Wildguzzi.com
General Category => General Discussion => Topic started by: ohiorider on January 21, 2017, 06:06:28 PM
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Possibly some Guzzi content.
At 128k miles, I had an experienced BMW tech rebuild much of the top end of my R100GS engine. After I saw the prices of the OEM valves, I opted to go with Black Diamond valves and guides, made by Kibblewhite. Also had new valve springs installed. Today at 150,500 miles I checked the valve clearances for the 3rd time since top end overhaul.
In the past checks, the clearances were either spot on, or slightly wide.
Today, 5k miles after the previous check, I found both intakes at about .002", and one exhaust at approx. .005". Normal is:
INT: .004"
EXH: .008
I had new valves installed since the bike had a lot of life left in it that I didn't want to terminate by having a worn valve snap and drop the valve head into a cylinder. That'd be a costly event.
Have any of you airhead owners used Black Diamond valves in a BMW top end rebuild, or perhaps used these valves in a Moto Guzzi? If so, I'd be curious to read about your results, good or bad.
Bob
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On my R100RT the exhausts would close up some in a 5K mile interval. The intakes were rock stable. This was with a reputed rebuild by a BMW expert
The heads of my 850T3 were redone by Memphis Motor Works with Black Diamond. That engine would go 20K Miles without needing an adjustment.
Both engines had "unleaded fuel" seats installed.
Heard from the Airheads group that the BMW Liter engines were more prone to valve and seat problems than the smaller displacement engines.
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On my R100RT the exhausts would close up some in a 5K mile interval. The intakes were rock stable. This was with a reputed rebuild by a BMW expert
The heads of my 850T3 were redone by Memphis Motor Works with Black Diamond. That engine would go 20K Miles without needing an adjustment.
Both engines had "unleaded fuel" seats installed.
Heard from the Airheads group that the BMW Liter engines were more prone to valve and seat problems than the smaller displacement engines.
N3303j, thanks for your comments.
Ted Porter, Beemer Workshop in CA, was at one time a proponent of Black Diamond valves, but no more. He wrote a short article discussing why BMW and others, including Euro auto manufacturers, preferred the two piece welded valves vs the single metal B Diamond valves. He commented that over the years, Euro mfg. found that one type material worked better as stems, another worked better as a valve seat in the middle of the exhaust blast. So he quit selling Black Diamond and found a Euro mfg that made a two piece valve that was less expensive than the BMW OEM valve.
Well, I've done what I've done, so perhaps I need to shorten my valve check intervals ..... perhaps 3k miles vs 5k. It's not a big deal, actually less to do on the GS than on the 1200 Sport (but not that different.)
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Bob , I can't remember , were the valve seats replaced ?
Dusty
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I haven't used the Black Diamonds because of the negative 'press' and went with the Swiss Intervalve instead.
I have since talked to others who have a lot of miles on Black Diamonds with no issues.
In hot weather it's a good idea to check clearances sooner than five or seven thousand miles. Another trick is to increase clearance to .004 and .008. The extra couple thousandths allows more cooling time resting closed on the seat.
You shouldn't be having a valve seat issue since that was only 1981-4. But it's a good idea when asking tech questions to state the year and model bike - not everyone knows the GS was built from 88-95, so it doesn't have the valve seat problem.
Is this summer on your corner of the planet? What were the riding conditions since the last valve adjust?
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Bob , I can't remember , were the valve seats replaced ?
Dusty
No, Dusty. The seats were in pretty good shape and were (whatever the hell they do to seats that don't need replaced.) The old gal is actually running better than ever. I think you, as a long time airhead rider, would appreciate the cushy, smooth ride this 26 year old machine provides.
Bob
Wirespokes - I may be over-reacting. The valves now have slightly over 22,000 miles since top end refresh. Re clearance ... I've owned the bike since new, and have always set clearances at .004 and .008. And yes, I do take for granted that the world knows I own a 1991 model :grin:
Conditions since last adjust? One valve replacement (my aortic) which kept me off the bike all this past summer. Last adjust was Nov of 2015, with very few miles put on in between. Summer? Nope! Today was unusually nice and warm for a January winter day.
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No, Dusty. The seats were in pretty good shape and were (whatever the hell they do to seats that don't need replaced.) The old gal is actually running better than ever. I think you, as a long time airhead rider, would appreciate the cushy, smooth ride this 26 year old machine provides.
Bob
Yeah , no matter what Chuckie says , the damn things are like a good working dog , always ready to go , and eager to make you happy . I would probably just keep an eye on this for a couple of service intervals , and maybe set the lash a bit wide . Could be an issue , but maybe not .
Dusty
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Au Contrair, mon ami.. I've never said that they didn't work.. just that they bore me to tears when they are doing it. :evil: :smiley:
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I think the problem with the Kibblewhite BD valves was using them in combination with use Ampco 45 guides on the exhaust valves. The BD stems and Ampco 45 guides were not a good combo. The guides would wallow out too early, valves would hit the seats off square, resulting in dropping a valve head.
Happened to a friend of mine on at 1500+ mil trip in summer of '15. Dropped the right side exhaust valve, destroyed piston, head, cylinder. Had his father express shippped a spare top end out to him at the national in Wyoming where he repaired it in the grass with many onlookers.
He rode that 79 RS home with the swapped top end and bike still running on the swapped top end.
It IS unusual for the intake valves to be closing up..mostly happens on the exhaust. I would just shorten the inspection interval and track the movement. If I was really worried about it I'd pop the heads and dismantle the heads for a really good look at how the valves, seats, and guides are doing.
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I think the problem with the Kibblewhite BD valves was using them in combination with use Ampco 45 guides on the exhaust valves. The BD stems and Ampco 45 guides were not a good combo. The guides would wallow out too early, valves would hit the seats off square, resulting in dropping a valve head.
So maybe use KW guides if available? And another contributing factor is using the tight guide to valve clearances recommended by KW...Tight clearances need precision valve work with seat to valve head runout less than half a thousand of an inch...Many shops cannot do this precision.....The seat runout loads the valve stem to one side and often it seizes...And then the piston might hit the valve and it all goes to hell quickly....
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I think I'd use the "Swiss 2 piece valve" and OEM guides, and I will on my next top end
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I used Kibblewhite valves and guides on my '83 R100 and Norton. The valves had nearly 200k when I sold the beemer. I think I replaced the guides once in that time. I also run loose clearances on all my bikes, like plus 2 thou. Loud valves save lives.
Pete