New product -Domni 500 lightweight pistons and Stuart's Velo

Now available - high compression 66mm & up racing pistons for dominator 500cc Nortons (170 grams bare). 11.5 C.R. and special ultralight Carrillo rods (lighter than my usual light rods for big twins). These domed pistons ultralight rods are custom and expensive and are special order - not advertised on my web page. Several people have asked for these pistons and I finally broke down and designed them.



I just got an interesting email from Stuart Metge - the customer I designed the domni pistons for:

"I was looking on ebay USA tonight, and I was shocked to see a completely unauthorised photo of me on my Velo (at Eastern Creek in 2010), as the cover photo for ebay USA. I am unreasonably honoured. Please have a look. I am keen to apply some of the information I have gleaned to upgrade the performance of the engine in the Velo, given that it is almost one half of my new 750 Norton race engine."

see his Velo photo at:
http://www.ebay.com/motors/motorcycles

Re: New product -Domni 500 lightweight pistons and Colin on

Thanks for making these available, Domi 88 pistons are far and few between. At 67mm these are about .040" over standard 66mm bore is that right?

My guess is that this was the closest that the piston manufacturer had to 66mm? I was just wondering as I have a few 88 cylinders that have not been bored over standard yet and it would be a shame to punch them out to 67mm on their first overbore. If they are available from 68-69mm, then that would cover the Model 99 and 650ss bikes also.....and increase sales for you maybe if you advertised as such.

Keep up the good work......

Re: New product -Domni 500 lightweight pistons and Colin on

Is there any way to get a twin port head onto a 500cc dommi without cannibalising a 650ss ?

Re: New product -Domni 500 lightweight pistons and Stuart's

beng said:

Thanks for making these available, Domi 88 pistons are far and few between. At 67mm these are about .040" over standard 66mm bore is that right?

If they are available from 68-69mm, then that would cover the Model 99 and 650ss bikes also.....and increase sales for you maybe if you advertised as such.

Keep up the good work......

Click to expand...

Making them any size between 66 & 69mm should not be a problem.

Stuart has a 650 SS head on this motor.

Re: New product -Domni 500 lightweight pistons and Stuart's

ALL dommies had a twin port head*, so this seems an odd question ?

Unless you are referring to the downdraught heads on the 88SS, 99SS and 650SS....

(*Except the very first iron head domi, the prototype, ever made)

------

Yes, dommie 500 are 66mm std bore, so 66mm pistons seems a more obvious size choice ??

Re: New product -Domni 500 lightweight pistons and Colin on

acotrel said:

Is there any way to get a twin port head onto a 500cc dommi without cannibalising a 650ss ?

Click to expand...

The 88ss was fitted with the same cylinder head as the 650ss for 1962 and later, the 99ss was supplied with the same head as the standard Slimline Model 99, but the 88ss/650ss head would retrofit onto any 88 or 99.

Mahle in Germany made the high compression pistons for Norton to use in the original Domiracer, and Berliner in the USA got some of the Mahle racing pistons for their racing efforts with the Model 88, here is a photo of one, I am not sure what compression ratio it gave, but it looks damn high:

Re: New product -Domni 500 lightweight pistons and Stuart's

" given that it is almost one half of my new 750 Norton race engine."

looking at it like that , gives a benchmark . If Yr 750s not going as well as two 350s in a f'' bed , it needs sorting .

Have to be about 11:1 C.R. that domed Mahrle piston . Would be good to see a few 500 Domi screamers about .
The old T100Rs from 55 could be run to 8.000 if you wernt to wworried about preserveing them for the grandkids .

Modern metalurgy & precicision should make a race 88 reliable at 8.000 al day , if they get the rest of it right .

Re: New product -Domni 500 lightweight pistons and Stuart's

Sir Eddys Domi 500 on here will rev to 11,000.
Did we see mention it was a short stroke (o he of little memory...).

Re: New product -Domni 500 lightweight pistons and Stuart's

Hi Jim

Looks vey good. But as usual with race bikes a small issue.

My Dommie, like most race bikes I expect, has a one piece crank with 1 3/4 big end journals. I use 6 " trumph alloy rods from Thunder engineering in the UK. Changing them every few years.

Does your con rod have the original big end size. I imagine it does

Regards

John

Re: New product -Domni 500 lightweight pistons and Stuart's

JS you and that Velo cut a sharp image for a cover shot, cool.

