Topic: Newbie Engine Condition

[pineappleshake]

Hello,

I have a 1978 CB 750 that I bought a few years ago and am just now starting the process of restoring. The odometer had 15k on it and the oil in it was clean. The condition of the engine makes be think the odometer is correct. I pulled the head off and want to get some feedback from experts about the condition of engine. One valve has some rust on it, but the others look pretty good I think. The cylinders are smooth and don't seem to be worn. The cam shaft does not look worn either, but I need to measure everything to be sure.

I don't really want to pull more stuff apart if I don't need to, but want some advice on that.

Some questions I have:
Should I go ahead and replace the valves, since one is rusted?
Am I ok to put the head back on (assuming pistons and cylinders are ok) or do I need to pull the cylinder block (it is not loose yet) now to replace the gasket?
Are there other things I should be looking at in regard to the engine/transmission?

Thanks,
Brad

[Jerry Rxman Griffin aka MuthaF'er]

If the valve faces and seats are not corroded/rusting/leaking you are probably good to go. Of course this might have been determined by a compression test/leak down BEFORE you opened it up.

Someone has already been in that engine before you as witnessed by the head gasket brand. 

[jakec]

I've read many times that if you take the head off you will have disturbed the base gasket as well.

[Bodi]

Rust on the valve head and seat is no problem unless there's pitting on the sealing ring but that valve looks to have only slight surface rust. I would pull it out and inspect the stem, if that's pitted then the valve should be replaced. Replacement should get the seat cut - but it it's OK you just need to clean the rust off the head and seat, and lap in the valve.

[pineappleshake]

Thanks for the feedback, everyone. I'll pull out the valve and inspect the stem. Any recommendations on gaskets for putting it back together?

[bryanj]

Full top set including pucks and yes pull the cylinder you need to be 110% certain no gasket bits or anything else is in the oil pathways

AND NO GASKET GOO ESPECIALY SILICONE

[seanbarney41]

I've read many times that if you take the head off you will have disturbed the base gasket as well.

I have not found that to be true...at least with cb750's and big Kawasaki 4's

[Stev-o]

Visual checks only tell you so much.

+1 - should have down a leak down test...

[ekpent]

 Was everything that clean when you tore it down or did you do some cleaning ? If it was like that then it had very little run time. You may already have new rubber puck washers/orings etc. in there if the previous owner did it right. Probably a good chance it may have been good to go if it was still in the bike.