I finally blew one up.

maniac57

maniac57

Old, Fat, and still faster than you
Had the GenV up and running again today. Everything was hunky-dory at first with the engine running strong and smooth like it should.
Rode about an hour or so and was almost ready to put it up when...BLAM!
Pulled the clutch instantly and coasted it back to the bench to find the busted part.
Pulled the jug and discovered a busted and snagged ring in one of the transfer ports. My first thought was the circlip came out and ate the rings, but it's still installed correctly. Both rings were still in the groove too, just busted from snagging the land chunk.
From the look of the piston, I had a section of the ring land between the rings break off and catch on the transfer breaking the rings and wasting the piston. Lots of galling and gouges in the piston. The transfer has some damage from the ring chunks as well. Might be okay with touch-up but I doubt it even though there was no damage to the chrome. There's a chunk out of the lip of the transfer. Looks like I need a new piston, rings and jug to get things back running.


Just one of those random failures. Nothing broke to cause it, just a random material failure in the piston ring land.
Luckily I was quick on the clutch and caught it before any worse damage was done.
Back to the stock engine again. *sighs*
Guess I gotta start saving again for some new top end parts. All my other motors are a different stroke and therefore a different piston.
 
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Looks like FOD to me. Did it swallow a 1/2" nut, or a small dog? Maybe a better air filter is in your future. :)

Seriously, that is some bodashios damage and I can't see how the cylinder wall survived.

Tom
 
It looks like the chunk between the ring grooves broke off randomly. No marks of any debris getting in on the head or piston top, air filter was on. You can see where the ring land came off before it ingested it. There is cast aluminum visible where the chunk separated. Both rings were still in the grooves although busted, so it does not look like a ring snagged. Might have snapped a ring and caught the transfer rather than the ring land I guess. Either way, it was not good.
It is a good example of just how hard that cheap thin chrome plating really is! If not for the gouge in the lip of the transfer, the cylinder would be useable still, even with a good 1/8'' deep gouge in the piston! The cylinder wall is untouched!
Honestly? I have been waiting for something like this for a while now. I've been enjoying far too many happy miles without a single ''typical'' chinagirl failure and it was only a matter of time.
I am thrilled that the seal replacement worked.Now I know the motor runs like it should after all the skull sweat figuring out the overheating.
This was simply a random failure and had nothing to do with the rebuild. (Thankfully I didn't forget the circlip!)
I could buy another identical motor for the price of a fred motor huffydavidson. Why would I do that? Your personal problems with MotorBicycleRacing mean nothing to me.
Aside from a few random problems not related to quality this motor is every bit as smooth and powerful as advertised. Stuff simply happens sometimes.
Murphy finally caught up with me.
 
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Keep us informed on the rebuild and any other info on the failure. My guess is a ring let go.

Tom
 
I'm with 2door: how the HECK did your cylinder survive that one?!? That jug is just fine for reuse; just dremel the promontories off, throw in a new piston and rings, and you should be fine. I grenaged a piston last year where one of the transfer-port skirts got partially shattered. The combustion-area of the jug-wall was fine though, so I just ground down the jagged edges, made sure the piston/rings cleared, and was on my way...no probs.
 
Saw the comments in the chatbox.


Well, sorry to hear you have to build a new one, but hey! At least the damage is spectacular. :D
 
What problems? We talked for good while on the phone just tonight!! You don't know what your talking about ray.
 
I really am astounded that your jug survived...you must be like Quick Draw McGraw on the clutch-lever!
 
I've always been a paranoid wreck about new engines. I'm like a long tailed cat in a room full of rocking chairs with every new engine for at least the first 100 miles.
Although this was not the first ride on this bullet, it was the first after splitting the case so I was right back to square one.
Being quick to kill it when something feels wrong has saved me untold cash over the years.
 
It seems the ht gods WILL collect their due....
And I even sacrificed a moped to them last weekend.
(DON'T ask)
 
Being "quick to kill it" is more important for saving your hide.

Happy time motors are cheap. Hospital time is really expensive.
 
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