Banshee blew

[JesseDR]

Hello, I recently got my top end rebuilt a couple months ago and this happened after an hour of riding. Can I get an idea what happened? Do I need to get it rebuilt? Thank you. 

[locogato11283]

Holy shit.. You likely had a serious loss of fuel.

Is that a stock crank?

[SKEETER]

Hone it n go

[JesseDR]

2 minutes ago, locogato11283 said:

Holy shit.. You likely had a serious loss of fuel.

Is that a stock crank?

It had a full tank, and no. It’s not stock. 

[JesseDR]

3 minutes ago, locogato11283 said:

Holy shit.. You likely had a serious loss of fuel.

Is that a stock crank?

Is this something that happened over time or during the duration of the hour ride?

[locogato11283]

Is this something that happened over time or during the duration of the hour ride?

That’s something that happened quick most likely. Either a massive air leak or no fuel.

[JesseDR]

27 minutes ago, locogato11283 said:

That’s something that happened quick most likely. Either a massive air leak or no fuel.

Is this something I could’ve prevented? I’m in total confusion here.

[Sully78]

Guessing the crank seal started leaking and instantly leaned that cylinder out. I say that because I had a friend who had a seal go on the opposite side last winter and his piston looks identical to yours


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[97Screamer]

Air leak. Complete rebuild and leak test before you run it.

[machinegunbanshee]

How sure are we that it was an air leak?

I've been dealing with this pretty regularly. 4 rebuilds... all within a couple of hours or less of riding. Every rebuild requires new cases and crank as well as cylinders refurbished. Im honestly thinking that its a loss of fuel. Im to the point where I dont think the hole in the fuel cap is drilled out big enough. 

[machinegunbanshee]

I forgot to add that every rebuild passes a leak down test. Less than a half pound in 6 minutes. 

[fastbanshee8]

Remove the fuel petcock from the tank, and clean the screens.

[bansheesandrider]

What was the reason for the top end rebuild before it happened? Was the crank and rods properly inspected while it was apart? Did the crankcase get properly cleaned out of all foreign material during the top end job? At the minimum, you are going to need a new or rebuilt crank assembly, all the gaskets and seals, and redo the top end. Make sure you get the crank welded while you are in there. Inspect your cases very thoroughly , replace anything else that is worn or damaged. Don't cheap out on anything, use good quality parts and fix everything so you don't have more failures and collateral damage.

[machinegunbanshee]

Did you by chance do a leak down test before you tore it down?

[SKEETER]

Sounds like you need to send engine to someone with a clue, to do the 5th rebuild.