Can someone explain what blew up? And what I should do now?

K

Koobs

Member
Not mechanically inclined so I just want a guesstimate as to what might of happened tonight.

2005 Kawi 636 got it with 28000km

rode it for 3000km and got an oil change done. Put another 5000km and this happened....

I consider myself a good rider (had chicken strips gone after two weeks and its my first bike) but as for wheelies ive fallen way to many times on my dirt bike that im scared and i guess since i fell so many times also not very good at wheelies lol... So I was Riding it pretty hard, practicing first gear power wheelies just to get the bike up a bit so this was definitely giving the bike some beating.

then I was just cruising and noticed lack of power and when I let off the bike was engine braking very hard (or slowing down fast just by letting off gas) So I clutched it and let it cruise and it shut off, I found neutral while on the clutch and tried to start it again (still rolling at like 50-60)... When it started I heard what I would describe as jackhammering or piston slapping.

Wondering what I broke (oil was very very low as I neglected to check recently and only did 2 weeks ago). I figure its bottom end but not too sure on specifics. No hole in the motor and if I wanted to I could probably start it.

What are my options? Should I fix it? (How much)?
should I make it better in some way like forged pistons? Also how much again?
should I try to find a new motor and just swap it? Also how much should I be paying for something like that?

not a very happy first post :(
 
In your 2nd post you said you spun a bearing? This will make the rod knock pretty loud, not necessarily damaging the head or valves but that's a great possibility.

Johnnyp636 is an expert on these engines, and will probably have some idea of what's gone wrong, what it'd cost to fix or what a replacement engine would cost: http://www.gtamotorcycle.com/vbforum/private.php?do=newpm&u=2974

Good luck, and check the oil level more than once every 5000km's in the future. If doing lots of wheelies I always over fill my oil by 1/4 liter or more.
 
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Hmmm ...

You let the oil level run low. You wheelied the bike, which put whatever oil the engine had right to the back of the transmission and starved the oil pump pick-up screen. The engine ran low on oil pressure under load. Within seconds, this will start scoring the con-rod bearings and shortly thereafter, every other lubricated part inside the engine. The con-rods started running hot (oil also serves to remove heat from the bearings), the drag from the friction is the power loss that you noticed, this spun at least one of the rod bearings in its housing, leading to excessive clearance, leading to the rod bearing pounding against the crank. The excessive clearance also lets the piston travel higher than normal in the bore, making contact with the head. That's the clattering sound that you heard.

Needless to say, this is all very bad. Repairing it will likely cost a couple thousand bucks: new crankshaft, new rods, all new bearings, all new seals, new piston rings, possibly new pistons, possibly new camshafts, probably new oil pump. Obviously the engine has to come completely apart and all components carefully inspected and measured. This is a rather substantial amount of labour if you are paying shop rate.

If this were a rare, semi-unobtainable vintage bike, it might be worth it. Given that it is a reasonably late model that is likely readily available used or in junkyards, the best choice is to just get another engine.

Take-home lessons ... Keep an eye on the oil level, and either don't do wheelies, or if you do, run the oil level extra high and hope!
 
I saw a 636 on Albion Rd that was coughing up smoke on Friday (and travelling around in a low gear), wasn't you was it?
 
Crank gone = motor is junk. It's cheaper to buy a intact used motor and swap it out.
 
Above descriptions are very likely correct. The engine will need either a complete tear down or to be replaced. Cheaper option would just to replace.
 
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