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Hi,

I recently started a Mach 1 which had been sat untouched in my garage for the last six years or so.

The bike started on about the fourth kick ,however, I'm concerned that the noise which sounds like two ball pein hammers banging into each other isn't correct. There is copious oil in the front rocker box. I then started up another Mach 1 which hadn't run for 40 years, quite a bit of faffing later this bike started on the second kick and sounds much quieter and I believe is how it should sound.

I've attached a link to you tube of the noisy bike.

Would you be able to point me in the right direction of where to look?.

I guess I could swap the heads over and see if the noise travels with the head, this would eradicate a bottom end issue.

Thanks in advance

Bob

https://youtu.be/Fu8_Unjw_-I

Noises! You will probably get fifty people giving you a different answer. It doesn't sound too bad to me, but could be loose bevel gears, valve clearances...It actually sounds a bit like a loose exhaust pipe in the head, with the pipe flange vibrating against the port and wheezing a bit as the gasses escape.

Definitely a bit too much noise . Check tappets of course ,try 5 and 7 thou. That's not as per the book but works well for me. Also could be a bit of piston slap , if it gets better when hot that's a clue . OIl getting to the cam? .that can take a while if no restriction at the gear end.Makes me want to fire up my 250!!.

Check top bevel shaft bearing mounting, sometimes a problem area on Ducati singles.
Look for Nigel Lacey's solution.

Hi again,

I guess I've found the reason for the noise-the exhaust valve has been hitting the piston.

What is evident is that the valve is not entering the piston cut out centrally, so I'm assuming that the valve guides will need replacing.

If the valve guide was perfect, although this would centralise the valve to the cut out, would you agree that the valve would still be hitting the piston?

Thanks for your help, as with everything experience counts

Cheers

Bob

Yikes! Nigel, Eldert, your views are needed!

Could someone have fitted a bigger inlet valve 40 mm is normal, Valve loose in guide?,guide loose in head? Head surface been skimmed? Valve sticking in guide and getting knocked back in?. Piston in back to front?

If the guides have been replaced a few times they tend to move slowly off centre. I also note the piston is 75mm, it may well not be bored centrally, that's something to look at as well. I will add that I have noticed the exhaust pocket on the Borgo pistons is often a bit tight and I have often machined the pocket to suit.

Good engine building practice should always involve checking piston to head and piston to valve clearance. Clearly who ever built this did neither...the piston is also hitting the head, see the faint witness mark at the top of the squish. Insufficient squish clearance will also reduce the piston valve pocket radial clearance.

Regards Nigel

The new forged Borgo piston as fitted to my current 250 desmo when I first got it in cardboard boxs with its engine semi stripped was showing very slight signs of valve contact on the edge of exhaust pocket of the piston crown, its something I always check, dry build the head on the engine and smear a little softened plasticine in the vale pockets and on the squish band of the head, turn the crankshaft through a couple of revolutions and then strip the head off again, the squashed plasticine thickness will show you how close your valves are getting to the piston and how close the piston is getting to the head, I like to see about 20/25 thou clearance.
Cheers,
George

No wonder the engine was noisy!