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Finally trying to get my basket case 1997 220 back together. Cylinder was repaired and re-plated by Millennium, had them provide the Wiseco pro lite kit with it. Doing a "dry assembly" today and it seems like there is a lot of clearance (no rings on it in the pics). I don't have the proper tools to measure the bore but it looks like a lot more than .004" clearance to me. I have a good set of calipers (yes, I know, not the right tool) to measure piston OD and that matches spec. and the hand written notes on the box (I assume this was Millennium's inspection). It's the bore that seems big but I don't have a method to measure it. I can bring it to a local shop to double check for me but I figured the gurus would know by looking at it. The piston seems to be smaller at the crown as opposed to near the base per inspection instruction. Picture is me biasing the piston to maximize gap. Would you have bore checked or slap it together?

Since you have doubts, weigh the options:

one. you get it checked out an it's wrong - you keep from blowing it up

two. you slap it together and it works fine - no problem

three. you slap it together and it blows up

four. you get it checked out, nothing's wrong and you are more confident in your bike


There may be some difference in what the OEM manual says about the OEM piston and the OEM cylinder vs. what you have (a forged piston and replated cylinder)

The clearance is on the side of the box. They have done it a few thousand times, but having it checked would not hurt in my noggin.

Remember the arrow points to the exhaust port. As you said your positioning the piston to maximize the clearances. Wiseco pistons expand at a different rate than the cast pistons. Call the platers and get more answers to your perceptions. Wonder if it’ll be looser since wiseco are billet pistons.

Your piston is in backwards.

If Millennium did it then I would bet that it's good to go. I've done four replates and pistons through them and they were setup perfectly.

Well, conveniently I happened to be driving by the local engine builder so I brought them the cylinder and piston just for my peace of mind. As expected dead nuts on the money, he measured .0025" clearance which is what the sticker on the the piston box calls for (I assume this is min. clearance). He was also very confident in Millennium's work. Now if it blows up I know what WASN'T the issue.

Congratulations on the peace of mind. That is worth a lot!