'85 R80 Top End Rebuild

[fencermatt]

Hi Everyone,

I have a 1985 R80rt engine with an unknown number of miles on it that needs some love. It's been feeling pretty underpowered so I did a leak-down test. Both cylinders have air whistling out of the intake, exhaust, and dip stick hole, so I think I'm going to need to do a top-end rebuild. I've replaced rings before, but I've never done any valve work, and I'm wondering if any of y'all can offer any advice before I start taking things apart.

--What exactly is involved in a 'valve job?'

--What parts will I need to replace?

--Will I need to send the heads out for any machining? If so, can any of y'all recommend someone in the Seattle, WA area to do the work?

Thank you all for your help, I really appreciate it.

Thanks!

Matt Pearsall

[khittner1]

Leave the head work (valves, seats, guides, any "decking" necessary, etc.) to experts. I'd start with Hansen's BMW down in Medford, OR. I'd send the work there, but they may have a referral for the work in the Seattle area.

[Duane Ausherman]

Send the heads out and pay the bill. There are a few really good machinists who know airheads. Collect several names and recommendations, then decide.

[Rob]

If you ship them out somewhere, put each head in it's own box with lots of padding, and then put those two boxes in one box, with lots of padding.

DAMHIK

[Major Softie]

Matt, the only thing you can practically do yourself on a "valve job" is if they just need a little hand lapping, and it sounds like yours is in much worse condition than that. A "valve job" of this nature will probably involve new valves, new guides, and new seats. Guides need to be reamed to match the valve stems, and seats have to be removed, replaced, and have new valve mating surfaces cut into them. All of this not only requires expertise and precision, but also a number of special tools. Even many machine shops experienced with doing this kind of work on autos have been known to screw up Airhead heads - thus everyone recommending that you send them out to a known Airhead expert.

[fencermatt]

Thanks for the advice everyone, I appreciate it. I've found a place here in Seattle, Hill Machine and Headworks, that gets good marks for doing airhead valves over on ADVRider. While they've got the heads and I'm replacing the rings is there anything else I should check while the top end is apart?

Thanks,

Matt Pearsall

[Jeff in W.C.]

Thanks for the advice everyone, I appreciate it. I've found a place here in Seattle, Hill Machine and Headworks, that gets good marks for doing airhead valves over on ADVRider. While they've got the heads and I'm replacing the rings is there anything else I should check while the top end is apart?

Thanks,

Matt Pearsall

I would pull the cam followers out and make sure they're in good condition.

[dwerbil]

Thanks for the advice everyone, I appreciate it. I've found a place here in Seattle, Hill Machine and Headworks, that gets good marks for doing airhead valves over on ADVRider. While they've got the heads and I'm replacing the rings is there anything else I should check while the top end is apart?

Thanks,

Matt Pearsall

Yes, pull out all the lifters and inspect the cam-side surface. I just had the head's done on my '84 RS. Three of the four lifters had pitted cam surfaces or missing chrome. Could cause cam lobe issues if not replaced. I got four good used one from Martindale Cycle Works for 100. Course too, replace your pushrod tube seals. Order in your jug base gaskets. #4, 5, 6....
http://www.maxbmwmotorcycles.com/fiche/ ... v=04282014

http://www.maxbmwmotorcycles.com/fiche/ ... d=04282014

[Rob]

And don't let them sell you pushrod seals for an R65, they won't work.

[Major Softie]

DAHHHK