help installing BBK??  By  nwhicks21 (Read 2,346 times)

If you can post CLEAR pictures of the rings I can help. Timing is easy. My bbk can with NO directions- but ring installation is fairly universal. There should be 5 piston rings. 2 compression rings (the thick ones) and 3 oil control rings (2 thin ones and a wavy one). The oil control rings all go on the bottom slot. Be careful installing all rings, they can break easily. The wavy oil control ring probably has notches on the inside where the thinner oil rings sit on it. It will install with the 2 thin ones outside the wavy one (like a sandwich where the thin rings are the bread). First put some assembly lube (or 2-cycle oil, or clean motor oil if all else fails) on the rings and the piston grooves. Next install the oil control rings- making sure the thin ones remain outside the the wavy one. Next install the compression rings- IMPORTANT! there should be one compression ring that is either silver or that has a silver edge, or has some writing on it. This one MUST BE THE TOP RING! If there is any writing on ANY of the rings make sure the writing is installed facing UP (towards the top of the piston). ALSO VERY IMPORTANT! make sure when you install the piston into the cylinder that the ring gaps (the space where the ring is open) are 180 degrees apart. One compression end gap should be on one side, the other on the opposite side. The oil control ring doesnt matter so much.
Now- timing-
Before you disassemble the engine set it to Top Dead Center (TDC). Remove the valve cover and the flywheel cover (the cover opposite the variator). On the flywheel (the brass thing with a fan over it) there are some marks- some lines with one having a "T" next to it. Rotate the flywheel by hand so that the "t" mark lines up with the notch in the engine casing that sticks out at approximately 9:00 on the case. Look at the cam sprocket- there should be 3 holes in it- one big one and 2 little ones. The big hole should be facing straight up and the 2 little ones should be lined up with the top of your head. Boom- you're at tdc. When you reassemble simply make sure that the brass wheel is in the same place (T mark lined up) and the cam sprocket is lined up the same way. If you are even one tooth off with your chain it will be obvious. Rotate the engine by hand before you start it to make sure there is no interference and you're good to go. =)

[replyingto=nwhicks21]nwhicks21[/replyingto]You need to put the chain guide back in (long black piece). It's important or it wouldnt be there. It sits UNDER the gasket in a little notched area with the two stubs sitting in there- if that makes sense. Make sure you reset the chain tensioner- you push the little clip in and slide the toothed piece all the way in, install it THEN screw the spring in.
Check this link out, read it carefully and see if you missed anything.
ebay.globaldc.com/scooterparts/borekits/100ccGY6/install/bbk.html
Did one of the compression rings have ANY silver on it? even just the edge? This one needs to go on top with the edge thats silver facing up (if it has a "side"). This is important- the writing should be facing up, too, but the silver ring actually helps to "wear in" the rings to the cylinder and while it may work or run improperly installed, it might suffer in the long run. Also were the end gaps installed opposing each other on the piston rings? VERY IMPORTANT! The timing shouldnt matter as long as it is assembled in time. Make sure you hand crank it (just spin the flywheel or variator by hand) before you put the starter or kickstart to it. If there is interference you wont mess it up hand cranking it.

D8 Yes, the chain guide is that important. Put it back where it belongs.

The rings? maybe. Some rings are manufactured with the inside edge beveled so that when the combustion gasses hit the bevel from the top side, it will actually force the ring outward so that it seals better. If it's upside down it can't work like it supposed to.

The manual I was reading when I assembled my motor actually said the ring gaps should be staggered at 120 degree angles and never aligned with the wrist pin. As long as they are spread out they're probably fine. It's a BBK anyway. You're going to be blowing it up and rebuilding it before too long anyhow.

So the oil rings only go 30 degrees apart?