Recoating nikasil cylinder

[The Stranger:Me]

Hi NZ Cylinders in Ashburton New Zealand do the repairs and replating of Nikasil

Can you give an indication of price please?

[jt119]

the price NZ Cylinders gave me to weild and replate mine was 570 + post the guy was really helpful

[flyingcr250]

I had my ktm cyl welded and replated by dg engine sevices second half of last year not cheap but great sevice and it was back in under a week

http://www.engineservices.co.nz/cylinder%20plating.htm

theres an old guy in the south island that does it, does real beautiful work, just trying to find his card

[camchain]

Here's a link I found was a good place to start for some basic quick info on Nikasil coatings that most will probably find very useful to know: http://www.electrosil.com.au/news1.htm

Apologies for this lengthy post but I hope it might save someone else a very frustrating experience. Been doing some reading up on this subject and it's something I wish I'd known a bit more about earlier. Personal impressions at this point would be to go with an outfit that has a lot of experience doing the job. The reports of coatings ending up wrong final size/too soft are a bit of a worry.

Nikasil (and other) surface coating is high tech stuff and you're dealing with extremely fine tolerances - a very different kettle of kezzafish to the old days of air cooled engines, sleeves and boring for oversize etc. It's now a real mix of science and engineering.

My own basic top end refresh has proven to be far from straightforward. After cleaning my glazed up bore with a scotch brite pad/CRC then hot soapy water, put my vernier across it - seemed OK for size. Bore surface had some fine lines where rings had caught carbon buildup on end of power valve (previous owner a slob) but nothing major I figured. Vernier not the best instrument for measuring a bore so I took cylinder in to shop for inspection/measure before ordering piston.
It wasn't measured but eyeballed and pronounced OK, just needing a 'light hone' and standard piston. I wasn't keen about this as I'd heard not to hone nikasil, but Fizz - Whizz - bore now looks very pretty, almost like new in fact. Hmmm. Ordered standard size piston and later found ring end gaps to be suspiciously over spec. After already waiting a month for piston, temptation to just re-assemble and ride was hard to resist but took cylinder to engine reconditioner and he very accurately measured with bore guage and DTI. (Charged me nothing but I gave him a ten pesos anyway)

Despite bike being only 2 years old, cylinder found to be bang on max size limit and therefore in need of max oversize piston for correct clearances. My cylinder wasn't perfect to begin with and now there's no way of knowing how much material was removed with the hone but I certainly wish I'd measured it properly first.

Here's the real important stuff to keep in mind when cleaning your airfilter and/or thinking about trying to get a few more hours out of a tired sloppy piston: The standard coatings are apparently only about 0.1mm (tenth of a mm) thick, maybe even less. The standard bore size for my cylinder is 64.000mm and wear limit is only 64.025! that's almost nothing. A sharp, well directed fart could easily shave off 0.01 I'd say, let alone what a hone might do.

To put it in perspective, I remember from my apprentice days that the average human hair is 0.05mm or about 0.002 of an inch.
So the coating is only about 2 hairs thick and bore wear tolerance is only a thou of an inch, or half a the thickness of a hair! The piston oversizes come in tiny 0.01mm increments so I figure piston/bore clearance must be extremely critical.

Hey Tommorth - I'd wondered how you got on after your bad luck with the new bike. Did you ever figure out what caused it?

[crazyxr250rider]

Very accurate info camchain,as for the kx250 barrel i find the only reliable easy solution to aquire is a new barrel....very expensive,but your safest bet.
Try trade me,ebay,ect... for a NOS barrel.

[kezzafish]

lol, my name is mud. I looked at re-plating my (4T) after i lunched it (you may remember the thread about my motor running water lube instead of oil). I'd heard that Nicasil plating could be dodgy and there was no one doing it here so it turned out to be only slightly more expensive to just buy a new barrel from the states (KTM) forget buying a new barrel from KTM NZ.

