Adjusting carburettor

Hey,

Recently I got interested in mopeds and I got a cheap one in December (€ 100).

I bought a Jawa Babetta.

I have / had very little to no knowledge about mopeds, but with the help of the information on this forum, I have restored this moped, which actually no longer drove.

After I replaced the fuel cock and cleaned the carburettor, the moped started running again. Only the rear wheel kept turning at idle speed. In the beginning this did not bother me and after a lot of sanding (rust) I drove around with the moped like this.

A few days ago when I tried to adjust the carburettor by turning the screws and the throttle cable, the engine stopped. I visited the forum and watched a lot of YouTube videos, but due to my lack of knowledge I couldn't get the engine running.

Could someone please help me and tell me how to adjust the carburetor and throttle cable so that the engine runs well again?

Thanks in advance.

Attached you will find a photo of the moped and a photo of the carburettor. I tinkered with all circled things.

jawa.png
carburator.png

Re: Adjusting carburettor

Green and red are throttle. I believe blue is the air mixture screw. Did you touch the blue? If so you gotta try to figure out where that screw needs to be adjusted and leave it there

Re: Adjusting carburettor

if you get your eyeballs down near the carb about 5 inches away from those screws you need to look real close at the bolts and thread and look for clean vs dirty part of the screws and be able to see how close they were! Adjust them to the original positions. Its not difficult.

Re: Adjusting carburettor

this must be the cleanest jawa ever

Re: Adjusting carburettor

@khool1499

Thank you for your quick reply. I've touched all three circled things. I have tried several times to adjust the screws, but I still can't figure out the right solution.

@marcalan47

Thank you for your quick reply. I have completely removed the screws to have a good look (see attachment). I cannot distinguish between the clean and dirty part.

@ggspeed

Thanks for the compliment. I would like to clean the suspension of the shock absorbers from rust, but I don't know how yet, and then I'm completely done with it.(edited)

bolts.jpg

Re: Adjusting carburettor

Maybe I'm wrong but it looks like there's a difference in oxidation there. The throttle adjustment is less relevant than the air mixture screw in getting the bike to run

moped army.PNG

Re: Adjusting carburettor

Put both back in and then turn them both all the way in till they bottom out. (not super tight). Then back both out 1 1/2 turns. Remove your spark plug and crank on the motor for a while to dry out any excess fuel that might be sitting.

Put the plug back in and try to start normally. Avoid using the choke at this point and just keep trying to start it by cranking.

make sure the switch is on

Re: Adjusting carburettor

Thanks a lot for the tips! After a few attempts of turning the screws in and out, the moped started running again. The rear wheel continues to rotate at idle speed. Is this normal?

Finally, I have two more questions that I cannot find an answer to.

Question 1: How can I find out what the year of construction of this Jawa is? Or just the exact name of the moped. Attached you can find a picture of the steering head. The rack behind the saddle says 'Lux'.

Question 2: Can I do something about the rust on the suspension? Repainting or placing some kind of foil over it?(edited)

Jawaa.png

Re: Adjusting carburettor

> Tom VB Wrote:

> -------------------------------------------------------

> Thanks a lot for the tips! After a few attempts of turning the screws in

> and out, the moped started running again. The rear wheel continues to

> rotate at idle speed. Is this normal?

Yeah.

> Finally, I have two more questions that I cannot find an answer to.

>

> Question 1: How can I find out what the year of construction of this

> Jawa is? Or just the exact name of the moped. Attached you can find a

> picture of the steering head. The rack behind the saddle says 'Lux'.

It's a Jawa Babetta 210

> Question 2: Can I do something about the rust on the suspension?

> Repainting or placing some kind of foil over it?

You can buy new shocks, they're cheap enough that it's not worth the hassle of trying to disassemble and paint those.

Re: Adjusting carburettor

> Nick Haber Wrote:

> -------------------------------------------------------

>

> You can buy new shocks, they're cheap enough that it's not worth the

> hassle of trying to disassemble and paint those.

Just wire brush the complete shock and paint it all one color . Done , cheap and easy .

I did exactly that to my FA50 shock . Looked great until I had to replace it due to being blown .

Re: Adjusting carburettor

Carb info from the manual. If you are all stock including all the air filter hardware, all passages are clean in the carb and no air leaks it should tune in nicely. You should make an honest 33mph mostly stock.

5. Carburettor (Fig. 21)

The moped is fitted with the JIKOV 2912 DC

carburettor with the following parts and adjustments :

Main jet 63

Idling jet 35

Needle valve

- needle position 2nd notch from top

Fast-idling screw 540º (1 to 1½ turns)

Routine maintenance of the carburettor includes its

removal, flushing and swilling with clean petrol, and

blowing through with compressed air. Clean the jets

only with petrol (or acetone) and compressed air, never

with lengths of wire or other hard objects which are apt

to damage the calibrated holes.

To give the carburettor a thorough overhaul, proceed as

follows:

1. Remove the carburettor from the engine, take it apart,

and clean its parts thoroughly.

2. Discard worn parts and replace them with new ones.

3. Check the flatness of the flange and true it up if

necessary on an abrasive cloth stretched on a flat board.

4. After trueing up the flange clean the carburettor body

thoroughly once again.

5. Check the jets and adjustments for compliance with

the recommended values.

6. Adjust the needle and the fast-idling screw as

recommended and reassemble the carburettor.

7. Refit the carburettor on the engine. Start the engine,

warm it up, and adjust the richness of the mixture by

means of the air-correction screw. Then adjust the

idling speed (from 1,600 to 1,800 r.p.m.) by means of

the stop screw, and the needle valve and the free

movement of the twistgrip by means of the throttle

cable guide.

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