Mr1 HO bore? Nikasil ?

[wajetter]

Can MR1 HO be bored and overuse rings put in? They sell oversized rings for it, so they must be bored and honed to oversize? How is Nikasil plating in these? Is it there?
Replacing worn pistons and rings. Some cylinders have scratches deeper than I’m comfortable with.
I heard Nikasil needs to be reapplied after boring - but unclear if these have Nikasil plating at all

 

[Neutron]

Can MR1 HO be bored and overuse rings put in? They sell oversized rings for it, so they must be bored and honed to oversize? How is Nikasil plating in these? Is it there?
Replacing worn pistons and rings. Some cylinders have scratches deeper than I’m comfortable with.
I heard Nikasil needs to be reapplied after boring - but unclear if these have Nikasil plating at all

Yes its Nikasil. Yamaha has beed using it forever on everything. Never heard of anyone boring and recoating. I will say these engines and especially the MR1 has thin cylinders linings. And not much material to the water jacket.

 

[wajetter]

I called WSM - they sell oversized piston kits (0.25 and 0.50). According to them, there’s a ton of demand. People do bore and hone these MR1s.
Stopped by a local reputable shop today - they looked and determined there’s no Nikasil. The cylinder surface is lined with steel.

Also called Mongoose Machine in Vancouver BC - the only place that does Nikasil plating on West Coast. They also said this engine does not have Nikasil.

Is your Nikasil claim based on “Yamaha used Nikasil in everything” or concrete data?

Ordered 0.25 oversized piston kit from WSM and will drop off at the shop later this week. We shall see!

 

[Neutron]

Yes they are steel sleeves with Nikasil coating. Can they be bored, yes but yamaha coats them to make the surface slicker and better heat transfer. When you have an engine that revs 10k it would only make sense for reliability.
Tons of manufacturers use it because it lasts.

 

[Neutron]

Some of these 4 stroke engines use a plasma type coating not necessarily nikasil. My direct engine builder in Florida that builds daily said that seadoo, Yamaha and kawi all use steel sleeves with their own coating. And yes can be bored but wont be as long term reliable if not recoated. This is why the "magnetic" test doesn't work because the steel liners.