So here’s a pic of the two with some Allen keys in for a rough guide, vertical has 4mm gap while the horizontal has 3mm gap. I’d love to see some 916 belts for comparison?
No, the bigger radius makes the run further on the roller and the pulley needs to sit further back to compensate. It does make them tighter to get on though. My research showed me there were three sizes of roller, each a different diameter; silver, black and gold, each one being a standard fit on a certain model but interchangeable on Desmoquattro engines.
Interesting. Would they be a direct replacement as in take mine off and put these on with nothing else to do.
Funny you should say tighter to get on the last change I was cursing getting the belts on this time it was easy I’ve ordered a new set from exact to put my mind at rest
No, using a larger pulley on one side only will slightly move (advance?) the belt position and so affect the cam timing - not sure by how much though? When I did mine I had the head skimmed for more compression which required the bigger pulleys to get the tension on what is now a shorter cylinder height but I also had the cam timing set to suit.
Here's my 916 before the skim work, so a standard 916; Not a super close up pic but you can see a decent gap. Here it is as is now with 1.2mm shorter cylinder and larger pulley; Quite close but been OK for over 10 years...
So after looking at dukedesmos pics and seeing how close his belts are and for how long they have been running like that I think I’m ok to put her back together. What’s the worst can happen!!!!!!
I was going to after looking at those pics, but looking at horizontal adjuster mine is much further round So I’m waiting for some exact fit belts
I've just taken these pictures of my belts (ST4 916 engine) before I replace them for comparison of running clearances
I don’t think it’s a problem as long as there is some room. What important is is that the tension is Super correct so the belts doesn’t weave to much, certainly after some use when they slack a bit. If you know what I mean
They were the standard fitment, it also has the 'Testa Bassa' 10mm lower exhaust camshaft head but I think the idler pulleys are the same fitment as standard 916. Those belts are Exact fit, the original Ducati belts fitted from factory as below;
Agreed ... I've got the same bike , same pulleys If I'm not mistaken , the belts are slightly longer than a standard 916 belt ? But while I'm prattling on .... .... I've often read about the 5mm allen key method of setting the tension , but never understood clearly what was being described . Where you supposed to be able to pass the allen key through ??
