Molnar Precision Ltd TGA Commando Parts

Torontonian · Jan 30, 2023

ashman said:
All these goodies and I can only dream in building a Norton with all these goodies being a self funded retired person and cost of living it getting harder to just live a normal life.

When I built my hot 850 Commando/ Featherbed back in the 80s I followed the high performance section in the back section on my manual and did everything on the cheap with talent machine shops in my city, Ivan Tighe cams in Brisbane did the 2S cam grind, crank balanced by a old gentleman that Ivan Tighe put me onto, head work was a stuff up but was fixed at no cost to me, but after that getting a job at a Tec college and 2 very talent motorcycle teacher one who was a Kiwi and work for a Norton race team back in NZ the other older teacher rode British bikes from the early 60s to very experienced teacher and a good machine shops as well.

So was lucky I built my Norton on a budget and it's still going strong and things were cheap to do and buy back then, now cost are so high and spending $10k on my motor is out of my price range, but what I done to my motor when I did all thought years ago has proven it worth for long life and reliability so done something right and the last 12 year major upgrades to make it even better. My motor is quick and torquie without over reving it and with a light bike still does it job great.
It still gets up to and well over the ton if I want to pretty quick but it's the handling and lightness of the Norton that has proved it worth all these years of riding and a good experience ride help who know how to push a Featherbed, it's like riding on rails.
But would love to build a hot 750 Commando motor with all these new bits that were not around in my time of building my Hotrod Norton and before the days of the internet, maybe when I win lotto, well just another dream I suppose lol.

Do you play the Lotto ?

ashman · Jan 31, 2023

The wife and I do one each week Saturday night lotto. We just had a big win a whole $9.50 lol seems to be all we win is minor prizes, but still got to be in it to win it I suppose.
We can always dream, I am not a gambler except for one lotto quick pick and 7 regular numbers each week.

Seeley920 · Jan 31, 2023

Schwany said:
That is very impressive and probably costs close to $55 per mph to achieve often in a reliable motor.

Not even close

Seeley920 · Jan 31, 2023

mdt-son said:
I guess it's not the crankshaft which produces 62 ft*lb by itself ;-) Good result though.
By billet crank I guess you mean a one-part crankshaft. I am curious - who made it? The low weight hints at one of Mick Hemmings' crankshafts ....

- Knut

No, it takes a lot more than the crank, but "certain people" say a light crank doesn't work and will stall going into a headwind

You are correct, Mick had a couple of cranks made for me, standard and short stroke

They worked well in the JPN replicas !

Fast Eddie · Jan 31, 2023

Seeley920 said:
No, it takes a lot more than the crank, but "certain people" say a light crank doesn't work and will stall going into a headwind

You are correct, Mick had a couple of cranks made for me, standard and short stroke

They worked well in the JPN replicas !

15lbs is light!

Maney‘s are listed at 17-18lbs. Which is what I have.

I’m with you, I like the feel of a light crank. I gave up trying to argue which is best and basically concluded it’s probably mostly down to rider preference. I love the way a light crank spins up so fast. Just feels ‘right’ to me.

Schwany · Jan 31, 2023

Seeley920 said:
Not even close

Well, I started with $140 per mph, but that is a big number for just the motor parts. So.... I lowered it to $55 per mph for poor folk like myself who like to fantasize.

Can you elaborate on the cost to build a Norton engine that will do 145mph?

TomU · Jan 31, 2023

Schwany said:
Can you elaborate on the cost to build a Norton engine that will do 145mph?

You need to build a motor that’s roughly 113 HP

acotrel · Jan 31, 2023

Seeley920 said:
No, it takes a lot more than the crank, but "certain people" say a light crank doesn't work and will stall going into a headwind

You are correct, Mick had a couple of cranks made for me, standard and short stroke

They worked well in the JPN replicas !

