NIKASIL electroplating

[ghostrider]

 I found this on the elsinore web site in the states.Some very important info on Nikasil techniques....and I quote:"
The chrome bore on the 79 was done by Honda at the factory, if you look at it real close you will see it is relieved, on all of the Honda engines it is about .004" right in the middle of the bridge, and feathers out at the top and bottom. If you replate the cylinder a good shop will relieve the bridge, even on Nikasil. My suggestion is that if you replate the chrome bores, go Nikasil, less headaches and they seal better. I have bored the 79 oversize, we relieve the bridge before it goes to plating, then if they don't relieve it, we do it when it comes back. We are extreme here on race engines, that charge being blown out the exhaust port is unacceptable in my opinion, but like I say, I am extreme and like to get every last bit of power out of the engines.  Got a 75 CR250 in here right now getting some very trick work done, it will be interesting, it should be faster than my 74 engines, which is kinda scary to think about!

[ghostrider]

  AND THIS ,,,,Quoting also:"
The stock pistons did not have the holes because the bridge was relieved from the factory. The bridge gets hot and swells up from the exhaust heat and closes up the clearance on the piston. Usually when people bore engines they do not relieve the bridge, so they seize, same with a replated cylinder. The holes supply some lubrication to the bridge area, and more importantly they cool the bridge and keep it from swelling. With all that said, I do not drill my pistons, but I always make sure the bridge is relieved. As for Wiseco pistons running less clearance than stock, that is not true, Wiseco pistons are forged, and the factory pistons are cast, a cast piston does not swell as much as a forged piston when hot, so a cast piston does not require as much clearance. The old Wiseco pistons were very bad about seizing, the new stuff is top notch, still I have not been able to run an engine as tight on the clearance as what they say and not scuff the piston, at least not on the high horsepower air cooled stuff

[Lozza]

Ghosty I think this bloke has got a few things arse about.Firstly drill holes AND relieve the bridge not one or the other, when the ring is riding on the middle of the bridge(this blown out the ex port bit) the exhaust port is well and truly open.In Honda RS 125's Wiseco's,Vertex, Pro-X and standard HRC all run the same amount of clearence(about 2thou or 0.05mm) and he's got very good eyes to see bridge relief as it not even approching 0.1mm.Trick with old Wiseco's is to bake them at 200C for an hour then bore and hone to size.  

[ghostrider]

  Thanks Lozza, getting a bit too precise to check that bridge gap  I thought as well, Good tip about baking those old Wisecos (how long ago is the line between the crap Wisecos and the Good Wisecos) I have a few around the 1980 mark???

[elsie 125]

I have a mugen head and cylinder for my 77 CR125M3, which was renicasiled in victoria, and its a great job.
I didnt think the early cylinders were plated but the mugen cylinder was standard.
They would had to off been made in 1975 for the 76,77,78 cr125m models wouldnt they??
My sons CRF250 cylinder now needs renicasiling, and the quote from brisbane was half the price from victoria!!

[Lozza]

The surface finish is a good give away.The 'modern' Wiseco's are diamond finished the early one is just machined.The diamond finish has more and more defined radial grooves.Hard to explain but the box is the 'non technical' way, a blue or the oval Wiseco logo on the box I would consider old.

[Nitram]

On a slightly different track, but still to do with NIKASIL- Does anyone know what the proper grade of aluminium is to use in making an alloy sleeve which is to have a Nikasil bore ?  I'm about to embark on a project along those lines, and there's a fair bit of work involved in the making of the sleeve.  It'd be a shame to go to all that trouble and then find that the Nikasil didn't stick.
Any ideas ?  Or any idea who I should ask ?
Cheers,
Martin

[Lozza]

Ah ha you will run into 2 problems from the outset 1)For say a 125 with a 56mm bore, your Can-Am sleeve will need to be about 65mmOD top hat with say a 62mm OD where the ports are and roughly 130mm long.No commericaly available aluminium tubes/hollow bar(if you know of some I'll buy some to) will have these dimensions(65 X 54mm).Unless you buy some solid 6061 and start machining.2) Casting ali is usually 4000 series and this plates the best but 'apparently' 6000 can be plated to but not quite as good.
However I do know where I can get some 4000 series  hollow sleeves , various dimensions...  

Oh yes Peter Campbell is the bloke in Goulbourne

[BultacoMacca]

And is it correct that with Nikasil or 'chrome' bores, you have to use chrome piston rings?
So a change over from iron to chrome bore mightn't be that easy if rings are a sourcing problem?

[Lozza]

Nikasil and hard chrome bores are 2 different things. Chrome needs the special rings.

[090]

I have just bought a barrel (Mugen) that needs to be re-chromed / nicasiled. It came with a replacement set of Mugen rings. Where do i stand with all this?
1. Is Nicasil what has to be done as apposed to chrome ?
2. Do they 'de- chrome' first as part of the process ?
3.Will the chrome bore Mugen rings suit Nicasil?
Any help is appreciated.

[Lozza]

To not run over old ground, avoid the platers here like the plague.
1.Yes
2.Yes the bore is stripped of old chrome or nikasil
3.NO NO  NO NO NO Chrome bore and Chrome rings go together.
What you have to do is find a replacement piston that is normaly used in a iron or Nikasil both these rings are compatable.

[GMC]

I was always under the impression that chrome bores & chrome rings were never to be run together???

[090]

3. To explain differently, the original Mugen rings that SUIT the chrome bore ( not chrome rings), can they be used on nicasil bore?

[Tim754]

Chrome bores must run chrome bore compatible ring sets, these may be of a chromium infused or coated metal origin also.  Quote from preface in an replacement bore sleeve manual. Yes the name I have temporarily forgotten but it is a large company. Cheers Tim