Re: New product -Domni 500 lightweight pistons and Stuart's

Carrillo has a standard part number for Dominator 88 connecting rods, and JS has been selling special long and light Carrillo rods for bigger Norton's for years, so I am sure that he could supply almost anything anyone who has the money would want or need.

Has Edward Bilton-Smiths engine even run at this point? I have a lot of respect for him and those putting time into finishing his bike, but saying something is going to turn X rpm, make Y power and go Z fast is a lot different than actually doing it in the real world.

Around 1964 Heinz Kegler had Carrillo make up the first set of rods for a Norton 88 which he put into his road racer along with an 88ss crankshaft and Mahle pistons. He raced the bike several years through 1972 without any crank, rod or piston failures. This included running at Daytona more than once, winning more than one eastern championship and placing 6th in the Grand Prix of Canada in 1967, many hundreds of racing miles using a red-line of 8000rpm according to his notes.
One engine failure was from dropping a valve, which although putting a hole in the top of the piston did not break it up. The only crank failure he had was much later while trying to race in a vintage event in the 1980s the crank cracked but did not break or hurt the engine.

Of course these days 88ss cranks, with their special small sludge trap and thick rod-journal walls are not going to be found in quantities or qualities necessary to support serious racing efforts, so if someone is going to the expense and trouble of having a custom racing crank and rods made for a model 88 racer it makes sense to go with the 750 size rod journals.

Those restoring old Norton 88s for show or road use who don't like the idea of using their old aluminum rods could just order the standard replacement parts from Carrillo that work with the stock crank and pistons.

I am still a fan of the Real Model 88 Nortons, that have their stock bore and stroke as even the factory Domiracer used. The bore and stroke is all that differentiated the Model 88 from the Model 99 and 650 in various years. When someone makes up a custom engine with a short stroke using a 650,750 or 850 Bore, then it would be much more correct to call it a de-stroked 650ss or Commando as nothing that is Model 88 is left!

Re: New product -Domni 500 lightweight pistons and Stuart's

I'll be disappointed if those 11,000 rpms are theoretical rpms....

Nortons experimented, wildly it must be said, with manxes.
Long stroke, short stroke, big bore, big bearings, outside flywheels, desmodromic, rotary valves, etc etc.
Does that mean if it doesn't come out of the parts book, its not a Manx ? Or not a Norton ??

All those ideas came from outside, someone else had already proved they worked.
Featherbed frames being a famous example.....

Re: New product -Domni 500 lightweight pistons and Stuart's

johnm said:

Hi Jim

Looks vey good. But as usual with race bikes a small issue.

My Dommie, like most race bikes I expect, has a one piece crank with 1 3/4 big end journals. I use 6 " trumph alloy rods from Thunder engineering in the UK. Changing them every few years.

Does your con rod have the original big end size. I imagine it does

Regards

John

Click to expand...

This customer uses 1-3/4" big ends of the rods. These rods are special and not typical Carrillo rods because they are lighter. They use DLC coated pins and there is no bushing on the small end of the rod. That makes them a lot lighter on the small end that causes the vibration. Furthermore - these rods were designed specifically for smaller displacement Norton twins 500 up to 750cc. These are not the same as the bushless Carrillo rods I sell on my website for 750s, 850s, 920s etc. They weigh 10 grams less on the small end but use the same rod cap. They are rated for up to 100 crank HP. You do not want regular Carrillo rods with bronze bushings because of the extra vibration.



This customer also uses JS stage 1 cam kit with lightweight lifters (to avoid valve float).



These components easily rev beyond 8000 RPM without valve float etc. See lightweight beehive valves springs & black diamond valves below.

Re: New product -Domni 500 lightweight pistons and Stuart's

My 63mm stroke Triumph engine revved reliably to 10,500 rpm but the lack of t orque, and the nasty power band made it difficult to ride without extreme anxiety. My feeling these days is that I wouldn't reduce the stroke to less than 75mm in a twin cylinder motor. There was a guy from New Zealand at Phillip Island last weekend with a Mk2 Seeley fitted with a 500cc Nourish engine . He said the stroke is 59mm. I said it must be difficult to ride, and he agreed. Some of these ideas are great in theory, but in practice..... ? I think for that sort of bike, a six speed box is essential.

