Crank/piston slop?

[mudking]

I pulled my jug off this weekend because at higher RPMS it sounds like an internal rattling going on...

The cylinder could use a honing and the piston is scored pretty good. But how much slop should the crank and piston have?

the crank has some side to side play, and it also has some heat damage on it. The piston is sloppy back and fourth (Like a 1/2 inch) but not much slop up and down.

What should I do? Just rebuild both the bottom and top? just do the top? not real sure what way to go...

 

[yamahaman126]

It's time for a rebuild! If you have a half inch of play in anything in your motor, bad things are going to happen if you continue to run it.

 

[xJust_Causex]

If you have a 1/2 in of slope the motor would have grendaded already, haha. Not sure on the crank side play, but there should be very little clearance around the piston, I'm thinking something like .006-.010 in. I would take it to a shop and have them look it over and prolly go up to the next size bore and new piston kit atleast.

 

[Kgibson]

I think he is sayin the piston has side to side play when the cylinder is off. Which is normal.

 

[blasterfreek30]

^^ yuppers and any up and down play in ur crank rod is very bad, u can have the slightest 0.010 side to side but thats about it

 

[xJust_Causex]

I think he is sayin the piston has side to side play when the cylinder is off. Which is normal.

ya, I went back an re-read it and I think you are right. you will have a lot of side play in the piston with the jug off. whats more important is how much gap you have between the piston and cylinder wall.

 

[nd jat]

If there is noticably tilt play to the rod from the crank (tilting the rod from side to side of the motor), that's not good. you should have a hard time feeling up down if the bearings are good on the crank, rod bearings. side to side on the crank isn't as critical but has a limit.

 

[scotj77]

what all did you replace on your last rebuild? if you did a new crank and piston the only way to distroy that crank would be water intrution or extreme overheating. if there is any question in your mind if the crank is bad you should probably replace it. I ruined three brand new pistons and wasted the last bore on two jugs discovering for the first time that my crank was bad. it felt a bit wobly side to side but the up and down on it felt pretty good, just a very slight movenent. but when the one of the thrust washers( the washer on either side of the rod) came apart on my freshly bored jug and band new weisco piston i wished to god that i had spent the extra money the first time. I wish i could get my computer to post pics and I could show you my nightmare. I save them as reminders to not cheap out on a rebuild. $100 beat up paper weights

 

[mudking]

ok thanks for the input guys!

Just curious, but what is the best way to rebuild it? Like as far as the honing and a piston kit, and new crank?

My dad owns a cornwell tool franchise. It would probably be easier to get a drill motor run hone from him than take it and have it honed? as far as matching a piston kit to a honed jug? How do I do that?

I dont want to replace the crank, but probably should. OR should I just by a fresh motor from someone on here trust worthy? What is cost effective, and efficient?