Gudegon pin circlips

[blethermaskite]

I can see their use but it seems a bit like 'reinventing the wheel' to me......if wire gudgeon pin circlips were good enough for Hailwoods Honda six, good enough for the BRM and good enough for my Yamaha FZ 400 rrsp road bike that could run up to 17000 rpm, and dozens of other 'fast' engines I think I will stick with them .
Cheers, George.

[IanHood]

I think the teflon buttons were originally used in high performance engines that were regularly assembled and disassembled and I can understand that. It would make it a much quicker and much less fiddly situation. Like a lot of mods in high performance engines, perhaps they have made their way to 'cooking' engines in the mistaken believe they would make a difference (a bit like go faster stripes )

Ian

[themoudie]

Aye Ian,

Are you suggesting that my black/white chequered tape doesn't reduce my quarter mile times and increase my top speed?

Good health, Bill

[LaceyDucati]

Sorry Bill, Black and White tape is about as effective as a Desmo head on a Ducati Single.

I'll get my coat

Factory twin cam Race bikes aside....

[Jordan]

That's true, but desmos are such fun.

[IanHood]

…in the same way a monk might describe self flagellation as fun!

[themoudie]

I would agree Nigel, though maybe apart from a good 250, or the short stroke 236cc special built by Stotfold Engineering that revved to 13,500rpm.

Good health, Bill

[Jordan]

If the cam profiles are aggressive enough to cause valve bounce, desmo could be useful.
But there are other ways a designer can solve that. Honda-san was aware of desmo mechanisms, but went in a different direction.

[blethermaskite]

To reinforce the point that the 'desmo' singles (at the time) were pretty much a marketing tool by Ducati to sell more bikes, in my experience there really is no performance difference between a 'good' road going valve spring single and its 'desmo' variant. Well set up a std.road going 'desmo' engine is mechanically quieter and with an open megga a 250/350 is no more than about 5mph or so faster than a comparable road going valve spring engine. While in theory the 'desmo' engine is mechanically capable of revving to much higher figures than the valve spring motor thus producing more power, the whole thing falls apart (no pun intended ) with the small bore rubbish VHB carb, the silentium silencer, and the fact that if you could achieve sustained high rpm it will result in the crankshaft limitations becoming destructively apparent. I have stashed away a perfect rebuilt 'desmo' head for my 350mk3 with a view to building a 350 'desmo' replica at some time......but I was only ever going to do it for aesthetic reasons not for performance.
I have pulled down quite a few Ducati single valve spring engines (mostly badly abused) and at worst a new cam and rockers will sort the head out.......thrashed 'desmo' heads are a very expensive mess! I would say a 'desmo' head on your Ducati single (whilst alluring ) is about as useful as an ashtray on the handlebars .............Just my experience and opinion, others may disagree
Cheers, George

[Jordan]

The fun I had was to run my desmo with no valve springs.
With spark plug removed, it was easy to turn the engine over by hand.
In theory, although not used enough to confirm it, the whole valve system including the guide would wear less.
It was just as easy to start as with springs.
Why did the factory add springs? I think it was to ensure that a hot valve would have adequate contact with the seat.
That's how most of the heat is transferred away.
A road-going bike would be unlikely to get due inspection and maintenance, such as with a racer.
I tried to keep an eye on valve clearances.
Last time I removed the desmo head, I could rotate a valve with my finger, even though it was closed. Starting was still OK in that condition.
OK, enough fun. I put my standard non-desmo head back on.
There was no palpable performance reduction, just easier and quicker starting with its valve lifter.