1917 4HP Belt Advice Please

[47Dougie]

I am truly sorry if my red text offended anyone it certainly was not my intention.  Thanks for those who offered a reply and advice.  Very much appreciated.

Hi Folks,
I hail from Victoria, BC, Canada.  Acquired a lovely 1917 4HP.  Requires extensive tank repair which I'm attempting to address but it also needs a belt.  I've read extensively on the site and see that Opti belts, likely in the 78"-80" range, should suit but can anyone supply a little more info on width, profile, possible part#.  Basically anything that will help reduce the likelihood of a blank stare from my SKF bearing dealer when I describe what I need it for.  (not many early belt-driven bikes around here).
I'm also looking for any literature, parts manuals, owners/shop type documentation that might be available.  E-files would be fine.

Thanks in Advance,
John

[Dave]

Hi John,

Unfortunately, January is the quietest month of the year for forum activity. I see some forum regulars haven't visited for a while. Things get back to normal from Feb onwards.
Someone will be able to help, might just take a little while.

Dave

[cardan]

Hi John,

I have quite a fleet of belt-drive motorcycles, but not a four horse.

The first thing you need to know is the width of the belt: C section is 7/8" and D section is 1". Chain-cum-belt bikes like the big Douglas often use/need a 1" belt. If the belt is too narrow the risk is that the belt will pull to the bottom of the pulley, often after a little wear, at which point there is no forward progress.

Next step is to figure out if an endless belt can be used. Not sure if you can undo the rear seat stays to get the belt in? If so, there is nothing quite like an endless belt. Smooth and no trouble, ever. The only problem is getting the length right. A really good stockist might have belts in 1" increments, sometimes even 1/2", so if a C79 is a bit loose, a C78 might be perfect. They are cheap, too. Fiddly to fit because you need to slightly disassemble the frame, but you should only need to do it once.

Good quality re-enforced, cut to length, v-belt is hard to find, but works well with a proper, articulated belt joiner - not the rubbish flat plates that are sometimes supplied. The belt needs some canvas/fabric layers to make it strong enough so that the joiner screws don't pull out. Often endless v-belts have a cord of some kind at their core, and don't respond well to cutting then drilling for joiner screws.

Some people swear by multi-link belts, and if you can get one that isn't bright orange it would probably be fine.

Can I recommend "The Vintage Motor Cyclist's Workshop" by Radco. He devotes a couple of pages to belts, not to mention everything else to do with real vintage bikes like the 4 horse.

Cheers

Leon

[47Dougie]

I am truly sorry if my red text offended anyone it certainly was not my intention.  Special thanks for those who have offered a reply.  Very much appreciated.


Thank you for the great advice.  I shall go forward with that info and I'm sure I'll find something suitable.  The old belt that is on the bike presently is a very untrustworthy and tattered looking thing so a change will be essential for riding..

Stay safe and thank you both Leon and Dave,
John

[Black Sheep]

Linked belts are rarely of decent quality. My late friend John MacMillan became quite expert at removing links from his Rudge at every stop on a run. The VMCC used to supply good quality belts but couldn't source them at a good price and stopped supplying them. I would have thought that the one thing the VMCC could do with it resources would be to source and supply drive belts for veterans but it seems not, despite my regular entreaties. Oops, a bit of a rant there.