RGM Belt drive

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Jerry Doe

Jerry Doe

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I was out tearing around on my 750 yesterday. Look what happened to my RGM belt drive. I must admit I was not hanging around. Not overly happy about the situation, but I still love RGM even though I wont use their belt drive anymore!

RGM Belt drive
 
A couple things. How did you check the tension? Any way the gearbox could have moved? RGM doesn't make the belts, they are standard bits off the shelf.
 
I had just checked the tension last week as I was indexing and checking my timing too. Everything was perfect. Gearbox did not move (I have an extra adjuster on the timing side). Everything was/ is lined up properly. I think the problem was that I was powering through the gears at about 8000 RPM testing my new ignition system. The bike certainly flies. Thanks Jim Comstock :)

I am not sure who makes the belts, but I purchased the kit from RGM.
 
Not good!

Looks like it was originally a red belt?
I've seen similar issues with red belts on Triumph triples, but the RGM kits I've used have white(ish) belts which have fewer reported issues.
How old is the kit?
 
Jerry Doe said:
I think the problem was that I was powering through the gears at about 8000 RPM testing my new ignition system.
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Really ?? 8,000 RPM's... I expect my crank to hand grenade right about there, taking out the cases and the fuel lines, turning me into a 200lb flaming human projectile. Is it me or do people really run their bike's RPM's up that high?
 
I know; my 750 really flies and is dialed in. Webcam 12A, Premiers, lightweight pushrods, 1.5 mm over valves etc, etc. I am not really sure exactly where I was revving it (tacho is broken), but I was accelerating very quickly and its very fast and free revving. Note- I dont normally ride it like that. I was showing off. The person trying to keep up with me was impressed until that happened.

That belt has been on there since I put the bike together (3,500 miles ago). I think I purchased it in 2017.
 
And could you turn the belt 45˚ or 90˚ to check the tension? Or did you check defection?
 
Hi Dave,

Yes it had plenty of play in the belt like its supposed to when cold. I checked it hot as well to make sure it was not too tight because I am paranoid about that.

What does defection mean? I have not defected yet, still here...;)

Jerry
 
Jerry Doe said:
Hi Dave,

Yes it had plenty of play in the belt like its supposed to when cold. I checked it hot as well to make sure it was not too tight because I am paranoid about that.

What does defection mean? I have not defected yet, still here...;)

Jerry
Click to expand...

It means when you defect to Colorado and your Norton revolts and eats a belt.
 
Hi Jerry

When you fit your new belt have a look at the keeper plate on the front pulley. Mine allowed the edge of the belt to push up on it. It then peeled out the first wire in the belt shredding it into a bird's nest. I replaced the keeper plate with a larger diameter.
It's a good clutch/belt drive 8000 revs might have found some limitations lol
All the best Chris
 
Ive read where this has happened in the past with Triumph. I believe they were Tony Hayward products. NOT slagging him here it is just
that the belts he used were the red ones. As for power I know the dyno shows the bottom falls out at 6200 rpm on a stock motor but there sure
is a lot more power up there that you would think if you have done work to allow it. A whole different bike as you know.
You are near Jim so ask him about belt choice, Kenny at NYC Norton gave me a lead on a good one so ask him as well perhaps.
Look at it this way: if it was a chain there would be a much bigger mess.
 
I would definitely report this back to Lawrence at RGM - when I ordered a replacement belt for mine he was very keen to understand the reason why, and they do stand by their products.
In my case a stator nut had escaped and punched a hole through the belt, so clearly not a fault with the belt itself.
I've had four belt drives from them in the last 7 years and they've all had the white belt, so I'm really surprised to see a red one, especially given the issues mentioned above.

If you're going to throw the rest of it away, please throw it at me ;)
 
i guess i use the same kit as yours. at first i had the standard white belt installed like the instructions came with it. After some time of hard riding , the belt tried to climb the pulleys thooth over 5000 rpm. not nice.
I changed to the red belt (for me "609 synchroflex AT10/890 GEN III" with less slack. i did about 5000 now and it looks like new and didnt lengthen a bit, but my bike isnt as strong as yours.
at high rpms the belt begins to flatter on the slackend half, which might cause problems.also i did not recognise the belt getting tensioned while getting warm.
excuse me, just a stupid question: did you align the clutch basket to the pulley under load by pressing the belt together? this did a big difference for me.
 
I had a black belt shred after approximately 6000 miles. Damaged the stator too. I thought maybe got too hot or perhaps engine oil got in the primary and degraded it. Mine came from Norvil (as did replacement).
 
I did 3,500+ with my belt. Last week I took the primary off and inspected it carefully and all was perfect. Originally I aligned the pulleys very slightly offset so when it flexes it pulls straight in align if that makes sense. I have the inner g/b adjuster too. I will inspect it carefully during disassembly to see if I can figure out how this occurred and will report back.
 
How warmed up was the bike before you hit it hard? As we know the belts are pretty loose when cold so a blast to 8k with a cold belt might have unintended consequences.
 
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