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Harvey wrote:I only used the rocker spring on the exhaust to aid starting, the inlet didn't need one, and didn't clatter.

That makes sense also because the spring helps to cool the exhaust valve face when it is pressed against the seat.
There's scant opportunity otherwise to cool it after passing burnt gas.
Inlet valve only passes cool air and fuel, so won't need a spring.

Hi Jordan, I didn’t think of that at the time it probably did help, but with the 150* of valve overlap that the inlet blew cool gas past the exhaust valve, it probably cooled it OK.

Eldert wrote:i got a pair of saddles last month from John Wittmann (formerly Witty Ducati in Luton). John is living in Spain but you can get a hold of him thru facebook .

Off-topic, I know; so please indulge me ...

Thanks for posting that, Eldert. Good to know John is still around - he rebuilt my 450 engine many years ago, before he went to Spain. I don't 'do' Facebook and had lost touch with him.

Craig

I have been running without any valve springs for quite a few years, no issues.

Hi All,
Thanks to everyone for your input on this, all advice has been greatly appreciated, thanks Eldert for your contact info on John Witman, Great to report that through the help of fellow contributors to this forum I now have all I need to build a standard spec 250 desmo head and am looking forward getting the little desmo back on the road after nearly 27 years hidden away in a bedroom.
By way of explanation ref. my desire to build a standard set up head with hairpin valve springs.....it is obviously proven to be perfectly ok to convert from hairpin springs to bevel v type springs while at the same time reducing the overall loading on the valve train, and if I had been unsuccessful in finding the parts I needed this is exactly the path I would have followed, I have in the past run (single) desmo heads in a number of different specs.
1.....as suggested without any springs......result......ran perfectly for several thousand miles, but eventually clearances became out of tolerance due to the split ring collets getting hammered as a result of running the predictable wide closer clearance ( I only do nil closing clearance at the tightest spot on camshaft rotation not at tdc).
2.....for curiosity (when desmo's were not so valuable) ran a 250 without any closing rockers........result...... ran perfectly even at fairly high rpm, however I was scared to run it up to 10k plus just in case????
3.....set up as completely std. spec. with hairpin springs and nil closer clearance at the tight spot on cam rotation........result.......ran perfectly for over 6000 miles......( when inspected all clearances as when first built).
If I was building a competition engine I would happily run with out any springs or maybe very light versions of the v type springs, but for a completely standard road bike rightly or wrongly I am going for the standard head set up again. ( photo's to follow in due course)
Cheers,
George

Good idea to adjust on the tightest spot on the cam's base circle.
My desmo head varies a lot in that regard.
I ran it without without springs, incident free for a few thousand miles, then took off the head for inspection.
The inlet valve, when closed, surprisingly could be rotated by finger. Not good, glad it wasn't the exhaust valve.
I put my spare non-desmo head on it for now - runs identically, nice to have a valve lifter for starting.
But the added load on the cam drive train is a negative.