Man i just got finish rebuilding the motor in my blaster and i put a yamaha piston and rings and clips, a bearing and i put new gaskets, and i tried to start it but it makes a knocking sound i dont know what it could be i need help if you kno or had the same thing tell me I:I
rebuilding my motor
- Thread starter pj01blaster
- Start date
did you pre-lube the cylinder with some 2 stroke oil befor you cranked it over for the first time? how much clearence is there between the piston and cylinder. does it sound like the piston is hitting the head, or just ratteling around in there, or does it sound like a noise from the bottem end?
do you pre mix or is it still oil injected? if its oil injected maybe your pump is shot and its not getting oil up top. if you pemix and your doin a bench test with the engine out of the bike make sure you have sufficient oil getting in the cylinder or it will seiz up. did it start making the noise as soon as you started or did it get louder as the engine got hotter?
do you pre mix or is it still oil injected? if its oil injected maybe your pump is shot and its not getting oil up top. if you pemix and your doin a bench test with the engine out of the bike make sure you have sufficient oil getting in the cylinder or it will seiz up. did it start making the noise as soon as you started or did it get louder as the engine got hotter?
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Try and be a little more specific and give a LOT more details
a) DID you get it to start ?
b) did the knocking start right from the git-go , or ?
c) when you pushed down on the kick starter , did it knock then ?
d) if you DID start it , how many times did you kick it over before it popped off ?
Not trying to hijack here, but are the rings supposed to be lined up a certain way like on a 4 stroke? Mines been knocking for a long time like yours and thats only thing i didnt check or think of....
sounds like pistin slap, mine knocked on a fresh piston that the previous owner put in, had too much clearance
I think the piston is hitting the head. I see that happening before a loose piston in cylinder. It's a new rebuild so a pisto/head problem seems more likely imo.
Most of the time, knock is going to be piston slap. The bore and cylinder need to be measured before the top end is assembled. You should do this even if you have the cylinder bored to check the "machine shops" work.
