Squish Clearance / Deck Height

[clevtrev]

Roger is going to put them up on this Forum . My poor skills at this digital stuff defeat me at doing it .
Been feeling very poorly these days , lots of Doctors in my life . One took a half Liter of blood from me ! Big friggin bottle . No fun ,
Sid .

Half a litre is about what thousands give here in England to the blood transfusion service, a cup of tea, half hour rest, and away you go. Some do it every three months.

 

[Martyn Goodwin]

HI Sid, Would LOVE to see the photo's - email them direct to me - you know the address. Martyn G

 

[johnmead]

Is that's the engine Steve Hamel did. I say it sitting on his bench a couple of years ago.

John Mead

 

[Big Sid]

To John Mead . You were building a really exotic Vincent powered special for quite a few years , maybe a decade . Have you finished it ? How did it turn out ? Got any photos of the completed machine we could see ? Sid .

 

[Big Sid]

Clearly feeling somewhat better , stronger . Got way down after the second half liter later in the same week . A full liter in the span of a few days damn near did me in ! I'll send the vampire to work on Trev . Sid .

 

[clevtrev]

Clearly feeling somewhat better , stronger . Got way down after the second half liter later in the same week . A full liter in the span of a few days damn near did me in ! I'll send the vampire to work on Trev . Sid .

No problem with Vampires, I used to build them, back in the fifties.

 

[Upstreeter]

I have an Ian Hamilton big bore Comet. Remember the slogan, 'give your Comet the performance of a Rapide'? Does it go! I run a Mikuni carb and used it three successive years running at the old Montlhéry 'bike events including the Vincent anniversary 'do'. I managed to destroy two expensive JE pistons before realising that by gently relieving the small pockets in the piston it cured the problem. As timetraveller rightly observes there are a few variables to deal with and not a lot of room with a squish band. Taking the sorry remains of the 2nd destroyed piston to the Sussex club night for helpful suggestions, the sage John Renwick drily observed 'how many times do you boys have to do this before you realise what's causing the problem'. Answer? twice for an engineering dunderhead like me, but at £110 a throw pistons one eventually learns. By the way, the engine assembly by the late Ian Hamilton is really rather lovely.

 

[Big Sid]

One must always clay strip test across new pistons to access the chance of kissing a valve . No serious racer ignores this proceidure . It is repeated after the first hard run to make sure valve float doesn't bridge the gap as this narrows at speed . Sid .

 

[Upstreeter]

As you can tell Sid, I'm not a serious racer! But thanks for the information...which you were also generous with when I first considered a big bore Comet many years ago.

 

[Big Sid]

The British Terry valve springs quite rapidly loose poundage and length with hard use so lowering the rpm at which they float and so the speed potential . With my drag bike I employed S&W progressive springs which largely eliminated this problem . Also I used Webco racing Tri. Top collars and double groove Bullock keepers . I'd noticed that the std Vincent keepers were pulling down through the top spring retainers threatening to pull through at the revs we were turning the engine , often 7,500 if pushed .
The added weight of 2 inch inlet valves in the Big Port heads added to this concern . With the upgrade there was never a problem . . Sid .