Stumped- Jawa Babetta

Hi, everyone. I recently got a 1979 Jawa Babetta from my grandfather, in the hopes that I could get it to run. However, Ive worked on it quite a bit, and it still wont run.

So far, I have:

1) Made sure I have gas flow. (even gets into the chamber, then seems to leak out exhaust port-not pipe)

2) I have spark (nice big blue one)

3) I have compression

And yet, the moped wont run. It DOESNT have a CDI, and the points seem to be mounted on a ring on the right side of the engine (under a cover). Are they misadjusted? (these are NOT the kind of points that come apart then close again). It seems that its a ring with a rotating cylinder inside of it. I cleaned those with carb cleaner and 600 grit sandpaper, no luck. Ive never dealt with two-strokes before, and have no idea what could be wrong. I even pedalled it downhill (no tailwind :) but to no effect. Any suggestions are welcome. Finally, some suggestions may be things ive already tried, but forgotten to mention.

Thanks,

Conal.

p.s (sorry, no pics....need to take some)

Re: Stumped- Jawa Babetta

Have you tried cleaning out the carburettor? Maybe one of your jets is clogged (they are not very big, it doesn't take much). You say you've never dealt with 2-stroke engines before, did you mix 2 stroke oil in the gas (about 2.5 - 3 oz per gallon)? Have you read Freds guide? Click on recources, then articles, then freds guide - Its pretty much the online moped bible and covers tons of stuff that might be wrong.

Re: Stumped- Jawa Babetta

Yes, I cleaned the carb (both jets) and the gas flows freely. It does get into the combustion chamber. Ive mixed the oil to the right ratio, and downloaded freds guide (ive gotten this far due to it), but im still stuck. One of my dads's friends (whos a mechanic) was over today, and he said theres no reason why it shouldnt run. He tested everything on it he could think of, pedalled like crazy up and down the street, but to no effect. Its really baffling. Thanks for all those suggestions. he did say, however, that maybe the spark wasnt "hot" enough. How would I go about checking this?

Thanks,

Conal.

Re: Stumped- Jawa Babetta

There are no points that "don't open and close".

I don't know the ped so I really can't help.

You didn't say you bought a new spark plug ?(they will sometimes spark outside the cyl... then not inside)

Did you /can you check timing?

Sorry I don't have more.

Re: Stumped- Jawa Babetta

Yes, I did buy a new spark plug (as recommended by a sticker on the bike)...it does spark outside the cylinder, but there isnt a way to check that in the cylinder (is there?). I dont know how to check timing. Hopefully, Ill get some manuals for it in the next little while. I dont even know where the points are. Ive practically had the engine apart, and havent come across anything that seemed like they might be the points. Ill try to take some pictures and post them here, to see if that helps at all. I thank you for all your input, its much appreciated.

Re: Stumped- Jawa Babetta

Well it seems like a long shot but have you tryed running it without the exhaust on? seeing as how the gas doesnt come out of the exhaust, only the exhaust port. maybe the exhaust is clogged?

Re: Stumped- Jawa Babetta

yeah, thats a good point. when I took the pipe off, (and cleaned it off a bit) I was able to blow through it. I also got my brother to put his finger over the end of the pipe -while I pedalled- and when he took his finger off, there was a steady hiss of air escaping....so, could the pipe be too plugged for the engine to run, but still allow some air through?. Id also like to be able to take the pipe off, but when i try to do so one of the nuts/bolts holding it on just rotates. Ill try and get that fixed (or, more likely, have it done).

thanks again,

Conal

Re: Stumped- Jawa Babetta

Conal...

There is a fairly thorough guide to basic moped troubleshooting here... click on 'resources'... then 'articles' ... then "How to fix your Moped".

Re: Stumped- Jawa Babetta

Yes, ive read the guide and printed it off....thats how Ive gotten as far as I have. Thats your guide, is it not? Thank you. Im going to go out and see if I can remove the flywheel to get at the points - I thought I'd done this, but I havent...however, the flywheel is really on there, and its reluctant to come off...Im going to go "persuade" it with some big wrenches....I think this is the source of my problem. If I fix that, I should be set.

Later,

Conal.

Re: Stumped- Jawa Babetta

This a set of breaker points sitting by themselves.

You will find them inside the flywheel on either the right or left side of the motor.

(the flywheel spins as the motor runs).

