yfz450 failure

jgonie

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So 5 hours on this motor. Cylinder works bbk. Vertex piston. Hot rods crank. And mmad ported head. Cam mod. And oil mod done .05 cases. Looks like whist pin journal failed. Bent exhaust valves and bent connecting rod and busted sleeve been running great for 5 hours and this happened. Whist pin still has oil on it deff not dried out and opinions. If cylinder works don't cover it which the better be going Weisco crank. Stock bore cp piston not happy
 

SAVAGE420

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Brutal. Were you up in the upper RPM's when she let go or just ****ing around on and off it?

Who threw it together?

What was the ring gap?

Pressure test it?

What did the compression kick at when tested?

What fuel?

Stock timing?

On YFZ central & YFZtech?

Sucks when **** happens............
 
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jgonie

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Got her running again with Athena cylinder and cp piston and wr crank everything checks out by few diff guys I no that are small motor mechanic s seems to be just a crappie vertex cast piston learned clearly not buying anything thats related to cylinder works. It's was low rpm just off idle when she went. Thank god. Don't have the specs with me on what the gaps were never did that part but can't see that creating a wrist pin journal failure rings I'd say are still perfect. Cam mod exhaust and mmad warpspeed intake cams
 
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SAVAGE420

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Yes , im not a fan of cast pistons as well. Some guys swear by them...i just swear at them :d Reason i asked about the gap was if it was way off there could have been some piston rock back and forth leading to what happend.

Lucky that happened just off idle, would have had a nice set of cases for a trophy on the bench.....

Just curious what timing ,comp and fuel your using.
 

jgonie

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Oh makes since that vertex was 12:1 with 91 now using 13:5:1 cp shelf with av gas or vp and cams are yz exhaust and mmad warpspeed intake
 

250mark1

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I always had good luck with vertex pistons. On 2 strokes never used a 4 stroke one
x2 on the cylinder works stuff if there cylinders and cranks are of the same quality as there pivot works bearing kits they are absolute garbage I wouldn't use pivot works bearing kits if they were free
 

jgonie

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Yep she's a blast update one this new motor. 13.5.1 cp piston. Athena 98mm bore. Wr crank. Mmad porting . kibblewhite valves. Mmad warpspeed intake and cam mod exhaust cam. J&t oil upgrade. 8 hours on this motor and so far so good. My new skats came in today so pumped for brule nxt weekend to try this guy out there. May use my old sand sharks though
 
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SAVAGE420

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Did it survive Brule?
Should try some 21x11x8 9 paddle Skat trak Haulers with a bead to bead buff. (Or any light weight haulers) They hook ****ing awesome for me down in Oregon.
 

jgonie

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Yep motor worked great could not compain but sold the motor last week for a pretty coin. I accually had a 7 paddle extreme hauler 20/11/9 out there deff was fun on the hill. Liked my sand sharks for just carving the hills. Currently building a 470 motor. Outlaw innovations +2 head. 42.5mm taper bore carb. 13.5.1 97mm cp piston. Falicon crank. Mmad lightspeed cams. And maybe a small shot of boss noss. Then obs still a fci intake and then a ris designs inframe drag pipe
 
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