Atlas primary chain replacement

The single row primary chain on my Mercury (650 SS, same chain as Atlas ) needs replacing.
Looking around on the web, some folks say to stay with Renolds chain, and that everything else stretches too much.
Others say the new Renolds chain is no longer made in the UK and is not up to the job.

The chain is a 76 link 1/2 x 5/16, also known as #428 chain.
#428H chain is a heavier duty version of 428.
Some folks use a 428H rear chain for the primary: cut to length, and apparently holds up well.

Any comments on the above??
I can buy DID brand 428H, or RH brand 428H. Preferences??

Stephen Hill

Contact andychain through this site...

Why not fit a belt and be done with leaks?

Jean

Jean, great question. I don't have a good answer, yet.
What do you know about grafting Norton Commando inner and outer primary cases onto an Atlas/650ss, etc?
I have a spare set and wonder if it can be or ever is done.
Stephen

Stephen Hill said:

Jean, great question. I don't have a good answer, yet.
What do you know about grafting Norton Commando inner and outer primary cases onto an Atlas/650ss, etc?
I have a spare set and wonder if it can be or ever is done.
Stephen

Click to expand...

You do know that there are belts designed for the Atlas that would fit right in don't you? I know they can be expensive like all belt drive kits, but they would retain the stock covers.

Fitting a Commando primary drive is also feasable, I've done that years ago and you could do one better and install an Alton electric starter as long as you get rid of the point housing which is at the rear of the crankcase. If you have a magneto, selling it could pay for the starter :wink:

There are Converta plates made out of alloy cut especially for doing that conversion, I'm not sure, but you could have the cylinders tilted à la Commando or straight like the old Atlas. To fit the starter, the engine MUST be tilted in order for the starter to fit. I am presently fitting an Alton starter to my café bike and if it had been fairly stock, it would have been a breeze to install.

Jean

I used a Renold chain on my P11. It uses the same clutch and sprockets as the Atlas, just a few links inside an AMC primary. It failed after about 350 miles and blew out the front of my primary. Inspection of the chain revealed poor riveting of some of the plates - It failed about six inches away from the master link.

Renold doubted the veracity of my correspondence with them. I had the primary repaired (about $200) and installed a D.I.D. 428HD chain.
4000 miles later, I adjusted the chain once. Used the same chain in my G15 - again, same drive as the Atlas.

The DID also tests out at almost double the tensile strength of the Renold.

Stephen Hill said:

Jean, great question. I don't have a good answer, yet.
What do you know about grafting Norton Commando inner and outer primary cases onto an Atlas/650ss, etc?
I have a spare set and wonder if it can be or ever is done.
Stephen

Click to expand...

When my Atlas is in need of a new primary chain, I will contact andychain. The newly made Reynolds chains from India are junk.

The hardest thing about the Cdo inner and outer chain case swap out is dealing with the left footpeg. It can be done if you are willing to bore holes in the Cdo cases and mount the footpeg ala Atlas. Boring the holes is the easy part .... making it oil proof is harder.

I have mounted the Cdo clutch and triple row chain in my Atlas and ran it for about 15K miles, but went back to the Atlas clutch due to the lack of a cush drive using the Cdo clutch. Gears are stressed without a cush drive.
I had no problems in 15K miles, but I was not pushing it hard.

A belt drive would be nice, but I do not know of one that also has a cush drive. The belt IS NOT a cush.

Slick

Re the comment about a belt not acting as a cush drive /shock absorber.......
Belts are industrial devices and like chain were not designed for motor cycle application.
I very much doubt that any belt manufacturer has ever done testing to determine if they act as a shock absorber but what makes you think that the 'shock absorber' fitted to your Norton/BSA/Triumph actually works as one??? Mr Jack Williams wrote in one of his 1950s AJS 7R and Porcupine A4 design note book (which he wrote up at the end of every working day - as did Mr Hopwood and Mr Hele) that for the AJS 7R and Porcupine motors the clutch mounted shock absorber did not have enough mechanical movement within it to work correctly and that he had requested a car type shock absorber mounted on the crank. I very much suspect that Mr Williams had investigated transmission shock absorbers previously whilst working at Vincents and a VERY vague memory tells me that they had one mounted in the crank drive sprocket but I could be wrong.(Its a bit late to phone my tame Vincent man now who is probably in bed clutching to his chest one of the 4 valve heads he manufactured from the original Mr Phil Irving drawings.....
At one time Gates conducted a development program with Harley to develop 'The All Belt Drive Motorcycle' but had a primary belt failure problem that theory said should not be occurring. They eventually traced the problem to the Harley transmission shock absorber ...as the bike was being accelerated the shock absorber wound itself up and when gear changing or closing the throttle occurred it unwound itself shoving big shock loads into the system.Does the same occur on our olde BSA/Triumph and Nortons?? Was removing the clutch shock absorber for Commando actually an improvement?? The Harley shock absorber was redesigned to spread a smaller shock load over a greater number of engine cycles and hey presto the belt problem no longer occurred. Gates did a very serious amount of testing and you can read all about it by obtaining the S.A.E. Technical Paper Series Document 'The Development of a Belt Drive Motorcycle' number 800972. It is dated 8-11-80 which I suspect is the 11th of August 1980. I dread to think how much a copy would cost these days. Luckily mine came to me for free many years ago.From where I cannot possibly say.
Personally I regard Norton BSA and Triumph so called shock absorbers as shock increasers.
I also have a copy of a 1980 BSc thesis (A Study of the Application of a Toothed Belt as a Motorcycle Primary
Drive)in which a T140 was converted to a USA made QPD belt primary system and the test results are very
interesting. For example through the rev range the fuel economy increased by an average of 15%, the engine efficiency rose by 6 -11% and engine noise levels reduced by 1-1.5 db. Yes of course I have a copy.
Over the years in talking to people such as Mr Hopwood and M Hele and others trying to determine if any testing of the transmission shock absorbers fitted to the British motorcycles they were responsible for had ever been conducted and I totally failed to find anyone who could even remember any such testing being done although I bet Mr Jack Williams did some whilst at Vincent shortly after WW2.
I doubt any belt manufacturer will admit publicly that their belt products act as shock absorbers but I tend to talk /pick the brains of some senior people in the industry with decades of experience and off the record I get a different story. Personally I am TOTALLY convinced as to the superiority of primary belt systems and believe that belts do act as shock absorbers ....and I personally DO NOT make belt systems for sale to the public.

