Oh bother!

Back on the bike after 19 months, second run out when I stopped to check for any leaks etc. All OK so I let clutch out and nothing, just a slight forward movement and rubbing noise. Tried a couple more times and then it dawned the belt had lost its teeth. It has done 25k miles between May 03 and Oct 10 and yes it has seen some oil when it shouldn't have. Once again my own fault for not changing it after contamination. New one on order from Norvil.

Thats just your bikes way of saying welcome back, I'll teach you to leave me in a dark garage for a year and ahalf

Thats just your bikes way of saying welcome back, I'll teach you to leave me in a dark garage for a year and ahalf

Click to expand...

Probably, but not through my choice.

That wouldn't have happened with a chain Keith! I have seen a few car cam-belts looking like that though, I might be old fashioned but I reckon chains are the better way of transferring drive whether it be primary or final drive on a bike or camshafts in cars!
On second thoughts maybe those wide final drive belts on Harley's etc. might be a different matter,

Dave.

Keith,

If you can hold the order to Norvil, I suggest you get in touch with Kenny Cummings at NYCNorton as he has spent some time and effort on this matter.

Not all toothed belts are created equal. I had been stripping teeth on one of my race bikes for a few years and went to a few different brands (Optibelt Omega, Jason etc) without success. There is a supplier that Kenny has identified that has a belt solution.

Inspecting the newer replacement belt one can see the marked difference in the construction of the sheathing of the cogs.

Dances with Shrapnel said:

Keith,

If you can hold the order to Norvil, I suggest you get in touch with Kenny Cummings at NYCNorton as he has spent some time and effort on this matter.

Not all toothed belts are created equal. I had been stripping teeth on one of my race bikes for a few years and went to a few different brands (Optibelt Omega, Jason etc) without success. There is a supplier that Kenny has identified that has a belt solution.

Inspecting the newer replacement belt one can see the marked difference in the construction of the sheathing of the cogs.

Click to expand...

Gates Polychain GT is regarded as the strongest in the industrial world. Seen a lot of them used in automotive/MC applications. JFWIW

For what it is worth, I have broken Gates Polychain before.

Two types of failures I have seen, one is where the teeth strip off of the belt and the other is where the belt simply breaks.

Your results may vary but for the money, I would recommend getting ahold of Kenny Cummings on this matter.

Order two, and keep the extra one stashed in the bike........ just in case this happens down the road again... it'll save a tow,


JD

Thanks for all the replies gents....

That wouldn't have happened with a chain Keith! I have seen a few car cam-belts looking like that though, I might be old fashioned but I reckon chains are the better way of transferring drive whether it be primary or final drive on a bike or camshafts in cars!
On second thoughts maybe those wide final drive belts on Harley's etc. might be a different matter,

Click to expand...

My first thought, which is why I'd intended to replace it. It had been contaminated at least twice, the last time flooded in oil when the crank seal popped out (reversed one way breather after a cleanout - my fault). Oddly a Harley rider stopped to offer help and he'd lost his drive belt on the same road last year.

If you can hold the order to Norvil, I suggest you get in touch with Kenny Cummings at NYCNorton as he has spent some time and effort on this matter.

Click to expand...

Thanks for that, I will do that but in meantime I want to get on the road and if Norvil have one in stock I'll take it. It still ran 25,000 miles under less than ideal conditions.
I do run it loose but not as loose as Norvil's recommendation, just loose enouigh so that when the clutch drum is stinking hot and fully expanded the belt can just be twisted 90 deg. Looking at the Gates site there is a useful guide to failure modes and mine seems to fall into the 'tooth rotation' class, which is a loose belt and medium/high load failure. Still these belts hate oil and mine has had a good occasional dosing over the past 7 years.

Order two, and keep the extra one stashed in the bike........ just in case this happens down the road again... it'll save a tow,

Click to expand...

Also thought of that and always take enough tools to take care of major work. However I'd have been short of the correct socket for the crank nut (rotor and pulley side plate need removal to fit belt). It was also difficult to undo that nut without the belt in place and in gear to lock the drive. Still, on the road some rope in the plug hole would probably do the job!

What are the advantages of a belt primary drive? Just curious.

It still ran 25,000 miles under less than ideal conditions.

Click to expand...

that's pretty darn good!

I finally replaced my belt last year after 15 years, it actually looked pretty good to go longer but replace anyway

WHY a belt primary?
1) Blessedly dry clutch basket, plates, and entire no leak prmary
2) less weight than a chain so smoother and quieter

I think the standard instructions for belt tension error too much with too loose belt

Yes the baskets and the engine plates heat up and take some of the slack out but the pull is across only the top of the belt and as long as when fully hot the belt is not pulling the front and rear baskets together, the tension is fine

this results in a grabbing the middle top of the belt when cold and twisting it 75 degrees or about 30mm total
up and down movement

much more slack than that and it just slaps on the bottom on the primary and takes up in the basket a little later,
both of which are somewhat undesirable

Fudge.