Bent valves (all 8)

3719 Views 32 Replies 18 Participants Last post by Coot, Dec 20, 2005

Momboy007

Discussion Starter · Sep 28, 2005

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Hello All,
Well, as you all recall I got a 1981 Goldwing for nothing from a neighbor, it would not run, so I began tearing it down and it appeared the timing belt was out to lunch on both sides, left about 100 degrees and the right about 90 degrees.
Over the Weekend I tore the heads off and ALL THE VALVES ARE BADLY BENT, the pistons appear to be fine.
I still don't know the condition of the rest of the bike (Carbs, brakes, electrical system)
How would you proceed, I would like to save this machine, but would like to get the valves done as inexpensive as possible, does anyone have suggestions for me?
Thanks all in advance,
Rick

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21 - 33 of 33 Posts

Kyle

· #21 · Dec 18, 2005

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On my 78 Yamaha 1100, I replaced the head. Didn't even think about plate testing it. Did a great job re-seating the valves and a lot of love, labor, and was meticulous as to how everything was done. Set it on, torqued it down in sequence and when I was done I thought it was kind of neat how you could see daylight. Needless to say, a lot of work for nothing including the $80.00 the head gasket cost me.

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Wingcommander

· #22 · Dec 19, 2005

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It might be a folk tale and there's probably a work around, but arent these valves/seats given a special coating treatment that shouldnt be lapped by hand with carborundum paste?

I just checked my Shop Manual and it says that all but the earliest GL1000 valves are.

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exavid

· #23 · Dec 19, 2005

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If the valves aren't seating what's the alternative? New valves or a grind and lap?

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Wildcat

· #24 · Dec 19, 2005

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I've done many a valve job on cars, trucks tractors n such. If the valves are not bent then I hand lap them with a grinding compound. Used to use a suction cup style handle that stuck on the valve, rotate back n forth, lift and rotate, long process. Then I discovered variable speed reversable drills

I now use that with lapping compound, back and forth, lift and turn, trick is not to go to fast and cause grinding compound to flare. Works very well with practise.

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Eamonn1200

· #25 · Dec 19, 2005

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Lapping works, even on valves with hardened seats. The drill trick works better on hardened seats, but you need to control the speed, a consistent slow speed is best as it stops the paste eating into the head and also stops the valve stem wearing the guide out (small drop of oil or grease on the stem helps too). On heads with limited space, a flexible drive with a small chuck at the end can get in easier.

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Wingcommander

· #26 · Dec 19, 2005

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This stuff is called Stellite and I guess is some kind of case hardening treatment(?) I can't remember where but on some website I read that engines can soon screw up if it is ground off. The only answer seems to be new valves.

I just checked my Clymer manual and this telling me the same thing - the valves are manufactured with a special surface on the valve face and must not be ground.

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Coot

· #27 · Dec 19, 2005

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It's cheaper to replace the exhaust valves than to have them ground. They run about $12 apiece and they are the only ones that are stellite-faced. They areground with a gray aluminum-oxide grinding wheel. Also I wouldn't trust everything inthe Clymer manual, it is full of mistakes. Anyway Momboy007 is going to need all new valves or a good set of used ones, his are all bent. Coot

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teacher

· #28 · Dec 20, 2005

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I bent 4 out of 8 and was think about new valves but decide on used heads on eBay.
My wing runs great now. I think I paid $100 for the set and shipping. Plus the new head gasket.

http://www.goldwingfacts.com/forums/forum1/3888-3.html

http://cgi.ebay.com/ebaymotors/1983-Honda-Goldwing-GL1100-HEADS-MECHANICS-SPECIAL-NR_W0QQitemZ4597676905QQcategoryZ35595QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

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exavid

· #29 · Dec 20, 2005

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I'd still go with used heads, these engines usually don't have problems and if you can buy a pair of heads cheaply the only other thing you'd need would be a head gaskets and may as well put on new stem seals. Hunt on eBay, there's lots of people parting bikes out and most of them are honest. Many will send you extra pictures if you need more to determine the condition. You can also post the item number of the heads you're looking at here and we can all help you take a look.

With eight valves bent the chances of valve train damage is pretty high, the cam, rockers, rocker shaft and all have been subjected to very high stress. If you're going to reuse all that you really need to disassemble all of it for inspection and testing for bending or cracking. When a fast moving piston drives the valve back into the rockers it's much like hitting the valve stem with a sledge hammer it's a major trauma to everything that's involved.

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Coot

· #30 · Dec 20, 2005

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There is more than just head gaskets and stem seals. I would NEVER put a used head on any engine without having it checked and serviced. There is just too many thing that can beF#%&ed up. First it would have checked and surfaced in case itever ran hot and warped. Then the valves, guides and seats would need inspecting anda good three degree valve job done. Then you know you have good heads that will last on that journey, Coot

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exavid

· #31 · Dec 20, 2005

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Different strokes, Coot. The Goldwing heads don't commonly warp and serious overheating is fairly rare so the odds are good that you could find decent used heads. Yeah I'd check them with a straight edge and feeler gauges before putting them on an engine but I'd be surprised to see a really bad pair. Valve guides and stems usually hold up for well over 100,000 miles so it's likely you wouldn't have a problem there. Replacing the stem seal is a good idea since they do deteriorate with age and some models have had seal problems. Most of the bikes being parted out on eBay and other places isn't because of major engine problems, it's because people who are willing to work on them or hunt parts are more scarce than bikes that need a little TLC. Not to mention that most bikes bring more in parts than whole.

I'd bet a pretty penny that you could put any decent looking set of heads on and and the engine would run trouble free for thousands of miles. These engines aren't hard pushed aircooled mills that run at extreme temperatures with light weight thin castings but some pretty robust machines. Kinda like Cadillac Sedan Devilles, you don't find a lot of them that have been worked hard.

Each of us has a different way to do things, I haven't had an engine I've rebuild on anything fail or perform poorly, there's more than one philosophy and I'll stick with what's worked for me for a lot of years.

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dean_3326

· #32 · Dec 20, 2005

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Sometimes when a piston is hammered it causes the rings groves to be squeezed and sticks the rings in place, just looking at the tops of the pistons does not always tell the whole story of damage to them.

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Coot

· #33 · Dec 20, 2005

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I have bought a set of heads off Ebay and all four exhaust seats and valve faces were pitted. If I had not checked them and just bolted them up the pitting would have continued. The pitting issmall pieces of the seat being welded to the valve face and then thrown out the port. Letting this deterioration to continuethe seatswould not havecool the valves properly and the oil in the stemscould gum up due to the increased heat causing sticking valves. Sooner or later a valve head could come loose and Bamm- stuck in nowhere land because I trusted someone I didn't know on Ebay who said it was a low mile bike. Like the mechanic said "you can pay me now or pay me later" Coot.

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