The pin that hold the piston to the arm... how do I get it off?? I took off the little clips on each side and now I tried taping it with a hammer and screwdriver but it will only mover about 2 cm. How do I get it clear out?

 

I've had the same problem with my YZ 250. What happens is from wear the pin gets stuck in the bearing. First thing you have to do is support the rod so you don't bend it while hammering on the pin. A piece of wood cut to the correct size will do. Use a socket as close to the same size as the pin. Put the socket on an extension and use that with the hammer instead of the screwdriver to tap out the pin. Keep tapping the pin one way then from the other side until it comes out. Make sure to replace the pin, bearing and both circlips with new.

 

ok thanks I will go try that right now!!

 

If the pin is not stuck too tight, the hammering can work it out like Ridnwarrior said. But, actually, you never want to use a hammer on the piston/pin/rod. If some hammering impact reaches the rod lower needle bearing, it can dent the bearing surface and eventually result in lower rod bearing failure (costly).

The best method, use a pin puller (K&L Supplies sells them for around $30.00). Or, you can make a home made puller. Get a 1/4" threaded rod (all you need is about 6&quotwith 2 nuts from hardware store. Put it through the pin and put a washer and a nut on one side (the washer must be smaller OD than pin OD. On the other side, slide a deep well socket (or piece of pipe) slightly larger ID than the pin OD (pin have to be able to slide inside it). Put a washer and a nut and tighten. Keep tightening the nut and you'll feel the pin being pulled out into the socket/pipe. That's a piston pin puller without damaging other part. If piston is to be reused, put rubber washer or plastic washer between the socket/pipe to prevent denting the piston.

OD= Outside diameter
ID= Inside diameter

Good luck.

 

Be VERY careful, make sure you hold onto the piston tight when you do it, if you are not careful you can EASILY mess up the rod, one scratch with the screwdriver in the top hole will chew up wrist pin bearings, or even worse you could bend or tweak the rod.. just use caution when you do it.

 

I did the hammering deal and with a few light knocks it poped right out. The rod looks ok so I hope I didnt screw it up. Also is there any way that you an take the sleeve out of the just or do you have to bore it completely out to get rid of it?? thanks for the quick replies!!

 

Come again. Not sure what you mean??

 

Well the sleeve is inside the jug/head. Well I need to get it out and was wondering if I could take it out and install a new one myself or will I have to go to a machinist and have them bore out the old sleeve and install the new one for me. I would much rather do it myself but dont know if it is possible to take the old one out.

 

I recommend you take it to a shop. The sleeve might come out, hold it tight with both hands and slam it straight down on a block of wood, it might come loose, but you can also screw it up, personally I'd leave it to the person doing the machine work (Im pretty sure sleeves come un-ported, somebody is going to have to cut the ports). I'd just take it to a shop and have them re-sleeve it. You gonna get the big-bore???! You can get a vitos pretty cheap, I've heard good stuff about the regular vitos piston also, I plan on throwing one in next top-end.. I'm gonna get the cylinder/head sandblasted too, mabe put a colored clear powerdercoat on it, I think it'll look sweet..

 

Hey thanks for the info!! I will take it to the pro to do the rest of the work. But I would like to know where I could look at or order those vito kits online?? thankns