Well, I finally got my headers off today. Turns out they were so corroded that the cross-over pipe sheared off. So, I'm looking for a new set of headers.
Now, onto the valves, which look pretty nasty.
http://s610.photobucket.com/albums/t...t=IMG_2064.jpg
http://s610.photobucket.com/albums/t...t=IMG_2060.jpg
Any opinions?
Mine look like yours they look worst on the inside.
Pull yer spark plugs out and see what they look like through the plug hole when the valves are fully opened. That'll give you a much better idea of their condition.
What year - model are you talking about?
I've got a 1976 r90/6. It has "54000" miles on the clock, though when I bought it it had "38000." That is, the odometer went wonky last riding season and I don't know the actual mileage.
I'm slightly concerned because the headers had a heavy coating of carbon/rustish stuff on the inside, and the interior of the heads had some flakes/pieces of stuff (metal?) where the headers go into the heads.
They don't really look that bad. As mentioned in above post-look at sealing surfaces thru spark plug hole.
Has anyone tried Chevron's Techron? I use it in cars fairly regularly.
'73 R75/5
Never had a bad day skiing!
Were it me, and if it bothered me, I'd just pop the heads off and have 'em gone thru...and it probably would bother me, to be honest...it's a simple enough task, and it's good maintenance to have that done once in a while...I'm sure some of the guys here have an idea what the interval is for head work...but it sounds like your machine is ready, in any case...especially if it hasn't been you putting on those miles!
All I see are deposits. The actual condition of the sealing surface can't be seen.
So give it a compression test. And then a leak-down test. That will let you know if you have a sealing problem. You could have a recession (valve seat wear) problem but that can't be seen in the picture. To see that you need to remove the heads and manually open the valves to look at the heads and seats.
Techron or Seafoam in a few tanks of gas will deal with those deposits. Read and follow the instructions on the bottle.
Paul Glaves - "Big Bend", Texas U.S.A
"The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
http://www.bigbend.net/users/glaves
Having now peered through the spark plug hole, I don't think there's that big of a problem. Each of the valves seem fine (no sharp edges, etc.). The compression as of last testing (beginning of last riding season) was 130 on the right side and 128 on the left. Not great, maybe, but not bad, either. Unfortunately, I can't do one now, as the bike has no starter.
I think I'm simply going to decide not to worry. It was running great when last it ran, so I'm just going to clean things up and replace the pushrod seals (which was the original purpose for all this disassembly anyway).
Isn't it funny how one smallish project on these bikes tends to lead to something bigger and bigger and bigger?
Also you will know if you have recession based on the amount of exhaust valve clearance "close-up". If you were doing frequent valve adjustments and the exhaust valves were always tight (.000" lash) every time then suspect either recession or valve elongation.
Years ago I had a VW 1600cc that would lose .006" every week, finally replaced the #3 exhaust valve and it was .125" longer than the others. #3 was behind the oil cooler and always ran hotter.
I suppose that's why BMW says to limit idle time to like 10 minutes? Air cooled engines need air flow.
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