[tommorth]

camchain general consenus on the ktm talk foum is its standard practice to change to b size piston on the 200 on first piston ring swap but you cant believe everything you read
I never found out what caused my bike to go but suspect that it may have just been due and after my rattley kdx I didnt notice the noise till it was to late

havent even done 10 hours on it since i fixed it which is pretty slack hoping to get out this weekend fiddled with the clickers last time and it made a world of difference its amzing how big a change small adjustments make

[camchain]

Cheers crazyXR. The coatings are obviously very tough but I still can't get over the miniscule wear tolerance of these bores, and with mass production processes being what they are, it'd be very interesting to know what sort of bore size variations (and coating thicknesses) you get from bike to bike. I'm guessing the factory teams probably get their pick from the parts bin so they can start with a blue-printed engine. For some reason KTM only offer 2 Vertex piston sizes yet Vertex makes 4 sizes. My jug has a '1' cast on the side of it. Possibly something to check when buying a bike? Anyone shed some more light on this?

Heh heh. No mud intended on your name Kezzafish. Just thought the two words sounded nice together and I like a little alliteration. Yeah, now that you mention it I remember your post on the KTM submarine testing (I felt your pain). Retail for the 200 jug aint cheap at $1200, guessing possibly dearer than a 4t due to complex casting for 2t ports? Is your top end still spinning OK?

Thanks tommorth. I'll have a dig into that. I've read some very strange stuff on KTMtalk, but certainly also has a lot of good info. I'd wondered if maybe your bike had been re-ringed and a too thin base gasket used? Sounds sorted now though.

[Reckless]

Hey Cam I think you should send the bill for the re coat and your time to the guy that put the Hone into it!!!
Cam how did you judge that the bore was Glazed? They are often very shiny, completely different to a steel bore. They very seldom need any doctoring unless they have worn through which almost never happens to a bike less than 2 years old. Also quite often there's the odd light scratch down the bore from foreign matter that makes little or no difference to power output. As long as your not using very high fuel/oil ratio the 2 stroke oil will take care of minor marks and still give you just as good ring seal and therefore compression. Especially on a non race bike. I've seen some really shit bores go really fast. It sounds to me like you've been the victim of bad advice all the way through. You should have just replaced the piston with the same A or B and run it in as described under!

Read this mate re running in- http://www.mototuneusa.com/break_in_secrets.htm.
I was doing it for years through impatience in my karts. Always wondered why my engines did quite well against all the professional tuners who practiced slow 3-5 x 20 minute run in sessions. I never had the Patience always did 10 laps then found I was flat out?? Only discovered Moto tune a few years ago.

With my MX bikes! I can't resist starting them in the garage for 10 secs just to make sure they actually go and I haven't made a stuff up! Then I take it out the sandpit or thunder, warm it up properly and just ride it, don't "run it in", don't thrash it, but ride it like I want it to go! In fact when I put my sons 200 together The slide in the carb was stuck on full throttle so when I started it, it screamed its head off until I could quickly get to the the kill switch, the thing goes like a cut cat now and I don't expect that its done any damage to it considering the generous layer of 2stroke I put around the bearings and rings when I put them together.
Also I always warm my engines before riding, always. Even if I start slowly riding I always wait till I know the cylinder and water have come up to temp before going hard. This of coarse is a must with a wiseco piston.

Secondly Re the Tommorth post. I'm no expert by far! BUT going to a B size piston to early therefore making the tolerances to tight or tighter would accelerate the bore wear in my humble opinion. Its quite often the piston skirt that shows the most signs of wear/damage when you do a piston replacement (this is why you measure it there) so this practice makes no sense to me. Also a bigger or smaller, A or B piston has little or no impact on horse power, its the ring seal that is important to compression. A looser tolerance (as long as the piston isn't banging about) makes more sense.

