KDXRIDER.NET

Since the KDX cylinder is made with the electrofusion process, is there any cylinder surface prep normally done when changing out the piston? My understanding is the coating in the cylinder is very thin. The on-line manual mentions only that no boring or honing is done on this cylinder.

Lightly with a dry scotch-brite pad only.

Indawoods wrote:Lightly with a dry scotch-brite pad only.

So we're talking basically just buffing up the glaze, right?

This is a more generic question because I really don't know any better (and maybe it doesn't matter) - is any particular pattern or direction preferred?

Thanks Inda!

Yes... just breaking the glaze. I just stick the pad in and turn the cylinder and my hand around a few time and it's good.

GREEN ones NOT the RED ones. I used the pad much like you would a hone.

Cross-strokes, right ??

Rick

Your not honing it... your just breaking the glaze.

I don't think the color matters.

Brown will take more effort than the green scotch pads with the burgundy (red) ones taking the least effort. (The gray ones are somewhere between the green and burgundy ones.) I believe the bore is coated with tungsen/molybdenum and steel composite which is not going to be abraded away by hand use of scotch bright pads - IMO

Bottom line for me is - if a cylinder has sever glazing I will use the burgundy or gray color pads since it seems more efficient and the pads stay intact; since I'm not scrubbing the cylinder surface as hard trying to break the glaze.

Like Inda says - your breaking the glaze only - no way are you honing the cylinder!!

P.S. I do believe most people stick with the green scotch bright pads because everyone seems to have the pads in their tool chest or under the sink.

I was reading in the KDX owners manual the break-in procedure. Then it says to install a new set of piston rings for optimum results. Wtf? I thought that was the whole purpose of breaking in, to seat the rings...

stringburner wrote:I was reading in the KDX owners manual the break-in procedure. Then it says to install a new set of piston rings for optimum results. Wtf? I thought that was the whole purpose of breaking in, to seat the rings...

Go to the link listed below. Click on "KDX Tech Tips" ** and choose "New Bike Prep" under the GENERAL***. It seems to give a reasonable explanation.

http://www.dirtrider.net/justkdx/

There's some other good links as well. The topics are brief and generalized but they seem to make sense and they'll get you thinking. Then when you want more details/specifics on a particular topic come as the seasoned experts on this site!!

** If you'll right click on the link and select "open in new window" you'll get a better view

*** If you can't see the text, click and drag over the page and you'll see the text: it's as if both the background and the letters are white.

Thanks Jeb. I appreciate the link. It does make sense I guess. I just never thought of "breaking in" to mean the rings to the piston, but rather the rings to the cylinder. I don't know much I reckon.

I think that statement is silly myself.... saying that the rings don't have to seat to the cylinder????

Silly? Let's be blunt. It is stoopid and illogical. Parents, see what too much Saki does to kids!

Eric Gorr also recommend using the scotch brit pad method.

My tip: Roll the scotch brite pad around a roller paint brush. Its the right diameter and enables you to do easy in-out-twist motions with risk of scratching anything.

johnkdx220 wrote:Eric Gorr also recommend using the scotch brit pad method.

My tip: Roll the scotch brite pad around a roller paint brush. Its the right diameter and enables you to do easy in-out-twist motions with risk of scratching anything.

Cool!! Very creative

The link about "break-in" was more to provide some insight about what the writer was saying in general, i.e. mfg flashing, look for scoring, etc.

I, too, was trying to understand ring-to-piston sealing vs. ring-to-cylinder sealing (I wasn't ready to call anybody "stoopid" though). And then I pulled the green "M Series Piston Installation Instructions" pamphlet that came with the Wiseco and re-read it. It states that for cast iron sleeved cylinders, ". . . to ensure poper ring seal, it is necessary to hone the cylinder . . . " and that " . . . crosshatch is necessary to ensure proper ring seal and adequate lubrication." The pamphlet goes on to say that for "plated cylinders" - which include Electrofusion - ". . . if the plated cylinder is in good condition" that deglazing may not be necessary. No mention of ring seal.

I thought ring-sealing was, in the presence of the crosshatched cylinder surface, the fresh piston rings literally resurfacing the cylinder surface for a smoother, tighter clearance. If that's right and you don't crosshatch a plated cylinder, exactly what kind of ring-sealing will be occuring in my 220? And, please, if I'm wrong - let me know how

Ring-to-piston sealing? 'Don't know about that yet, and I'm lookin', but I'm not ready to buy the ring-to-cylinder seal for the kdx quite yet.

They are dis-similar.... therefore they MUST seat to provide a good sealing surface.... period. If they were made of say... Jello.... then yeah... no breakin needed and they will seal perfectly....

Indawoods wrote:They are dis-similar.... therefore they MUST seat to provide a good sealing surface.... period. If they were made of say... Jello.... then yeah... no breakin needed and they will seal perfectly....

. . . and how are they seating? Of what exactly is the seat/seal comprised?

. . . and what is happening to the cylinder wall as a result of being forced to use a non-gellatinous substance for rings?

It is a high pressure fit... the ring forms to the cylinder and any imperfections are worn into the softer ring material forming a closer seal fit.

I imagine on a 0 hour motor with an absolutely perfectly round cylinder with a perfect coating and brand new rings... it wouldn't be as much of a concern but Ma Kaw has been known to make more than a few mistakes from the factory.

Re: 'It is a high pressure fit... '

When the intake charge lights off, it's certainly a high pressure fit!

THAT is what seats the rings. Pressure, yes..but pressure coming from the burn, not merely the rings spring-fit against the cylinder.

Re: 'I thought ring-sealing was.... the fresh piston rings literally resurfacing the cylinder surface for a smoother, tighter clearance.

'Resurfacing' doesn't happen. SEATING does happen.

Piston to cylinder clearance is important, too. A large part of that seal is a result of mixing oil with the fuel. Same for the ring-to-cylinder seal.

Remember the 2-stroke is pumping air on both sides of the piston.

Re: 'The lining is incredibly hard so the chances of actually tearing the lining is very very slim..'

MY 'chances' of 'tearing the lining' have been 100% when there have been ANY piston problems. I guess that makes me special!

Something to keep in mind: Not everyone agrees with the type of 'break-in' described on CDave's site.

Where to find another approach?

How 'bout HERE!??