Norton twin engine

Andy - At the top of this page is a horizontal line of quick links.

If you click on the one labelled Models you will find a brief summary of the Hybrid Bikes that used a 750cc engine similar to yours.

Better still - After clicking on Models, look at the left hand side of this page for another list of boxes and you will find more quick links for particular bikes. Click on the box marked Hybridand this will provide you with some serious information and a few photos to wet your appetite.

Enjoy!!!

I just posted a very long post and this piece of crap never up loaded. This is now getting to be a very bad JOKE.

So why bother to up load a post if you are going to loose it all. That motor is a February 1964 Norton N15CS, the G15CS N or the N tells you that. So i guess i shall loose this as well.

I have ridden an Atlas 750 cafe racer for many years. Despite the popular anecdotes, I do not consider the vibration significantly worse than other British parallel twins. Mine had a resonance at about 55 mph in top gear that was unnoticeable when accelerating. It was fine when going faster. Doubtless others will disagree

Cheers

Alan

I rode a 600cc 99SS Cafe Racer for nearly 30 years and found it a great, reliable engine. Once I got the serious touring and rally bug, I bought an Atlas and got hooked on the extra power available to help shift camping gear and my bulk around.

I was so impressed by the engine, that I even replaced my 99 motor with a tuned 750cc motor to use for track days. This engine would rev to over 7000 rpm, was very smooth and never broke during 6 years of thrashing.

The early road tests of the standard Atlas engine are not wrong when they criticize the vibes that appear above 5000 rpm. They will shake you and the bike to pieces.

The answer to this issue, is to tune the engine to avoid this point.

The first thing to do is to rebuild the engine to give most power and smoothness lower down the rev range. First I added a few Commando parts such as 8.9 to 1 pistons, conrods and a cylinder head to boost the power. I got my crankshaft rebalanced by a firm that knew about Norton engines and the need to oil fill the shaft before working on it.

Finally I added electronic ignition, a Concentric 932 single carb conversion, a belt drive and a 21 tooth gearbox sprocket.

The end result was touring bliss. The engine started really easily every time. It had heaps of bottom end grunt for pulling away and quick acceleration. It would cruise smoothly at 70 mph, with revs just over 4000 rpm and giving 60 mpg into the bargain. Ok it still gave some vibes over 5000 rpm but there was rarely any need to push the engine that hard.

I put a similar engine in my Cafe Racer but with a lot more engine mods to give extra power at higher revs. So I used twin carbs, lightened rockers, camshaft followers etc in the head plus matched Powermax pistons, matched polished rods and a slightly different crankshaft balance factor. Again, electronic ignition helped with easy starting and smooth running compared to the magneto on my old 99 engine.

Try either and enjoy!!!

Previously wrote:

I rode a 600cc 99SS Cafe Racer for nearly 30 years and found it a great, reliable engine. Once I got the serious touring and rally bug, I bought an Atlas and got hooked on the extra power available to help shift camping gear and my bulk around.

I was so impressed by the engine, that I even replaced my 99 motor with a tuned 750cc motor to use for track days. This engine would rev to over 7000 rpm, was very smooth and never broke during 6 years of thrashing.

The early road tests of the standard Atlas engine are not wrong when they criticize the vibes that appear above 5000 rpm. They will shake you and the bike to pieces.

The answer to this issue, is to tune the engine to avoid this point.

The first thing to do is to rebuild the engine to give most power and smoothness lower down the rev range. First I added a few Commando parts such as 8.9 to 1 pistons, conrods and a cylinder head to boost the power. I got my crankshaft rebalanced by a firm that knew about Norton engines and the need to oil fill the shaft before working on it.

Finally I added electronic ignition, a Concentric 932 single carb conversion, a belt drive and a 21 tooth gearbox sprocket.

The end result was touring bliss. The engine started really easily every time. It had heaps of bottom end grunt for pulling away and quick acceleration. It would cruise smoothly at 70 mph, with revs just over 4000 rpm and giving 60 mpg into the bargain. Ok it still gave some vibes over 5000 rpm but there was rarely any need to push the engine that hard.

I put a similar engine in my Cafe Racer but with a lot more engine mods to give extra power at higher revs. So I used twin carbs, lightened rockers, camshaft followers etc in the head plus matched Powermax pistons, matched polished rods and a slightly different crankshaft balance factor. Again, electronic ignition helped with easy starting and smooth running compared to the magneto on my old 99 engine.

Try either and enjoy!!!

Hello yes were Norton,s engines are concerned the Biggest is not always the Best the 650 is were it should of stopped , all the Big twins 750 and over are over stretched motors , and will vibrate around the 60 mph speeds and the power tries to pull the gearbox to bits and the clutch off its splines ,this is why that fitted them in flexie frames and knicker elastic mounts , have fun yours AJD

Previously wrote:

I rode a 600cc 99SS Cafe Racer for nearly 30 years and found it a great, reliable engine. Once I got the serious touring and rally bug, I bought an Atlas and got hooked on the extra power available to help shift camping gear and my bulk around.

I was so impressed by the engine, that I even replaced my 99 motor with a tuned 750cc motor to use for track days. This engine would rev to over 7000 rpm, was very smooth and never broke during 6 years of thrashing.

The early road tests of the standard Atlas engine are not wrong when they criticize the vibes that appear above 5000 rpm. They will shake you and the bike to pieces.

The answer to this issue, is to tune the engine to avoid this point.

The first thing to do is to rebuild the engine to give most power and smoothness lower down the rev range. First I added a few Commando parts such as 8.9 to 1 pistons, conrods and a cylinder head to boost the power. I got my crankshaft rebalanced by a firm that knew about Norton engines and the need to oil fill the shaft before working on it.

Finally I added electronic ignition, a Concentric 932 single carb conversion, a belt drive and a 21 tooth gearbox sprocket.

The end result was touring bliss. The engine started really easily every time. It had heaps of bottom end grunt for pulling away and quick acceleration. It would cruise smoothly at 70 mph, with revs just over 4000 rpm and giving 60 mpg into the bargain. Ok it still gave some vibes over 5000 rpm but there was rarely any need to push the engine that hard.

I put a similar engine in my Cafe Racer but with a lot more engine mods to give extra power at higher revs. So I used twin carbs, lightened rockers, camshaft followers etc in the head plus matched Powermax pistons, matched polished rods and a slightly different crankshaft balance factor. Again, electronic ignition helped with easy starting and smooth running compared to the magneto on my old 99 engine.

Try either and enjoy!!!

Hello yes were Norton,s engines are concerned the Biggest is not always the Best the 650 is were it should of stopped , all the Big twins 750 and over are over stretched motors , and will vibrate around the 60 mph speeds and the power tries to pull the gearbox to bits and the clutch off its splines ,this is why they fitted them in flexie frames and knicker elastic mounts , have fun yours AJD

The best thing I did to my 99 was to fit an Atlas engine with a single carb. Vibration is not bad and smooths out at 4,200 rpm at which point it really gets up and goes.