Engine Area Knocks Loudly

[Dynamo]

The bike starts, idles ok but has a loud consisent knocking noise coming from piston area and the repetition increases with the rev. During diagnostics the bike still seems to run pretty strong but something is obviously wrong. I'm thinking of rebuilding the top end, any other ideas?

 

[xxxxfloodedxxxx]

as i just wrote in another post.. all blasters have a knocking noise from the motor.. imo it wouldnt hurt to take a few hours an examine the top end. you may have some "piston slapping" occuring... examine the cylinder wall very carefully for signs of scoring before replacing the piston.

 

[Dynamo]

I'm familiar with the normal knocking sound but this is definetly not it. The cylinder wall doesn't appear to have any damage although it's discolored. The piston itself is discolored and is black on top with build-up, is that bad?

 

[xxxxfloodedxxxx]

no.. i just put my engine back together.. an my piston had a "carbon" like build up on top.. if it worries you, just soak it in gas or brake cleaner an scrub it with fine steel wool. an when you say that the wall is discolored, what color is it... if its semi gray/light light pink? then that is normal... dont really matter what color it is as long as its not black or real shiny silver (scoring)

 

[pittboss45]

Measure the clearance to be sure.

 

[xxxxfloodedxxxx]

agreed pitboss, agreed I:I

 

[Dynamo]

Measure what clearence? I've taken apart the cylinder and it doesn't appear to be damaged nor does the piston which also fits snub. Could it be a crank bearing or something else?

 

[Warhart]

Be sure the Head Bolts are on tight..i know it sound dumb but mine had a bad knock. but it was air comming out of the head

 

[suprex]

they are saying to measure the diameter of the piston rings.. then measure your cylinder on the top and on the bottom with a caliper.

( right? is that what you are saying pitboss?)

 

[flyers42091]

I think he meant the distance between the piston and the cylinder wall.

Woot 1000th post, lol

 

[suprex]

that is exactly what i just posted would give you the answer to.