Timing belt.

This will be nothing new to members here who are also on the Guzzi Facebook page, but I just thought I’d mention it here in case anyone has had experience of timing belts on the big twins.
15 years ago I changed the original chain and sprockets for helical alloy gears. I’m about to go into the Convert’s timing chest for the first time since then for other reasons, but if any wear is present on the gears I plan to change them for this belt set up. I obtained it from a Belgian friend, complete with brand new belt.
Any views on this, both positive and negative will be gladly received…

only thing i dont like is the relatively short service life compared to chain or even gears

Guy reckons ditto Ray…
We did Keiths timing chain in his Mk 5 at 40, 000 miles and to be fair it didnt really need replacing…

Wouldnt these belts be running in oil ?

Yep, designed to run in oil. Reports say folk have done upwards of 30k and the belt still shows no sign of failing.

reports i had seen with the one i got was change at 18,000 miles but yes oil is fine on them

About right, my 30k was kilometres. I normally do less than 3000 miles a year on the Convert these days, so I’m thinking it’ll see me out!

In the car world where toothed timing belts are common, the usual advice is DO NOT exceed stated belt mileage / years lifetime, unless you like fixing bent valves when it snaps! :smiley:

I thought Al specifically wanted to know if anyone had experience of timing belts on big twins … Well if we are now talking about cars, my Renault Megane broke the auxiliary (generator) belt and that got sucked into the cam belt jamming it, it bent all the valves and did £900 worth of damage. My local mechanic had just changed the cam belt because of it’s age not the mileage which was relatively low and didn’t change the auxiliary belt as well. When I asked him should he not have done this as a matter of course he said I hadn’t asked him to. He added that I was lucky I didn’t have a 16 valve engine. I take my car to be serviced elsewhere these days.

Had the toothed timing belt from Steve Wesson on a Spada, ran well for over 19K until I sold it, new owner used it for 3 years until moving away, still going strong.

Interestingly Steve Wynne told me that belts seldom just snap. A badly adjusted belt jumps a tooth, valve hits piston and then the belt snaps.
Roy Green for the Forest of Dean

Reckon there is something in that…

Whatever, the thing is, will you be able to get a replacement belt when the time comes, if not you’ll be putting gears or a chain back on.

Belts are a standard industrial size available in many lengths, just make sure you get the oil resistant one.