Little bike go boom.

[dudescoot]

So I was helping a friend fix his scooter the other day, he said he was riding heard a loud noise then nothing. I come over crank it and it sounds like the starter is not coming out and engaging just spinning. So pull off side case to take a look. After watching the starter do what it was supposed to do and seeing how easily the motor turned I had a pretty good idea what was wrong but before I pulled it completely apart I tested compression using the finger method absolutely none.

So I pulled the motor apart when I got the head off I pushed on the piston and it slid right down clearly not connected to the rod anymore.

I'm assuming the worst cranks bad or rod snapped etc, but after I got it out I realized the piston must have seized and the connecting rod kept on going ripping the bottom skirt of the piston clean off.

I did notice he was very low on oil is this what caused the piston to seize or is it something else?

Luckily for him I had a spare top end from my BB build and threw it together started right up and sounded better than before.

I did inform him with the amount of metal in the crank case that the bike was now a ticking time bomb.

[90GTVert]

Sounds like it may be the lack of oil, but here's a document with a bunch of pics that show how to figure out what may have been going on.
download.ms-motor-service.com/ximages/ks_50003973-02_web_leseprobe.pdf


Whatever it was, I agree with the time bomb assessment.

[dudescoot]

Yea I dumped it's oil put a new quart in hand turned it for awhile dumped it and then did that again every time decent sized pieces of metal came out so I'm sure the crank is drowning in metal bits.

Too bad it was a great running bike one of my old ones for some reason it was at least 10mph faster than a comparable bike and it was stock it was odd.

[katastroff]

Could be worth it to open the cankcase and clean it good if it hasn't went BABOOM!!!yet.

[dudescoot]

Haha if it weren't my bike I would but considering I did a top end swap for him and provided the parts free of charge I wasn't gonna go crazy fixing it