[__ktm525sx__]

So I’m having issues with my 525sx, I bought it a while back running good and he didn’t tell me much about the motor he said he believed it was rebuild not too long ago. After I got it home I rode it around and it was a fun bike then I did some research on it the vin says it a 2005 KTM 525sx I found out the SX model comes with a 4 speed…. This is a 6 speed so I instantly knew something was up, but I didn’t really care because the transmission shift. It’s fine for a while and then one day I was riding the bike and it was shift and funny and it kind of scares me but I just kept riding it and then later months down the road, I was coming up my driveway and shifted down to first and it locked up so then I instantly knew my first gear broke and I put it in the garage i tore apart and knew someone did a 6 speed swap on it so I fixed a couple gears that were broken and messed up then I was looking at the crank and looked up a new crank for it and it was different so then I did my research and found out that was a EXC crank. It was a heavier crank, but it was fine so I put it back in and I decide to put a high compression Wiseco, 12.5.1 in the bike I didn’t do anything to it. I just put the original gaskets on it and then I found out that the head was the SX head so wasn’t a completely different motor. They’ve just been in it and added the 2 gears to the transmission because the first 4 gears was the sx transmission original gears after starting the bike after the rebuild. It sounded fine until I went down the road for about five minutes and it sounded like it was knocking. I didn’t think a whole lot about it so I grab the throttle Being a idiot and the whole entire front of the piston skirt blew out the front and now there is a big giant hole in the front of my cylinder, and then also made contacts with valves and destroyed my head and cylinder. Yes, this piston was supposedly meant for a 525 sx/525exc but now my question is is the cylinder different that he put on maybe the cylinder number casting on it it now is a 95/7R and I’ve looked it up and that is supposed to be the original 525SX cylinder. But I’ve done my research and found out that there is a 95/11r or that is supposed to go on a KTM 450 Exc so now I’m in the process of buying new parts and I just bought a JE piston 13.1 but when I rebuild it, I guess I will check clearances.if you guys have any information for me that would help.

 

[quad97]

Sounds like you got a bit of a Frankenstein engine. Good thing about the RFS engines is you can mix and match a lot of parts. Bad thing is you can mix and match a lot of parts! You might not get a lot of good info here as it looks like you have a bike and this is a forum dedicated to the ATVs. The RFS 450 and 525 engines that were used in the ATVs were actually put in the XC models, not the SX. The RFS engines used in the ATVs are actually a 5 speed with reverse taking place of the 6th that was put in yours. The RFS ATV engines also have a few differences from the early RFS bikes, but I'm not sure what that all entails. You may have a different stroke length and cylinder height in which case it takes a piston specific to that configuration.

The guys over here on the bike forum might be able to get you sorted out! (1) RFS-Racing 4 Strokes | KTMTalk.com