what to do about a broken sv crank?

my 04 STOCK motor blew the crank this past weekend right at the rotor.

The way I see it, I can

buy a parts bike for around 1300 somewhere, swap motors and keep spares and sell the junk I wont need.

buy a motor somewhere for 500-700 and put that in, but with both of those options I have no idea if the motor will be any good.

pay 1500+ parts for prieto to rebuild it

I can probably rebuild it myself, but how do I go about making sure it doesn't happen again? Should I get an oem crank on fleabay or is there a better more durable option that doesn't cost $2000.

pics for the lurkers who just wanna see some carnage:

 

I would look for a low miles motor...

Now if you want to help prevent failure again... Buy a crank, have it balanced and cryo freezed... I would opt for Carrillo Rods as well...

 

buy another motor. pray it doesnt do the same thing. thats your cheapest and best route. been there, done that.

 

Get a lighter ignition rotor and have the sprag unit lightened while you're at it. I'm working on doing my own rotor (along with a dozen other projects!)
Unless you're running in supersport classes, then you just pray like Kris said.

 

Happens with SVs. A gen one crank will last longer. Don't rebuild, it is an insanely expensive way to go. Sell the motor and buy used. You can't really take much weight off the rotor unless you dump magnets.

How do you make sure it does not happen again? When you figure that out, there are thousands of SV racers that will pay for the secret.

 

so buy a new one and pray. its definitely the easy route so I can do that...anyone need spare jugs?

 

Save them. Or ebay them. If you are racing SVs it is nice to have a B motor.

 

Same exact thing happened to mine. Sold the broken engine for $150. Got a new one and had a supersport build done to it. Runs great. Only has like 8 hrs on it so hopefully the crank holds for a long time to come

 

what did you pay for the new motor?

 

I believe $400 then had it gone through and a couple things done for like $800 so 1200 total. Not cheap but it runs awesome. Just started it yesterday from its winter rest and started right up and pured like a kitten.

 

buy 06 or newer 07 -2010 swap heads and you"ll be good to go!!!!!!!!!!!!!!!!!!!!!!

 

Is this pretty common on raced SV's or are broken cranks hit-or-miss?

 

I presume you are saying if he gets a 07-10 that he should swap the heads off his 04 onto the newer bottom end, because the older heads are better than the new twin plug head.

 

from what I'm reading and I just started researching this as of this week, It typically happens on superstock bikes that put down more than 85hp. I'm in the mid 70s so I just got unlucky. I think.

 

Cool - starting an SV program for this season so I'm weighing what to look and plan for.

 

I bought a motor with a popped freeze plug for $200 shipped and took the crank out to replace the broken one in my race motor. I also have a spare motor with 13K street miles on it that I bought for $270 shipped. I'll just take the good stuff off my current motor if I break another crank. Even with the cost of refreshing the motor that's pretty cheap.

My motor put out about 80 hp. The crank broke after something like nine 3 hour endurance races and a half dozen trackdays.

 

I think the way You ride it has more of an influence. Don't bang it like you do an inline with a slipper clutch. I adapted my corner entries after I broke a couple, then had 5 straight seasons with no issues on 80+ HP motors. Its not easy to use the clutch that way, but it worked for me.

 

Appreciate that :up:

Are you kinda coasting into turns (no clutch) and feathering out, or what's working best?

 

Yep pretty much. Its only tricky cause most of the time you're leaned over when you do release it so you better be smooth or the rear end wont agree much. Its not every turn kind of thing either. Once you ride em enough you figure out what they like.

 

I once had an RC Fiddy-one that tried to throw me on my head on a semi-regular basis, so I hear what you're saying

Thanks man.