Cracked cylinder

Got a crack starting in my cylinder....

I really like the porting on this so I'm thinking about getting it repaired since I don't know who did the original porting.

Probably going to use Ken O'conner racing.  $280 includes everything.

Whats your opinion?  Cylinder still well within specs, PO had a wiseco piston in it.  was past the service limit according to measurements piston was in good shape.

I'm not a racer although I do like riding MX...I just like riding



Ken O Conner seems like a decent dude, his videos are good and seems like he does work that he's got a conscience about.

I'd be tempted to give him a shot for any of his work.

your pic is a thumbnail, it's too small to see the image.. I would buy a new cylinder, and I would think any good port guy could match up what you have already.


replace the cylinder because that little chip ?  i guess you cant expect any better answer from a bunch of nobodys


ill take it off your hands if you toss it

replace the cylinder because that little chip ?

The top of the bridge is cracked, as well as the port

The bridge isn't cracked, but the seam is visibly showing from stress (another undrilled wiseco) but there's no physical crack there....yet anyhow.

I'm still going to send it out to see if it can be fixed.  Ken seems like a good guy, I spoke to him on the phone for a few minutes and he said to send it and let him get a closer inspection before we do anything.

If it can't be fixed where I can get some good life out of it then I'll get a new one and go from there.

ken could probly chamfer any sharp edges of that chip and tell you to keep running it but other than that he cant do anything with it. if the plating needs to be removed or welded youll have to send it to millenium

According to his website he does all of that....or he sends it out somewhere to be done after he looks at it.

I was considering running it "as is" for another season.  I really only get to ride about 20 hours a season.  There's certainly no visible signs of any scratching on the piston or rings.

But as insurance I am just going to fix it now since there's no real riding time anywhere in the next few weeks.  We still have about 12 inches of snow on the ground.

he can inspect it (but you can do that yourself as well), he could chamfer down any sharp edges (im guessing you dont have the tools to do this), beyond that he cant do anything.  most likely its been chipped for some time. small chips like that are usually harmless. if it was a big piece of plating flaked off then it would be another matter. honestly i would slap it back together. if it was anything to worry about your rings would of already snagged it

replace the cylinder because that little chip ?  i guess you cant expect any better answer from a bunch of nobodys


ill take it off your hands if you toss it


Dude, you ride a KTM that's 548 cc, and we're a bunch of nobodies for suggesting a new cylinder when his present one is CHIPPED?!?  Come on now.

Besibes the chip, the nickel plating is absolutely cracked on the exhaust bridge. It we I'll flat spot both the piston & rings. If you take your rings off the piston & look, they will be thinner where they met up with the exhaust bridge.

Can you run it, yes. Should it be repaired, yes! If a bike has a mechanical problem but starts & moves, you can run it. Alot of people do but they are simply making matters worse (more costly). The cylinder needs to be repaired or replaced. Of course, it's your bike so what you fix or not is on you. If you enjoy riding, fix your bike.

Ken can not do nickel plating. He will be sending it to a nickel plating company of his choice. Something you can do yourself. I know u.s. chrome or millenium can repair the damge.

Can you take some pictures of the ports so we can see the "porting" that was done. The exhaust shape looks stock & the transfers look like they too are stock. Better yet, if you could measure the port heights & let us know the measurements (in millimeters). Then measure the overall height of the cylinder. A simple caliper is all you need.

These cylinders are famous for cracking there. Any plating company can fix it for you. No need for inspection. Send it to millennium or power seal or US chrome

Yea, I already sent it out....ordered a OEM pistion kit from Honda of Troy.  Specified a A piston and they clearly sent me a B.  :banghead:

I have had the same thing happen before.. I would measure it first, it could just be the wrong packaging.. but then again.... who ever has that kind of luck..

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Small weld. Re-chamfer the port. Get the cylinder re-plated. boom, Bob is your uncle.

Its definitely a "B" piston.

Looks like on most websites the A was replaced.  There some sites listing part number 13101-KZ3-L20 for A and B.  I of course got the straight up B part number with a big fat B stamped on the top!  

Ordered a new "A" piston from Partzilla last my surprise it shipped the same day!!!  First time ever with Partzilla.

I wish they would list on their site what is in stock or not.  That is the only reason I rarely use them anymore 

Got everything back all sparkly clean....I went with Racers Toy Store for the repair and replate.  They did a great job on everything.

All back together and ready to fire up.


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