:Question: lower crank bearing....

mapbike

mapbike

Well-Known Member
I got my thrashed 66cc engine taken completely apart today, I think I know what wrecked it but I'm not for sure. I think a roller bearing broke and made it up on top of my piston and then wedged between the piston and intake port.
In the post I did a few days ago about the engineI had said that I was concerned about the bearing on the crank journal, after taking the crank out today I noticed that all of the roller bearings are just loose between the connecting rod and the crank, I have seen on sites that sell parts for these engines, lower crank bearings that have a cage that holds the bearing rollers in place but my engine doesnt have that cage around the bearings.
: Question: IS THIS NORMAL, OR DO SOME OF THESE ENGINES HAVE WHAT I WOULD CALL A PIN BEARING SET UP LIKE MINE SEEMS TO HAVE INSTEAD OF A CAGED NEEDLE BEARING SET UP?
PISTON BIKE HAS A NEW CRANKSHAFT WITH THE ROD ALREADY INSTALLED ON IT FOR $37 AND SOME CHANGE, $20.00 PLUS $17.--SHIPPING, THE SHIPPING ON THIS SEEMS A LITTLE MUCH TO ME ON THIS ITEM.
Anyone know of a better deal on the crankshaft and rod assembly?
 
I had mine apart yesterday and it didn't look like there was a cage around the needle bearings like the wrist pin has.
Unless you're determined to bring this engine back to life it's getting to the point where a replacement motor would be cheaper.
 
your at almost new engine price and you dont have new seals, and are the crankshaft bearings damaged at all,those are pricy too
 
All other bearings and seals are in good shape, the lower end of the engine was free from any chunks of metal just good and oily, It looks as though one of the roller bearings made it to the top of the piston and was then pushed between the piston and the cylinder wall as the piston moved upward, so I figure based on what I see that the crank and the rod are toast.

I already have a new jug, piston, rings & gaskets, I have been debating the route I should go on this, I did find that BGF sells the entire lower engine unit minus jug piston,rings,head and gaskets for $49.00 + $15.00 shipping or I can spend $37.00 and just replace the crankshaft & rod assembly that piston bikes sells, the cheapest route is replacing the crank & rod, but I would have $89.00 tied up in the rebuild that way verses buying a NEW engine from BGF for $90.00 delivered to my front door, I would really like to keep my engine block because it is the block made for the large tube frame I have and I dont have to use a makeshift mount on the front like I would with the standard engine block.

Anyone know where I can get the crankshaft and rod any cheaper....?
 
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