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I just got a 99 Kdx 220. I have been doing a lot of reading & thinking (scared about what piston is in my bike). So I pulled it down, the piston looks to have a W in a circle on the bottom side of one of the wrist pin holders, Is this a Wiseco Piston? I thinks it all looks OK. What now new gaskets, & rings?

Measure the piston at the bottom of the skirts and measure the cylinder. Make sure it's all within spec. If the piston is perfect, no scratches, scuffs, blowby, etc, put rings and a gasket set in and ride. The W on the wrist pin boss is Wiseco, yes.

Pictures would always be helpful!

Congrats on the bike too and welcome to the forum!


J.

Thinks, I'll try to get some pics. up soon. What are the specs?

I don't have a 220 manual. Someone else will have to shout out the clearance and ring end gap for you if they feel so inclined. My advice is buy a service manual before you ever put a wrench to the bike.

I'd just put it back together. Re-ring if you want. You can't really measure the clearance without some high dollar tools.

Huh? Micrometers and feeler gauges are high dollar?

Hmmmm.........

I'll check the bore for wear. What about the piston do you think it's a Wiseco, looks to have a half of a W stamped on the under side of the piston on the wrist pin part????

Micrometers and a feeler guage son't even get close to the specs on these piston's / cylinders. IE just try to figure out if you need an A B C D E F piston with those tools. Wiseco is always sized like an E/F. You can certainely check to see if something is way out of wack.

I'm sorry, I don't follow.

Using a micrometer you measure the cylinder bore at the skirts and you measure the piston size at it's skirts, and then you take the difference between these two measurements as your piston to cylinder clearance. You can check the bore in a few other places as well to make sure it's consistent, but the largest wear area is usually down toward the bottom so that's an ideal place to get your measurement. A,B,C,D,E piston sizes are all listed in millimeters, as are Wiseco pistons, so it's pretty easy to extrapolate the clearance you would have with a given piston using the measurements you take from your cylinder. So long as you can subtract, that is.

For ring end gap you push the rings into the cylinder before they are installed on the piston. Push the rings squarely down into the bore and measure the ring end gap with a feeler gauge.

You don't need anything more high tech than a micrometer and feeler gauge to get these measurements. If you can't get the measurements accurately, you're doing something wrong.

I get by with a caliper, a set of telescoping gages and feeler gages. The cylinder measurement is 16 mm down from the top, so t-gages or an ID micrometer are needed. The caliper is good for the piston and measuring the t-gage. Feeler gages take care of the end gap measurment. Maybe $5 for the feeler gages, $25 for a used set of t-gages and $40-$50 for a caliper. If you are patient, you can aquire everything you need for less than $100. Figure 4 to 5 times this if you go top shelf and buy new.

Maybe I should say to check the bore size where your service manual specifies, and as many other places as possible.