I am not saying a light crank does not work. But when you use a light crank, the bike behaves differently. Two-strokes work extremely well with light cranks, but they make their power at very high revs, and they handle differently to a Norton 850. My Triton 500 had a light 63mm stroke, billet crank and very long duration cams. Is characteristics were very different. My mate had built it during the 1950s , and he knew all the theories. If i'd had a 6 speed close box, it would have been unbeatable. But I would have been a nervous wreck. It was extremely fast, but nasty.
I did not believe in the heavy crank when I built my 850, - but now I do.
I bought my 850 motor for $1300 in about 1975. It has had almost nothing done to it, and it is still fast enough. I think the design must be correct.
I do not know what a light crank would do. When I ride my bike, it does everything perfectly, even with the heavy crank. I can flick the bike into any corner and power full blast all the way through it. I do not care how much power the other guys have, they cannot beat it. I come onto the next straight much faster, and they have to make up the difference, or I get to the end of it first. When you power through corners, you bike must be stable. With the heavy crank, the bike is more predictable. If I had tried to power through corners with the 500, I would have crashed. every time.

acotrel · Jan 31, 2023

Most people who ride bikes which have motors with light cranks, probably get them upright and pointed before they give them the berries.
I gained a fair bit of experience when I was a kid. When I ride on a race circuit, I usually practice braking right up into the corners while cranked over. then getting straight back onto the gas in the middle of the corner without rolling any distance in the middle. After I increased the trail by changing to fork yokes, I found the change-over point from braking to accelerating had moved to earlier in the corner. I then suspected I could power all the way through the corners, but I'm sure I must brake before them. As long as my bike squats when I accelerate., it steers in the direction in which it is leaned over. However you would not need to do it with a bike which is jumpy. When I do it, I always think 'I should not be doing this'.

Schwany · Jan 31, 2023

TomU said:
You need to build a motor that’s roughly 113 HP

I think it can be done with less HP, but that would get er done. My Rotax 604 single did 130mph and I doubt it made anywhere near 113HP. Granted 130mph is not 145mph though.

I was expecting a response like, "if you have to ask you can't afford it". lol

Seeley920 · Jan 31, 2023

Schwany said:
Well, I started with $140 per mph, but that is a big number for just the motor parts. So.... I lowered it to $55 per mph for poor folk like myself who like to fantasize.

Can you elaborate on the cost to build a Norton engine that will do 145mph?

Well, There is 30 years experience building Commando race motors, so forget about probably £200k (gotta learn some things the hard way) over the years. To build a good race motor now is around £12k, before you put a gearbox/clutch behind it!

Seeley920 · Jan 31, 2023

TomU said:
You need to build a motor that’s roughly 113 HP

Nope, not true

Peter Williams/ Crox & co did 160mph in 1973, with around 70 rwhp

Chris · Jan 31, 2023

My 750 came up at 62BHP Steve was clocked well up there at Daytona with the same engine over 135mph. Thats nearly twenty years ago. Steel flywheel standard rods welded plate on the cases. Maney cam, lightweight valve gear, originally Maney Coswoth pistons. Not the crap I ended up with lol.
I have nothing in my 750 that John has in his lol. He has experimented a lot & had stuff made for him.
But mine wasnt cheap to rebuild.

I may have to put my 960 on a dyno one day but my racing is about keeping it reliable. As when it last went bang it took me years to save up enough to money to sort it. I dont rev it past 6,500 & on the gearing I have thats fast. However everyone knows its my bike ( its orange) & that its a Norton Commando lump. How much I take off the top speed with my size & bulk im unsure but no fairing on this one.

Fast Eddie · Jan 31, 2023

Wot that 960 needs is bigger carbs !

Plus, of course, you’re carrying around several lbs of orange paint… everyone knows the fast Seeley’s have bare frames…

jan nelder · Jan 31, 2023

very canny to get enough power without going too high on revs and crank stresses!

SteveA · Jan 31, 2023

Schwany said:
Well, I started with $140 per mph, but that is a big number for just the motor parts. So.... I lowered it to $55 per mph for poor folk like myself who like to fantasize.

