[dswartfager]

Guys

just a heads up.

450 and 505's both had stock pistons crack inline with the piston pin at around 40 hours. We have also been breaking wiesco 14:1's at 4 - 6 hours. The only good thing is that at 40 + hours the valves were perfect.

 

[bradmulvey]

Dang dude, Not such a good weekend huh

 

[So-IL Mxer]

Im assuming these are race bikes? I race but for the people who dont, do you think this would still be an issue for rec riders? Race bikes really get worked over and bring any problems to the surface which is a good thing and bad thing at the same time. Btw thanks for the heads up, any issues with the CP high comp piston?

 

[dswartfager]

These are race bikes

We have had trouble with CP, Weisco, and Stock pistons

 

[bradmulvey]

So you gonna try a JE piston at all?

 

[dswartfager]

So you gonna try a JE piston at all?

Doubt it, never had any luck with them in the past. Have been talking with wiesco about a new design though.

 

[So-IL Mxer]

Keep us updated, I can make my way around an engine like the back of my hand, but still dont want to be blowing through pistons, I ride minimum 4 days a week and race on the weekends so I put lots of hours on my quads, but Im still getting a 450sx either way.

 

[JM317]

Just curious, are the sx stock pistons cast or forged? I know the 450xc is cast and the 525 is forged.

 

[kiwi-craig]

SX are forged

 

[quad97]

Probably want to change them at 35hrs then?

 

[SM-Racing]

35 hours on a race motor thats not bad for stock piston.

 

[Fast64ranchero]

Doubt it, never had any luck with them in the past. Have been talking with wiesco about a new design though.

If you haven't used a JE lately, they have become an outstanding piston manufacturer, as far as my motor builds go, they hold up as good as CP pistons, which should say something right there,
I know everyone has a opinion, so take it for what it is worth, but I'd use JE's stuff in any motor, ask Driver, his old LTR had over 200 hours on the motor build (one of them anyway) it was running a JE,

 

[kiwi-craig]

Ranch, some engines are alot harder on pistons than others........ from my limited LTR experience they are "easy" on pistons where as YF's when pushed hard kill pistons in relativily short racing use run hrs.

I've seen JE's crack in one days TT racing on a 60hp plus YFZ, same engine gets around 8 hrs on a CP race series piston and 4-5 on a wiseco, it's a screamer pulling 0ver 12k........... That was 2 years ago so if JE have have upped there game, good.

Yet a fellow racers 58HP LTR, it also pulls to just over 12K and gets long engine life (30hrs+) on a JE ???

So , I dunno ?? KTM themselves have recommended using the stock forged SX piston or a CP. Others don't last so well according to the supermoto racers.

Again from my limited experince, quads are harder on pistons than 2 wheelers; more traction + more weight = way more stress loads.

I'd like to thanks Derek for letting us benefit from his hard won findings.

 

[jrjack]

Do you think it coud be that the rod is just too short, causing high side load on the piston. I know on my YFZ I replaced the piston 2-3 times a season (the wristpin area would be scored even after the "oil mod")and some bigbore kits were available in a long rod version. Also isn't the Can-Am the same bore and stroke, are they getting about the same life out of a piston? Or could it be the RPM limit being too high? Maybe its just the norm and 40hrs is all that can be expected.

 

[kiwi-craig]

my race yfz 480 wouldn't get past 30 hrs on a piston, we where changing it out at 20hrs, yet my stock 07 yfz rec bike has 150 hrs on the stock piston so...........

40 hrs on a hard wrung SX sounds fine to me !

 

[dswartfager]

Wiesco finally got a good piston out for the 505 and 450 SX's. I will take some picture's of Derek's 505 with 13 hrs. on it. The piston is in very good shape considering the fuel and moto's that are on the bike. Almost all of the wear coating on the sides of the skirt is intact. This was at 14:1 with .015 off of the head.

I am sold on the Wiesco pistons :lol:

 

[jrjack]

Is that a 14:1 piston plus shaving the head, or it comes out to 14:1 after shaving the head?

 

[kiwi-craig]

the wiseco hi comp is 13.5 off the shelf so probably the head trim egts the 14;1

 

[kiwi-craig]

can you advise from a visual look over what the difference is, I'm getting a wiseco through Mikee and want to make sure it's the whizz bang new deal !!

We are going o get the crown ceramic coated to try and get a few more hr's out of it (i've got some hard out TT racing coming up mid year)

 

[dswartfager]

the wiseco hi comp is 13.5 off the shelf so probably the head trim egts the 14;1

No this is a 14:1 piston. I will take a pick for you to see the additional height in the center of the piston. I think our comp is at like 14.4:1 with the shaved head and new style piston.