Stephen Hill said:

The single row primary chain on my Mercury (650 SS, same chain as Atlas ) needs replacing.
Looking around on the web, some folks say to stay with Renolds chain, and that everything else stretches too much.
Others say the new Renolds chain is no longer made in the UK and is not up to the job.

The chain is a 76 link 1/2 x 5/16, also known as #428 chain.
#428H chain is a heavier duty version of 428.
Some folks use a 428H rear chain for the primary: cut to length, and apparently holds up well.

Any comments on the above??
I can buy DID brand 428H, or RH brand 428H. Preferences?? Stephen Hill

Click to expand...

Renold’s chain are now made in India and are not to the same spec as the old Renold’s chains were.

Having just phoned and asked the question I can safely inform everyone that Renold no longer manufacture motor cycle chain and have not done so for a while.
Mind you some of us considered they hd not produced chain in the UK since Renold in the 1950s bought out and closed the Perry Chain Company in Tysley Birmingham ........ I still have a new boxed 5/8 x 3/8 Perry chain somewhere and the difference in quality. Personally I would only use a dry belt these days so I can obtain a proper clutch.....one that does NOT slip when fully engaged even when hot, which frees off instantly without drag when required even when hot, that is EASILY operated by the rider using no more than 2 fingers and which posssesses the LIGHTEST rotating weight reasonably possible.........these being some of the qualities a clutch should possess......according to Mr Irving but not according to the British motor cycle industry!!

J. M. Leadbeater said:

Having just phoned and asked the question I can safely inform everyone that Renold no longer manufacture motor cycle chain and have not done so for a while.

Click to expand...

That's been common knowledge for some time-so I'm surprised you wouldn't have known.

Oh I knew all right from a GREAT many years ago when so called Renold chain was no longer stamped on the side plates either 'UK' or Made in England' and proper Renold motor cycle chain had to obtained from old stock Army etc sales.
I had heard a rumour a few years ago that Renold motor cycle chain was being made again so I thought I would phone and ask the question to get the FACTS....out of pure curiousity. EXACTLY why others are incapable of picking up a phone and doing the same I have no real idea.......you simply Google Renold obtain their telephone number pick up the phone and ask the question and obtain FACTS....

I am a shareholder in Renolds and will not sell the stuff, not just made in India !!!!!!!

The iwis (German) is by far the best chain, even has a chromised pin (usually only found in automotive).

Please the tensile strength is not important as the chains run at high rpm. Bearing area and quality is
by far more important. Not a big heavy whacking about a high speed.

For those in UK I will come and bore your club with a talk, for those in USA or OZ send airline ticket.

Andy

Jeandr said:

Fitting a Commando primary drive is also feasable, I've done that years ago and you could do one better and install an Alton electric starter AS LONG AS YOU GET RID OF THE POINT HOUSING which is at the rear of the crankcase. If you have a magneto, selling it could pay for the starter

Click to expand...

I like the Alton electric starter idea on my Dominator however I am afraid (electric)starting the bike without ignition unit will be a problem :?:

Ted Bloomfield of Motor Cycle Shop in London could often be heard muttering that the Germans had never ever made proper chain in their lives.....
Personally I was rather impressed with the D.I.D motor cycle chain web site and the fact that they give a design life for their motor cycle chain products.
If you intend putting a Commando primary system on please BEFORE doing so read the Peter Williams book and learn what the ridiculously wide chain line of the triplex chain did to the Commando gear boxes not helped by the even more ridiculous rotating unbalanced gearbox flywheel weight of Commando clutches especially the bronze plated lumps....... According to Mr Phil Irving a gearbox mounted motor cycle clutch is supposed to possess the LIGHTEST rotating weight reasonably possible ........ Personally my belt driven Commando clutches made for the very few friends who successfully talked me into doing so have an all up weight of 61/2 lb and less if fitted with an alloy clutch centre FOR RACING PURPOSES ONLY.

I use single row 428 primary chain as used on the rear of some Honda MX bikes. My 850 pulls like a train. I've only dropped the chain once, that was when I forgot to wire the clip. It cops a hell of a beating and has lasted a few meetings. Belt drive is probably excellent, however makes changing gearing more difficult.