Seized Piston?

[MachoMouse]

Hello, I have been riding my 80cc (66cc?)motored bike 5-6 days a week for the last 4 months...I followed as many of the suggestions for the break in etc as I could and felt like I had gently brought the motor into a fully broken in state...It has performed very well for trips from 5-30 miles...I would say I have somewhere around 500 miles on it...well tonight I think my engine seized and I have no idea why...It was running very smoothly today, I rode about 20 miles in 5 mile increments...then I popped out for a quick trip to home depot and then pow! clunky engine noise follwed by stalling out..I tried restarting once, which was rough and the noise I heard made me shut it off immediately...kind of like something clunking around in the front of the engine...I rode home about 1/2 mile and took the top of the head off...there were a few salt grain sized pieces of metal in there, with maybe 5 or so simlilarly sized holes along the edge of the piston...the bike rolls with the clutch in but freezes the back wheel when the clutch is out...I took out the little pieces, replaced the top of the head and tried pedaling very fast only to have the bike skid when i let out the clutch...The piston seems to be frozen in place...I've never been able to remove the clutch plate, as the screws that came on there were of the "strip-o-matic" variety..
..I read some posts on here regarding the "woodruff key" (is that correct?) I can go and buy the drill bits to try to get them out if I need to...although I'll be walking to home depot.....can anyone help!!??!! I really hope that I don't have to replace the engine...the bike is my main, daily transportation...

 

[stude13]

hi mm; pull the head and tap the piston out of the barrel. i think you will need a piston, rings, wrist pin, barrel and gaskets.

 

[MachoMouse]

thanks for the info

hiya stude...thanks very much for the insight...i'm going to begin the teardown/ordering process...I hope I can get it back to the smooth running beast it was before...I miss riding it already! Any thoughts as to why it would seize?...I've taken the best care of it as I can, I was definitely hoping to get several thousand miles on the engine....running 32:1 synthetic blend marine 2 stroke oil...custom exhaust and lots of TLC...
umm mr. moderators...should I post my progress?

 

[stude13]

sure, let us in on what you find. it isnt something you didnt do. it is about making a silk purse out sows ear. a ring might have hung on a port. an air leak might have happened. the poor quality metals used are very likely at fault. i tried to clean up the combustion chamber with a dremel and finally gave up. in fact after putting up with this **** four times im done with them. im now buying gopeds to power bikes. search--motormaker--and briggs style. you can motor a bike for almost nothing. and those motors run forever. i have 47cc that cost 100 delivered. you can back-half a scooter and just bolt it to your axle dropout and drive off. good luck mitch

 

[Mountainman]

just some reasons for a seize may be

you may find a broken ring
over heated
not proper oil
cracked piston let us know what you find once broken down

soon you will be back up and riding that THING

 

[MachoMouse]

thanks for the help stude and mountain!...I'm not ready to give up yet!...I will certainly post my progress...I'd love to be a contributing part of this forum...Is there possibly a thread somewhere that details taking the engine apart to get to the piston rings etc..?
It sounds a bit delicate, and I don't want to break anything else while trying to fix it!

p.s. stude...I think in the long run, I'd like to try a custom build with a more reliable engine...HT tinkering is an awesome hobby, and breakdowns can be a chance to learn, but ultimately safe reliable transportation is what I'm looking for...my wife lives 400 miles from me, I'd love to putt-putt there on a custom 4 stroke for $8 in gas!

 

[BSA]

if your running at 32:1 tbh I'm not suprised You've seized up. A lot of people would tell you thats the correct oil ratio, but in my opinion 20-1 or 16-1 is the best, for not only peace of mind but for longer lasting rings, and bearings ETC. I'm not worried about smoke or decoking however.

BSA

 

[srdavo]

running 32:1 synthetic blend marine 2 stroke oil...

I'd be concerned about the marine oil...... outboard motors are water-cooled?

 

[MachoMouse]

oil ratio

thanks for the tip BSA, I will certainly consider that in the future...

would the failure happen so sudddenly if oil ratio was the case?

 

[Mountainman]

would the failure happen so sudddenly if oil ratio was the case?

yes - failure due to lack of oil can happen real fast

surprized that so many want to run as lean as possible
I have always went with
a little extra oil is a lot better than running too lean

if you are looking for some long lasting care free miles
maybe a nice engine from Japan next time

to remove
take off the head
as you pull on cylinder -- tap piston lightly with wood end of hammer

ride that ting