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Old 03-23-2011, 05:40 PM   #16
lloydunknown OP
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Thanks to all. I didn't expect so many replies. Currently, the bike is apart for fork work. Also, we're slated to get some snow at the end of the week. It should be a few days before I'm back on the road.
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Old 03-23-2011, 09:05 PM   #17
Lornce
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Lloyd,

'81 - '84 airheads had valve seat material that was too hard for it's own good.

Your exhaust valves are probably toast or on their way to being toasted. Your exhaust guides are probably shot, too. They're usually shot before 60k miles rolls around.

If you want to save some money, just have your guides and exhaust valves replaced and count on doing it again every 60k miles.

If you want to spend a wad, have your seats replaced too. If you're fortunate and it's done correctly, you won't have to worry about it again for a very long time.

Take heart, you're not alone: This is an historical and well documented issue with 1000cc airheads mfg'd between '81 and '84.

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Old 03-24-2011, 09:48 AM   #18
supershaft
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Every 60k miles? I thought that was the magic number for transmissions? Anyway, I think it all depends. Even for '81 to '84 models. Yes, a lot of them do have valve issues before their time but some don't. Other model years have valve issues before their time as well but not in such large numbers. Personally, I have seen a lot of exhaust guides with around 60k miles that could definitely stand to be replaced while you are in there but they usually aren't shot although I HAVE seen it. IMO, it's rare that you take some heads off with any kind of miles that still have perfect exhaust guides. I wore out a set in 60k miles in my LS but those heads warped beyond usage in another 25k miles. I don't think that is common but, still, I wouldn't have called the guides completely shot. My current ride's heads and guides are doing fine at 100k miles. I plan on fixing them when they need it. That could have been 60k miles ago or another 60k in the future. Who knows?
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Old 03-24-2011, 10:04 AM   #19
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Lloyd,

As evidenced by the rapid change in clearance, your exhaust valves are shot. It's the seat face of the valve that's giving up from the hot pummeling it's taking from too-hard exhaust seats. I bet you a doughnut your exhaust guides are finished, too.

Valve guides are a whole $10 for the good aftermarket pieces from CC Products.

If you're going to take it all apart to change the exhaust valves, I wouldn't mess around with it. I'd change the exhaust guides, too.

Your intakes, valves and guides, are probably fine. They run nice and cool and properly adjusted last 4-ever. Almost.
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Old 03-24-2011, 10:24 AM   #20
supershaft
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Those CC Product's guides are great IF they don't come brand new with a ID that is already half way to worn out. Overall fit wise, I think you might be better with BMW guides. Personally, I would install CC Product guides undersized and Sunnen hone them to fit. I would machine a sharper oil scraper on them too. I think it does make a difference.

I have seen those seats get hammered PLENTY of times. I would most likely change the exhaust guides too but I wouldn't change them at 60k miles just because.
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Old 03-24-2011, 10:28 AM   #21
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Are you done?


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Old 03-24-2011, 11:02 AM   #22
lloydunknown OP
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I understand that the guides and seats are an interference fit. Would it be possible to heat the heads to remove the seats and guides? Then, could I freeze the guides and head the areas in order to install the new parts?

I can't afford the big bucks to send this out to a shop. I was hoping I could get away with not having to machine the heads.

Has anyone ever done it this way?
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Old 03-24-2011, 11:12 AM   #23
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Quote:
Originally Posted by lloydunknown View Post
I understand that the guides and seats are an interference fit. Would it be possible to heat the heads to remove the seats and guides? Then, could I freeze the guides and head the areas in order to install the new parts?

I can't afford the big bucks to send this out to a shop. I was hoping I could get away with not having to machine the heads.

Has anyone ever done it this way?
You're not going to be able to change your seats at home in your garage, but the guides are doable if you're handy, reasonably experienced, properly equipped and careful.

I don't know you, but it's probably not the sort of thing you want to try alone without a bit of guidance and the correct tooling. You could do a lot of damage if you weren't careful.

If money's tight, take the heads to a competent auto engine overhauling shop with CC Products guides and new exhaust valves in hand and specify 1.5mm valve seating surfaces. (iirc?)

Better double check that spec.



edit: or wait until you can afford to send them to a motorcycle head specialist like Randy Long.
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Old 03-24-2011, 01:33 PM   #24
supershaft
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If you have an electric welder ( stick, MIG or TIG), you might be able to do it at home although I would not recommend it unless you are sure you are up to it. Chances are the seat bosses are too out of round and need to be machined anyway. Be sure and have the base of the bosses straightened as well as the sides. Then be sure your seats are taller or they won't be proud enough. Typically, proud seats flow better and, of course, get you more compression. You can very often see where exhaust has been getting under the seat. You have to have the right setup to get them back in plus all the measuring tools. It not for the faint of heart!
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Old 03-24-2011, 07:57 PM   #25
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But all of this is conjecture. Valve lash doesn't normally go away that quickly.

Give it some time to get more data. And, who knows - you just might stumble across some low-mile or recently rebuilt heads for a song. These bikes are actually pretty rugged and have travelled loooong distances with worse troubles.

Don't worry yourself into a dither before you really know if something needs attention. Ok?

Also, I wouldn't consider doing my own heads even though I do most everything else. It's one of those things bordering on art and can trash an engine all too quickly if not done right. Especially the seats! Don't even consider them!
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Old 03-24-2011, 08:10 PM   #26
One Less Harley
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get valves and guides as a kit from motobins and save yourself some cash. After market valves (swiss intervalves). A good engine machine shop can do the seats.
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Old 03-24-2011, 11:10 PM   #27
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Quote:
Originally Posted by Lornce View Post
You're not going to be able to change your seats at home in your garage, but the guides are doable if you're handy, reasonably experienced, properly equipped and careful.

I don't know you, but it's probably not the sort of thing you want to try alone without a bit of guidance and the correct tooling. You could do a lot of damage if you weren't careful.

If money's tight, take the heads to a competent auto engine overhauling shop with CC Products guides and new exhaust valves in hand and specify 1.5mm valve seating surfaces. (iirc?)

Better double check that spec.



edit: or wait until you can afford to send them to a motorcycle head specialist like Randy Long.
I agree. I too would have real serious reservations about your servicing your heads unless you're familiar with doing that kind of work on Airheads and are in possession of the right tools. Airheads engines aren't that complex but the work does need to be done correctly. (In the German sense of the word!)

As far as having them done at a non-BMW specific shop, you might inquire at whatever shop builds race car heads in your neighborhood. In my town, the local hot rod head shop does heads for all of the MC shops, including those specializing in Beemers. The work is first rate and there are real savings in using them.

Quote:
Originally Posted by Wirespokes View Post
But all of this is conjecture. Valve lash doesn't normally go away that quickly.

Give it some time to get more data. And, who knows - you just might stumble across some low-mile or recently rebuilt heads for a song. These bikes are actually pretty rugged and have travelled loooong distances with worse troubles.

Don't worry yourself into a dither before you really know if something needs attention. Ok?

Also, I wouldn't consider doing my own heads even though I do most everything else. It's one of those things bordering on art and can trash an engine all too quickly if not done right. Especially the seats! Don't even consider them!
More data? Absolutely! But beyond that, I'd do a visual inspection of those exhaust valves and I'd continue to look at em on a regular basis. Remember, I said look! The last couple of millimeters of valve frequently disappears very quickly (JAMHIK!) and if you drop a valve, the costs of repairs are going to skyrocket.

Also +1 on finding a set of good used heads. Keep your eyes open and good luck!

Heres a severely recessed exhaust valve:

Click for full size!



Heres the valve that might have lasted another 1K miles:

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