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Need new nikasil?

By majo212,
in KTM 2 Stroke

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Grand Master

SnowMule

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How long has it been in service?  What's the recommended service interval?

How hard does it get ridden?  Raced?

General rule-of-thumb ... if you can scrape perpendicular to the wear marks and "catch" the groove with your fingernail, then it's time for a replate.  If they're real shallow and don't catch a nail, that can be honed out.

If I hone one rebuild, i'll replate the next rebuild.  Alternate between the two. 

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Grand Master

Motox367

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You really have to clean it up first to tell. Hard telling by that pic. Id say scrub it with scotchbright and some lubricating oil then wash with scotchbright and blue dawn dish soap and see what looks like then. You can use a diamond hone but dont got crazy with it just few secs on light setting 

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ride200mi

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Posted (edited)
3 hours ago, RichBaker said:

Never, NEVER hone nikasil. All you'll do is ruin the cylinder!

NEVER!

The companies that re-coat cylinders say it is perfectly fine to run a hone through a coated cylinder. I'm not sure if they use "nikasil" per si, but you can defiantly see it after they have re-coated them...... Husqvarna mentions you can do it also in their cylinders......Just saying..... As for the OP, I would run a hone and then install a new set of rings and go for it.....

Edited by ride200mi
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Grand Master

mlatour

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While a 3-prong style stone hone might be okay if properly executed (I wouldn't)

it's really those 'dingle ball' style hones that should never be used in a 2-stroke cylinder

as the risk of catching a port is quite high, and chipping the plating on the very edge.

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Grand Master

William1

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Pictures only tell half the story. and often not accurately. Make/Model/Year?

Is the cross hatch still visible everywhere? Any marks on the barrel you can catch a fingernail on or feel? If yes to either, time for a replate. Send in the piston you want (or have them supply one) and have them give you the specs. Be sure to refit the rings, check the measurements yourself.

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Grand Master

ohiodrz400sm

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The definitive way to answer the question is referring to the service manual for the wear limit and measuring the cylinder. Judging by the appearance of the cross hatch I would take an educated guess say it's about due for a replate. Will it still run if you de-glaze it and put in a new piston? Absolutely. Is the engine making it's maximum potential horsepower? Not a chance.

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EnglertRacing

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14 hours ago, RichBaker said:

Never, NEVER hone nikasil. All you'll do is ruin the cylinder!

NEVER!

Mmm its a matter of diamond hone vs aluminum oxide hone.

11 hours ago, ride200mi said:

The companies that re-coat cylinders say it is perfectly fine to run a hone through a coated cylinder. I'm not sure if they use "nikasil" per si, but you can defiantly see it after they have re-coated them...... Husqvarna mentions you can do it also in their cylinders......Just saying..... As for the OP, I would run a hone and then install a new set of rings and go for it.....

Companies that recoat use a diamond hone.

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Grand Master

turbo dan

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Looks serviceable.  It does show some wear but I've seen them run for hundreds of hours looking worse than yours. 

I am strongly against honing plated cylinders.  Honing a worn cylinder will only make it worse.  A diamond hone, done properly, will cut the silicon carbide particles embedded in the cylinder wall, leaving them embedded in the nickel matrix.  An ordinary abrasive hone, ball or stone type, will simply rip the carbide chunks out of the nickel matrix and loosely embed abrasive particles throughout the bore.

The only time it is beneficial to hone a plated cylinder is in the final stages of the replating process to set the final dimensions of the bore.  Honing a worn cylinder will exaggerate any irregular wear or taper.  The less you do the better off it will be.

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Grand Master

RichieGoatGruff

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Posted (edited)
1 hour ago, EnglertRacing said:

Mmm its a matter of diamond hone vs aluminum oxide hone.

Companies that recoat use a diamond hone.

Companies that recoat have many years of experience and the proper tools, AND the proper training.... I don't, PO* definitely does NOT, and I doubt you do...

 

 

 

*Poster originale, for the benefit of our friends from the great country of Nueva Mexico....

Edited by RichBaker
Brain fart...
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Grand Master

Shawn_Mc

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Nikasil is so f-ing hard, you cant even cut it with an aluminum oxide hone. If a ball hone is improperly sized, you can chip the port edges of the Nikasil. But, a properly sized ball hone, it's ok to use an Aluminum oxide ball hone to remove the glaze.

It takes a diamond hone to cut Nikasil. Period.

If it was me, I'd take that cylinder to a machinist with a rigid hone and touch it up before I made a decision on the condition of the Nikasil. And Ive done a shit load of these things.

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Rising Star

kgmkgm

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Posted (edited)

That's what my 200 looked like. Not brand new, but nothing torn through the plating. Clean the heck out of it. Green scotchbrite pad, hot water, lots of soap. My bike is running great, and looked very similar. I'll check it out next piston (50-75 hours on trails, aka 15-20 MX) and consider a replate and bottom end then, but that means I'm keeping it, ha ha

Edited by kgmkgm
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Apprentice

majo212

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I tried clean cylinder with soap, but it does look same to me. I cant catch anything with my fingernail or feel anything on the wall. I cant even know what kind of piston was in it, it only say "C" and some number on it, but i cant figure out what brand it is. 

And btw. its KTM EXC 200 2007

 

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Grand Master

Dirtbug26

Posted
Posted
9 hours ago, majo212 said:

I dont know when was that engine serviced, I just bought it and didnt measure anything because I dont have tools for that. 

I will try clean it and send new photo ?

How old is the bike? Take to a shop and have them measure it.

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