v7 750 main bearings

Hi, I’m new member and not sure if I’m in the right place but this is a question for the technical guys out there. I’m resurrecting an old 1969 loop frame and the main bearings look like solid aluminium with no white metal lining, yet speaking to somone the weekend (who should know) tells me they should have white metal linings. can anybody throw some light on this please. Any help would be appreciated!

Hi - should be in Big Block/Loop Frame section but I don’t know how to move it. A Forum Moderator will be along soon…

I’ll see if my books say anything about bearing shells, hopefully this evening.


Main bearings would not be bare aluminium. Not sure but I’m guessing bearing shells would be pressed into the crankcase front and the rear bearing carrier? If you received the engine in pieces maybe they’d been removed beforehand?

Bought in an aluminium housing having a white metal surface shrunk into it…which in its entirety bolts into the crankcase… pricey…

EBay guzzi main bearing…sorry can’t paste the link…

Power cut at home last night so couldn’t use PC.

By candlelight I did look through my manuals. I was surprised to see that all big blocks have the same size main bearing and big ends, although later ones seem to have improved tolerances. Shells for big ends are only 1.5mm thick and are just described as ‘low friction’ alloy so I don’t think they are steel-backed like those in a car engine. It also says that main bearings are supplied with the flanges as Kate describes. There is no separate part shown in the catalogue.

The manual gives all the dimensions. If you haven’t got one yet I can look up for you.


Only numbers I can find in Guzziology are for the front main bearing in early gear timed and late chain timed loops which are 1201 1900 and 1401 1900 respectively. There is also a list of 3 oversizes for each. The rear bearing should have a hollow dowel through it to feed the cam bearings.

Just looked on eBay and there is a good selection of stock and regrind sizes on offerÂ

Hi, sorry for the tardy reply and thank you for your help. Having pressed the bearing out of the carrier and looking closely at the bush it definitely does not look like it’s white metal, both front and rear bushes are in the order of 6 and 7mm thick. There were aluminium alloys that were and still are used for bearing surfaces (look on the heads of most modern bike’s cams). I might look into it further, see if I can get some alloy that would do the job!? Will keep you posted

are they worn ? mine all look like alluminium


No mention of aluminium.