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finthat

2003 yz450f bottom end

14 posts in this topic

Hello people. Just bought a blown up 2003 yz450 with a golf ball sized hole in the front of the crank case where the rod decided to exit. Just wondering what others experience's are with have such holes repaired by a welder? I haven't split the cases yet but the hole is mostly on the right hand side with a small chunk out of the other. Is there any important passages in the front part of the case that may have been left where ever the engine let go?

Does anyone have a good place to find used cases. Ebay has none right now.

Thanks.

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Get insurance through State Farm. Pay for about 6 months. Tell them a rock came up when you were riding on the farm for farm use and hit the case. You should get more money than you payed for thee bike.

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Get insurance through State Farm. Pay for about 6 months. Tell them a rock came up when you were riding on the farm for farm use and hit the case. ...
One of our customers tried that same thing. The adjuster came out and took a look, and the owner ended up on probation for a 1 to 3 year sentence for insurance fraud.

Yeah. That's good advice, alright.:thumbsup:

If the holes don't intersect the crankcase joint, it may not be too big a deal. If it does, the cases will have to be surface milled after the weld. There's no hidden passages in the front of the case, but you'll want to check for internal damage, too.

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do you have any of the peices that came out of the hole when she blew? if you have some and they are still kinda straight you can JB Weld it all back together! its crazy but it works! i have seen it done. never done it myself. i did JB weld a small hole up in my 250s case when i had it. works awesome. that stuff sets up and feels harder than the metal.

P.S. I would try finding a new case before you resort to this.

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Get insurance through State Farm. Pay for about 6 months. Tell them a rock came up when you were riding on the farm for farm use and hit the case. You should get more money than you payed for thee bike.

Yeah dude insurance fraud is awesome!

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No pieces. I am going to split the cases this week and see whats inside. I pulled what was left of the rod out of the hole and both end have broken off. The jug is marked up and I can see marks down the front of the case to where the hole is. There is also a round aluminum tube about an inch long that came out of the hole as well...not sure where that goes. I think I may be new case time but will know better after I split it.

Insurance fraud is great until you get caught.

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I doubt it will fit but has any one put a yzf and a yfz right hand case half side by side before? I found one and it is the one that is most damaged on my bike...??? will it work??? The part # don't match for the assembly just curious if the right sides are similar.

I have been comparing pictures of the right halfs from bike to ATV and do not see any difference.

I know they are a little different but how can the cases for a yz45f cost just about double that of a yfz450? There isn't that much difference in them is there??

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There is a huge difference. To begin with, the YFZ case will not bolt into the frame, as the forward hard point is different. Also, the YZF stator won't fit the case, and the YZF ignition cover won't bolt on. I believe the quad transmission is wider, too.

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Time to either bite the bullet or watch ebay for a month or two. Can't ride in the snow and I'm on the mend from surgery too.

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My '03 had a similar "problem". The rod failed at the piston pin. I'll bet the round aluminum tube is part of the balance shaft that runs along the front of the engine. When the rod went on mine it came down and broke the balance shaft in half then put a hole in the case.

I think the total parts cost was about $900 and I got most of them at dealer cost. New piston, cylinder, cases, balance shaft, crank assembly, main bearings....there may have been more but thankfully time helps you forget. Good luck with the rebuild!

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what was the reason the rod let go? was it heavaly modded or what?

From what the guy I bought the bike from said it sounds like the reason the rod decided to exit was the handle bar to footpeg link.:smirk: also know as the dummy riding the rev limiter while trying to run from the cops :thumbsup: because he was riding on the road.

And both ends of the rod failed some how. I figure the piston end gave out first and with the road speed and traction on pavement (preventing a wheel lock-up) when the free end hit something hard like the edge of the jug it exploded the crank end of the rod. The engine has amazingly not to bad a damage from the loose rod jumping around inside. I 've see a jet ski four stroke saw the whole end of the engine off with that type of high rpm blow out. But they do have 2 other cylinders still driving I guess.

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