Mini-stroke Stock bore

[HELLAFLUSHED!]

Hi i just traded my spree with an arnada and the bike has an AF18 block with a 2AB ministroke crank inside. It had a 72 polini corsa but it was siezed so i put on a old stock bore but the piston touches the block. Is it possible to use a stock bore with a mini-stroke crank?

[bakaracer]

yeah you can. you will have to round off the edges of the skirt on the piston. thats where it usually touches. use a degree wheel to see how many base gaskets you need to set the port timing. what pipe are you going to use with that setup?

[HELLAFLUSHED!]

I have a pg long. The other stuff i have on the block is a kelli pulley, 7:1 gears, SEF ramp, zx trans, koso clutch, 1500 center / 2000 clutch, ct chrome mani, and a 28 oko. Idk if it'll run well but the stock bore is all i have, and the old owner had a 72 polini corsa but siezed it so its un-useable. So how do i cut short the piston? Can i just keep sanding it till it doesnt touch?

[dv/dt]

I have a pg long. The other stuff i have on the block is a kelli pulley, 7:1 gears, SEF ramp, zx trans, koso clutch, 1500 center / 2000 clutch, ct chrome mani, and a 28 oko. Idk if it'll run well but the stock bore is all i have, and the old owner had a 72 polini corsa but siezed it so its un-useable. So how do i cut short the piston? Can i just keep sanding it till it doesnt touch?

Is the bore really that messed up? Usually iron bores arent all that difficult to clean up.

[Wheelman-111]

Greetings:

HellaFlushed! axt:

Can i just keep sanding it till it doesnt touch?

I'm pretty sure that's what Baka-san meant. If you can examine the dimensions of the wrecked piston, you'll know how much skirt needs to be shaved. "Sanding" might require patience if you mean a square of paper. Perhaps this is a good job for a die-grinder or Dremel?

[devenex]

Is nobody else going to raise concern over the 7:1 gears?

Can the stock bore with a ministroker crank really push that ratio?

[Wheelman-111]

Greetings:

I had 7.97s and the scooter went 69.9 with the ZX trans.

Installed the 7.58s and really don't notice much difference except 0-5 MPH - until the clutch hooks up. Top speed so far in the 68+ range without ideal conditions or duration. I expect about the same top end with these - maybe a bit faster Down-wind.

I imagine 7:1s would be still slower on take-off, but the Magic of the Variator makes it all balance out once underway. The extra Grunt of the ministroker might help a bit even there.

[HELLAFLUSHED!]

okay so the piston is all good now. I sanded the skirts of the piston and now it can function regularly.

But now, i have another problem... When i crank my bike, gas isn't feeding into the lines and carb. So i suck on the line to get gas into it, and i start it. It started up but only stayed on until the line ran out of gas. So even though my motor is running, gas is still not flowing through the lines and in the carb. By the way, this bike is an arnada, so the gas tank is under the floorboard. What could the problem be? Theres 3 holes on the fuel pump right? 1) The one that connects from the gas tank to the fuel pump. 2) Fuel pump to the carb. 3) Vacuum? ....Where is the best place to hook up the vacuum? Cause right now it has a hose but the hose is plugged. Could that be my problem? Suggestions...



Sorry, im still a newbie. And still learning. Thanks!

[Petrock's 1984 Spree]

I had this problem too. You need a downward slope in the line for it to function

the vacuum opens the petcock but doesn't necesarily suck the gas into the line. Get a negative slope in the line and try again. That fixed my problem

[HELLAFLUSHED!]

My friend from quickfix told me to connect the vacuum to the nipple in the block thats located by the starter. I heard that the fuel pump needs a good vacuum in order to function, maybe that was why... because the vacuum line was pluged and wasnt connected to anything.. it was just plugged with a screw and thats it. I already connected it but i cant start it yet cause i need to get me a new mushroom gear for my kicker, but i will keep you folks updated. Thanks again!

[spree-rider]

HE HAS A FUEL PUMP

[HELLAFLUSHED!]

Okay, so now the fuel pump works good now. I have one more concern, what difference does a stock bore and a 66cc bore have? Can you feel a little difference? Or theres not much difference? Im thinking of running a 66 bore that my friend has. It's brand new. I would rather go to a 72 bore but im low in funds at the moment so hopefully in the near future ill swap it out, but in the meantime is the 66 good?

[HELLAFLUSHED!]

Still wondering about that 66 bore stuff! ^^^



...but i've also got another concern. Im currently running a stock bore with a PG long, 28oko, 7:1 gears, kelli pulley, SEF ramp, koso clutch, 1500 center spring, 2000 clutch spring, and idk whats my weights. ...But what could be a good setup of weights that i could start with for good tuning on this stock 50 bore.

Also whats a good setup for my springs? Im thinking 1000 center w/ 2000 clutch springs. Im currently running 1500 center w/ 2000 clutch springs. Any other suggestions, as well as suggestion for the weights? Any advice will be greatly appreciated. Thanks!

[bakaracer]

the gears are way to much. even for a 72cc setup. look to getting 8to1 or 8.44to1 gears. you wont top those gears out with that setup. not enough torque to get it up to speed plus your just going to wear parts fast and burn stuff up. as for the pipe, try and run a stock or close to stock pipe. that pg long is really more for 80cc bores or bigger so you will loose even more torque by using it on your stock bore.

[HELLAFLUSHED!]

ok, thanks for the advice. Howbout a V8 copy pipe. Will that work for now?