Blown up R65

[montmil]

Multi-day conversation going on over on the AirList regarding a topic: "Tales of a Burnt Valve". Submitted for your enlightenment, enjoyment and edification.

Specific bike in the thread is an R90/6, but Snowbum did post a couple photos he took of an R65 that had an exhaust valve let go. Following photos and comments are credited to Robert "Bob" "Snowbum" Fleischer.

"I have seen several R65 bikes blown up. We used to have a gal...who kept her hand well wound around the throttle...and saw the resulting mess from going up a very long grade in that throttle position without enough regards to the rpm and conditions...led to $$$ problems."

"The R65 is particularly prone to damage from lugging the engine, otherwise the bikes are reliable. One of the reasons for the damage is that the old R65's had smaller valve stems and the combustion heat is dissipated far slower at/in the valves."  

"Mostly, though, it has been the larger bikes, since there are so many more of them."  -Da Snowbum

[Bob_Roller]

 I think the first generation R65's, '79-80 model year bikes, also had two piece valves .

Valve recession ( valve face plastic deformation ) on the '81 model year bikes also led to valve failure issues .

When I had the heads reworked on my '81 R65, with 44,000 miles on it, I had very little time left on the exhaust valves, before they would have been pulled past the valve seats, the edges of the valves were worn that thin .

The shop that did the work back in '98, San Jose BMW also recommended that I upgrade to valves that had a thicker stem and wider valve head, I think I have valve stems 9 mm wide and intake valve head width 40 mm and 38 mm on the exhaust .

[clonmore1]

The guy that is putting my 65 together has said he has had three 65 customers with this problem.

With all the experts on here, is there something we should be aware of ?

One of the 65 has an engine rebuild just 3k miles ago...

[Bob_Roller]

Any idea what model year bikes they are

[clonmore1]

Pre 1980 Bob,

I have just spent a small fortune getting my engine back to a 'zero' hour unit (jan 1981, updated engine) and now wonder if I have a problem coming down the line?

[Barry]

It's not just R65's that drop valves. Yes we have thinner valve stems but other airheads also have two piece valves and dropped valves happen to them too.  I knew about Snowbums caution against lugging an R65 but AFAIK he never explained until now that the concern was based on overheating the exhaust valves. If that is at the root of the problem there are several other things that could be done besides avoiding lugging like replacing the interim valve seats that had poor thermal conductivity, ditching the air injection plumbing and making sure not to run too lean.

I don't think we should get paranoid about the reliability of our engine compared to some of it's contemporaries. I'm currently reading Ted Simons Jupiters Travels for the umpteenth time and it always strikes me that his brand new Trumph 500 only does 3000 miles before needing new pistons. Valves are needed sometime later and in all I think it takes 3 engine rebuilds to get him all the way around the world. By contrast when he repeats the same trip years later on a BMW the engine does the whole distance without problems. The mono shock fails but then mono's are all overstressed to start with and he should have chosen a dual shock bike for simple reliability.    

[clonmore1]

I hope so Barry, the bike is about 6 weeks away from being Mot'd, I don't want to get a few miles down the road and have a major engine problem

[montmil]

I certainly did not post this thread to cause folks any high anxiety or sleepless nights. Weather here in North Texas is not Chamber of Commerce quality and idle hands...
    The full commentary from Snowbum was rather lengthy... no surprise there, right? His inference was the female owner of the first-gen R65 in question was not particularly kind to her two-wheeled beast of burden.

Barry's note about removing the pulse air system, plus running the exhaust lash setting at 0.001 or 0.0002 thousandths greater than the manual's specs, will add life to the exhaust valve and seats by leaving the valve on the seat just a nano-second longer and transferring more heat from the valve.

Two months ago, I removed the original heads from my '81 R65 due to smoke coming through the left side muffler. The valves were not damaged but the left-side exhaust valve guide was sloppy and the rings were worn out. Excess oil was crusting on the exhaust valve. I replaced both heads with a refurbished pair from a 1984 R65. Plus new rings. All good now.

It is possible to do a casual inspection of the exhaust valves by removing the spark plugs and header pipes, then rotating the engine to position the exhaust valve fully open. A flashlight and a Mk.1-Mod 1 eyeball application into the exhaust runner may settle the troubled mind.

[nhmaf]

I don't think that the R65 engine is really any more prone to valve/head damage than any of the larger airheads.    Of course, one has to be smart about avoiding detonation problems (some people raised on FI automobiles are criminally ignorant of what it is or sounds like) as well as avoiding lugging the engine (which IMO is more likely to cause failure from stressing the bearings and under lubricating things more than heat buildup in the head, as heat production is a function of RPM, among other things).  But lugging the engine going up grades can also contribute to detonation issues, which can lead to problems like seen in the earlier picture

Keep up the maintenance, and, if you see things starting to close up with the valve lash, start to plan accordingly.  

[Tony Smith]

I think the first generation R65's, '79-80 model year bikes, also had two piece valves . .

There certainly is nothing wrong with two piece valves (almost always exhaust valves) they have to be made that way to get the sodium in there to help cool them.

Two piece valves falling apart due to inferior manufacture is a myth.

Before any of us here in this forum were born VW decided to use sodium filled exhaust valves in the humble Beetle. To do so required that they extend a technology until then only used in "premium" products to the more pedestrian world of the Beetle.
 
A very few, quickly rectified, failures in the first batch and a myth was born.....

[Motu]

I used to search through all my 36hp exhaust valves and pick out the best ones in my engine builds...I knew they had problems, but still dropped one.  I gave up on the 36hp after that and got a 1300 engine....but still managed to blow it up.

[Tony Smith]

I used to search through all my 36hp exhaust valves and pick out the best ones in my engine builds...I knew they had problems, but still dropped one.  I gave up on the 36hp after that and got a 1300 engine....but still managed to blow it up.

Except for the absolute most "bucks down" rebuild I routinely threw exhaust valves away - there was just no way to know how many miles they had done, once Brazilian and Mexican parts became available here I recall exhaust valves being about $2.50 each. I never lost a valve in a 36 horse, threw a few rods, and ran a few mains due to oil pressure reduction due to case pounding though.
 
For a brief period of time engines were made in Australia - the "H" series 1,500 cases being prized amongst engine builders for their accuracy and strength.

[Motu]

No, never threw anything away - just the cars after I had finished with them. I used my VW's very  hard, they weren't able to be used for much after I'd had my way with them.

[suecanada]

I really don't know if my comment here will be relevant or not but: When my 1981 R65LS had the valve work done by Ted Porter's Beemershop, it was not the'tulip" end of the valve that we can see down the sparklug hole that was bad (read worn) noooo it was the keeper end or collett end and it has been worn down so that the squared edges had become knife sharp and were ready to give out at any moment

Ted Porter said LRB's valves were of really poor metallurgical characteristics. These were already a set of replacement valves probably replaced to handle the unleaded gas issue back in the early to mid 80's.

[Ed Miller]

I think the pics Monte posted are of Joan's Blueberry.  

I had an '82 Honda Accord burn a valve though it didn't cause any other damage.  It just lost compression on that cylinder.  

My Triumph is much more prone to detonation than my R65, so I learned long ago not to lug the things.  Here's a good article:

http://www.factorypipe.com/t_deto.php