Seized Piston?

[MachoMouse]

oil type

Hi...thanks for the piston removal tips...should i use a rubber mallet to tap?

...the oil I was adding says specifically synthetic blend for air cooled 2-stroke engines...it's from autozone..the bike really loved it when i switched...it idled and ran so much smoother...

upon recalculating i was running about 20:1 ratio...always had a bit of oily residue on engine...i think it wasn't too lean, maybe it was though, it felt indestructible during the 16:1 days...i'm very curious to pull the motor apart...

thanks for the instructions and tips everyone, I appreciate it very much!!
I'm dying to get back on the road...

..oh, one thing i failed to mention earlier is that I rear ended someone a week before the failure...my heavy steel frame seemed like it was fine not even the rim or fender was bent...but could this possibly have contributed to the piston seizure?

does anyone know of a piston removal thread with pics by any chance?

THANKS!
p.s. where would i find a japanese engine?...is that like the 'robin'?

 

[arceeguy]

You can have the "proper" oil/fuel ratio and still seize up a 2 stroke if the carb is set too lean. Other than the idle stop screw, there are no external adjustments on the carburetor. You can raise and lower the main metering needle to adjust idle and part throttle mixture, but WOT mixture is regulated by a fixed metering jet. If you run at high speeds, and the mixture is just slightly lean, the engine will self destruct, regardless of how much oil is in the fuel. Lean mixtures cause combustion temps to skyrocket, and they starve the engine of vital lubrication - which is a very small amount in any two stroke.

 

[Mountainman]

Hi...thanks for the piston removal tips...should i use a rubber mallet to tap?

p.s. where would i find a japanese engine?...is that like the 'robin'?

for those pistons
I have always used the wooden end of a hammer (handle) -- got some weight
should tap right out

well -- the Robins and Hondas seem to run forever

I sure like that when I ride those THINGS

 

[MachoMouse]

replacement parts

Hi thank you for everyone's help and tips...although now I'm not sure that I can get replacement parts...I contacted Dax and they are not sure that parts will match up...I can't imagine that my only option is to replace the engine, any suggestions?
Thank you everyone, your knowledge is priceless.

 

[Technocyclist]

Piston seizure can also be caused by intake leaks. I suspect your intake gaskets might have been damaged during the accident or the needle bearings. I also had a piston seizure after a day when I fell from my bike. When I opened the engine, the needles of the bearings were stucked between the piston and barrel. No way I could remove the piston which was stuck in the middle of the barrel. And I tried everything, and it just won't budge. I just throw away the whole thing in frustration, but I retain the crankcase.

 

[Mountainman]

99%

..oh, one thing i failed to mention earlier is that I rear ended someone a week before the failure...my heavy steel frame seemed like it was fine not even the rim or fender was bent...but could this possibly have contributed to the piston seizure?

thinking that the odds are about 99.9% that no
your little rear ender caused no damage to your engine

my grandfather spent a large part of his life
buying motor cycles and cars from junk yards that had been totaled
even after some real fast stops in accidents
engines were fine

ride that thing

 

[MachoMouse]

well, that certainly gives me something to think about...I've been wrapped up in wife/weather stuff for the last few days, so I haven't yet had a chance to pull the motor apart...the bike felt a little shaky the day of the accident, but within a few days, it was running smoother than it ever had...curious...but I will for sure check the needle bearings etc, and report back...thank you again everyone for you help...

 

[duivendyk]

1)Don't use marine type oil in these engines,but use ordinary garden variety 2 stroke oil, nothing exotic or synthetic and don't go a higher than 25:1,20:1 is even better if the plug does not foul.The HT engines were designed decades ago when these ratios were SOP.Better to have a messy exhaust than a seized piston.You probably have a broken ring.Looking into the ports may give you something to go on.

 

[MachoMouse]

Thanks...yeah, the marine oil may have been a bad call..it ran sooooo smoothly for 2 months with it in there though!...I'll be pulling the motor apart soon and I'm sure I'll have more to post...thank you for your insight

 

[MotorMac]

Take picts

Take some pictures as you proceed with the teardown, It would be interesting to see what went wrong.