920

Does anyone have tips, advice or warnings? Cams, carbs, jets , etc. Do they work or is a big mistake?

Yes they can work great, and yes, they can also be a big mistake!

Some Norton barrels look like Swiss cheese when bored out to take the liners. Some kits do, or did, use very heavy car pistons not really suited to the task.

Many sensible folk will ask why you want to do it, as a well built 850 or 750 will go very well indeed.

Some fools still persist with the idea though. He’s a link to how I did mine which may be of interest: https://www.accessnorton.com/NortonCommando/maney-920-tti-transplant.27113/

I got one of the older kits from fairspares , the engineer that did the machining wasn't very impressed with the quality ,but with a few mods and paired with Khein flat slides it goes very well & has done, trouble free for a long time .
I may be biased , I love it.

Nigel, just reread that thread and listened to the engine at the end. It sounds really sharp!
Not much Norton left in there but I think that's probably a good thing at that power level.

Glen

Ian Hi a friend of did the 920 conversion a few years ,he had no end of drama with the head gasket and trying to seal the very small piece of barrel left beteen the bore and the pushrod tunnel.The engine always blew oil smoke badly on one side,oiled plugs up ,not sure if he ever solved it.After seeing that I know I will never do the conversion,but others have had success,maybe there are some tricks such as copper wire around the headgasket bore edge.
Where are you in Australia?
Brett

My 850 is a couple of sizes over standard capacity and runs on methanol. But a standard size 850 should be quick enough for anyone. Going to 920 might be OK, but bigger is not always better, especially if the pistons are heavier or you get problems of leakage between the cylinders. It is not something I would do, especially with a road bike - where you might need the ability to rebore to get longer life out of the barrels. If you are on 920, the next rebore might be throw away the barrels.
Going to 920, might be about bragging rights ? If you want more performance, fit a 5 speed box with the top 4 gears close together. That will beat any standard 850 and give you a real thrill.
I still cannot believe that I never believed in my 850 motor for all those years. For a piece of shit, they are excellent.

Ian
Go for it. Makes for a fabulous bike to ride.
A 750 is a very different bike than an 850. It likes to rev an 850 feels different slightly dull after riding a 750. But the drive away from slow corners is great & it's a good bike to ride. My original Fairspares 920 kit had Ford pistons? & it was good but really I should have had it all balanced. As stated better quality items make for less problems.
Big bore engines can do it all but the grunt just makes it a joy to ride.
Chris

Rosey said:

Ian Hi a friend of did the 920 conversion a few years ,he had no end of drama with the head gasket and trying to seal the very small piece of barrel left beteen the bore and the pushrod tunnel.The engine always blew oil smoke badly on one side,oiled plugs up ,not sure if he ever solved it.After seeing that I know I will never do the conversion,but others have had success,maybe there are some tricks such as copper wire around the headgasket bore edge.
Where are you in Australia?
Brett

Click to expand...

Coleambally. I am going to do , it too late to turn back now

worntorn said:

Nigel, just reread that thread and listened to the engine at the end. It sounds really sharp!
Not much Norton left in there but I think that's probably a good thing at that power level.

Glen

Click to expand...

Thanks Glen.

You’re right about the lack of Norton in there though!

Remember, I went for really light pistons and crank with long rods, race cam, a tad under 11:1 with tight squish, and a stage 3 head. So really it’s a pretty high race spec motor, hence it sounds so crisp I guess.

What is impressive is that even with that spec, it starts reliably, ticks over like a Honda and still has great low down pull.

Frankly, I wish I’d built one years ago !

Rosey said:

Ian Hi a friend of did the 920 conversion a few years ,he had no end of drama with the head gasket and trying to seal the very small piece of barrel left beteen the bore and the pushrod tunnel.The engine always blew oil smoke badly on one side,oiled plugs up ,not sure if he ever solved it.After seeing that I know I will never do the conversion,but others have had success,maybe there are some tricks such as copper wire around the headgasket bore edge.
Where are you in Australia?
Brett

Click to expand...

yes - .005" dia copper wire and pliobond glue takes care of the leaks.