holy!!!! look at this piston!


Mar 26, 2007
i went to my buddies house to look at his blaster, he tried, saprk plugs, coils, gas, caruebreuter, but it would not get running so w edecide to pull the head off and we find this!

his little brother admited that he tried to ride the blaster, his little brother also admitted that it would make a chugging noise when he was riding, we agreed that his little brother was in too high of a gear and not going fast enough (my friend was pissed!) man on the one side of the piston there is a piece missing, you might beable to see it in the pic.
Sorry to see that, it looks expensive...but I've seen this too often before not to know what happened. Diagnosis: the engine was run without oil. Fortunately the piston never seized. I'm surprised it ran at all. It would have eventually worn itself to shreds and stopped running because the compression pressure would be 0psi. The cylinder will surely have scratches and bits of metal imbedded in it. It may clean up with a hone, but, depending on the damage, a rebore (and oversized piston) may be necessary. Don't forget to rebevel the ports or the rebore will be wasted. Also depending on how long the engine was run in this condition, the main bearings and lower rod bearing may also have bits of metal caught in them and they will probably have to be replaced. In fact, I hope your friend doesn't take the chance and DOES replace them.
However this won't solve the problem because you weren't getting oil to the engine. Check to see if the oil tank in back has any oil in it. If it doesn't, you can decide who's at fault for not checking it earlier before your friend's brother went riding. You might also check the oil warning light on top of the headlight to see if it's working. But make sure you put injector friendly two-stroke oil in it next time, and you fill the lines with oil before you start the engine.
If the tank does have oil, just start checking the oil line to the pump and then up to the carburetor for a crack or obstruction somewhere. The oil pump could be faulty, and if it is it should be replaced. These two-stroke oil injector pumps are generally pretty complicated, and you'd be better off finding a good used one on Ebay or something.
Now if you're a pre-mixer like me, just find out who "mixed" the batch of fuel you last used; they shouldn't ever mix it for ANYONE again...
the piston was only 5 months old it was running perfect until my friends brother tried to ride it, as soon as he heard the chugging and bogging down he thought he was supposed to shift up.my friends brother has never roden a clutch atv in his life and hes only 9 he was underreving it making the piston not go down straight so it was hitting the sides.
i talked to my friends parents, they talked with my friends little brother, i showed them the head and piston, i told them that i could have my uncle do the work on it for cheap, they agreed, i'm gonna be up tommarow to take it to the shop, and help my uncle a little. my friend was mixing his gas correctly, he had good gear oil in. ohh as for my friends brother has to pay 25 percent of the price. my uncle and me are going to take the bottom apart as well and look for pieces, shreds all that stuff, we are gonna look everything over.
my friend is really mad that he was going to ride but then he couldn't get it running, he asked his brother if he messed with it before he even called me over, his brother lied and said no, but then after we talked to him he finally admittted to stealign the key and tryign to ride it, as soon as my friends brother had it stall out and he couldn't get it started he just put it back in the garage for me and my friend to find the problem.
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my friend argued with his parents a long time, then finally they understood tht it was all his lil bros fault and now his little brother has to pay 95% and my friends little brother is in big trouble with his parents becuz he lied to his parents about what he told us, he left out alot of details.

well i would say his little brother rode it long distances in 4th and 5th gear with only 1/3 throttle, like i said he does not know how to shift, it would seem like its bogging down but the piston is actually hitting the walls sideways a little
ohh and i'm the youngest in my family so damit! i have two brothers, i get along with them most of the time, an doen fo my brothers works at a computer place and he bought me a video card so i could play games like halo, and counterstrike on my comp. my other brother hes pretty cool he takes me to the track sometimes.
sure his lil bro didnt put the wrong gas in it?? that looks like no oil to me.. Worse thing ive ever had happen from underreving a 2-stroke is a fouled plug
no, it was the shifting!, we checked the gas it was mixed and correct.

i'll try to explain this,he would be in like 4th or 5th gear with bearly touching the throttle, it would act like its bogging down but the piston is actually hitting the walls, my friends little brother even said he would rev it full throttle in nutreal, me and my uncle worked on it today, we found tons of pieces in the bottom of the motor

i am sure that my friend mixed his gas, and had enough gear oil.

ohh and the first day i lloked at it and tried tog et it started for him, the kickstart would get stuck alot.
he was underreving it making the piston not go down straight so it was hitting the sides.

Where do you get this diagnosis? Just because he was in too high a gear has NOTHING to do with the piston hitting the cylinder walls. The only time that type of damage can happen is when either the cylinder bore is too large for that size piston OR there is a lack of lubrication between the cylinder and the piston (i.e.: lack of or no oil at all).

I'm sorry, I have problems with you making up stories about how he was in too high a gear and that automatically constitutes a piston scraping the cylinder walls. Regardless, I hope for his sake you take the time to drain the fuel tank and pour a decent mix of 2-cycle fuel in. I would venture to say that someone filled the tank with regular gasoline instead of the mix as you said he has the oil injection blockoff. Either that or it's jetted way too lean.
That couldn't be the problem man, i can be in 4-5th gear on mine an bearly be touching the gas an nothin happens to it. It probably leaned out while his brother was riding it or the piston was already slapping an it finally just went ahead an broke, but that does not come from under revving it otherwise they would have never produced a 2 stroke engine if that was going to happen if you wasn't constantly on the gas.
As far as the kickstarter getting stuck, the grinded an broken chunks of metal that fell into your crankcase is the cause of that.
As far as the kickstarter getting stuck, the grinded an broken chunks of metal that fell into your crankcase is the cause of that.

While your suggestion is possible, it's highly unlikely. The tolerances between bearing material and the rod and crankshaft are so slight that even if some material got between them it would have to be in an unusual situation to make it hard to turn over. What is likely to make it turn over hard is the lack of oil between the piston and cylinder wall.

Think of it this way. Ever have a long-sleeved shirt or coat that was a bit too small and hard to get your arm into? Try fitting your arm in it, hard right? Now coat your arm in Vasoline (or in this case, motor oil) and now try to shove it in there. In this case, your arm is the piston, Vasoline is the oil, and the sleeve is the cylinder wall. It works the same in theory, just in a different way. With no Vasoline on your arm its hard to fit it in there. With the Vasoline applied it's very easy.
alright i'll have to admit i was wrong on some parts, my friends little brother is not telling us everything so i'm not excactly sure, after taking a closer look on the old gas it seems like there is some unleaded gasoline along with race gas

and throttlesteer to make it clear i'm only telling you guys what i think and what my friends brother told me.
my uncle is going to either bore or hone the cyclinder, not dure yet we did not have time to look at the whole thing.