Why oh why did i check my valves lol

Howdy boys and girls. I had posted about some low compression issues previously. Well, i took the advice of the wise men and decided to check my valve clearances. On average I’m looking at about a .005mm of clearance. There were some variations but everything was close to the same. My shins were (from cyl 1-4, ex-in)
cyl 1).260/.280,
cyl 2)burnt valve/?,
cyl3).255/.265,
cyl4).255/.270.
I didn’t start measuring in that order, but this is what i have. All of the valves actually looked ok from what i could see through the spark plug hole, but the exhaust valve on cylinder 2 was visibly smoked. And that’s when i basically stopped pulling shims.
The intake cam love tip on cyl3 showed some discoloration, and the shim on the same definitely had a different color to it than the rest of the shims.
So I’m looking at the very least at pulling the head. Which brings me to my question.

Should i bother rebuilding the head?Alternately, there appears to be a guy local to me that’s selling an 82Maxim 550 (mine is an 81) with similar mileage to mine. His is basically a roller with the engine, and exhaust, but at least from the pictures appears to be in good shape.
Thoughts, ideas? What should i offer the guy?
Any suggestions would be greatly appreciated.

 

How can we be sure HIS engine doesn't have 2 burnt valves? I'd want to see and hear it run first.

 

Yeaahhh, that was kinda my concern too.

 

Take a battery, jumper cables, compression gauge . Looking for 125-145 with no more than 10 psi difference.

 

if the cost of the roller is more than a valve job do the valve job. start pricing up the valve job,
of course you can part out the bike. is there anything you can use off of the bike? always nice to have a spare tci. if you have done your carbs you could just slap them in and see if it runs.

you could ask if he does not mind you checking his valve clearances?
if the cam is damaged you would want to buy a head with cams in it because they are not all the same size all the time at the caps

 

complete the shim change and see f the motor runs properly and do the compressiot test no point in buying parts if it is ok after you change shims.

 

From what I’m seeing on pricing;
So far I’ve found a place that will rebuild the head for basically the price of the roller(when you factor in shipping). The one valve will definitely need to be replaced as it has a “channel” on it that’s pretty visible. So at least one valve will need replacing. Factor in gaskets and other misc seals and im way over the cost of the roller.
The guy claims that the engine runs well, and is willing to toss the starter back in and carbs so that i can hear it run. So far I’m leaning towards the roller. My logic there is that if it is indeed in good shape, I’ll check the valves and be out the cost of a few shims if need be.

 

get the roller

 

Well. As long as the guy doesn’t back out. I’m picking it up Sunday.

 

Well. Got the roller.
Started up fairly easily in 40ish F weather. Mine doesn’t like starting at anything below 60f so i guess that’s good. The engine sounded nice with no weird issues or signs of major blow by. But it will need a crank seal, and I’m definitely going over the valves. With that said, just wanted to thank everyone for the wisdom. I’ll also be parting out what i have left of the roller in the near future as space at my place is sort of at a premium.

 

Are you talking about expected cylinder pressures? I did mine a couple months ago (been having issues with my 1982 xj650, posted a thread about it) and got all between 93-100 psi. At the time I thought this was the expected pressure. Is it meant to be higher?

 

Yes below 100 is not good. Rings may be stuck and after a good soak with diesel and acetone mix in each cylinder for a few days. Safety Warning “ disconnect the coils before cranking engine with plugs removed “

 

if it runs, ride it
maybe it didn't crank fast enough, maybe the gauge was off

 

Thanks, I'll try that.

it runs... a little too well. It idles at 8k rpm and I'm trying to root out a cause. I don't think low cylinder pressure could cause that but who knows