MOPED ARMY

What do you want out of it?

I think 40 is doable with a pipe/carb and stock kit, maybe ditch the head gasket for a smidge more compression.

REQUIRED ZA50 ROFFMAN NOTICE

ZAs apparently don't like high RPMs so if you do kit it, flip second and gear high. Enjoy 2 gears it rules as long as it doesn't break

Do the transmission pucks + flip second whatever you do

The 70cc treat kit / 14 bing will be good. Ditch the boss pipe for a low RPM pipe like a circuit or estoril. Gear tall to keep rpms down to protect your stock crank. Oh my two ZAs I’m at 19/38 (city bike) on one and 19/35 (cruiser bike) on the other.

Enjoy low to mid 40s without having to even think about messing shims and save $250 on bearings, seals, crank, and another $250+ for the factory shim tools. (edited)

A za50 doesnt need a 70cc kit to do 40. If you regear the rear down to like 38t or 40t. You can make it. Back it up with a nice circuit pipe and you can have some decent low end still. Maybe not wheelie city, but a good top end.

The crankshaft brass bushings on both ends, good luck with your high rpm kit.

They require 500.00 worth of specialized tools. I have some of these tools.

I've been away from mopeds for awhile. I replaced the shift pucks and flipped the clutch. I got lucky and I do have a 1.5/2 HP transmission.

I went ahead and put the 70CC treats kit on it and lightly port matched the case. I put a 15 bing clone with on it that I had and pulled the circuit pipe from my Pinto2. Also put an 82 jet in for break in. It 4 stroked bad. Next size down I have on hand was a 79 so that is what it got.

It ran fine during break in and easy riding. I put about 5 miles on it before trying to go WOT. I got to 33MPH and it sputtered and died. It fired up perfect later that day but died again after a WOT pull. Next morning it fired up and made it about 1/2 mile under WOT before it died. The engine never seized, fuel flow is perfect, carb is clean, I THINK I have a bad condenser. Ran out of time to test it anymore.

I have the cylinder spaced up with some gaskets and the piston clears the exhaust port. I havent measured squish yet, but I have a high compression head on it so I'm sure it's decent. Im trying the high compression since it won't be a high RPM engine. 18x40 gearing right now, im waiting on 19 and 20T front sprockets and 37T rear to come in the mail. Timing is at 16 degrees checked with a timing light.

The Bing clone has a 2.17 atomizer, bing needle, bing top, bing slide, etc. Its just a clone body and bowl.

The petcock, fuel hose, and inline filter are new. The bike stalls out and I immediately checked for fuel. Fuel flow was great.

I'm thinking that the engine gets hot on a WOT long pull and the condenser craps out. Then it cools off and works fine again. I might be wrong, probably am. But I'm out of state for work and can't work on it right now.

Maybe. I havent tried that. I'll see what it does when I get back in town. I just wanted to go for a quick ride and maybe a jet change or two while I was home. I was pretty frustrated when it died.

When it dies, it does not restart until it's cooled off. No amount of starter fluid, pedaling, etc will get it to fire up. No water or debris in the fuel bowl. The 14 bing was doing the same thing so I swapped the 15 bing clone onto it.

If you have points and condenser , replace the condenser .

Quality counts huge .

I got home and replaced the condenser last night. I tested the compression at 215 PSI, so I swapped a different head on and it's now 175 PSI. Then went on a 15 mile night ride. I had no major issues! The silencer fell off of the circuit pipe but that was an easy fix.

It runs great, no 4 stroking, I could probably lean the jet out a size or two judging by the plug. 33 MPH is the fastest it'll go with the stock 18x40 gearing. The speed/rpm calculator show its turning right around 7,000 RPM. Still waiting on 20x37 gearing to come in the mail.

What is the typical RPM for a circuit pipe? I will need to be closer to 9,000 RPM for a solid 45-50 MPH bike. The kit is spaced/clearanced correctly. Using a 15 bing with no filter. Im thinking the intake might be holding it back some. I have two aftermarket ZA50 intakes on hand. They are both round port intakes which I assume is to match up with the stock ZA50 high torque cylinders. I think I have something coming for a square port ZA50 intake and hopefully that'll give me more RPM.

I put the 20x37 gearing on it. And swapped the intake out for a 3D printed intake from Wirth It llc. I ended up with 43MPH.

I still need to convert the wheels to sealed bearings and do some minor porting on the cylinder. I think 45MPH on flat is doable with the circuit pipe.

I wouldn't bother with the carb myself. Get after those wheel bearings, you might be surprised at how much free speed is hiding in there.

You know what helps? Quoting the spam so the link lives on after the post is removed...

Haha, I removed the comment

7k is great, that setup will live forever, you didn't say what circuit pipe, the proma will give you 1000rpm over the tecno, if you have a tecno now. The techno isn't a bad pipe per SE but they have a tendency to shut off abruptly on kitted setups, imo they are best to use on stock only just because they can be weird and unpredictable on different kits.

Dos circuit is basically a proma copy but actually a little better silencer.

I had to crunch some numbers myself because something seems off, I'm running 15*40 on an e50 with the airsal 44, bing, proma GP and topping out at 45=9000 ish rpm. If anything my gears are a little bit too tall, it was good at 14*40 but I didn't like how buzzy it was at top speed.

You should be going a bit faster barring dragging brakes, bad bearings, etc. That pipe should hit peak power around 8k, and you want to be geared so you rev a little past peak power so as you slow down, your bike digs into the power band and doesn't slow down as much.

My original advice a few months ago was to gear that setup for 8500 at top speed, that works out to 18*35 (assuming you have a 2hp engine) that will probably get you the highest top speed and the best accel. That kit should have no problem pulling those gears.

But seriously, if you like it the way it is, nothing saying you need to screw with it. It's just fine and will run for ever the way it's set up now. I highly doubt the carb will help much, it's just too much gear. Since you probably have the 18 (stock) and wouldn't have to break the chain to swap, it might be worth a try just to see if you like it better.