Andover Norton Replacement 750 Cylinder Barrels

Cammy66

Cammy66

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Hi Everyone,

I'm just getting into rebuilding my 1972 Combat motor. Looks like the cylinders have been bored to +.060", and there is a small gouge in one of the two cylinder walls. As I understand it, this cylinder barrel is toast and I need to source a new one. Does anyone have any experience with the replacement barrels sold by Andover? Are they new production? Hard to tell with the one picture attached to their listing.

Thanks for the advice as always!
 

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Cammy66 said:
Does anyone have any experience with the replacement barrels sold by Andover? Are they new production?
Click to expand...


No personal experience but they are new and the stronger '850' pattern casting requiring the 4x 06.3085 '850' through bolts, etc.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
andover-norton.co.uk

Andover Norton - CYLINDER BARREL ALLEN BOLT - 06.3085

CYLINDER BARREL ALLEN BOLT
andover-norton.co.uk
 
Take a look at nikasil plating for worn bores. Nikasil is a proprietary name. There are are a few other similar processes available. Here is one short thread on the topic:

Nikasil Plating Norton Bores

I was wondering if anybody has used Nikasil plating in their Norton barrels. Access Norton archive has threads about Nikasil plating in alloy bores, which is not what I am asking about. I appreciate that Nikasil is usually plated on alloy bores, but as far as I can tell, it plates just fine...
www.accessnorton.com www.accessnorton.com
 
Cammy66 said:
Hi Everyone,

I'm just getting into rebuilding my 1972 Combat motor. Looks like the cylinders have been bored to +.060", and there is a small gouge in one of the two cylinder walls. As I understand it, this cylinder barrel is toast and I need to source a new one. Does anyone have any experience with the replacement barrels sold by Andover? Are they new production? Hard to tell with the one picture attached to their listing.

Thanks for the advice as always!
Click to expand...
I've never bought them but I have two bikes I got from others who did. They are new and quite good. As L.A.B said you will need the through bolts. Also washers and base gasket.

I have never had trouble finding good used cylinders, often standard bore, for much less. So many bikes in the US were ridden very little and are being broken down to sell now.
 
Thanks for the advice everyone! I think I'll proceed with ordered a replacement cylinder barrel from A-N. My current barrel exterior is not in great shape and has had some fins drilled for safety wire, etc.

I'll make sure to post plenty of pictures for anyone who would like them in the future.
 
I received my cylinder from AN today. Three days after ordering, cannot complain about the efficiency of fulfillment.
Yes, I could have used my original '71 barrel, but when I'm investing heavily for this rebuild/ multi upgrades project,
invest in the better technology. It will go well with the Carrillo rods, Comstock flowed head and Webcam 312 with
CNW Keihin flat slides. I'll mull over crankshaft, but at least use Molnar counterweight
 
With any rebuilds it all boils down to how deep your pocket are, I'm not a rich person so finding the cheapest way to go is always in my mind and resleeving would be my way to go as the outside of the barrels can be cleaned up and re painted.
 
robs ss said:
If I need this service then I would go this way (nickel plating)...
Mar 17, 2023
(thanks for the recommendation @texasSlick !)
Click to expand...

Nickel plating can bring your bores back to +.040, or less if you are so inclined and willing to bear additional expense.

Nickel plated bores have the advantage of million mile wear expectancy.

I would not consider re-sleeving; there is a significant risk of over heating if not done well.

Slick
 
Last edited:
texasSlick said:
Nickel plating can bring your bores back to +.040, or less if you are so inclined and willing to bear additional expense.

Nickel plated bores have the advantage of million mile wear expectancy.

I would not consider re-sleeving; there is a significant risk of over heating if not done well.

Slick
Click to expand...
Would Nickel/Nikasil coating fill in a gouge?
 
cash said:
Would Nickel/Nikasil coating fill in a gouge?
Click to expand...

AFAIK, Nicosil is a process that is only a few thou. thick, but nickel plating can be as thick as required to take out a gouge.

Best to Google a nickel plating shop and consult with them. I gave a link to one such shop in the link robs ss posted (reply #11).

Slick
 
SteveA said:
I don't think you should re-sleeve a 750 barrel, even if you can.

850 bolt through, sure, had that done.
Click to expand...

I have written above that re-sleeving may lead to overheating. Let me explain why :

In a liquid cooled engine, the cooling medium is in direct contact with the outer surface of the sleeve. There is no extra barrier to heat transfer offered by the sleeve, and re-sleeving liquid cooled engines is routine.
In an air cooled engine, the sleeve is press, or better, shrink fitted to the finned barrels. Better still, the bore in the barrels is copper plated first. Regardless of the extra steps taken to mitigate a heat transfer barrier, there is the unavoidable seam or joint , which may be microscopic in width, but nevertheless offers a heat transfer barrier that is greater in heat transfer resistance than a cast in joint.

Of course, there are many examples of sleeve jobs without overheating problems. But the risk is there, and as long as there is an option, I would not go the sleeve route.

Slick
 
750 barrels can be re-sleeved, and work just fine when done by a competent workshop - who else would you use?
My original post states 'for a road motor'.
Given the tuning goodies going into the OPs motor, I agree that re-sleeving wouldn't be the best option, but this wasn't known at the time.

Any job done badly, or not to spec, is likely to end badly, and shouldn't really be featuring as a legitimate argument for or against any process - especially the adiabatic wall argument.
But re-sleeving a flange-mounted barrel on a tuned motor isn't something I would recommend either!
 
texasSlick said:
I have written above that re-sleeving may lead to overheating. Let me explain why :

In a liquid cooled engine, the cooling medium is in direct contact with the outer surface of the sleeve. There is no extra barrier to heat transfer offered by the sleeve, and re-sleeving liquid cooled engines is routine.
In an air cooled engine, the sleeve is press, or better, shrink fitted to the finned barrels. Better still, the bore in the barrels is copper plated first. Regardless of the extra steps taken to mitigate a heat transfer barrier, there is the unavoidable seam or joint , which may be microscopic in width, but nevertheless offers a heat transfer barrier that is greater in heat transfer resistance than a cast in joint.

Of course, there are many examples of sleeve jobs without overheating problems. But the risk is there, and as long as there is an option, I would not go the sleeve route.

Slick
Click to expand...
With an 850 barrel, the boring for a sleeve will cut through to the fins. I can show you one. They then use the fins more like a sweated on set of heat dispersing fins. May not be ideal, but it works.

Consider also our old friend the 920 81mm barrel. Traditionally achieved by sleeving 850 barrels. I have one of those here too. But a slightly oddball set as they were intended for sidecar cross, so in fact every other fin has been ground off!
 
A bit out of topic indeed, but may be interesting for some of you: I'm going to use Molnar TGA 850 alloy barrels (available in 750 too) . Received, not yet installed. Top class quality and very easy and fair to deal with Andy. Details on his website of course.
Laurent
 

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