Reynold vs Diamond final drive chain

At the beginning of the season I replaced my Reynold chain that had over 10,000 miles with a Diamond at nearly half the cost. My reasoning was why pay for shipping a British made chain when a US made should work the same. Since then I've been told the Diamond doesn't fit quite right, the link pitch is slightly different. Why would this be the case if the chain size is the same? So far there haven't been any problems.

I thought the pitch was always supposed to be the same, regardless of brand. Ditto for the roller width. I've heard that some of the "heavy duty" chains have thicker sideplates which could cause clearance problems on our Nortons. If not, would be useful to know which brands are non-standard!

Debby

Illf8ed,

I echo Deb's comment.

Pitch is the distance between the chain rollers. If the advertised chain pitch is, say, .600" then that's would it will be, regardless of who manufacturers the chain.

Regards,

Jason

I have run Diamond chains for 25 years. No problem, no premature sprocket wear. This sounds like some one wants to unload their stock of Renold chain. Don't get me wrong, Renold is excellent chain. I just don't want to throw money away just because "it's genuine Renold".
As far as pitch. 530 chain means it is 5/8" (.625) pitch by 3/8" width. That's a standard, so why would any one market a chain that is any different?
By the way, 420 is 4/8" X 2/8", 520 5/8" X 2/8". You get the idea.

speaking of chain

Does anyone know the exact size, links wise, of the rear chian on 1973? (too lazy to count them !)
Philippe

Philippe,

According to my Norton factory shop manual, your rear chain should have 100 pitches (links) unless your gearbox has a 20-tooth sprocket, which would be unusual and pretty darn small. This smaller sprocket calls for a chain with only 99 links.

Jason

Actually, for the U.S., the 750's came with a 19 tooth countershaft sprocket for the Roadster and a 20 tooth for the Interstate. The 850's jumped up to 20 and 21 respectively.

Philippe,

Well, it sounds like you better start counting.

If you buy a chain that is a little long, you can easily shorten it to your exact needs with a chain breaker.

Jason

20 or 21?

Yes, best to count the links yourself. No fun buying a chain that's a couple of links too short.

Speaking of gearing - my 750 Roadster is geared way too low for the highway. I assume it has the std 19 tooth sprocket though I haven't checked yet. Would a 20 or a 21 be better? Was wondering if the 750 would be too sluggish and overgeared with the 21...

Debby

I just put a 21 on my 750 combat. yes it took some of the snap out of it but it also lowered the RPM by 500 on the road . it is a lot better @70MPH now. it was about 4750 with a 19 now its 4200 with a 21.

bill

Debby,

As you pointed out, the larger the gearbox sprocket, the faster the bike will travel at a given RPM. Or put another way, the less the engine has to spin to maintain the same speed.

I currently have a 21 tooth sproket on my '75 Commando and find it works quite well.

I assume your concern about a larger sprocket is sluggishness during take-off from a fully stopped position. The 21 tooth sprocket does give up some snap on take-off but it's very liveable, considering the lower revs at highway speeds, which reduces engine wear and increases gas mileage.

Hope this helps.

Jason

Oops!

Sorry for the duplicate reply; Bill's reply must have popped up without me knowing it when I was typing my response to Debby.

Jason

It depends on the type of riding you plan on doing. The 19 tooth tops out the Commando at 107 mph at redline (7000 rpm). And it will pull usually pull top gear to redline in fourth! A 20 tooth will give 113 mph, a 21 tooth 119 mph, and a 22 tooth 124 mph. This assumes your using a 4.10H-19 tire.
As you can see this is pretty low. In the 70's the US market wanted that quick jump so 750 Roadsters were fitted with 19's.
I have a 22 tooth on my 850 Interstate and that is as tall as I'd want to go. It definitely saps some acceleration, but cruises nicely at freeway speeds. My 850 Production Racer replica is quite happy with a 21 tooth. A good compromise for a bike with a ported head, oversize valves, cam, carbs, and head mill. My stock 750 MkV still has the 19 tooth, but next time I have the primary off, I have a 20 tooth waiting to go on.