Y'all may remember a week or 2 back I posted about the "Melted Piston After 4 Hours" thread. Well for a recap, basically the airintake boot ripped on my '89 200 and made the mixture so lean she lean siezed. Seized at 4 spots on the piston/cylinder. The 2 spots on the intake side was the worst, a small piece of the plating flaked off. This all after 4 hours of riding on new bored/plated +2mm Wiseco kit. :scream:
Total repair cost: $1. Yup, all I ended up getting was some new circlips from Wiseco (is it just me or are they making them real cheap nowadays?). Oh, and about $5 for some 280 and 240 grit emory cloth. So $6....I already had extra gaskets before hand.
The bore of the piston cleaned up pretty good, I removed all of the fused aluminum from the bore with diluted hydrogen chloride (20% if I remember.) After that I just sanded down where the plating chipped with the 280 grit, and added a little bit of cross hatching to the parts of the bore smoothed out by the siezing. The bore looked like new again, except for the little chip... :yeehaw:
With the piston, I just sanded down all the rough and high spots along the sides and in the ring grooves. The rings were in great shape, and they collapsed/moved around freely in the grooves. The end gap was .010 or .011mm I beleive, well within the limits...so I reused em.
Slapped it all together today, re-torqued the bolts down after 15 minutes, and headed out again. Man, this thing friggen RIPPPPS! The top end pull is unbeleivable! I cut out the "reverse flow" section of the stock pipe as well, about 5 1/2" shorter now, and not really louder at all. ProCircuit pipe, stock reeds/needle, 155mj and 48 pilot. The pilot is rich, I know that much, just haven't had time to go get some jets to fool around with. Looks like I'll need to lean out the main a step also.
I'm running the stock head and porting, and even with +2mm overbore I didn't notice any detonation with 94 octane. Right now the low end power is a little soft, maybe because the o-rings on the pipe are pretty much shot and it could use new reeds... But man after that powervalve opens up HOLD ON, it pulls like a bat outta hell on top. I was really suprised (and delighted) at how much more power it had!
So hopefully my cheap repairs will hold for the season anyhow, I'd like to get another year out of the old KDX before I sell it, which will be hard to do... :whiner: I'm extremely satisfied with the results of the Wiseco +2mm kit. With boring, plating, piston kit, and gaskets it will run you about $320. I got the piston through FRP for a buck and the rest from Langcourt down in Alabama (who did an excellent job might I add). So if you have to replate the bike anyhow, I'd suggest splurging the extra $30 and get it punched out 2mm. ;)
Sorry for rambling on, just so happy I had to share it! :yeehaw:
Total repair cost: $1. Yup, all I ended up getting was some new circlips from Wiseco (is it just me or are they making them real cheap nowadays?). Oh, and about $5 for some 280 and 240 grit emory cloth. So $6....I already had extra gaskets before hand.
The bore of the piston cleaned up pretty good, I removed all of the fused aluminum from the bore with diluted hydrogen chloride (20% if I remember.) After that I just sanded down where the plating chipped with the 280 grit, and added a little bit of cross hatching to the parts of the bore smoothed out by the siezing. The bore looked like new again, except for the little chip... :yeehaw:
With the piston, I just sanded down all the rough and high spots along the sides and in the ring grooves. The rings were in great shape, and they collapsed/moved around freely in the grooves. The end gap was .010 or .011mm I beleive, well within the limits...so I reused em.
Slapped it all together today, re-torqued the bolts down after 15 minutes, and headed out again. Man, this thing friggen RIPPPPS! The top end pull is unbeleivable! I cut out the "reverse flow" section of the stock pipe as well, about 5 1/2" shorter now, and not really louder at all. ProCircuit pipe, stock reeds/needle, 155mj and 48 pilot. The pilot is rich, I know that much, just haven't had time to go get some jets to fool around with. Looks like I'll need to lean out the main a step also.
I'm running the stock head and porting, and even with +2mm overbore I didn't notice any detonation with 94 octane. Right now the low end power is a little soft, maybe because the o-rings on the pipe are pretty much shot and it could use new reeds... But man after that powervalve opens up HOLD ON, it pulls like a bat outta hell on top. I was really suprised (and delighted) at how much more power it had!
So hopefully my cheap repairs will hold for the season anyhow, I'd like to get another year out of the old KDX before I sell it, which will be hard to do... :whiner: I'm extremely satisfied with the results of the Wiseco +2mm kit. With boring, plating, piston kit, and gaskets it will run you about $320. I got the piston through FRP for a buck and the rest from Langcourt down in Alabama (who did an excellent job might I add). So if you have to replate the bike anyhow, I'd suggest splurging the extra $30 and get it punched out 2mm. ;)
Sorry for rambling on, just so happy I had to share it! :yeehaw:
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