AN/Hemmings Aluminium Barrels

The alloy barrel on my 920 has the tappets running in aluminium. Same as you, I'm wondering if that will hold up long term. Actually I'm quite unsure of the 920 part as well. I've read about a number of failures of these when done in cast iron. I'm hopeful that the improved cooling with aluminium will keep things in the round. I read of one owner who used Maney parts for his 920. After 10,000 miles or so he gave up on that (bores distorted, burning lots of oil, not much power) and went back to stock 850 cast iron.
That worries me. If anyone knows how to make this stuff it would be Steve Maney.
Anyway, I hope to ride this 920 quite a bit this year, just insured it yesterday.
Will let you know how it goes. Right now it's running great, but it has only done a couple of thousand miles.



Glen
 
I think it should be fine so long as it’s kept clean, ie no gasket or carbon particles dropped down there when taking the head off.

But even iron barrels get chewed up by that.

Of course… JS cam and lifters would solve it for yer…
 
I just reread one of those 920 problem threads, probably shouldn't do that but couldn't leave it alone.
I had forgotten this bit

"OK lads here's were I am.

Talked to Norman White, Steve Maney, Mick Hemmings, Geoff in SRM & Pete Lovell.

They ALL said if I was looking for a reliable motor do not go down the Norvil 920 route!!!!! or any 920 route, nuts:("


We could add Jim Comstock to this list. He converted the 920 (iron) in that thread to 880 capacity. I would like to know how that has held up over the years. It's probably fine.
 
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Gotta mention that it's pretty great how well supported these old bikes are, 60 years on.

worntorn said:
They ALL said if I was looking for a reliable motor do not go down the Norvil 920 route!!!!! or any 920 route, nuts:("
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Seems like none of the issues are catastrophic, so enjoy it until it poops out. Might as well; the money's spent, and no point in taking apart a (currently) working, insured motorbike. Hopefully, a summer to formulate a new plan while you're out enjoying the bike. Your 920 is bitchin'! If we were looking for easy and reliable, we should all get KLRs.
 
Thanks!
I kept the stock 850 barrel so there is that (heavy) option.
I'm glad I reread the thread because I had forgotten that Jim Comstock ended up fixing that 920 by converting it to an 880.
If the 920 doesn't work out, a sleeve down of the alloy barrel to 880 might be a good option. That is if the follower tunnels in aluminium work out ok.

Ludwig runs an alloy barrel on his 850. I believe he has done quite a few miles with that one.

Glen
 
worntorn said:
I just reread one of those 920 problem threads, probably shouldn't do that but couldn't leave it alone.
I had forgotten this bit

"OK lads here's were I am.

Talked to Norman White, Steve Maney, Mick Hemmings, Geoff in SRM & Pete Lovell.

They ALL said if I was looking for a reliable motor do not go down the Norvil 920 route!!!!! or any 920 route, nuts:("


We could add Jim Comstock to this list. He converted the 920 (iron) in that thread to 880 capacity. I would like to know how that has held up over the years. It's probably fine.
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I agree Glen, I am SO over 920’s… hence my last build was a 1007 !

Seems to me you should follow the modern automotive trend of down sizing… and forced induction…!

Or (and more seriously) stop reading the doom and gloom and just enjoy it. If it breaks, you can fix it.
 
Certain aluminium alloys are very good bearing materials eg AS15 for shell bearings which is Aluminium/Tin, pistons are a hi silicon aluminium alloy. Briggs and Stratton make their con rods from a similar material to AS15 and run them direct on the crank journal.

Honing takes 10ths of a thou off so easy to take under 68 to 68 plus 3 or 4 thou clearance.
 
Fast Eddie said:
I think it should be fine so long as it’s kept clean, ie no gasket or carbon particles dropped down there when taking the head off.

But even iron barrels get chewed up by that.

Of course… JS cam and lifters would solve it for yer…
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Following on from that,,,,
Has anyone done a Commando barrel with Domiracer-style pivoting follower/lifters? No sliding to go wrong there. Much less reciprocating weight too.
If not, I wonder why? (other than small market comprising cranky old bastards)
Cheers
 
This, I believe, is a cross-section of how the dimiracer "lifters" worked.
Unbelievable that it hasn't been tried on Commandos!
Cheers
Domiracer.jpg

Wrong drawing - as @Matchless points out below!!
 
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robs ss said:
This, I believe, is a cross-section of how the dimiracer "lifters" worked.
Unbelievable that it hasn't been tried on Commandos!
Cheers
View attachment 112822
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I don't think it is. Looks more like ES2. The Domiracer followers were a hollow version of the twin type, where the pushrods ran inside them, at least on the cutaway drawing I've seen.
As for Maney 920 aluminium barrels, my own bike has done 15,000 hard ridden miles & no problems........so far.
 
t ingermanson said:
Pick your poison.

View attachment 112837
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Thanks for that - the lower one was what I was thinking about.
It's a very clever design that could be made to fit without much modification.
The hardest part, for a home mechanic, would be to finger-lifters. More precisely, the hardened surface that rests on the cam.
I would have thought that someone would have done something similar for a Commando - no?
 
Y'know - the more I think about it the more certain I am that I'm going to do this as part of my 650SS rebuild.
I'll have to compare the space constraints with available finger lifters (80's Suzukis?)
I know that for road use there is no benefit, but, that's not the point.

As a slight side-line - it appears that some type of dam is required in the lifter tunnels to regulate and direct oil onto the critical cam/follower interface. Not shown in that photo (that I can see)
Cheers
 
robs ss said:
As a slight side-line - it appears that some type of dam is required in the lifter tunnels to regulate and direct oil onto the critical cam/follower interface. Not shown in that photo (that I can see)
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Was thinking the same. Funnels of some sort, however, just dripping from above won't oil the surfaces on the underside. Will be a tricky bit of work in creating an oil way onto the surface, without adding friction. Perhaps dripping through onto the cam lobe as it approaches the lifter face?

Also hard to imagine a finger lifter lighter than the BSA/Triumph style that could put up with the wear.

Sounds fun though. Keep us in the loop!
 
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Matchless said:
I don't think it is. Looks more like ES2. The Domiracer followers were a hollow version of the twin type, where the pushrods ran inside them, at least on the cutaway drawing I've seen.
As for Maney 920 aluminium barrels, my own bike has done 15,000 hard ridden miles & no problems........so far.
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The Domiracer follower drawings exists, and they are exactly like that in the diagram above, the drawing will from part of a talk later this year.
 
t ingermanson said:
Also hard to imagine a finger lifter lighter than the BSA/Triumph style that could put up with the wear.

Sounds fun though. Keep us in the loop!
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Those pivoting (unfortunately leading link) lifters in your second photo (post #13) would definitely be lighter, in effect, than the BSA/Triumph ones - even though they are lighter than the STD Norton ones. JS mod is based on these, no?
Most of that Domiracer mod in that photo is a doddle, except the lifters. I'll have a look around at Jap finger lifters from the '80's - maybe some promise there?
Just need them to be short enough to expose the reverse rotating cam to the dribble of oil from above.
Will also need substantially longer pushrods - probably about 2" longer. The pushrods will have to pass through the dams I mentioned in post #16.
More & more interestinger :rolleyes:
Cheers
 
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Another (weird?) thought is that you could use the finger lifters as a "cam-amplifier" by changing the position of the pushrod-ball socket.
Move the socket forward and increase valve lift for the same cam (and vice versa!)
As I said - interestinger!
Cheers
 
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