Big valves conversion made in Germany

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mdt-son said:
Hello Klaus,

I didn't want to mess up the thread on rocker trust washers, and am posting in this thread instead.
I am an advocate of rotating valves too. Can you please post a picture of the Norton vs. the BMW valves and collars and keepers and the valve caps you are using? 42/38 mm is quite an upgrade to the stock 37.8/33 mm valves and I note you do even bigger valves. What is the stem size of your valves? How does your valve guides look like compared to the stock ones?

Rgds.
Knut
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Hello Knut,
I use standard- sized guides. If you sent me an E- Mail, I send you the drawings about how it is done. It's too complicated to explain here directly in tve forum. You definately need fixtures and a lot of tooling for the job.
Best Regards
Klaus
 
Fast Eddie said:
Looks like your man knows what he’s doing there Yves!

Should be a rocket ship when it’s done !!
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I'd like to see the results of two tests. Take a 750 head and reseat the valves using the three cutters, then dyno. Thentake the same head and fit the larger valves and do a comparison on the same dyno.
 
Klaus Monning said:
Anyway, Yves gave my E-Mail address further above. If you want the drawing and the (Excel-) calculations for the following valve sizes: 41/36, 42/38, 43/38 and 44/38 (mm) give me a message.
Best Regards
Klaus
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That 44/38 combination is pretty impressive. I've been looking over the data I have collected over the years on big valve heads, and the largest I've seen anyone else do is 43/36. With so many others who have also done big valve conversions over the years, there may be some who have also gone this large, but I don't have any info on them. I'm guessing that Herb Becker might have pushed the limits a bit too, but I don't know any details of that.

Ken
 
Just found the info on the head Herb Becker did for Andy Cox's land speed Commando. He also used 44 mm intakes and 38 mm exhausts.

Ken
 
https://www.accessnorton.com/Norton...its-after-andy’s-154mph-bonneville-run.25886/
Using huge valves (44 & 38mm) that are splayed/angled wider to avoid valve hookup with the highly overlapped 480 cam he has achieved about .220” between the valves on the seats (stock is approx .185”) This puts the intake valves right up against tho 81mm cylinder bore. The head is heavily milled to reduce the combustion chamber size – so much so that the valve pockets needed to be deepened. This required special one off pistons with the rings dropped so that the oil ring is all the way down into the pin bore (common practice with racing cars).
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Fast Eddie said:
Good idea Al.

You’ve got a suitable test bike... I look forward very much to seeing your posted results...
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When I had the Triton, a friend re-seated the valves in the Triumph using the three cutters. There was a noticeable improvement in performance. Often there is a ridge left on the seat beside where the valve sits. There are two aspects to gas flow - velocity and pressure. If the hole is smaller, the flow can be faster with higher pressure, so the mass transfer is similar. If you can hear gas flow, it is sonic - so any minor ridge in the inlet port or exhaust system can cause a major obstruction. I believe that some people who use flow benches when porting cylinder heads, might be kidding themselves. If you increase the port size on a 650 Triumph, it will never go fast. I made that mistake with my 500cc Triton. I enlarged to ports in the 650 Triumph head. The motor had to be spinning extremely high before it would do anything constructive. - Simple-minded idiocy !
I openly admit that anything I know about motorcycles, I have learned by doing it wrong. Even my riding skills have been learned by crashing.
 
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