Commando motor in solid frame

This is my personal favorite style of Norton. A super efficient Commando motor with the vibration reduced by 1/3, mounted in a solid frame and set up cafe style.

That's a very nice looking bike. Just needs a proper front brake. This winters project will probably be an 850 Commando motor in a Slimline.
Jim, with a set of your rods & pistons & the correct B.F. will the vibes be of an acceptable level at ALL revs? My 650ss is dynamically balanced to 70% & is really nice to ride & the handling is, for me, so much better than my Commandos.

That would be good way to lose your licence. The riding position dictates faster speeds and so would the balance factor. I think this bike simply takes you closer to straight-out road racing. It would be not so good as a commuter bike, however it is probably what a commando always should have been, or at least sold as an alternative . I sometimes wonder about the P11 and the NC15, they might not be all bad ? The front brake is a common mistake - looks good, but dangerous on a fast bike.

Hi Jim,
Can you give us the details of the "super efficient Commando motor"?

Ed

Ed and Matchless

Here's what the owner of the bike say's

"Hi Jim, I’m finally sending you those promised pics of my ’64 Atlas. She’s done 7,000 Km now. The engine has your lightweight pistons, Carrillo rods and complete Stage 1 cam kit. What can I say, the engine is unbelievable, makes the bike a joy to ride, and gives the later model Trumpy twins a serious run for the money."

Matchless
What I have to help bring the vibes down are flat top pistons that can be ultra lightened to 170 grams bare. And the special longer Ultralight Carrillo rods have the small end down to 95 grams. This with a WET dynamic balance factor of around 65% gives you a very smooth ride and with these parts mentioned a 750 may run smoother than the 650SS because of the longer rods.

My similar bike has a tall overall gear ratio of 4 to 1. This lets me cruise on the freeway - 4000 RPM = 80MPH and thats as fast as I want to cruise. Its smooth enough everywhere for the rider but my right hand still needs a break when it starts to tingle after 1/2 hr. At 3000 RPM - 60 MPH I'd say its dead smooth and you could fall asleep on it. Higher RPMs always bring in more vibes per second.

Ed
The lightweight parts are what makes the motor "super efficient". It has to be experienced to be believed. I also have the lighter beehive springs in my own bike. The motor runs much freer and all that saved energy which was wasted speeding up and slowing to a stop all those reciprocating parts is now directed to the R wheel - and you feel it. Mine has raised Axtell ports as well and it pulls 100MPH at only 1/2 throttle. See throttle marks I use to check this.

Matchless said:

That's a very nice looking bike. Just needs a proper front brake. This winters project will probably be an 850 Commando motor in a Slimline.
Jim, with a set of your rods & pistons & the correct B.F. will the vibes be of an acceptable level at ALL revs? My 650ss is dynamically balanced to 70% & is really nice to ride & the handling is, for me, so much better than my Commandos.

Click to expand...

Thats a very good looking bike Jim.

As most of you know I have been running my hot 850 motor in my Wideline Featherbed since 1981 at the time there where no lighten pistons or Carllo rods in them day, well maybe they were but I could never afford them anyway, I had my crank balanced at 72% B/F and it runs pretty smooth all throught the rev range, this was a every day ride till I brought my new Thruxton just over 3 1/2 years ago, I have never had any problems with vibrations at all and have never had anything fall off it in the 35 years of riding it in the Featherbed, I can ride in around town at 40 mph in top gear without any problems, but the cam comes into play just over 4000 rpms and will rev freely till it goes bang, so I got to keep it below the bang factor.
The handling is so good and the whole bike is so light to ride and I don't have any problems with riding it all day, my next rebuild if that ever happens, I would love to put Jim's light weight inturnals inside my motor, but being retired now it just wouldn't be in my budget but if you could afford it be a good way to go, when I first built it up into the Featherbed I was on a very tight budget and has gone throught a lot of changes in those 35 years of riding it.
If you ever get the chance to build one, go for it as it will out handle the Commando and surprise a lot of moden day bikes, its so much fun to ride, but of course you have to watch out for the fun police, its hard not to open it up all the time.

Ashley

acotrel said:

That would be good way to lose your licence. The riding position dictates faster speeds and so would the balance factor. I think this bike simply takes you closer to straight-out road racing. It would be not so good as a commuter bike, however it is probably what a commando always should have been, or at least sold as an alternative . I sometimes wonder about the P11 and the NC15, they might not be all bad ? The front brake is a common mistake - looks good, but dangerous on a fast bike.

Click to expand...

That would be a shame to have such a beautyfull bike just for roadracing, just because you are to scard to ride on the road, no offence, but being so light and nimble they can get you out of trouble when needed, life is a risky business and these bikes need to be ridden dayly if possible, it is hard to keep the speeds down as I know I just started a 3 month suspension of my licence for lost of points (bloody motorcycles :roll.

Ashley

jseng1 said:

Mine has raised Axtell ports as well and it pulls 100MPH at only 1/2 throttle. See throttle marks I use to check this.

Click to expand...

