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Actually most (all?) of the 4 stroke scooter CDIs use a "wasted spark" system where it is basically a 2 stroke cdi in that it fires once every rotation.

You can wire a "4 stroke" CDI to a 2 stroke bike and it will work in most cases. Its not like there is some mechanical physical difference between the two besides the wires/harness.

I can't say whether that particular CDI is good or not, just saying.

As to why 4t parts are cheaper even though they are more intricate/breakable is because of something called economy of scale. In many parts of the world (especially Asian/third world countries) new 2 strokes are outlawed or heavily restricted because of emissions.

So while the Chinese factories crank out 4 stroke bikes/parts by the millions and choke our junkyards with their carcasses, the few 2 strokes they make either go to Europe or a dew lucky people in America.

Its like at least 10-1 4 stroke Chinese garbage to 2 stroke passable Chinese fun.

Most of the 2 stroke kits come from Taiwan or preferably Europe. ALL of the 4 stroke garbage comes out of China.

However the CDIs, 2 or 4 stroke, all come out of China and are pretty much the same thing.

I have bought some Malossi CDIs with honest to god performance capabilities and it is really noticeable on kitted set ups, not so much on stock stuff.

Can I just take a moment to say, "ATM, hahaha".

Sometimes you get lucky on Chinese 4 stroke 50s, sometimes you really really don't.

Its like Russian roulette but with your wallet.

Personally I wouldn't sweat it too much about the electrical thing.

Thing is why I (and most professional scooter shops) wont work on the 4 stroke Chinese 50s is because its way too easy to break stuff while trying to diagnose/fix something else.

Oh the plastic shattered trying to get it off, oh that tapped hole in the frame just stripped out trying to put it back together, etc. etc.

My advice is if it isn't really truly broke, don't fix it, because there is a good chance you will muck something else up trying to fix it.

Yeah probably .97 cubic meters when paired with a certain crank shaft.

Thats pretty massive.

How are you going to bore the case?

I have done it on mopeds before where you buy a grinding disk (the size that will equal your case mouth) for a drill, chock it into a drill press, secure the case and slowly work your way through it.

Seems like it would be way harder with a scooter case though just because they are not symmetrical.

Running the stock carb on a kit that expensive is like putting pearls before swine.

Also I am going to go ahead and say your jet is way lean. Upjetting 3 sizes for all that stuff is way too small.

If you don't want to spring for the bigger carb/intake upjet. A lot. And do your plug chops because I can guarantee you will seize that kit on an main jet.

3 sizes is like what you up jet for winter or a performance pipe or something, not 50% increase in displacement. I

For a performance pipe you are going to look for anything labeled for a Yamaha Zuma.

You can find them on ebay used for fairly cheap, like $50 or so.

A little throttle for starting is normal, especially after the choke cuts out.

As far as the brand goes its no big. They are all the same thing from the same factory.

That plastic metal painted piece should just pop back in if its the one I am thinking of, it has a bunch of little holes in it, yeah?

For 2 stroke engines I like top break them in with crappy chainsaw 2 stroke oil. Lawn boy or something from the gas station with a picture of a weed whacker on it. No I am not joking.

Then after a couple hundred miles switch to amsoil saber but I assume you are going to run oil injection so just whatever you can find at your local auto parts store with the words "synthetic" or "semi-synthetic" on it.

Thats a pretty good bike for the price.

Most of the "Chinese crap" label comes from the 4 stroke 50cc engine being just too complicated to manufacture cheaply so the Chinese cut corners and end up with a bunch of moving parts that can fail.

A 2 stroke engine is so much more simple that the possible points of failure (PPF) are cut to a fraction.

I know my way around Chinese scooters and truthfully most of the components are fine. Forks are nice, brakes are good, mag rims are fine, etc.

Thats that overly complicated under powered 4 stroke 50cc engine that screws them.

Ah that bracket idea is a good idea. I was thinking maybe drill a hole in the stump and make a bracket there but it would be way more sturdy where you point it out.

Here is what the rest of the bike looks like.












Less than 2000 miles.

I really like these long case QJ 2 stroke Minarelli clones. They are the poor mans Zuma. They are fast and performance parts are everywhere for cheapsies and if you kersplode them its no big deal because they are cheap and easy to work on.


Dude wants $100 and has a clean title so I reckon its not a huge gamble either way.


Thanks for the advice there Alley.

Yeah dude you never want to see in oil injected bike leaking 2 stroke oil.

Maybe even just switch to premix if there is even a question of oil being delivered.

Did your new top end have better/different porting than your old top end?

If so its possible you are running lean and need to upjet.

The other thing that is common when messing about with these 2 stroke Chinese scooters is the air box hose/hoses not being air tight and leaning out the mixture.

Just do your plug chops.

Sounds to me like you are lean and either need to upjet on account of better porting or there is air sneaking in somewhere and leaning you out.