Cracked crankcase, what should I do?

[roblav96]

I recently bought a 2005 Suzuki RMZ250 from a private seller off craigslist sunday. On tuesday, I get on my bike kick it twice. The second kick, I heard a loud crack/pop so I figured the engine back fired or something. Third kick the bike starts and I go riding for around 5min till I get to my friends house. As I turn off my engine, I notice oil leaking all over his drive way. I look down and see a crack from the kick start baring all the way to the other side. The pictures show it all.

(idk how to insert pictures)

So after saving up for months to get this bike, it's worthless in two days. :(

Could someone give me some advise as to what I should do about this? My first intention is to just weld the crack because the engine ran fine and started fine even with the crack. The crack isn't near any key components to the engine so I'm not sure why I shouldn't. My other alternative is to buy a whole new engine and swap it out or buy the engine cover piece and the two crankcases and replace it from there.

What's the best thing to do in this situation?

 

[IndyMX]

Find a welder who can weld aluminum, get an estimate. Compare that against the cost of a new set of crankcase halves (you'll need both, they're machined pairs).

Then figure which you could stomach best.

I had the balancer gear shatter and come thru the right side case in 3 spots. None critical, so I had it welded. It's still holding up fine after a year.

Also you will need a new gasket set in either case. Plus you may as well put a new piston, pin, circlips and rings in it.

Might be a good time to do some other routine stuff too.. How are the valves??

Just figure this way. After you get done with the work, your bike is going to be fresh. If you fix it up, spend the cash, you will have a good running bike that you will likely get a few years of enjoyment out of.

On the otherhand, if you just sell it and start over, you never know what kind of other problems you might be taking on.

While you have it apart, I would also find out what caused the kick starter to crack the cases. This is not normal. I'm guessing the previous owner had it apart, and didn't get something on quite right and caused excess pressure on the starter gear. Just a guess though.

Get a service manual, and have your digital camera ready as you take it apart so you can document the disassembly, and incase you need to show us the pics.. ;)

Good luck

 

[_JOE_]

Yeah, you need to figure out what caused the crack.

Just a heads up, you may want to tear the entire engine down and measure everything while you're in there. The early RMZ250s had some reliability issues.

 

[roblav96]

I talked to my friend who has been racing dirt bike for 15 years and he said the same thing happened to 3 of his bikes. He said what caused it was that the timing chain was too advanced.

I'm buying a whole new bottom half of a 06 RMZ250 engine for 550 and using what I have on my 05 engine to make it work.

 

[Rich Rohrich]

This is a fairly common problem with the early RMZ/KXF 250F engines. It's one of the many basic design flaws in the engine.

It can happen even if the cam timing and everything else is correct.