replating vs sleeve

funktree

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#1
I had a power valve blow apart on my 92 yz 250. Scarred the cylinder right above the exhaust port. After checkin around and calling different comanies there seems to be two options. resleeving- Im not sure what the sleeve is made of but this was the cheapest option

replating- a couple companies strip off the plating, weld the damaged area, bore and replate the cylinder. This option is about 75-100 more than resleeving.

is the plating really better than the sleeve and if so why?
 

Farmer John

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#2
Get it plated.

Sleeve:
piston wears out- pay to have it bored to next size over & buy next size piston. You can only do this so many times, then you need a new sleeve.

Pated:
piston wears out - buy a new stock size piston. no extra boring cost.
You can repeat this process for a very long time.
On my 90 CR 250's original cylinder I ran somewher between 20 & 25 pistons thru it before I felt it should be checked out for replating.
 
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#3
Plating/Sleeving

The sleeves are generally made from cast iron and don't disipate heat as well as the plated aluminum cylinder you start with. Also the sleeve will not have the nikasil or other type plating on the cylinder. This plating exhibits less friction than the plain cast sleeve.
You can bore a sleeve to the next size over but you cannot bore a plated cylinder except when you might be able to bore a plated cylinder to a larger bore then replate it to use a larger diameter than std. piston.
I recently lost a crank bearing in one of my bikes and chose to have the cylinder replated by US Chrome. The total was about $150 plus shipping.
If they have to weld any deep gouges etc. it will cost $40 to $50 more.
Took 2-3 weeks but depending on the time of year they may be less busy and take less time. The cylinder came back looking good or better than new.
I look at it as the bikes come stock with a plated cylinder, there must be a reason.
Scott
 
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#4
Most definately shell out the extra cash to get it plated. I had a rod bearing come apart on my 95 wr 250 had it sleeved never was right again ie. detonation much worse than before. my .02:cool:
bp
 

motometal

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#5
I'm gonna play the devil's advocate here, even though I agree that plating is the best overall (if done properly).

1. Sleeves do not flake or peel.
2. Since cast iron has a lower coefficient of thermal (volumetric) expansion, it can provide a straighter, rounder cylinder than aluminum
3. Sleeves can be re-bored, and honed more easily
4. Cast iron has a built in lubricant called graphite-it's part of the structure

but, yea, go with the plating...
 

Farmer John

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#6
Originally posted by motometal
I'm gonna play the devil's advocate here, even though I agree that plating is the best overall (if done properly).

1. Sleeves do not flake or peel.
2. Since cast iron has a lower coefficient of thermal (volumetric) expansion, it can provide a straighter, rounder cylinder than aluminum
3. Sleeves can be re-bored, and honed more easily
4. Cast iron has a built in lubricant called graphite-it's part of the structure

but, yea, go with the plating...
1. Neither does plating with proper maintenance.
2. I do belive the variables are so minute as to not matter.
3. But on the other hand they NEED to be bored.
4. So does premix :p
 
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#7
Often times people run into piston sticking problems after sleeving due to the lower expansion of the iron bore.

In addition, sleeve installing companies are known for charging a lot more than you expect. Oh, you wanted the ports machined to original size, and the cylinder bored to the correct size? That is extra.

Also there is often a slight mismatch between the sleeve and the original port where they meet. This robs HP if bad enough.

Chris
 

motometal

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#8
I don't think the flaking/peeling thing is a matter of maintenance. It is related to the plating job itself. Just ask the hundreds of KX owners out there that are wondering why the piston on their brand new $5000 bike is already scored up. I had an overbore job done a few years back on a 250, which turned into a huge fiasco due to a poor plating job (and otherwise terrible service) done by a very popular vendor (not naming names, but it starts with "U.S."). I have been told that they have improved their service since then. Maybe, maybe not...in any case they lost any hopes of future business from me.

I still agree that plating is overall the best, but feel the readers of this thread need to see all sides of the issue.
 
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#9
Eric Gorr just did my '94 YZ250. Bored the cylinder to remove the deep scratches, plated and honed the bore. He modified the power valve and threw in the appropriate Wiseco piston and Cometic gasket kit. The price was great and the plating was virtually flawless.

Broke in the forged piston with several heat cycles and now we are back in business.

Definitely go with plating- and have Eric Gorr do it!
 

EricGorr

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#10
The issue of price comparisons between sleeving and plating are confusing. A few years ago there was an ad in Dirt Rider touting sleeving for $99.95 Most people would think that included a sleeve, the labor to install it, bore and hone, port matching and chamfer, and decking the top surface. However all the $99.95 included was the sleeve. Sleeves vary in price greatly based on the size of the engine and the geometry of the sleeve. Sleeves range in price from $40-120. The labor is the big thing.
I install sleeves and offer plating and honing through US Chrome. There is way more work involved in sleeving but the actual sleeve costs less than plating. My package prices are the same for plating or sleeving but plating is way better for performance. I've heard the friction argument regarding the graphite in the cast iron, and its certainly true that on a dry surface, a cast iron bore will have a lower CF than nickel composite when both surfaces are honed with the same grit stones. But internal combustion engines won't run without lubrication and when you measure the CF of the materials when oil is present, it all comes down to the oil film.
The biggest problem with conventional sleeving techniques is that the cylinder is heated to 450F in order to expand the bore to a clearance fit to the sleeve for installation. The 356 alloy commonly used on water-cooled Japanese cylinders, suffers material properties changes when the temperature is raised above 300F, let alone the stress and warpage that occurs from shoving a cold piece of cast iron in a hot aluminum cylinder:scream:
Thats why I use the same method as the automakers, contract the diameter of the sleeve using liquid nitrogen and press it into the aluminum cylinder at ambient temperature. The properties of the cast iron won't be negatively affected like heating the aluminum cylinder so its the best compromise.
Another trick I use is to turn the top and bottom surfaces of the cylinder on a mandrel centered on the bore, before the bore is finished, that way the bore is set perpendicular to the crankcase and head mounting surfaces.
Some cylinders are manufactured with sleeves originally. Those cylinders are usually cast around the sleeve, like Honda TRX250 and CR500. Thats another excellent technique.
Generally speaking about the overall state of the quality available in the motorcycle aftermarket service industry, plating is less likely to cause problems related to stress and wear than cast iron re-sleeving.
 

funktree

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#11
thanks all, I have decided to get it plated. us chrome actually came in 50 dollars cheaper to plate it than LA sleeve co was to sleeve it. Thanks for the info.