my motor lock up at 25mph and crashed!

HI,

Sorry to hear about your accident....glad you were able to walk away from it tho!.....

That is an interesting question about the possibility of the gas and oil separating over the long term....My bikes are often stored for a month or so between uses (I know I need to ride more! HA) but seem not to be the none the worse for it.....Maybe as a precaution one should drain the carb and shake the bike (to remix the tank contents) before riding after a long storage?.....FWIW - I use fuel stabilizer in my bikes since I know they are used only occasionally...

Maybe somebody else knows for sure if oil and gas mix will separate over the long term?

Andew

I also use Stabil in everything, and since I dont ride my MB much in the summer I only mix up a quart or two at a time. Who did you get the engine from? How old is it?

once the oil is mixed it will not seperate at least I've never seen it.
I'm wondering if you might have has a cold seizure. My one engine has a clearance of 0.001 at the piston skirt pretty close tolerance. running the engine too hard when not totaly warmed up can cause a cold seize.
where is it scuffed, the cylinder by the intake ports or exhaust ports or somewhere else. I also wonder if you might of snaged a ring on a port some of these engines the ring pin is inserted too deep and won't stop the ring from riding over the pin allowing the ring to go where its not supposed to and bang the ring snags on a port instant failure.
then there is a wrist pin clip that can fail and don't forget the needle bearing that can fail on the wrist pin, and all the other crap than can come loose and eat up the engine.

For parts, first check with the original seller, then look for "70cc" parts.

Sorry about your luck.

I bought a set of rings for my 80cc (ha) from boy go fast. He had them advertised on ebay.

sb bikes said:

could of seperated from the gas when it sat for 2 weeks. I tore it down and a chunk of cyclender wall was gone and damage pistion and rings but every thing seemed to be well covered with oil. .

Click to expand...

Could it happen...

Don't know.

But i have Never had a problem After i mixed 2 stroke oil with gas and had it sit around for years.
I would say the problem was not because your MB sat around.
A more logical explanation would be,
incorrect Mixture or
internal combustion complication from defective parts or misused operation.

Hope this helps

Cheers

Bob

sb bikes said:

I purcased this motor from boygofast on ebay last spring. The damage was above one of the crank case ports , sounds like what norm said about a ring snaging on a port hole.

Click to expand...

This isnt uncommon - specially in older engines. riders of the highly tuned fantic bikes used to carry a set of rings for this very purpose.

The problem is that the CIF engines are fairly poor quality so if something lets go its more likely that the cylinder lining/ports get damaged - in the case of the fantic motor the rings would let loose and just head off down the exhaust port.

hope you are healing ok - sorry to hear of the accident - and I hope the bike itself isnt damaged.

Jemma xx