Can you elaborate on the cost to build a Norton engine that will do 145mph?

In 1975 it cost me £300!

850 MkIII bottom end, with a Short Stroke fully hemispered head and matching Omega pistons, and a cam all out of Thruxton by the rear doors! Works dimension exhausts and 36mm carbs.

(crankshaft was polished MkIII balanced by Owen Greenwood with the drive side cut down to the taper, tapped with a big washer to hold the sprocket, it didn't explode in the 4 seasons I rode it)

I bought a kit of parts from a former Experimental Department engineer who had been made redundant!

The hardest part was finding somewhere it could reach 145mph, I only rode once at Oulton Park, with no chicanes, where it hit it's max indicated rpm (6800) on the highest gearing I had (calculated 149!).

At Snetterton, and a couple of airfields, with two more teeth on the rear sprocket, I reckon around 140 was it's best!

But....BIG but......we are dependent on my measuring of tyre circumference on the floor with chalk, a basic manual calculation, and of course an analogue rev counter!

SteveA · Jan 31, 2023

SteveA said:
In 1975 it cost me £300!

850 MkIII bottom end, with a Short Stroke fully hemispered head and matching Omega pistons, and a cam all out of Thruxton by the rear doors! Works dimension exhausts and 36mm carbs.

(crankshaft was polished MkIII balanced by Owen Greenwood with the drive side cut down to the taper, tapped with a big washer to hold the sprocket, it didn't explode in the 4 seasons I rode it)

I bought a kit of parts from a former Experimental Department engineer who had been made redundant!

The hardest part was finding somewhere it could reach 145mph, I only rode once at Oulton Park, with no chicanes, where it hit it's max indicated rpm (6800) on the highest gearing I had (calculated 149!).

At Snetterton, and a couple of airfields, with two more teeth on the rear sprocket, I reckon around 140 was it's best!

But....BIG but......we are dependent on my measuring of tyre circumference on the floor with chalk, a basic manual calculation, and of course an analogue rev counter!

Current 750 Short Stroke runs in the same frame, probably makes around 65rwhp, maybe a fraction more on 36mm Mikunis.

Cost to build?, guess is £10K, it was part of a £25K build that included a TTi box, Norman White Belt drive and full Maxton forks and shocks. (2010 to 2015 money).

Fullauto head on Maney bottom end, JSM rods and pistons. Haven't been anywhere that will allow the high gearing the 850 ran, but it does rev more, quite a lot more. Realistically, I haven't ridden it above 130!

acotrel · Feb 1, 2023

TomU said:
You need to build a motor that’s roughly 113 HP

A Manx Norton 500 can reach 140 MPH - downhill with a tail wind.

acotrel · Feb 1, 2023

SteveA said:
Current 750 Short Stroke runs in the same frame, probably makes around 65rwhp, maybe a fraction more on 36mm Mikunis.

Cost to build?, guess is £10K, it was part of a £25K build that included a TTi box, Norman White Belt drive and full Maxton forks and shocks. (2010 to 2015 money).

Fullauto head on Many bottom end, JSM rods and pistons. Haven't been anywhere that will allow the high gearing the 850 ran, but it does rev more, quite a lot more. Realistically, I haven't ridden it above 130!

High gearing with close ratios is good, but you need 6 gears, if you ride in races which are clutch start. For push starting, a Manx box with high gearing is quite OK. I think the gearing on my 850 is ridiculously high for a 3 Km circuit with 12 corners. But it works.

jseng1 · Feb 1, 2023

Andy’s land speed racer with fully developed 920cc motor, 95 HP at 7400RPM on the Dyno. 154mph on the Bonneville salt flats in 2018. The fastest unstreamlined, naturally aspirated gas powered Norton on the planet.

Big valve head, case plate, modifications, assembly and tuning by Herb Becker.

Molnar Precision Ltd TGA Commando Parts

1972 Roadster