Cam belt pulley ABC

[3potjohn]

My bike has a C pulley. I have an opportunity of a B pulley. Is it worth swapping with a view of making a generic belt fit better? I am not sure if they are graded by Mdina or the “ freshness” of these belts.The generic ones are much cheaper too.
I will need to change a belt this year sometime so that would be the time to do it. I have avoided having the belt in one position over winter ...by riding, with a hiatus by the initial phase of lockdown.
John in Sunny Exeter

[EVguru]

No harm in getting hold of a B, but try generic belts on your C pulley (which is the largest size).

As long as the belt slides on without having to force it (a bit of talc or french chalk can help) then a tighter belt is better, giving better ignition timing, particularly at idle.

[mad muller]

All belts are generic I don't know of anyone making graded belts it's pot luck some of the gates belts are slack and some fit ok same with megadyne Goodyear etc what Iam led to believe pirrelli stoped making graded belts years ago if Iam wrong please tell me were I can buy graded belts in my case replaced the crank pulley for a new one from nlm so the belt sizes went way out West unless the copy crank pulley is of different spec just a thought if you go for new pulleys not OEM

[EVguru]

Nobody has ever made graded belts.

Belts were simply made and then for this special application, graded, either by the manufacturer, or perhaps in house by Morini.

NLM had a grading jig, so Mdina must have it now as they're selling graded belts.

[Ming]

I once asked Stuart why his belts were so much more expensive than 'stock' belts - he said it was because they used their grading jig to classify them. As Paul says, if it slides on OK and is not too slack, don't worry. (The belt, that is )

[3potjohn]

I just had a look at a belt in my pile of bits,a Contitech belt.There is a code number on it A050917. I am assuming this is the date of manufacture?

[MickeyMoto]

I once asked Stuart why his belts were so much more expensive than 'stock' belts - he said it was because they used their grading jig to classify them. As Paul says, if it slides on OK and is not too slack, don't worry. (The belt, that is )

£5 per belt, the jig and labour to grade the belts must be horrendous. I change my £5 belts annually. What is the point of paying stupid money if my belt fits and is within tolerance?

[3potjohn]

I ordered one from RS as it’s cheap. I don’t know how hot it gets on a Morini ( today would be a good test) but I am guessing the Spec for the belt upper temperature limit must be a factor.I have changed belts every couple of years or so.