<IMG src="http://www.classiccarpartsfinder.com/images/AL4038MV.jpg">;

Its hard to see the actual "points"... they are two little round pads that are right tight up against each other in this photo... they are above and a little to the right of the 2nd hole from the left end.

The long straight arm is what moves and opens the points.

Re: Stumped- Jawa Babetta

Well you don't have to remove the flywheel to get at the points... you clean them thru the small holes in the flywheel.

The guide explains how to do that.

(yes its mine.. thanks)

But the points are working if you are getting spark... it won't hurt to clean them though.

You have to slowly spin the flywheel to see the points open.

Re: Stumped- Jawa Babetta

Hmm....would there happen to be 3 of those, possibly arranged in a triangular pattern? (and, there are no holes in the flywheel....I did have to take it off) I found 3 things that looked like that when I took off the flywheel cover...connected with springs. I noticed that they all open outwards at a certain speed, so could this just be the engaging mechanism for the engine? (once it gets to a certain speed, it begins to turn over). I will try to take pics, I promise.....This whole business is rather confusing.... As I said, I have spark, compression, and gas...could it just not be sparking at the right time? Id think that if theres gas in the cylinder, and spark -at anytime- it should run, then get out of time and stop, right? (or am I wrong). Anyway, thank you all for your help...I havent done anything mechanical in a while, and am appreciating this challenge. Ill have a look under the flywheel cover again, and see if I have, in fact, found the points.

Re: Stumped- Jawa Babetta

It sounds to me like you are messing with the wrong side of the motor.

There are not 3 sets of points.

What you described is the centrifugal clutch.

Look on the other side of the motor.

I am thinking you have either too much gas... or not enough... or the spark plug is getting gas fouled from puddled fuel.

Or the compression is not high enough.

How old is the gas?

Or the exhaust pipe or exhaust port is plugged.

Use that guide slowly and methodically...step by step.

Re: Stumped- Jawa Babetta

points are ELECTRICAL devices... they have wires running to them.

Re: Stumped- Jawa Babetta

gimmyjimmy /

fred, could it be the points?

Re: Stumped- Jawa Babetta

What if his float is not floating, wouldn't that flood him out and create this situation?

Re: Stumped- Jawa Babetta

yes.. you can take the float out and drop it into a pan of gas and see if it floats

or shake it and see if you hear/feel gas inside it (not supposed to)

Re: Stumped- Jawa Babetta

I think it is the alignment of the planets

Re: Stumped- Jawa Babetta

Well, it is a full moon at the moment.......

OK, the float floats, and the gas is brand new. Gas flow/amount seems OK, according to a mechanic (who races go-karts). On the side of the engine opposite to the flywheel, there is a collar with coils that fits around a large shaft with magnets embedded in it. I know this is the generator. So far, I have not been able to find any wires that lead to points. There are no wires sticking out of the engine anywhere else...the points would presumeably have wires running to them, but I have not found any wires I cannot trace to other things (lights, horn, etc). Is it possible that I have a different type of points from those that you describe? I will try and post pictures tomorrow.

Thank you all,

Conal.

Re: Stumped- Jawa Babetta

First off your Jawa does not have points or a condenser it has electronic ignition. You mentioned that you had cleaned the rotor with carb cleaner and sand paper. Did you get any of the carb cleaner on the coils surounding the rotor? If so you may have stripped the varnish insulation off of them. You said that you have spark. Did you test this just by laying the plug against the cylinder ? If so that may not have been enough. Do this instead. Remover the spark lug cap (the Jawa does not use a supressor cap) then with the spark plug still installed hold the spark plug wire about 1 mm away from the spak plug terminal and crank the engine. You should see the spark between the wire and the plug terminal. That is the best way to do it because it takes into account the added resistance that the engines compression will add. The best to check for the float is to place it in very warm water and hold it under for a while. The warm water will cause the air in the float to expand and any rupture in the float will easilly be visable as the air bubbles escape from it.

Chris

Re: Stumped- Jawa Babetta

Hmm...well, the condenser is the cylindrical thing that the spark plug comes out of, right?...it has one of those...I dont know what it could be besides a condenser. What do you mean by electronic ignition? I have to pedal it to get it to do anything.(lights, horn)..it doesnt have a battery, or a turnkey ignition...I dont think I stripped any varnish off of anywhere, because the lights still run and I get spark (if what youre implying is that by stripping off a coating, I killed the generator). I will try that method of testing for spark (yes, the way i did it before was to touch it against the cylinder head)...and the float does not leak.... Anyway, as I said, Ill try to post pics here, to see if you can spot anything Im missing...I really am stumbling blindly here...thank you all for your help and suggestions, Ill see what happens tomorrow...