So it will do 200 mph on full throttle ?
Zowweee !

I'll believe you, but millions wouldn't...
(Cheap humour, at your expense).

That is a nice Commando-in-featherbed above...

P.S. And before anyone says anything silly, and for those mathematically inclined, it is generally quoted it takes the average moddersickle plus rider just over 30 hp to do 100 mph.

So any Commando with a claimed 60 hp under its belt should be able to do the ton at 'half throttle'.
You can't argue with basic physics...

Depends a bit (a lot) on your gearbox sprocket size though.
Maybe too we haven't been marking our twistgrips ?

???

Beautiful bike, I really want to build a slimline Featherbed twin. I have a 75 Mark III in need of restoration, another MKIII parts bike and a 70, 750 Rolling parts bike and every time I think about what to do with them I think I would rather have a featherbed twin. So now my plan is to sell or trade them for something like a 650SS Or an atlas and rebalance the motor hoping to calm down the vibes.

gtsun said:

. So now my plan is to sell or trade them for something like a 650SS Or an atlas and rebalance the motor hoping to calm down the vibes.

Click to expand...

Some folks who own those bikes say that they are smooth anyway, so try it before you alter anything ?
I intend to try out my Atlas engine project as standard before doing anything radical, since it came with usable bits. This doesn't preclude a dynamic balance in the recipe, of course...

There is also that tale over on the NOC Forum about the contractor who was doing the crank balancing for AMC, and reportedly took some shortcuts. Seems that not all cranks may have been balanced as they should have been.
So if the crank balance was done to a standard balance - as it should have been - it wouldn't have been a Friday bike ???

Jims report does sound encouraging though...

I'm running Jim's internals in my 850. I run my iso's quite tight, so whilst my bike vibrates more than it would if I set them 'correctly', the vibration levels are still very low (I run them tight deliberately to keep the handling 'tight'. I also like to feel a little mechanical-ness in my rides). My experience doing this would certainly give me the confidence to try mounting such a motor rigidly.

Fantastic 60`s cafe racer style with a commando motor

Rohan said:

jseng1 said:

Mine has raised Axtell ports as well and it pulls 100MPH at only 1/2 throttle. See throttle marks I use to check this.

Click to expand...

So it will do 200 mph on full throttle ?
Zowweee !

I'll believe you, but millions wouldn't...
(Cheap humour, at your expense).

That is a nice Commando-in-featherbed above...

Click to expand...

Top speed is around 130 because the wind resistance rises exponentially. I made that 1/2 throttle test because I suspected what it could do and yes I know its hard to believe. 80 MPH is around 1/3 throttle. Above that I tuck in. It wouldn't be possible without the tall gearing and the flat slide carbs which seem to come on harder at medium throttle.

Ashley, you are dead correct about me being too scared to ride on the road. I've done that in recent years and I always feel as though a sniper has the cross-hairs of his sights lined up with the centre of my back. However I would gladly race my Seeley tomorrow if I could afford it. The difference is poles apart from road riding - you can actually use the bike as God intended without some retard trying to give you a ticket. And if you get really smart, there is always an ambulance on stand-by waiting to pick you up. When I drive on public roads, I use a 6 speed manual Mazda 6 with cruise control, anti-skid braking and auto suspension control. On a twisty road it is ALMOST as good as a bike.
I would love to own that featherbed commando in the photo, however I know what the consequences would be if I rode it on public roads - 'been there, done that' ! I gave it up when I was 29 years of age and went road racing - MUCH SAFER and you keep your licence.

acotrel said:

Ashley, you are dead correct about me being too scared to ride on the road. I've done that in recent years and I always feel as though a sniper has the cross-hairs of his sights lined up with the centre of my back. However I would gladly race my Seeley tomorrow if I could afford it. The difference is poles apart from road riding - you can actually use the bike as God intended without some retard trying to give you a ticket. And if you get really smart, there is always an ambulance on stand-by waiting to pick you up. When I drive on public roads, I use a 6 speed manual Mazda 6 with cruise control, anti-skid braking and auto suspension control. On a twisty road it is ALMOST as good as a bike.
I would love to own that featherbed commando in the photo, however I know what the consequences would be if I rode it on public roads - 'been there, done that' ! I gave it up when I was 29 years of age and went road racing - MUCH SAFER and you keep your licence.

Click to expand...

You're certainly not short of excuses for being scared.

jseng1 said:

Top speed is around 130 because the wind resistance rises exponentially.

Click to expand...

Lets not beat around the bush, air resistance rises with the cube of the speed.
THE huge factor in top speed.

A minor point, but good to quote accurately...

Thats a goodly rate of knots out of that beastie.

Rohan said:

Lets not beat around the bush, air resistance rises with the cube of the speed.
THE huge factor in top speed.

A minor point, but good to quote accurately...

Click to expand...

Again, .............no Rohan.

Air resistance rises with the square of the speed, ............power rises with the cube of the speed.

A major point, but good to quote accurately... :lol:

Power REQUIRED rises cubed. ..

Laughable! :lol: :lol: