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jojo1224

Who else has had major engine carnage?

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Well today the rod broke in my yz426f in 5th gear @ about 10k rpm, I was buzzing along at WOT for a short period of time then it went bang, crunch then quiet so I pulled over to find no compression. From what I found after pulling the head and jug was the Versah rod broke right below the small end and looks like it has been slowly cracking for a while now. It took out the valves, piston, cylinder, crank and cases. It had about 25hrs on a complete top and bottom rebuild after having my +2mm big bore (444cc) cylinder crack after 10hrs and filling the cases with coolant.

What major failures have you had or am I the only one with such bad luck?

Edited by jojo1224

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I haven't yet but my buddy was cracking piston tops and just kept replacing them without digging farther. Well, the rod finally broke at the small end which sent the counter balance flying out of the front of the cases...total loss.

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I have read about more than a couple of 444 motors popping. one theory is that the cylinder becomes too thin and billows allowing the piston to rock in the bore and side load and self destruct.

my kid was running a 450/533 ktm he pulled it apart to have a look and good thing he did, so now its going back together 2mm less with a steel sleve

more preshure and thiner cylinder wall,s may not be the best combination

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ImageUploadedByThumper Talk1384777244.275149.jpg

ImageUploadedByThumper Talk1384777289.058485.jpg

You mean like that, small end failed took out the case and the bore but the head is still good its a wr 426

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I had an 01 426 snap the head off the exhaust valve which took out the whole top end. Then an 06 450 break the big end of the rod which took out everything except the head...I'm lovin my new Suzuki!

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I had an 01 426 snap the head off the exhaust valve which took out the whole top end. Then an 06 450 break the big end of the rod which took out everything except the head...I'm lovin my new Suzuki!

 

let us know how that gear box holds up!

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let us know how that gear box holds up!

I've ridden suzukis since the early 90s, save the two yzf's, and never had a gear box problem. ..maintenance is key

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I recently blew a head gasket out in the desert riding wide open most of the day.

 

06 YZ450F that i picked up with only 20 hours on it..

 

Wasn't sure exactly what was wrong, so limped it about 4 miles back to camped..

 

Overheated the shit out of it and did the following:

-Piston chunks came off

-Destroyed Cylinder

-Got exhaust cam DARK BLUE from heat
-Warped head
 

Initially thought it wasnt that bad, further i am digging into it, the more i am thinking its damn near total loss! 

 

Argg

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Ive had four wr's the 400, 426 and the 450  i have never really had any major motor problems. Other than normal wear and tear and a bad hot cam for the 426 trying to the auto decomp mod. I have also seen the motors let go and most of this was down to bad maintenance or bad luck.

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