pitted Nikasil coated cylinders

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jseng1

jseng1

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Here's a photo from the Norton Commando facebook thread showing a new set of cast aluminum Nikasil coated cylinders with pitting on the bore surface. The pitting is from defects in the casting. I almost made the mistake of buying a set before I knew about the pitting. Now I'm hoping to see someone produce them from billet or better castings without the pitting problems.

pitted Nikasil coated cylinders
 
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It looks brand new. You would think some inspector would have seen this. Do you think it was tossed aside and an employee picked it out of the trash!?!?!?!
 
We have made prototype cylinders from billet, and they are in Stan Keyes bike for testing. We have found we can make billet cylinders cheaper than paying for patterns and core boxes for casting. Even if we did do cast cylinders, I would still put in billet alum liners. Nikasil, in my experience, has problems with the imperfections in cast cylinders
 

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Billet for so many applications seems to be replacing all types of casting. CNC makes it all perfectly repeatable and cheaper.
Entirely possible that some day printing will replace them both.
 
I never did see (at the time) the manufacturer or a full picture of that cylinder so maybe like a lot of FB posts a pinch of salt is in order.

My Moto Guzzi has replacement Nikasil cylinders which are perfect and have sold by the thousands (Gilardoni)
They are cast so there must be a way.

ddd.jpg
 
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Time Warp said:
I never did see (at the time) the manufacturer or a full picture of that cylinder so maybe like a lot of FB posts a pinch of salt is in order.

My Moto Guzzi has replacement Nikasil cylinders which are perfect and have sold by the thousands (Gilardoni)
They are cast so there must be a way.

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Gilardoni barrels are superb! Although my own experience with them is only with after market barrels for Meriden Triumphs.

I‘m pretty sure the Triumph barrels are die cast rather than sand cast though.
 
They very well might be but have to say even the OEM (chrome bore) Moto Guzzi cylinders going back to the late 1960's are a very nice finish.

I seem to remember you are not a FaceBooker, here is a recent picture of some old Norton engine in a wheelbarrow.
I looked up the cylinder as per this thread but it had faded away and well down the FB page, surely (I had looked at getting one) it is Not one of the UK made Norton cylinders.
The post it is in is a little sketchy at best.


pitted Nikasil coated cylinders
 
That bore probably looked good before going for plating, the dark staining in the bottom of all the pocks suggests a chemical reaction possibly caused by an element in the alloy not fully mixed in the melting furnace which the plating chemicals reacted to.
 
G81 Can Cycle said:
We have made prototype cylinders from billet, and they are in Stan Keyes bike for testing. We have found we can make billet cylinders cheaper than paying for patterns and core boxes for casting. Even if we did do cast cylinders, I would still put in billet alum liners. Nikasil, in my experience, has problems with the imperfections in cast cylinders
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Great job.
Do you nikasil the cam follower bores or do they stand up to the wear?
 
Time Warp said:
They very well might be but have to say even the OEM (chrome bore) Moto Guzzi cylinders going back to the late 1960's are a very nice finish.

I seem to remember you are not a FaceBooker, here is a recent picture of some old Norton engine in a wheelbarrow.
I looked up the cylinder as per this thread but it had faded away and well down the FB page, surely (I had looked at getting one) it is Not one of the UK made Norton cylinders.
The post it is in is a little sketchy at best.


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It was a Norton model to challenge Peter Williams 500 Arter Matchless "Wheelbarrow!"
 
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There is still no source posted for this cylinder, just a vague post on FB that was soon forgotten.

That is a big difference to buying something off known vender's and receiving junk or unusable parts not fit for use.
If the cylinder (costing ??? $$) is from a known manufacturer, perhaps it does show the low skill level out there (to let it pass QC) these days and the contempt they have for the buying public being stupid enough to not notice most of the time. :)

Not that any real information is known except for some cropped photo's of who knows what.
 
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Cast cylinders, whether die cast or sand cast will unfortunately show up imperfections, hence the reason they fit cast iron barrels- and these are spun cast btw to avoid those pinholes that occur in other forms of casting.
 
Bernhard said:
Cast cylinders, whether die cast or sand cast will unfortunately show up imperfections, hence the reason they fit cast iron barrels- and these are spun cast btw to avoid those pinholes that occur in other forms of casting.
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Perhaps so. For aluminum, either a low pressure die casting process w/venting, or a high pressure casting process w/pre-charge die vacuum degassing, an easy flow silicon alloy, and an optimized filling pattern, preferably using multiple radial gates in the future bore(s) is the way to go. The comination of measures will reduce overall porosity and allow the remaining porosities due to air/gas entrapment and shrinkage to form in an area where it doesn't affect functionality.

The example above appears to be a sand cast barrel which has been machined and plated. Sand castings are generally speaking not suitable for plating due to higher porosity, oxides and solid particle entrapments.

For those interested, here is a good webinar on the die casting process and how to avoid defects.





-Knut
 
The thing is, Andy Molnar must have more alloy plated barrels out there, being used HARD, including at the IOM, than just about anyone else involved in old Brit bikes. Spots or no spots.

Unless someone can demonstrate what the actual problem is, I’m thinking Andy knows what works.
 
Dances with Shrapnel said:
Well there you have it problem definition - cosmetic
where is it located, where the sun does not shine
whyI ask the purpose of this original post?
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I depends on how big the pits actually are. If they are too big then you have pressure leaks through the pits around the rings causing blow by and loss of power (like too big of a ring gap). If they're small enough then they might not matter. You can have cylinders with pits or you can have cylinders without pits. Take your choice.

The purpose of this post is to talk about the ongoing development of Nikasil lined cylinders for Nortons. The pitting problems encountered as shown in the photo at the top of this post were first shown on FB because the customer was concerned. Note that there are other Cylinders mentioned - Gilardoni MotoGuzzi etc that don't have problems with pitting. And there is John (G81 Can cycle) who has been making billet cylinders with Nikasil linings for Triumphs without pitting problems. It stands to reason that they should be available for Nortons (without the pits).
 
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