Piston will not move up or down top gets hot

most cyl gouges on two stroke engines are caused by improper gas/oil mix in the fuel ratio , some other causes are in order of there occurance are:

(1) wrong gas/oil mix used

(2) air cleaner missing /holes in allowing dirt to enter engine


(3) piston sleeve moved due to overheating (see #1 for cause)


(4) worn down piston rings allow dirt to be caught in them

as for worth the repair : that's 4 tech to decide parts cost + labor to determine weather its worth it . plus general appearance too counts !! ive got a 30 year old stil that runs like it was new !!starts 1st pull everytime and I just rebuilt it top to bottom !! I luv it !! its defiantly worth it !!!

may want to go bac and reajust valves--or try a synthetic oil like amsoil 0w30--they lower temp as much as 50degree and hav esters so motor seals dont wear

you might have to take it apart again and see whats up. maybe the new seal has come out of the slot and jammed it??

The brake hose is clogged. When under pressure from applying breaks, the piston is forced tight to the rotor. When released the fluid will not return through the hose because there is no real pressure. Replace the hose.
murf427

sound like one of your caliper is getting stuck or lock. The seal to the piston probably worn out causing the piston in the caliper not to work properly. The piston in the calipers design to move back and forth to release the pressure off the brake disk. when the piston is lock it cause the brake pad and brake disk to rub causing much friction and heat, long period of braking can cause a fire. getting a rebuilt caliper is much easier to replace than have a mechanic rebuilding the old one. you can check if the calipers is lock up by touch and feel the outer hub of the wheel to see if its hot. if its feel hot and smell hot, replace the caliper.

Yes, on any vehicle if it is in motion when the belt goes out the wheels continue to be engaged and turn the crankshaft of the motor, moving the pistons up and down. If the valves are open... and they are, then as the piston reaches the top of the cylinder it will strike the valve and bend it and the rod. It will also scar the piston top. Dependent on the damage to the valve and rod a valve job may repair the issue. More often than not if the piston and valve made significant impact the whole motor will need to be rebuilt to insure the crankshaft wasnt damaged, piston punctured, or block cracked.

did you check the clearances between piston & bore it sounds very much like its time for a rebore & oversize piston that is a top end rebuild rather than just a clean up

Sounds like to me that the motor is running way too hot which could cause detonation. This is cause by carbon build up on the piston crown still hot as a stove top, therefore, igniting any left over gas still on the piston. Also, it may be due to a bad kill switch connection.

Sound like your brake caliper for the front (I'm assuming that it's the front) is hanging up. They get corrosion and the caliper piston sticks. Have it rebuilt, or do it yourself. I take it off, and use compressed air at the hose connection to "blow" out the piston, with a piece of wood where the pads go to protect the piston from the blasting out. Be careful when doing this because it comes out like a shot!!! If it wont move, I have made a grease fitting fastener that threads in, and pumped grease into it to remove the piston, messy but safer. Clean up the piston and caliper real good and re-asemble. Use brake fluid to lube up the seal.

You know what they always say about the color of smoke... blue is oil, white is water and black is  i don't know lol.   Anyhow, if it was just recently rebuilt and you're getting blue smoke then oil is making it into your pistons OR you are burning off oil somewhere when it gets hot.  If you are seeing the smoke from the exhaust only, then think about piston rings, head gaskets, all the typical stuff that gets replaced on a rebuild.  It's near impossible to say exactly where to look so that's the best I can tell you.  I would lean more toward the piston rings.
Good Luck