Okay, here we go. I got plenty of new parts in; and finally assembled the scooter.
So far I have:
-Athena Big Bore Kit (for Zuma / Minarelli Vertical Engine)
-Stage6 intake kit (for Zuma Minarelli Vertical Engine)
-Tecnigas Silent Pro Exhaust (for Zuma Vertical)
Note: The variator I attempted to fit did not work. Newer Jog/Zuma variators are out of the question, but the rollers will work. If anyone has any ideas on this, let me know!
So, to the install. First things first, the new cylinder. Let's take a look at what the Athena kit comes with (kit # 070100):
-Cylinder
-Head
-Piston, ring
-Intake manifold gasket
-Exhaust manifold gasket
-Base and head gaskets (various base gaskets)
-Squish ring? Not sure why, no place for it.
-wrist pin (note: this kit SHOULD come with new circlips, but mine did not; as I bought it technically 'used' - likely returned, seems fine otherwise)
So, to installation. Take the old head off (4 bolts), remove 2 circlips. Tap wrist pin out. Use a new needle bearing if at all possible (I re-used the old one because I couldn't find a new needle bearing, just if you do have to remember to coat it in 2-stroke oil along with pretty much everything else in here). Install piston wring on piston (assuming you have already gotten ring gap set), then install piston, minding the triangle points toward the exhaust port, then install wrist pin. Install two circlips in the proper orientation (you don't want the gaps 'sideways'. Take note of how the old ones were installed.)
Now to check which base gaskets to use. Take the new cylinder, and slide it over the piston. You want the ports to be level with the piston, at bottom dead center. Use the gasket(s) you need to accomplish this, remove and check as necessary. Once you have this accomplished, install the head gasket and head. Now torque the four bolts to proper torque spec (7.2 ft. lb., according to the CG50 service manual), and time to fit the cooling shroud on it. Note you will have to cut the cooling shroud around the intake/exhaust ports, and spark plug hole, to fit. Only the one bolt will still bolt on, and you'll have to use a bolt and nut to hold the cooling vent on (you should also find a way to hold this sturdier.
Now you should have a 70cc Jog!
Few more challenges now, though -- your original CE50 intake won't work. It doesn't fit.
So, I used a Stage6 intake manifold from ScooterSwapShop. This did the trick. However, with brand new 2.75-10 tires, it JUST touches the tire. I had to cut some of the rubber off of the intake to get it to fit.
I also had to chop the 'rear fender' to make room for the tire now. Not a great solution, but I got it to work. I suppose a smaller tire could also solve the situation, maybe.
Onto installing the Tecnigas exhaust. I obtained this from Racing Planet USA. This was a tricky one. It was preeeeetty close, but not perfect.
The problems were:
-the bolt that joins the engine frame and rest of the frame; the 'cylinder'/bushing around it in the center got in the way a bit. I ground it down to make room for the exhaust (sorry, no picture)
-the oil injection pump gets in the way. It has to go.
-you will also need some sort of 'spacer' and some long bolts to attach the other mounting point of the exhaust, since it is about 3" further out than the original one. I suppose someone with the ability to work this material (I had considered heating and bending it, but I was worried I'd break it) could also do that, and probably get it to fit with no grinding or cutting or spacing.
Also, don't forget to de-restrict your exhaust (note: never break the law and de-restrict your exhaust
) by grinding the spot weld off the 'cap' on the exhaust outlet end, and using a dremel to grind the restrictor plug out of the exhaust inlet end.
Anyways, not a very well typed article, but I hope it helps and gets the job done! I'll add more information as I go. Hope it helps the next guy!