Tech Tip "Cylinder prep before instalation"

[Pete Payne]

Here are a few guidlines for prepping your cylinder before installing it onto the bottom end.

As far as honing goes you can hone a nicasil cylinder with a ball hone . This removes old burnt on oil and carbon deposits , but will not remove the nacasil. And when done properly will put a good finish on the cylinder wall to aid the rings in breaking in properly.

A note to Kawasaki owners with the original OEM cylinder plating.
The original plating on a KX cylinder is the thinest and easiest removed in the business. Use alot of caution when ball honing the original KX plating.

Now the part I want to get to . Do this even if you have purchased a new cylinder or just got it back from the cylinder Platers , or if you honed it yourself. The cylinder needs to be washed in warm water with some dish washing liquid . The warm water and soap will cut the honing oil down and actuly remove all the left behind grit and dirt from the honing process . After the cylinder is washed completely you should be able to use a white paper towel and dry the bore off and the paper towel will not show any signs of dirt. If it turns a little gray looking , wash it again!! When it is completely clean , dry it off and apply a little of your favorite 2-stroke oil to the bore.

Why use warm water and soap instead of varsol, contact cleaner etc ...
Not only is it a lot safer but Because they (varsol, keroseane,contact cleaner)are solvents and a solvent will only thin out the the oily grung left behind in the honing process. The warm water and soap will break down the oil and remove all of the contaminates from the surface . Now the rings and piston have a clean fresh bore to live in !!!

 

[wanrep]

Thanks for the tip.

I'm a "if a little's good, a lot will be better" guy so if I put the cylinder in the dish washer after honing I'll not only get the inside clean but the outside to boot....right?

My only question is, do I use the normal or pot scrubber cycle?

 

[Pete Payne]

Either will work (Just joking) , Be sure to go light on the high speed piston wax !!!

 

[agitt73]

I BET ALOT OF PEOPLE DID NOT KNOW THIS
GREAT TIP!

 

[yz_387]

Thanks for the tip. I have a new cylinder on the way for a friends bike, and I would have just wiped it down and put it in, but now I'll be sure to wash it.

 

[fourjs]

I am about to do my first top end on a '93 RM125, so let's see if I have this correct, do not put the piston in the engine straight from the box, you must hone the top of it first, wash it off second, then install it, is this correct?? What am I looking at when i hone it down, how much do you take off, etc..thanks for the help....

 

[Pete Payne]

Fourjs,
After tearing down the top end . Have the cylinder mic'd , to see what size piston will fit it . That bike has a cast iron liner and it may need to be bored for proper (closer ) tolerances. If it has the OEM (original ) liner in it , Suzuki only recomends overbores of 1mm (.040"). If it is on the 1mm overbore now and is too worn out for proper tolerances . You should have the cylinder resleeved with an LA Sleeve Heavy Duty or thick walled sleeve . This sleeve has enough material in it to allow for 2mm (.080") of overbores.

Now , if the cylinder is within spec:
1 - Hone cylinder.
2 - Wash cylinder .
3 - Coat cylinder bore with 2-stroke oil.
4 - Reassemble according to the service manual.
5 - Break in (Run in ) engine properly.
6 - Enjoy!!

 

[wanrep]

Pete,
Is a 240 grit ball hone the right one to use on a KX cylinder?

My local auto parts store has a 2.5"/63.5mm and a 2.75"/70mm hone available.
Which one would you use for a 66.4mm bore?

 

[muscle]

Hmmm. Is honing a cylinder something a machine shop has to do or can it be done by a fairly mechanically inclined person? I have a '98 RM 125 and "02 YZ 250. What about these bikes? If you could go into more detail with the honing process I would greatly appreciate it! (The RM is due for a top-end)

Thanks

 

[spanky250]

How heavy would you advise oiling the cylinder wall? I have always made sure to douse the bearings generously, but I am very sparing on the cylinder, using only enough to prevent scuffing the piston. I feel that excess oil on the cylinder wall only prolongs the time it takes for the rings to seat. Am I totally off-base with this?

 

[Pete Payne]

Wanrep,
I would use the slightly smaller hone if the cylinder has original factory plating, If aftermarket nicasil go for the larger one. The aftermarket nacasil applied in the USA ia way tougher.


Muscle,
A fairly good mechanic should be able to handle the ball honing that is needed to rough up the bore to properly seat new rings. The process involves an electric or air drill and a ball hone of proper size. Youy should apply some honing oil to the bore then insert the hone attatched to the drill and hone for 10 seconds and check your work until you get familiar with the process. A proper cross hatch is at 22 - 32 degrees to the bore . A cross hatch that is too flat (zero degrees ) will wear the rings fast. And one that is to steep (65 degrees ) will not allow the rings to seat in properly and on 4- strokes will promote oil consumption .

Spanky250,
You only need a light coat of oil on the cylinder wall. Ring seating is directly related to the finish of the cross hatch on the cylinder wall.

Hope this helps ----Pete.

 

[muscle]

Pete,

I take it my cylinders for my bikes are ok to hone and the only bike to worry about are the KX's?