In my humble opinion the two best pyhysical things you can do to a standard engine to improve mechanical engine performance is match the transfer ports between the the crankcase and cylinder and line bore and balance the crank. Part of the "Blueprinting" process in Karting. Of coarse the engine has to come completly to bits to do this!
Anyway enough of my raving. Feel free to disagree KB!!

[Reckless]

For some reason KTM only offer 2 Vertex piston sizes yet Vertex makes 4 sizes. My jug has a '1' cast on the side of it. Possibly something to check when buying a bike? Anyone shed some more light on this?

My guess is Ktm only need 2 sizes. Manufacturing processes are so good now the bore and Nikasil coating is very much the same each time so its measured and a piston size chosen to fit the bore, "usually for its life". The coating is so hard it usually out lasts the bike or should if its looked after. Its the piston and ring that are deliberately made of softer metals, to wear first, as they are cheaper to buy and easy to replace. Unless someone stuffs a hone down it (I'm bloody sure I've heard this stuffs the texture on a Nikasil Bore?) or never ever cleans his filter. Unfortunately both may have happened in your case?

You mentioned "blue printing" in your post while I was away typing mine.
I do know that they can line up say 100 Tillitson carbs and 5 will flow better than the rest for some reason?? The factory sells these as specials. In the karting world these cost many hundreds more in a governed/restricted class as they are better, but still standard. So maybe the same will apply to what you say about the engines. From my very small knowledge of a blue printed 2 stroke engines it is more "made" rather than produced. By crack testing, balancing, truing up the crank in the casing ie line boring, matching/polishing the transfer ports and a lot more things that each engine guy thinks works better than what the other guy is doing and thinks he won't get caught doing! LOL!! Its a very competitive world on and off the track! One look at the Karting Licence technical section (at the end of the book) on the Kartsport web site will show how very deep they go with the rules on engines and chassis! Measurement after measurement and pic after pic of the cannot do's!
Anyway enough of my opinions again. Quite like these discussions. Even if I am full of shit LOL!!!

[dammad1]

There is a lot of agrueing on the net about honeing of these bores, I gave mine a very quick going over with a diamond hone to help the rings bed in a little, and it has worked out mint. Certainly bought the power back up again.

I was told to stick with the standard size piston until it has at least 200 hrs on it.

[Reckless]

There is a lot of agrueing on the net about honeing of these bores, I gave mine a very quick going over with a diamond hone to help the rings bed in a little,

Just read the article Cam posted and it said this about Honing.

Also, many mechanics use a ball hone on cylinders before reassembling during a top-end rebuild. Ball hones are used to create fine oil retention paths on cast iron cylinders. On Nikasil cylinders, however, a ball hone won't do this. Instead, a ball hone will knock the Silicon Carbide peaks from the coating which wrecks the surface's oil retention capability. Ball hones are a bad idea for use on Nikasil coatings. LM use a special plateau hone, which they developed specifically for Electrosil. The main reason they use the hone is to aid with ring run-in more than oil retention. Nikasil cylinders should be cleaned but not ball-honed before reassembly.

Its the oil retention on the cylinder wall that creates the ring seal and therefore good compression in a 2smoker.
Camchain will have to make his own judgement as to whether or not the guy has stuffed his bore by honing it. But I've always thought it was a nono in a nikasil bore??

Secondly I personally wouldn't go up a piston size intil the measurements say you have to not because of the age or time on the engine. You may never have to! Especially if your running more oil than the minumim. Ie 40:1 instead of the factory 60:1 and your jetting has always been on the safe side!

[kezzafish]

yeah i had a reconditioned swear to me that it was fine to use a diamond hone but nothing else

[Reckless]

yeah i had a reconditioned swear to me that it was fine to use a diamond hone but nothing else

He could be correct, I'm not sure!
One thing I do think is Honing will shorten the life of a nikasil bore!

[dammad1]

yeah i had a reconditioned swear to me that it was fine to use a diamond hone but nothing else

Yeah that was my impression as well, I think if you went hard on it, it may take to much off but mine literally just had a very quick going over to scuff it slightly.