Tore it down - question about reassembly and break in

I finally gave in and decided to go ahead and tear my '02 450 down to put a new piston in. Initial inspection looks pretty good, cross hatchings still easily visible on the cylinder. Piston wear didn't seem all that bad for a piston that has 150+ hours on it. I did notice that my sparkplug was severally carbon fouled, I wouldn't be surprised if this is what lead to my hard starting problems.

I've got a question about deglazing though. I've lightly deglazed honed other engines with cast-iron bores before, and after you finish the bores have a quite dull finish to them. People on here seem to recommend using a scotch-brite pad to deglaze - so I tried that and the only thing It seemed to be doing was making the cylinder shinier? It didn't do anything to the cross hatchings of course, but as a whole the cylinder is now much shinier than it was before? I am thinking I should probably try again with a real hone, I only have access to the 3-arm type hone, is this acceptable? Or should I try to find a ball hone?

I don't particularly care for making the absolute most power, but I don't want a weak engine that burns oil. So how do I go about putting it back together. Do I just oil up the wrist pin and leave the cylinder and piston bone dry, or do I oil everything up? And for break in: Let it warm up then ride it hard?

Thanks in advance for your help

You should not need need more than scotch-brite to make the rings seal. As for breaking it in do several full throttle accelerations put high load on rings do this then just ride it hard hope this helps Do a semi dry rebuild just wipe rings and put a small wipe of oil on cyl. wall Seems to work for me.

I hear Scotch-Brite and I hear berry hone depending on who I talk to. Since the Nikasil coating requires a diamond-tipped boring bit, I cannot image that a Scotch-Brite pad would to anything other than remove surface contaminants. Personally, I will berry-hone mine to insure proper ring filing, then as stated above, high cylinder pressure to load the rings and promote file-to-fit of the new crosshatch.

Thanks for the info guys.

Just for kicks I took some measurements on the old piston, it's over 5 thousandths out of round:bonk:

Since the Nikasil coating requires a diamond-tipped boring bit

Thats a good way to ruin a nikasil bore.

Thats a good way to ruin a nikasil bore.

What I think he means is, you cant even cut nikasil without a diamond cutter. The factory uses a ridged diamond hone to finish the bores to spec.

When honing the cylinder on a rebuild, a 180 grit stone hone will do the job of cutting the glaze and wont even touch the nikasil size wise.

You could run a flex hone in a nikasil bore over night and come back the next day and all youd have would be a ruined hone and a funny pattern that doesnt even show a measurement change in the bore.

Using a scotch brite is a tool-less solution to trying to cut the glaze in the cylinder. It works on two strokes because the glaze generally isnt that bad.

A semi ridged stone hone is only about 20 bucks at your local Autozone or Oreilly or Kragen or Pepboys and it'll work just fine. It only takes about 10-15 seconds to cut the glaze anyway and youre done. Just get the bore good and clean afterward.

I'll go ahead and just quickly run the hone through it then.

Also, is the base gasket reuseable? It appears to some kind of plastic material?

Got 100hrs on mine and im at the same point. I used the burgundy scothbrite pad and it cleaned it up real nice. No wear and the cross hatch still looks as it did new. Im thinking put some assembly oil on the pin/rod/ a little wipe on the rings with a dry cylinder and run it?? Just my thoughts?

I'll go ahead and just quickly run the hone through it then.

Also, is the base gasket reuseable? It appears to some kind of plastic material?

Officially, no.

If you're in the middle of Baja and you've duct taped the thing together, sure.

Youve got it apart already, Good Man, put a new gasket in it....

I think they stopped using some of the super sticky paper gaskets on stuff because they dont like coming apart. All the gaskets crush out though. So, you could possibly get away with reusing it, why bother for the cost.

Ran a real hone through it today, de-glazed the bore very well. I can actually faintly feel the cross hatchings now where as before the bore felt perfectly smooth - and that was after attacking with a scotch brite pad for quite a long time. You weren't kidding about that Nikasil being hard though, after about 15 seconds of running the hone through, the stones had already started to show quite a bit of wear.

By the way, all pistons are out of round. They're cam shaped really.

I thought the cam grinding was usually on the sides with the skirts, as that area has more metal and would expand more? This piston is 5 thousandths smaller on the sides opposite the pin-ends. I can wobble the piston quite easily in the bore.

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