KDXRIDER.NET

encouragement and suggestions welcome.

I'm in quite the pickle with my klx 220r. While accelerating rapidly this past summer I thought I had blown the motor. I had shuffled quickly up to 4th or 5th when I heard a loud knocking in cadence with the rpms, I lost power and the bike died. I got off the bike and looked around. No immediate signs of oil and since we were edging on bfe I kicked it over and it started right up. I puttered slowly home 5-6 miles, besides a lack of umph it sounded fine. It starts and drives. I found this crack (please see pics) maybe 1/2 to 2/3 the width of a U.S. dime.

There's two possibilities: option 1: I hit something (a rock for ex.) along the case beneaath the actual crack, at or near the green fleck in the photo, hence causing the case above to fracture outward pivoting over the case bolt. The whapping sound I heard was the piston running dry of compression hence losing power. Option 2: Something (what exactly? - roller bearing for ex.) was dislodged internally and got stuck next to the casing causing the fracture. The sound I heard was the damage being done and like the alien jumping out of that dudes chest, the misc part was just simply trying to get out.

Geesh, quite the pickle. So I could tear it all apart, or if its the consensus view among the klxers, that its very unlikely the bike all the sudden started spewing parts, I could find a patching method (ultra high temp, high psi metal opoxy, or aluminum weld/braze/soder) put some oil back in her and let the good times roll. get a magnetic oil plug and watch for pieces? hum... now.. how do I upload photos?

Pocketumbleweed420 wrote:klx 220r.

...among the klxers...

Do you have a KDX or a KLX?

What piston is in the engine? (Stock/cast, or forged?)

I wouldn't think a rock/stone would flick up off the front wheel cracking your casing....
It's possible that the big end bearing has broken up & damaged the con rod which in turn broke & forced its way through the bottom engine case?

Jim B wrote:

Pocketumbleweed420 wrote:klx 220r.

...among the klxers...

Do you have a KDX or a KLX?

What piston is in the engine? (Stock/cast, or forged?)

This! It sounds like a stock KDX 220 piston letting go and taking your case with it.

oops... it's a kdx 220 r, I replaced the stock piston when I bought it a couple years ago. replaced it with oem (would a new oem gernade too?) since this problem appeared, I have taken the head off and looked at the piston, all looks good, no scaring inside the jug. I have also checked the compression, sitting right at 125 kicking it over cold at 8000ft

Pocketumbleweed420 wrote:(would a new oem gernade too?)

since this problem appeared, I have taken the head off and looked at the piston

Yep.

Have you removed the cylinder? You mentioned something about a "fracture outward" but there are no pictures, so it's tough to know what you mean.

I would not recommend the patching method, but I think you already know that's not a viable option. [emoji53]

I'd pull the head and see what's to be learned from it.

Post pics!


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You've got the head off, disconnect your kips nut and pull the cylinder!

Pocketumbleweed420 wrote:oops... it's a kdx 220 r, I replaced the stock piston when I bought it a couple years ago. replaced it with oem (would a new oem gernade too?) since this problem appeared, I have taken the head off and looked at the piston, all looks good, no scaring inside the jug. I have also checked the compression, sitting right at 125 kicking it over cold at 8000ft

the oem piston is the problem, it needs a wiseco piston to be reliable. you can't see the damage to the skirt with the head off, but if you pull the reed box, pipe, or cylidner you certainly will.

Right, of course a new oem piston is a time bomb. Nevermind it being purchased in 2013. Yikes.

Well, does anybody know what a case costs? I'll try and upload photos soon.

Has anybody had any luck with Alumiweld for these kinds of situations?

Pocketumbleweed420 wrote:Has anybody had any luck with Alumiweld for these kinds of situations?

Before you do anything, you need to figure out what damage was done to the internals when that piston let go.....and then figure out what route you are going to take.
Throw up a picture of the crack.....A boat shop can weld a crack, but if it's in a detrimental spot, you are looking at a new case half.

Not sure if this will work but ya go. We flipped the bike upside down and blew out the crankcase with compressed air, nothing large save a bunch of fine aluminum dust/shavings, we also found aluminum pieces stuck in the Muffler, in total 4 small pieces, not enough to add up to the missing piston pieces though. Hum... Let's see... the inside of the jug looked okay, as mentioned compression tested at 125 so walls didn't get too marred up, but I'm going to call machine shop Monday to get idea of cost for getting cylinder rebored and larger piston.

I did remove the pieces out of the lower piston knuckle. The roller bearings did not appear blue or discolored.

Pocketumbleweed420 wrote:...the inside of the jug looked okay...

...I'm going to call machine shop Monday to get idea of cost for getting cylinder rebored and larger piston.

-If the cylinder looks "okay," why do anything with it?
-It would be best to get the cylinder replated if the bore is damaged. It can't be bored without first removing the plating. Most local machine shops can't do this.
-I've used Millennium Technologies (for replating) with good success
-Pieces of the piston went between the crank and crankcase, which is why the crankcase got pushed out from the inside.
-You also have pieces of the piston stuck in the big end of the rod (see the last picture.)
-The cases should be split (and, really, replaced) to repair this properly.
-You might want to consider rebuilding the crank while you have everything apart.

You can have that crack welded up.....But, again I'd suggest splitting those cases and seeing what you have inside as far as damage goes.....Might be cheaper/safer to source a replacement motor and rebuild that, then do anything with the one you got....Get it split open and go from there.