Cracked crank case

[flippi]

Poor maintenance led to chain coming off and cracking crank case. Will get quote on Monday buy even if a rebuild cost $2000 I am scrapping a perfectly good Yamaha YFZ450. The motor is far for needing a rebuild and clutch, gearbox,starter, top to bottom is mint, its the saddest thing to my bike. New $300 DID chain and sprockets. So so sad.

The crack is about 1cm and hardly visible. What is visible is the oil pissing out. I have my heart set on a 2008 kfx450 and may keep my YFZ as backup and get it fixed some time later. Not sure if I can get a recond motor /or fix it/ or just part the motor or maybe mod it. My options are open and if you a bargain hunter / mechanic here is $$$. An idea I had was if the motor one day had to be overhauled, I'd want it properly balanced as its a bit rough compared to mates TRX450, although I have more power and speed overall.

Ok, so I have a perfect running 450 motor with a crack, what should I do? What will it cost to fix? Who will fix it. (Will insert Yamaha price). Keep in mind I can buy a 2007 YFZ450 complete for 4-5k.

[TrentNz]

is it just the crank case? you can have them rebuild and i doubt it will cost fuck all
a new one wont cost fuck all either

[flippi]

Crank case can be repaired for cheap, pretty sure. New one is between US$300-400. So if I remember correctly the kiwi is close to 1.2 to the US$. Done a few Ebay imports so I can get it here for say NZD500. Somehow YamahaNZ cant get that same GYTR parts and I expect them to say $700-1000.(and 3weeks time) where most Ebayers get it here in a week.

The sore point in the matter is paying $90-100/hr for labor. Remember they charged me 4 hours to replace the chain and 2 sprockets. These are the professionals. $800 later and it was all fixed, except they did not take it off the trailer and testride it. Unfortunately I had to take it to Sandpit and learned the lesson. Like this forum I know every stray dog will come and piss on me and its a one in a million chance the Yamaha god or (good mechanic) will show its face and reveal a path I should take.

I do alot of work on the bike myself ?(yes I know not the chain!). Found engineering shop and a god working there. The guys KNOWS and is proud of his work. May strip the motor myself, get the cracked fixed and pray for 6 months till a god-like mechanic comes along. But I am still taking 5grand to buy another one! (aka 5 grand well spent see?)

[flippi]

I am a mechanic on the Shore and can do the job 2-3k incl parts or excl parts.
or
I worked on many a Yamaha...atv god, know yamaha, blah blah blah... i charge x, will take y hrs.
or
Have spare motor, gimme 2k for swap.

There are a few MX racing dudes. (please God wake them up and bring them here)

I eagerly await your comments....

[pete376403]

Get the case welded (it's not magnesium, is it?)

Buy a service manual, learn how to strip and rebuild and engine - after all what do you have to loose - the engine is already unusable, so if the worst comes to the worst, you either part it out or buy another engine.

You can purchase an ok set of tools at repco, don't need super high quality stuff.

[Madness]

Give some Knead-It a go!

[ktm84mxc]

You'll need to be sitting down when you get the price for the crankcase half from a Yamaha NZ dealer, there are numerous dowels, o-rings, seals needed when you split the cases.
Crankcase cracks can be welded up successfully if done right. Have seen your tossed chain ailment on a few bikes , all caused by a to tight chain usually wrecked hub, sprocket, chain guide etc.
One mate even did it twice.

[DEATH_INC.]

Post up a pic of the crack. It can be welded (even if it is Magnesium), or (better than knead it) use Devcon and glue it if it's not stress bearing.

[popelli]

machine part welding onehunga

they welded up a 7" crack in a sportster case I owned 22 years ago, that bike is still registered and on the road

[TrentNz]

i had the exact same problem and these guys i know used some sort of clear glue stuff that dried like metal and strengthened it up.
looked like new and never cracked again

[vifferman]

Years ago, I dropped the VFR and cracked the clutch case. Knead it? Pfft...
Bought some JB Weld, removed the case, cleaned it up to be totally oil-free, JB welded it, gave it some heat, and it's been good as gold ever since. Saved me a few hundred dollars!