[ProDigit]

Carb adjust

I now remember why I told myself I'd never buy a Chinese bike again.
Somehow, I believe the Chinese have spent billions in research, on how to discourage people to rejet the carb.
The whole process is nearly an impossible task, from tools to space issue to taking all tuning away from the bike. IMHO it's the bike's first real flaw. A carburetor should be easily accessible, and adjustable.
This was anything but.

By default, my idle jet was rich. At around 25-75% throttle, it was lean, and very lean at higher RPMs, resulting in lack of power and top speed.
But overall the jets were set up pretty well, had I lived in a colder area, at higher elevation.

So I decided to take out the stock carb, and rejet it.
Little did I know I'd be spending nearly 12 hours on that job.
First to get the carb out, without trying to remove the plastics, was possible, but damn difficult! From issues like 'no space to maneuver', to no space to take the bolts off, to needing a long wrench, to needing a very short wrench...

I had to cut the hose clamp on the airbox, to get it off.

I had seen a video where a guy used a dremel to create a slit in the bottom bolts on the bowl, to get them off with a flathead screwdriver, however, my bike is 2 years newer, and the chinese had devised more trickery to make this job impossible.

First, they lowered the screws, so you'd have to significantly damage the bowl.
Second, they added hard steel inside the copper screws, not even my hard steel dremel could get through it.

Third, they added some plasticky goop in the idle mixture screw, that's not easy to drill or pry out.

So rejetting the stock carb wasn't going to be possible.

On a positive note, I did end up buying a PZ27 carburetor, and was able to transfer the a/f screw to the oem carburetor.

Why did I do this?
Because getting that carburetor to get in and out of the bike was a bitch.
I had to remove the left and right fairings to get some chance of success.

And the fairings is one reason I never wanted to have another chinese bike.
It's a 99% guarantee, either something will break, you'll lose some clips, or are left with a bolt or two...

Anyway, I put the stock carb back in, but not after removing the choke valve.
I only did that, because in my opinion it restricted airflow.

I used the OEM carburetor because I wasn't going to do another carburetor adjustment, the plastics wouldn't survive that, and I just don't have the time for it.

After reinstalling, I could play with the AF screw, and had to either go with the stock setting (AF screw all the way in), idle rich, top end lean,
Or, run it very rich at idle (bogging), and stoic at top end.
Running rich at idle isn't too bad, it'll help cool down the engine at a light.
And since I'm not using the bike as a hooligan bike, quick starting from a stop wasn't my main goal.
But making the bike a hoot to drive between 3-7k RPM was really my main accomplishment today!

I did make the mistake of adding 2 washers on the jet needle. I should have gone with one. This is probably why it bogs a bit.
To compensate for an overly rich idle (without the ability to adjust the jet), I increased the idle RPM, and set the AF to a happy medium (where the RPM dropped from 2K RPM at AF closed, to ~1500RPM with AF about 1 1/4 turn out.
This is against carb tuning guidelines, but the only way for me to get the bike to run well everywhere except for at starting. Idle still runs ok, but the first few percent sometimes bogs the bike to a stall. The hotter the bike is, the less the issue happens, it seems.

Once the bike does 2-3k RPM it pulls like a horse!
It pulls free to 7k RPM (with the OEM PZ carburetor), without me feeling like it's losing power!
Not sure if that's because of removing the choke valve (In Florida I won't need it, and the bike runs very rich anyway), or if it was because of raising the jet needle by approx. 2mm.
The good thing is, that the jet needle is accessible (somewhat), and I could in the future, just remove one of the washers, to lower the needle a bit more.

Also, as a result of not running as lean anymore, the exhaust is much quieter.
No longer that non-stop hollow droning during the rev range.

I did not have the impression that the airbox in some way was restrictive. The air intake is about as wide as 4 of my fingers.

The exhaust may be though....

Since I can't adjust the jets on current carb, I will try to do a top speed run with stock exhaust, then use an after market exhaust, and then do an AF adjustment with the new pipe.

If the new pipe will make my bike run even more rich at idle, and bogs it down or causes hard idling (even with AF screw fully in), I will keep running the stock exhaust instead.
If idle is the same or better with the new pipe, I will adjust AF screw to get better top end.

I wasn't able to do a top speed run yet, but will do so one of these days.

If I had to give this job a rating from 1 to 10 in difficulty, I'd say this is an 8.
Not as difficult as replacing camshafts, or swapping out engine bearings.
But certainly not a job for the average joe. And not because a carburetor is difficult, but because the bike was engineered to never take the carburetor out at all! There's no space, no ease of access, to get that thing in or out of the bike.