Top-end rebuild?

[bprivett]

I'm trying to decide whether to ship this off to a pro for a lot of money for a top-end rebuild or not. I'm leaning towards no, because: everything looks good, didn't have compression issues, and it only has 30k miles on the clock.

But, being a newbie, I want to make sure I'm not missing something obvious...

Some photos, post a first round of cleaning...

[Polarbear]

A 30000m engine is way too early for such,imo. You probably won't believe it but my R100/7 is at 380000m, YES over third a million miles with original heads/valves and all. My compression is still at near normal. I did replace the pistons/rings at 104000m, a long time back. I bought the bike new. Most go around 60-100000m+ before this is considered and many around 1983 had issues needing it early. Randy

[beemerguru]

Everything looks decent from the cheap seats. Was it using oil, smoking, or were the valves tightening up with every check?

If "no" to all the above..get new seals and gaskets, then go for a long ride...about another 5 years.

[44006]

Lightly hone the cyl, lap the valves and ride it

Oil consumption less than 1qt/1000 miles is fine - just check often till you learn just how much it uses

[mneblett]

This sort of visual check is, unfortunately, pretty useless, except to verify no cracks in the head. The valve springs need to be removed so you can inspect the valve seats for recession or other damage, the wear pattern on the valves' seating face, and the wear in the valve guides.

It appears these are 70's squish-band pistons and heads (if I'm mistaken, someone will pop up with a correction). Heads of this vintage are less likely to have problems than later heads with issues such as bad seat metallurgy or prematurely-wearing valve guides (I had an '88 with wallowed-out valve guides in ~15K miles, so mileage isn't always a good indicator).

IF the valve clearance was not changing rapidly, it is unlikely there is unusual seat or valve guide wear. That said, the only way you'll know for sure is having a knowledgable set of eyes look them over. For peace of mind, it may be worth shipping them to someone who knows heads for an inspection. Folks like Tom Cutter will give a fair assessment, without recommending unnecessary work -- in other words, if Tom C. says you need new seats or guides or need the valves/seats machined, you need the work; if not, he'll tell you that too.

[cycleman2]

If both heads look like this one, the engine has good compression and is running fine, then I would leave it alone. There doesn't appear to be much if any wear of the valve into the seat from the photos you've provided.

If you find that when you adjust the valves they are always closing up a bit then I would suspect valve seat issues. If you are not finding that then you are good to go.

[bprivett]

Thanks everyone... I feel better, and my wallet thanks you...