motor or pipe leaking???

[Blaster200boy]

im thinking that my rod is going out. When i rebuilt my top end, i looked for play in the rod and couldnt find any. there was very little side to side movement and there was no more than the regular on the up and down....When i ride, when i hit my throttle it makes a cracking sound almost as if something is hitting something....it doesn't do it when it idles.....only when i hit my throttle. I had my motor built back in september and since then i put a new top end on it...my 2nd option is maybe its my pipe flange leaking because there is no rtv silicone that is supposed to seal it...im hoping its no more than that, but if it is, i might as well get a 3+ stroker and be done with all of it...

 

[Awk08]

who did the top end, sounds like it could be piston slap

 

[yb200]

there should be no up and down movement on the crank

 

[bag0b0nez]

Re: f**cked up motor or pipe leaking???

there should be no up and down movement on the crank

yea what he said!!

 

[Little-J]

Re: f**cked up motor or pipe leaking???

if the pipe was leaking there would be a load of black oil around the leak.. sounds like piston slap, or... im not sure... does it more like buzz? or just crack randomly? whats the compression like?


also, try turning the engine over slowly with ur hand on the kick starter, when the piston goes past top dead center, and it makes that click noise, listen to it, that is the sound of play in the con rod bearings. there is always a little play hence the click, but is it louder than you remember?

also, the pencil test.. take ur plug out, and take off the flywheel cover, rotate the engine around and figure out where TDC is on the flywheel.. rotate the engine and as soon as the piston goes past top dead center, about 45 degrees of rotation on the flywheel, poke the piston with the eraser of a pencil.. If it makes a click sound, that was the play in ur con rod.. if it clicks, and especially if you can feel it click through the pencil, ur rod is condemned..

to rule out piston slap, see if you can get ur compression checked.

 

[Blaster200boy]

Re: f**cked up motor or pipe leaking???

My blaster has PLENTY of compression, i just rebuilt it....and it doesn't slap when i crank it over with my hand....it only does when i give it gas ...

 

[Blasterdude27]

Could be bad reeds flapping around ( I've had that happen before ) or it could be a small air leak cuasing you to run lean and denote at higher rpm's.

 

[webmonstro]

Re: f**cked up motor or pipe leaking???

hi
Could be crank bearings. Used to have a kx 125 that destroyed a crank bearing and still worked fine , just started to make a banging sound like a hammer...

Nuno

 

[Blaster200boy]

Re: f**cked up motor or pipe leaking???

i'll try getting a video of it running and you guys can help...

 

[Little-J]

ooohh.. key question.. does it start to slap/crack after a certain engine speed, or is it whenever you open up the throttle?

it may be that ur engine just has a of of compression, and its running strong.. and every crack you hear is just the sound of combustion from the exhaust..

If i had it here, id use a mechanics stethoscope to listen for the sound in the crank case, and find where its coming from.