2004 wr450 kicked back so hard it broke the....

well my 2004 wr450 has kicked back so violently that it actually broke the right side of the crankcase, where the kickstarter shaft rides on the left side of the crankcase, right behind the starter. local welding shop says that magnesium can not be welded???? Anyway i just purchased 2 halves of the crankcase $450.00 and about $100.00 seals and$100.00 bearings and $600.00 labor.....the bike has kicked back really hard maybe 6-8 times where it sounded that it might break something.....a couple of weeks later broke....whats so bad is that i J B Welded it and could ride the bike , but could never use the kick starter again because of the pressure of the kickstarter shaft on the piece just pulled the broke pieces apart apart .BEWARE

That sucks-Why though are you kickstarting when u have that nice little button? :naughty:

well u know how weak the battery is. usually kick start it in the mornings. afraid if i left it jb welded, that i would get stranded somewhere...even thought of removing the kickstarter just to keep from being tempted..

So whaddya figure was the cause of the kick-backs?

me like a stupid a** cranked on the throttle while trying to start it, caused the kickback

So whaddya figure was the cause of the kick-backs?

I understand the battery dillema, not sure why she's kicking back so hard. I have kick started mine numerous times w/o any kickback at all :naughty:

me like a stupid a** cranked on the throttle while trying to start it, caused the kickback


never had the problem with my 426....450 was used when i brought it....probally cracked when i bought it.................off to work i go.

your not the first. from what has been reported on line. (i'm assuming nobody knows for sure) if you open the throttle too much, the throttle position sensor "tells" the ignition and the spark is advanced.

by the way, i don't think your center cases are mag. they should be aluminum.

My 99 will kick back when cold. I never let the kicker slap back on it's own even when it starts. Let your foot take the brunt.Letting it slap back can do internal damage also. Oh yeah make sure you allways were boots when kicking.

well i thought the case was "cast aluminum".....went to the top welding shop in my small town and they said it was magnesium....did a search on "TT" for cracked crankcases....they also said it was magnesium. The welding shop said that "mag" could not be welded, because of the high oxygen content ....but on the search i did some reported that they had there cases welded...???!!!???...

I own a steel shop and I will tell you up front that magnesium cannot be welded, (have you ever seen magnesium on fire?) anyway if someone had there cases welded I am sure they were Aluminum.

I believe that the area around your starter is magnesium if I remember right, I do know that your cases are not 100% magnesium at least there not on my 05.

BTW, the bike in question is a WR not a Harley, I would have never thought it had enough back pressure to break the cases but I was wrong.

Good Luck.


Where It Broke Is Where The Left End Of The Kick Starter Shaft Rides.

My 04' WR450 is a bear to crank in the mornings as well and I have run the batter dead trying, but never had too much trouble with kick starter so long as I pulled the compression release. My bike ran very lean when new. My brother bought an 04' at the same time and his bike ran much differently than mine and started easier. I adjusted the fuel mix just a tad to richin' it up a bit and it cranks much better most of the time. I've also found rolling it into the sun for about a half hour helps a ton. Good Luck!

If you have to run the battery dead trying to start your bike then you need to go up one size on the pilot jet.

Your pilot will control your cold starting and yes mine was a biotch to get started before I rejeted the pilot.

Good Luck


the kickback on my yz450 almost broke my ankle when i first got it... talk about embarrassing.. first time on a thumper and i roll it off the showroom floor and start kicking on it for the first time and i crack the throttle and it kicks back... sprained my ankle pretty darn good.. dealer had to start it for me and then he tells me oh ya dont give it any throttle when your kicking it..

Comments about magnesium "not being weldable" are only true in normal atmosphere. If you weld in a argon envelope it's very weldable. I have a friend that uses an argon cabinet at his work to weld mag in. You're right about fire, try and weld in open atmosphere, and say hello to the fire department. Give it an inert gas, and it can't burn. Most shops don't have cabinets, know how, and know the hazzards, so they wont touch it. Mag is tricky stuff, there is a lot to know, and do before you start to puddle up a crack.

I am not familiar with any shop who would set up a special argon atmosphere to weld a set of cases for some guy off the street, the material being welded would have to be cleaner than most individuals would be willing to spend the time preping.

The quality of the welds would be that of welding cast iron, meaning it would never be as strong and would still have crappy integrity.

Thats why people don't weld Magnesium, It ain't worth time, effort or trouble.

Do what I do when my bike breaks down.

I Buy a new one :naughty:



I have a YZ 450 as well as my WR 450, about 8-9 months ago I was out riding with my step-son when I came up on a rock and it slammed into my shifter on my YZ. When I got the bike home I washed it and put it away. The next day I went out in the garage and noticed that I had a pretty good size puddle of oil under my bike. After careful inspection I came to the conclusion that some how hittling my shifter bent my shift spline and cracked the case. I took it down to my local Yammey dealer with heavy heart, knowing I was up the perverbial Creek with a fork. They (to my surprise) told me "yeah, we got a place that can weld that.... I breathed a heavy sigh and gave them my bike and skipped out of the dealership in the warm air, the scent of roses filling the air and a happy song in my heart. I went back a week later and picked up my bike, HAPPILY paid the $250.00 (knowing full well what a new case costs), loaded up my bike, drove over to desertwr's house for a great ride. Since then my bike hasn't dripped a drop. My brother in law owns a welding shop. I told him what happened and he told me that I just got taken for a ride. There is no way someone can weld on those mag cases. I was violated.... needless to say I went back there to give them a piece of my mind... instead i bought a WR from them....The moral to this story. None, just thought I'd throw that story out there!!!!!!

By the way, it was just a really good JB weld job......

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