Ex valves were all bad, guides included while in valves looked almost new, seats included. It got new Honda ex guides and almost new ex valves + new guide seals. Parts I had and a nearby shop did the job replacing guides, cut seats and a major clean up of chambers and ports.

[ekpent]

  A super easy test after you clean up some of the carbon is to flip the head upside down and fill the valve chambers with a thin fluid and see if any leaks past the valves.  If so a lapping may clean them up enough.

[zabzob]

Thanks for the replies everybody. Head was rebuilt in 2015 and probably has about 4000 miles on it so far. From research it seems the best way to get rid of carbon build up is with methylene chloride, so I'll get some of that. No brass wheel to blast it off unfortunately.

[PeWe]

Valve guide seals might not like that chemical. Use a brass brush on a drilling machine. Avoid the mating surface

[ekpent]

 I'd find something other then paint stripper. That chemical is pretty much outlawed now and all the stores around here either pulled or sold out quickly the stripper that had that chemical in it.  https://www.lawbc.com/regulatory-developments/entry/epa-bans-consumer-sales-of-methylene-chloride-paint-removers-seeks-comment