Piston discoloration question.........Mr Viper??

journeyman

journeyman

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Just pulled the cylinders on my stock Viper. I have this discoloration on all pistons on both sides. Any thoughts?
 

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Funny thing is these rings only have around 1600 miles on them. I am in the process of re-ringing and my compression was down in each hole by around 15-17 lbs.....but evenly. An old Yamaha mechanic friend had rebuilt it 1600 miles ago and I was guessing he used aftermarket gaskets (like Winderosa's) which can sometimes be thicker. I mic'd out the old gaskets and compared to the new OEM's and they are about the same. Funny thing is the new Yamaha head gasket is a three ply. The one I took out is a two ply.
 
looks like your cylinders must not have been deglazed for the last ring job. rings need to wear to the shape of the cly to make a good seal and a glazed cylinder don't cause enuf friction to let the rings seal up the way they should.
 
That's what I was thinking. I bought some scotchbrite pads and will deglaze them before the new ones go in.

thanks for the responses....I think it's human nature to get multiple opinions.
 
journeyman said:
That's what I was thinking. I bought some scotchbrite pads and will deglaze them before the new ones go in.

thanks for the responses....I think it's human nature to get multiple opinions.
Click to expand...
jmo,but i don't think scotchbrite pads are going to do you any good.the cylinders need to be deglazed with a hone either a 3 stone one or a ball hone will do the trick,try to acheve a 60 degree cross hatch for proper ring break in. I'am sure some will come on and tell you a regular hone won't do the job but thats b.s ,i use them all the time and they can scratch the nicacil just fine.
 
I use the ball hones to de-glaze nikasil cylinders too. Just be sure to order the stones with Silicon Carbide for Nikasil. The hones are also available in Aluminum Oxide for iron and steel that will not cut Nikasil.
Look on ebay. If you dont see the diameter hone you need contact the vendor anyway and usually they will have it.
 
DO NOT use ball hones if you value your cylinder ports,a search would have found the proper answer,been posted on before.


problem is they really don't cut very evenly in a 2 stroke cyl plus worse what happens is the balls on the hone will flex and bounce off the edges of the exhaust port and transfr ports and could chip the nic plating , you will get a much better job with out the risk using this type if you use a 3 stone spring flex hone,it can be adjusted so the tension of the stones to cyl wall can vary.

you can get this tool for cheap at any local auto parts store in 240-280 grit.


$.02
 
i've used the flex hones as well in the past, for a quick "de-glaze" of the cylinders and they work great. they don't chip the nicasil and they give a perfect cross hatch. i've also used a 3-stone hone before as well, w/fine results. for the nicasil, i would use a 320grit stone and for steel liners like a 220-240grit. the discoloration on your piston sides, or "blow-by" as its rather called, is from blow by of the worn rings. the oil is just blowing past the unsealing rings and burning to the piston sides. it seems that its always right around the wristpin hole on both sides. also, weird that you found a 2 layer gasket on your viper, as they all had 3 layers stock.
 
I called one of my trusted Yammie mechanics about honing right away and he really didn't recommend honing. He said that the nicasil is pretty thin.......003" thick I believe and claimed he really didn't like doing it. He was the one that recommended using the course (brownish color) scotchbrite pad. I cleaned the cylinders up real good today in a parts washer, blew them out with compressed air and used the scotchbrite as mentioned. Another thing I got to thinking. I think I still had Amsoil Interceptor in this sled when I last had it re-ringed. (synthetic) I only swithed back to Yamalube last year. Maybe that lead to the poor ring break in. I am going to run it hard for about 20 minutes and do a nice cool down this time.

http://www.mototuneusa.com/break_in_secrets.htm
 
journeyman said:
I called one of my trusted Yammie mechanics about honing right away and he really didn't recommend honing. He said that the nicasil is pretty thin.......003" thick I believe and claimed he really didn't like doing it. He was the one that recommended using the course (brownish color) scotchbrite pad. I cleaned the cylinders up real good today in a parts washer, blew them out with compressed air and used the scotchbrite as mentioned. Another thing I got to thinking. I think I still had Amsoil Interceptor in this sled when I last had it re-ringed. (synthetic) I only swithed back to Yamalube last year. Maybe that lead to the poor ring break in. I am going to run it hard for about 20 minutes and do a nice cool down this time.

http://www.mototuneusa.com/break_in_secrets.htm
Click to expand...
Right your not really going to accomplish much because that nic plating is hard!!! your just trying to clean the dullness up deglaze it somewhat.

usally OEM rings have a coating on them to help sealing.
 
Ball home Bad Information

Ball hones are perfect for our two stroke Nikasil Cylinders to remove the glaze and provide a surface that our piston rings require to break in properly. Bad info get passed along far to often on this site because someone remembers they once heard a story of a guy who....... - well you know the rest of that story. Ball hones do not chip cylinders. In fact the three stone can fall into a port window and destroy your cylinder far easier than any ball hone ever will. It is true that the ball hone will only follow the hole that is already in place. It will not straighten or true a bore in any way. It will provide a nice looking hone.

The only true honing machines are very expensive and owned by a company such as Millenium, US Chrome, that will diamond hone your cylinder. This machine will ensure perfect straightness, cylindricity, and roundness. It corrects taper, bow, barrel shape, high spots and other geometric errors. I called both millennium and US Chrome two seasons ago and they charged roughly $16-18 per cylinder of course you pay shipping both ways.

Below is a link to a thread discussing ball hones. Eric Gorr famous engine builder is quoted saying "the one type of hone that
you should never use on a two-stroke cylinder is a spring-loaded finger hone. The sharp edges of the stone will snag the port edges"

http://www.pilotodyssey.com/CylinderHone.htm
 
Mac said:
Ball hones are perfect for our two stroke Nikasil Cylinders to remove the glaze and provide a surface that our piston rings require to break in properly. Bad info get passed along far to often on this site because someone remembers they once heard a story of a guy who....... - well you know the rest of that story. Ball hones do not chip cylinders. In fact the three stone can fall into a port window and destroy your cylinder far easier than any ball hone ever will. It is true that the ball hone will only follow the hole that is already in place. It will not straighten or true a bore in any way. It will provide a nice looking hone.

The only true honing machines are very expensive and owned by a company such as Millenium, US Chrome, that will diamond hone your cylinder. This machine will ensure perfect straightness, cylindricity, and roundness. It corrects taper, bow, barrel shape, high spots and other geometric errors. I called both millennium and US Chrome two seasons ago and they charged roughly $16-18 per cylinder of course you pay shipping both ways.

Below is a link to a thread discussing ball hones. Eric Gorr famous engine builder is quoted saying "the one type of hone that
you should never use on a two-stroke cylinder is a spring-loaded finger hone. The sharp edges of the stone will snag the port edges"

http://www.pilotodyssey.com/CylinderHone.htm
Click to expand...
Bad info???

search....
 
After I get it back together I'll post on this thread to see if my compression goes back up after I break it in.

My good numbers in the past were 128/145/145

Before this rebuild it was 115/127/127


Also installing another Cobra track.......(getting rid of the Ice Ripper)
 
Brake In - Motoman or Cutler polar opposites

Journeyman - I liked that article by Motoman too. The argument to use his break in style seams to work well with the common sense approach. It just seems logical. How do we then explain the polar opposite??? Here is Cutler performance break in instructions that I now follow. The debate continues.

For those who have never read Moto-man its good reading. I think Motoman works primarily with Four stroke engines.
http://www.mototuneusa.com/break_in_secrets.htm

Below is Cutlers break in instructions. Total opposite.
http://www.cpcracing.com/site/256083/page/509138
 
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