Blown Piston +Carnage Pics

[cole454]

Well, I went to the Badlands again today. Rode for about an hour and everything was good.
Went to climb a hill and the blaster just bogged out and died. So I get back down and start it up again
and it seems to be ok. Tried to take off and it bogged out and died again. Then when I tried to
start it, the kicker was locked up. X(

Turns out it was seized. So I took it home (about an hour drive) and first tried to kick it. It turned over.
So I did a compression test. 60 psi. Not good. Did a leak down test. Held 7psi for at least 10 min before
I took it off. Spark plug showed signs of running lean. Don't know how it could have been. No air
leaks, running a UNI with no lid, running a 270 main, stock pipe.

Carnage Pics!

 

[0_o]

Damn that looks worse than mine, running lean makes it get messed up like that? Or what causes that

 

[99LRDblaster]

While at the bandlands did you get any water in the air intake/engine?

 

[cole454]

Nope. Never got to the trails. Was messing around in the dune area.

Would water cause something like this?

 

[lowkhalbalr]

sorry to hear that man...whats your mixture?

 

[cole454]

sorry to hear that man...whats your mixture?

32/1

151515151515

 

[99LRDblaster]

Nope. Never got to the trails. Was messing around in the dune area.

Would water cause something like this?

I'm just evaluating where you were. Water separates in hydrocarbons like fuel and can lean out mixtures, however if you were in sand, it's irrelevant.

Sand is a major culprit for engines. I've never actually seen one that has failed due it but I'm guessing it leaves extensive pitting in the head, piston, and causes ring failure....and wouldn't be surprised if it almost resembles glass from the heat. Your situation just looks more like a case of running lean though. Are you running oil injection or pre mix?

 

[scotj77]

I would assume you were overheating for some reason. only airleak you would have missed would have been in the carb or the spark plug. do a pressure test on the carb using your hand and mouth. here come the jokes

 

[York Racing]

Check your intake boot. My brother had a bad intake boot and it ended up blowing the motor.

 

[scotj77]

Check your intake boot. My brother had a bad intake boot and it ended up blowing the motor.

he did a leakdown. and the boot was good. you don't do a leakdown with the carb on.

 

[Braaaptor]

Real sorry to hear that, man! That engine got extremely hot for some reason. Look at the last pic. Your engine went into detonation right before it locked up. The exhaust side of the piston is melted away from the extreme heat.

I'm with Scott on this one. I bet your engine suffered from a massive airleak which came from the carburetor. Perhaps at the oil injection line fitting, or perhaps from a bad or leaky carb cap gasket. Another explanation would be overheating from a lack of airflow across the cooling fins. Were you idling for an extended period, or running with partially-blocked cooling fins?

No? It is possible that your stock exhaust was/is partially blocked. Take the spark arrestor screen out and see. Same with the header pipe. No worries there, I'm about to hook you up with your new Toomey come Monday morning...

What brand of oil were you running when the engine died? That 270 main sounds about right for your mods...

 

[cole454]

The only idling was when I was warming it up before we got started. The rest of the hour I was constantly moving, usually quite fast . My silencer didn't have the spark arrester in it when I bought the quad.

I'm using YamaLube 2-R oil, 32/1, premix

How do I test the carb for a leak?

Yah! Toomey! I:I

Boo. Have to wait to try it. X(

 

[Braaaptor]

Sounds like you were doing everything right in terms of mixing fuel and using good oil. Its kinda hard to test a carb for leaks, but you'll need to plug up both ends of the carb and all the lines going out of it and then pump it up with a few PSI of air pressure. Really the only place you can have an air leak on a carb is through the oil injector nipple (not gonna be a huge leak), or from a loose carburetor cap or one with a damaged 'O' ring.

Check your float height in the carburetor, too. It should be 20 - 21mm; if the float height is way off (too high), your engine may have starved for fuel and ran lean.

Another thought: Did you do a lot of 'engine braking' while riding? That is, getting off the throttle and slowing down using the engine's compression, without pulling in the clutch?

 

[cole454]

I do that some. Wouldn't say excessively, but I do it.

 

[99LRDblaster]

Well if jetting was on at all levels and whatnot and you didn't get into anything in terms of sand, not sure what to say. Sometimes people just run their quads too hard and they overheat and get hot spots on the piston and get pre-deflagration. sh*t happens. That's why I tend to run a main richer than optimal performance just to help keep the engine cool and it's important to do plug chops at 1/4 and 1/2 throttle too for needle adjustments.

On the plus side......now you might be able to mod up. With every negative, there is a double positive for you to improve on when crap like this happens. Off to get ported, stroker, BBK, head work, etc?

 

[Zwiser]

did your wrist pin clip come out?

 

[DirtDiggler]

What was the temperature that day? Cold, if it was significantly colder that what it was jetted at then that could be the bastard that did it . Cold air is denser air , winter riding requires jetting up 1 to 2 mainjets to protect the motor .

 

[cole454]

did your wrist pin clip come out?

Nope, Both were there when I tore it down.

What was the temperature that day? Cold, if it was significantly colder that what it was jetted at then that could be the bastard that did it . Cold air is denser air , winter riding requires jetting up 1 to 2 mainjets to protect the motor .

When I jetted after removing my airbox lid it was colder than it was when this happened.

 

[cole454]

Well, Most likely will be sending the motor to O'Conner for work. Not sure if the crank will need to be replaced or not. If so I'm thinking 3 mil + port job if its not too much extra. I gotta call Ken tonight to find out.

 

[con8quest6]

God that sucks man