 

[Pete Payne]

Muscle,
Yes, you can hone your cylinders without too much worry.
You just have to watchout with OEM Kaw plating.---Pete.

 

[dale williams]

All this honing sounds a bit aggressive to me. Honing is important for 4 strokes but for two strokes I’ve never seen the need to do it. I am especially concerned about getting the hone down into the port area and removing material from the webs. This is what keeps the piston straight and removing web material will allow the piston skirt to clip the bottom edge of the port. This could cause a skirt to crack and brake. I always just used emery paper on my finger on iron bores and just made circular motion until it broke the glaze and gave a light hatching pattern. On plated bores I did nothing but I do like the idea of water washing it before installation especially in the dishwasher. There is nothing like an excess of washing rinse solution to carry off dirt.

 

[RM_guy]

The reason you want to hone a cylinder is to reestablish the cross hatch pattern on the cylinder wall. The hatching is needed to retain oil to lubricate the rings and piston. The “glaze” that you may see is either an oil film build up or the hatching has been worn down and the plating itself is smooth. In either case you need to get the hatching back. Honing will remove the oil film and restore the hatching.

Personally I like to use a scotch brite first to remove the oil film and then hone it only if the hatching is gone from the plating.

As far as the fear of removing material from port webs, it’s already been done from the factory. The web is relieved so it doesn’t interfere with the piston when the engine gets up to temperature.

 

[Pete Payne]

Originally posted by dale williams
All this honing sounds a bit aggressive to me

. Honing is important for 4 strokes but for two strokes I’ve never seen the need to do it.

I am especially concerned about getting the hone down into the port area and removing material from the webs. This is what keeps the piston straight and removing web material will allow the piston skirt to clip the bottom edge of the port. This could cause a skirt to crack and brake. I always just used emery paper on my finger on iron bores and just made circular motion until it broke the glaze and gave a light hatching pattern. On plated bores I did nothing but I do like the idea of water washing it before installation especially in the dishwasher. There is nothing like an excess of washing rinse solution to carry off dirt.

Are ypou saying that 2-strokes do not need to have good ring seal ?

 

[aharoncross]

Do I need to hone the cylinder every time I replace the ring or the piston?

 

[dale williams]

Sort of depends if you want to. On a 4 stroke the X-hatching holds oil so when the rings go up they are lubricated. On a 2 stroke there is oil everywhere so the rings will be lubricated anyway. The X-hatching also helps "seat) the rings. I'm not sure I understand this philosophy unless the rings are not round to begin with because on a 4 stroke the rings rotate round and round. If they stop rotating it is because of carbon buildup in the ring groove and results in a loss of compression. In a 2 stroke the rings are pinned to prevent rotation. Rotation would be bad because it would result in a ring end getting caught in a port and subsequent damage.

All said and done, I generally sandpapered the bore of iron cylinders because I wasn't concerned about excessive material removal. On chrome cylinders I did nothing because I was concerned about excessive material removal and chrome cylinders run iron rings, which break in easily compared to the chrome rings that are run in iron cylinders. In all I couldn't tell the difference.

A point of interest is that the glaze that forms on the cylinder wall is actually carbon that is deposited because the cylinder wall is too cold. When I worked on aircraft piston engines we found it was important to not idle the engine too much before applying break in power or the cylinder would glaze and the rings would not break in. The X-hatching would still be intact but we would have to re-hone the cylinder to get the oil consumption down. There was also an electrolysis process (we didn’t have access to it) that would remove the glaze without removing any cylinder material.

 

[Pete Payne]

You guys should also check out the thread titled "cylinder finish" in Rich's advanced technologies forum.

 

[what]

Honda Recomends No-Honing

A mech at my local dealer says Honda Recomends a Stoch_Bite Pad only to clean-up the cycl...

If more is needed to clen it up, a new sleave is needed...

This only applies to the newer Electro-Plated cycl..

RF

 

[Pete Payne]

Ok. There is no sleeve in an OEM cylinder that is electo plated (nicasil).
Honda probably only recomends a scotch brite pad because they are afraid of legal issues. It is realyu hard to get a proper x-hatch with a pad in your hand.

The only cylinders that I have seen with a nicasil plated sleeve were on some older engines , like the honda trx 250r 4-wheeler ( I know this is not a 4-wheeler forum). The cylinders are stock cylinders that have had the OEM cast iron sleeve machines out and a new special aluminum sleeve installed and plated. They do this for a performance increase and better cooling, and less friction .
Hope this helps . _-Pete.

 

[TooTall]

I use a 240 grit aluminum oxide ball hone (per Eric Gorr) every time I do my top end. It takes only a few seconds and then I thoroughly wash my cylinder in the kitchen sink with dishwashing liquid. I've never had a problem after using this method.

I even honed a friend's CR250 cylinder in the RCA dome parking garage during the '01 Indy SX.

TT

 

[Pete Payne]

TooTall,
Thats the way I like it. The rings need a good cross hatch to seat properly.
Pete.

 

[tristan18au]

can you use 600 grit sandpaper?

 

[DEA]

And never ever use a stone type(like a brake cyl. hone), unless it is a Sunnen or equivalent on a two cycle cylinder. They can(and will) get hung up in the ports :(