How'd this happen???

[FordMan7072]

I just recently got my blaster put together and I went out riding a few days ago and I just kinda putted around not really any hard riding and I loaded the blaster back up into the truck and I put the front wheels on the tool box so I could fit a warrior in to and I went out to unload the blaster the next day and the second I got the blaster out of the truck it started pouring gas out of the exhaust,carb and I went to kick it over and it wouldn't start and had no compression so after work I pulled the head and it broke a little pice off of the very top of the pistion and a pice of the ring. How'd it manage to blow when I was just easy riding and I also don't understand the gas pouring out. Any ideas???

 

[245stroker]

Did you turn the petcock off before you loaded it into the back of the truck with the front wheels on the tool box? More then likely the carb was at an angle and allowed fuel to flow into the cylinder and pipe.
Was the blaster left in gear while in the back of the truck? Was it able to rock back and forth on the ride home?

 

[scotj77]

def a strange thing. did you hear anything out of the ordinary while riding. how was it acting when you tried to kick it. any strange noises?

 

[DirtDiggler]

gas pouring out of the carb where? the overflow ? if its the overflow then usually its the floats being stuck . where was gas " pouring " out of the exhaust? the flange?
Need more info . Plus what KInd of Piston ? Cast ? Forged? did you have the cylinder honed? was the piston sized to the cylinder bore? was the ring gap correct? Need more info. Plus are you pre-mixing your oil and gas? or still using the injector? If still using the stock injection , did it fail? or when you reinstalled the top end did you correctly re-connect the oil injection ? Need a lot more info , plus before ever riding on a new top end , it should only be started and let it idle to operating temperature several times and allowed to cool off for proper break in period.

 

[FordMan7072]

I don't rember if the petcock was on or not. It was in 1st but was strapped in tight where it couldn't rock around. When I was riding it wasn't acting strange and was running fine after I unloaded it and I kicked it a few times it seemed fine then when I got home from work and tried again when I kicked it once it felt like it had no compression so I just pushed the kickstarter by hand and I herd a scraping noise in the cylinder and that's when I pulled the head. The gas was coming out of the overflow on the carb and out of the exhaust flange and when I got it on level ground and when I pulled the exhaust off it dumped quite a bit out. The piston is the a stock one and I don't have the injector hooked up and I mix it at 32:1. I didn't have the head honed because the head and piston came off a running motor with a cracked case. I don't think I over heated it because after alot of riding I'd feel the head and let it cool down if it felt too hot.

 

[scotj77]

your head doesn't get too hot to touch? your head should be way too hot to touch while running. if you were loading the quad it will pour gas out when it is stood on end. the piston and the gas thing are most likely not related at all. you need to take it apart and try to figure out what hit the piston to break it. post pics if you can.

 

[FordMan7072]

Here's a couple pictures

 

[scotj77]

are those dings in the crown of the piston besides the huge gapeing chunk missing. this is a weird place to break a piston. need to inspect the cylinder to see what happened.

 

[FordMan7072]

There's no dings just that chunk missing. I'll try and get some pictures of the head and cylinder.

 

[scotj77]

where did the chunk go?

 

[FordMan7072]

Here's the best pictures I could get of the cylinder. The 1st picture in the cylinder those marks is just some dirt from taking the head off.

 

[FordMan7072]

where did the chunk go?

I have no clue it wasn't in the cylinder itself and I don't see it in the motor and it didn't come out when I drained the case.

 

[scotj77]

It cant get from the crank area to the transmision. they are comepletely sealed off from each other. probably in your exhaust header. what does the exhaust port look like on the top side? does it look like the piston smashed into it at all. that is the side that is broken on the piston. I would have to guess it is probably excessive clearance between the piston and cylinder wall. that let the piston twist a little and snag the exhaust port and it broke a chunk off the piston

 

[myusername]

it looks to me like that ring got caught up and it pulled enough to take that chunk of the piston with it.

 

[scotj77]

I have had that happen but my piston was also melting away at the same time. that piston looked fine besides the huge chunk missing. get the cylinder measured by a machinist then order the size piston he tells you to get to fit the new bore size dude. that would be my next step. and check out the crank to make sure it is still within tollerances.