Got a cheap little maxi to play with and started experimenting with some kits.
STOCK transfer ports. I kept these stock so these can be compared as a bolt-on-and-go kind of kit.
3 shoe clutch, kickstart springs
2.5" sava MC51 tires (tire size affects gearing)
Estoril pipe, derestricted, shortened 2"
Stock points, 17* btdc
First kit I threw on it was the treats 1.5 70cc kit with the stock 14mm bing and 14mm round intake. It didn't really like to idle, possibly due to the round intake on the square intake port of the kit... not quite sure. BUT it ran well, was easy to tune (72 jet in the 14 bing), and was super easy to install. That setup hit 47 on a flat road, GPS'd both directions. Took a while to get up to that speed though. Here's a picture of the bike with that setup:
And a plug reading with the 72 jet and no air leaks:
Next setup I've been wanting to try was the reed kit that 1977mopeds.com sells as the "Lil Gila" . It looked like a cool kit, having a bridged exhaust port and nearly gila size reed block and not having to bore the cases like you do with a gila. BUT I didn't like the price or the fact that it didn't come with gaskets.
Did some digging and found this thread where a guy states that the kit is made by MK (not to be confused with MetraKit) and is a copy of the awesome Athena/AJH 70cc big reed kit so I found some on ebay for $150 shipped with gaskets and a bigass intake .
I had a mikuni TM24 flatslide laying around that I figured would work great on it, so I picked it up and did some research while I was waiting the 13 days to get to my house. I found this thread and this thread that had good info on it.
So then I finally got my kit.
good looking nikisil
LARGE transfers with easy increase to metra large port transfer size. Barely seals on a e50 without welding.
Nice piston, drops through the cylinder easily.
Comes with gaskets and nice rubber coated 2 petal reed block (SS reeds, not CF.)
Sweet bridged exhaust
Huge nearly gila/mb5 size reed block
Nearly 360* intake duration
Ring gaps located near top of piston, not near exhaust port
Round exhaust port, could use some reshaping for a larger port to utilize the bridged exhaust.
Goofy fin pattern won't match a puch head
Intake duration could be raised to 360*
Long wrist pin clips. See notes later on.
I was itching to port the bridged exhaust port something like this , but I wanted to run it stock first, then port and retry.
SO I took some pictures of the kit and did a test fit. Seems like this has the same ring-in-the-exhaust problem as the 1977 kit. Here's some pictures. Transfers don't open all the way by 3.4mm.
You can see in this picture where I marked the ring gap locations:
Here's a port map:
With a single thin base gasket:
Exhaust: 25mm = 175*
Transfers: 35mm = 114.3*
With a 3.4mm spacer/base gasket combo:
Exhaust: 21.6mm = 193*
Transfers: 31.6mm = 135*
If you went somewhere between the two, with about a 2mm base gasket:
Exhaust: 23mm = 186*
Transfers: 33mm = 128*
I bolted it on with the thin base gasket, hope the ring still cools. 186* or 193* exhaust timing is pushing it for a one speed.
Reed block needed some cleaning. Picture with reeds:
After filing the upper, lower, and inner sides. Couldn't do the outsides without compromising the sealing surface area.
Wrist pin clips were too long for my liking and I didn't want to lose a clip from the extra mass, so I clipped them a bit shorter. Here's a comparison:
Here's pictures of the hose I bought from Kragen (with part #) to mount the carb and everything installed:
Here's a video of it running. Had to drop down to a 10 idle jet to get it idling right.
Went for a test ride with the GPS. Hit 48 but got there effin quick! Clutch engages at 25 and it RIPS from 30-48. I'm sure this kit could pull 18x36 easily and could benefit from a ported exhaust port.