2 stroke low end bearing replacement

[fastfredracing]

I am putting together a little quad for blasting around the yard. I need to replace the piston, etc.. but wanted to replace the lower end bearing, and pin while I was in there. Back when I was into riding, I always paid to have this done, and did the rest of the assembly myself. I wanted to try it. Any tips, advice?. I have a couple of spare cranks to play with, and I have already presssed the pin in and out a couple of times, but trying to figure out how to correctly "phase" the two halves. I have v blocks, and dial indicators, and have a pretty good idea of how to go about it, but could use some input.

[sammyg2]

Dunno, I was always told not to mess with the crank pin.

rumors are that you need to have special jigs, procedures, etc.

I know that if the crank halves are indexed off as little as a few thousandths or if they move on ya it can vibrate like crazy and take out bearings.

I bet we could do it but I was always too chicken, and it wasn't all that 'spensive to have soeone else do it.

[LakeCleElum]

Fredrick: I've had dozens of dirt bikes, go-karts, & m/c over the years. Always did all my own work - EXCEPT: mess with pressing apart cranks.

1) It sounds like you know what you are doing and have all the right equipment. So, my impression is: First, why do you think the bearings need replaced? I've had some 2=strokes go for over 20 years and not need attention. Unless you can show it's out of spec, let it be.

2) If you really have proof it needs replaced, I say go for it. You need a press, V-blocks, dial indicators, a brass hammer and a ton of patience to get it right.

You have to strive for perfection to get it right so it won't vibrate and self-destroy. It sounds like this a a low-stress application and you'll have a lot of fun. Give it a whirl!