Conal.

Re: Stumped- Jawa Babetta

As promised, here are some pics.

104-0415_IMG.JPG

Re: Stumped- Jawa Babetta

This is that part of the generator I was talking about (the one I cleaned) all wires running to/from the engine go to it.

104-0414_IMG.JPG

Re: Stumped- Jawa Babetta

The collar removed. The brush (?) in the middle here only contacts once every revolution, with a single magnet. I cant really see a way of getting the shaft out of there...it doesnt unscrew (or at least, not easily) and it doesnt pull off.

104-0417_IMG.JPG

Re: Stumped- Jawa Babetta

The entire assembly. If any of these pictures need clarification, just ask (I didnt know how to put all the images in one post). Thank you all for your time. All the wiring on the engine comes from the generator, goes into that black box, then works its way across the bike to the lights, horn, condenser, etc. Hope these pictures help clarify things, or make you think of another good reason preventing me from enjoying this bike (at the moment). Im Canadian, and its Thanksgiving here, so have a nice Thanksgiving (or Columbus Day) if you're in the States. Also, if you think the pics are too out of focus (or you notice something of importance in the background) let me know, and Ill try to get a better shot of it.

Thanks again,

Conal.

104-0419_IMG.JPG

Re: Stumped- Jawa Babetta

... if you are getting a nice big blue spark from a CDI (CDI's don't have points).. then forget the ignition (and timing)...

Any solution is in that guide... most people chase their tail around and around because they don't follow the instructions in there.

it's either not enough compression... or too much fuel or not enough fuel... or a clogged muffler or exhaust port.

Re: Stumped- Jawa Babetta

Ok, so are you saying that the bike has a CDI ignition then? (I honestly have no clue as to what it may look like). So, if it does have one, that simplifies everything. Ill just have to keep looking for whatever it is thats not letting it start. Ill read the guide again and see if theres anything I missed....the only things I can think of are that I dont have enough compression (there seems to be a lot) and that the exhaust pipe is too constricted-thats my bet. Ill keep you all updated though, in case anything else comes up.

Thanks again,

Conal.

Re: Stumped- Jawa Babetta

Man, do I ever wish I had caught this tread before this morning.. I just got my 1978 Jawa Babetta going yesterday I've been through all of these headaches trying to get it going allready. I just watched Momento so heres THE FACTS:

1. when siting on the saddle to your left side is the clutch, don't take this appart unless you have an hour or more to put the springs and arms back together.. From what I've read you don't have any issues with your clucth..

2. when sitting on the saddle to your left side is the coil (it looks like a can of V8 juice) it is powerd by your magneto which is the round thing with the magnets and wires that was under the black cap held on with the wire

Now.. I read your domain and it appears your in BC .. if that's true, is it cold out yet? I know it is here in NB.. due to this the only way I can get the ped to start and idle is to turn the air screw all the way in, set the choke and then pedal it.. if this works for you and it does start to turn over for a sec.. carefully without twisting the throttle (this will open the choke) push the ped back to wherever you're working on it and let it idle for a couple minutes.. then carefully turn the air screw out 1/2 turn.. let it idle longer 2-3 mins then use the trottle and try to rev the engine.. if this works.. go for a ride!.. if not start over (its the only method that works for me after dark when its too cold 5celcius or so) oh yeah.. the air screw in in the hole in your left faring right behind the choke button.. good luck .. If you do get it going let me know what your flatland top speed is.. mines hella-slow at about 17mph tops

Re: Stumped- Jawa Babetta

Hey Conal, try these 2 simple things. First, go out and buy a new light bulb for your brake light. Put it in, then try to start it. Some mopeds will not start if the brake bulb is blown or damaged. (plus if this is the problem, its a $1.50 fix)

The second thing is make sure the breather hole on your gas cap is not clogged. This can cause the ped to run poorly or not at all.

Re: Stumped- Jawa Babetta

OK, thank you...Ill try that when I get home. It is getting kind of cold here so that could be the problem. Also, does this bike have a CDI ignition?

Later,

Conal

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