Re: New product -Domni 500 lightweight pistons and Stuart's

I still keep in touch with the friend who built the Australian version of my old Triumph 500. In the early fifties the first motor was built by a guy called Baldo Meli who used to work for the Triumph factory, and made the first Bonneville head. He got a 12th on the IOM during the 1950s. He brought the motor to Australia, and sold it to Les Virtue who had it in a sidecar. Les broke the crank, and made a new one. My friend bought the motor and fitted it into a replica featherbed frame. He r ode the bike at Bathurst in 1958 and found it to be extremely fast. Got into difficulties at Murray's Corner, and just got round. Then bounced himse lf off the armco at Skyline Corner and broke both his arm and his leg. I knew him when I was 18 years old, and several times suggested we should race the bike - he always demurred, but he never told me about what happened at Bathurst. He sold the bike to somebody else after refusing my offer. I bought it in 1967, and when I tried to race it, it t urned me into an instant dud. I couldn't get decent lap times until I fitted the two into one exhaust to replace the 4 inch megaphones. I rode it once at Phillip island with the big megaphones, and the top end was simply amazing, and very frightening with the really high gearing. People speak of two strokes being 'peaky' - they have really no idea. I always had to get my head really straight before riding that Triumph. The Seeley commando 850 is a joke after that - so easy !

Re: New product -Domni 500 lightweight pistons and Stuart's

Jim, I save all the photos of your hot bits- don't know why, can't afford them these days and I really don't want to work again. I keep buying lottery tickets.

Re: New product -Domni 500 lightweight pistons and Stuart's

"There was a guy from New Zealand at Phillip Island last weekend with a Mk2 Seeley fitted with a 500cc Nourish engine . '

That would be John Carter from New Plymouth. He also rides Moto Morinis.

Jim it looks like I may need to contact you. Im away from home at the moment but give me a week.

Im the one who contacted you at Christmas about the fork bushes.

The bike has standard bore and stroke (OK - 60 thou over pistons because the barrels are as old as I am), Nucleus valves, It will rev to at lest 8300 without valve bounce as witnessed by the riders video camera. No point in my view because the power is flat above 7000 on the dyno. I wasnt pleased to see that cause I pay when it goes bang. Has a PW3 cam and normal followers. I spend a lot of time on valve spring set up. For the last year it has a six speed TT gear box.

John

Re: New product -Domni 500 lightweight pistons and Colin on

beng said:

acotrel said:

Is there any way to get a twin port head onto a 500cc dommi without cannibalising a 650ss ?

Click to expand...

The 88ss was fitted with the same cylinder head as the 650ss for 1962 and later, the 99ss was supplied with the same head as the standard Slimline Model 99, but the 88ss/650ss head would retrofit onto any 88 or 99.

Mahle in Germany made the high compression pistons for Norton to use in the original Domiracer, and Berliner in the USA got some of the Mahle racing pistons for their racing efforts with the Model 88, here is a photo of one, I am not sure what compression ratio it gave, but it looks damn high: ]

Click to expand...

So, the original 500 Domiracer raced by Norton in the 1961 IOM TT did not have a singe Dykes piston ring then :?:

Re: New product -Domni 500 lightweight pistons and Colin on

Bernhard said:

So, the original 500 Domiracer raced by Norton in the 1961 IOM TT did not have a singe Dykes piston ring then :?:

Click to expand...

The top-development Domiracer that did the 100mph lap of the IOM had a short alloy cylinder with chrome bores, the bikes that Berliner raced in the states had standard iron cylinders like any other Model 88 per AMA rules. The photo I have is of one of the pistons used in a Daytona 88 with iron cylinder.

Re: New product -Domni 500 lightweight pistons and Colin on

beng said:

Bernhard said:

So, the original 500 Domiracer raced by Norton in the 1961 IOM TT did not have a singe Dykes piston ring then :?:

Click to expand...

The top-development Domiracer that did the 100mph lap of the IOM had a short alloy cylinder with chrome bores, the bikes that Berliner raced in the states had standard iron cylinders like any other Model 88 per AMA rules. The photo I have is of one of the pistons used in a Daytona 88 with iron cylinder.

Click to expand...

Quite right Beng, I forget about the Alloy cylinders on the works 500 Domiracer used in the IOM TT for one moment.