ive got a 03 400ex. its got a brand new hot rod crank. i put it in so i know its new. i had a new weisco piston to put on it but didnt because of the movement of the pin. the movement was jiggly feeling. like up and down movement. so i bought a new je piston. this pin does the same thing.

my ? is... if its loose, will it destroy my engine over a period of time? and, is it normal for this to jiggle (move) like this? also if its not, should it be sent back>

any help would be great!

 

If you can actually feel up/down play in the wrist pin you won't get any length of life out of that engine ..

 

think god your online i just got a oil change and a new spark plug for my 1985 atc 125m and it still wont start just backfire every now and then some one told me to readjust or check the valve lash or if the valve slash is off it wont run just back fire is that true also if so they say the compression will drop like a rock true and if so will it still run and smoke. how do i adjust this pleas


<span class="FTHighlightFont">THANK YOU</span ft>

 

Is the small end bushed? If so send it back with the right size pin and have it fitted.

 

Yes the crank small end should be checked with a micrometer ..

 

its not much movement... at all!! but i would think it needs to be real snug!

 

I don't know what the specs are on your particular engine, but typically I'd expect a few thousandths of an inch maximum difference between the wrist pin and the con rod diameter, maybe a couple thousandths maximum clearance wrist pin to piston...

If you don't have the micrometers, I'd invite someone over who does.

 

Stock rod ID. is 20.020 - 20.041 mm (0.7882 - 0.7890 in)
Stock wrist pin OD. is 19.994 - 20.000 mm (0.7872 - 0.7874)

 

it seems to me that the rod is to specs. or within specs. i jus went to a local shop and tried a diffrent style piston again. this time with a pro x piston. still a lil bit of movement. weisco, je and now pro x pistons wrist pins all have movement in this brand new complete crank assembely. all these pins are snug in my factory crank. new hot rod crank, you would think that it would be too.

like i said its not a lot, but it does concern me! also i just found out i can NOT send it back. that was a lot of $$$$ to just throw away if i can not use it. thats why i was wondering how much life could i possibly get out of this enging with a loose feeling wrist pin?

 

It's a little hard to say over the internet how much clearance a "loose feeling" wrist pin has.

Drop by the local shop again and have the rod, wrist pin, and piston pin bore measured.