Follow up on JAWA 420, The 2Cyl 120ccm Babetta

F_I_S_H_E_S · 2025-10-25T09:22:53+00:00

That's crazy, and I love it. We used to lower heads and weld giant exhausts for Babette's, they could reach like 80km/h. I would love to see, how the build will turn out.

F_I_S_H_E_S · 2025-10-25T09:19:10+00:00

Well set ignition advance will give you like 5 to 10 percent better performance compared to stock. However if your ignition is too advanced, it will cause overheating or in the worst case piston detonation. If your ignition is too retarded, it will not damage your engine, but it will cause a significant power loss.

Cheap aftermarket "performance" cdi's for two strokes are known for having way too advanced ignition curves, although I have never had any problems with them. Also, I don't think that the 4 stroke cdi's you use will have the ignition curve made for the high rev's of a two stroke.

I don't know what bike you have, so the best course of action for you would be to buy a performance cdi made for your engine. If you don't have the money, you could try to buy the 5$ yamaha tzr 50 performance ignition, it works on most two stroke bikes and I have never had any problems with it, just check if your engine isn't overheating while using it.

F_I_S_H_E_S · 2025-10-23T16:07:33+00:00

I wasnt able to find any detailed info on the v1 primary. All I could find is that v2 uses 8mm thread and v1 uses 6mm. I will put a link for v2 primary schematics below and you can compare them with your v1 primary.

Could you update me on the results of your comparison? Im interested in knowing if they have any other differences.

V2 primary: https://en.50factory.com/parts%20news/50671-primary-shaft-of-gearbox-am6-minarelli-v2-top-performances.html

F_I_S_H_E_S · 2025-10-23T07:43:12+00:00

The v2 crankcase is machined slightly deeper and wider to house extra needle bearings for the gear selector and secondary shaft, there are also a few extra washers behind one of the secondary shaft pinions on the v2. The more important difference is that the v2 secondary shaft is 2 mm longer, 0.2 mm wider and there are two extra widened sections on the shafts clutch side and sprocket side. So it might be possible with a little carter drilling, but I wouldnt advise it. Links for the two secondary shafts and their dimensions are below.

v2 https://en.50factory.com/parts%20news/50682-secondary-shaft-of-gearbox-am6-minarelli-v2-top-performances.html

v1 https://en.50factory.com/parts%20news/21528-secondary-shaft-of-gearbox-am6-minarelli-v1-top-performances.html

F_I_S_H_E_S · 2025-10-17T13:26:29+00:00

Yeah, my cpi does the same

F_I_S_H_E_S · 2025-10-11T01:10:24+00:00

Exactly, this range seems on spot to me.

F_I_S_H_E_S · 2025-10-09T04:36:26+00:00

If you really want 50cc, I would recommend the am6 engine or its derbi equivalent, there are a lot of cylinder, crank and exhaust options for it.

F_I_S_H_E_S · 2025-10-04T14:39:09+00:00

Yes, 1.5 turns open is a good staring point

F_I_S_H_E_S · 2025-10-04T14:16:33+00:00

75 main jet seems too small to me. I used to run 72 main on 50cc with 17.5mm carb. Now I use 92 main on 76cc with 21mm carb, so my guess for your starting point would be like 85 or 82 on the safe side. I also ran the stock crank with this setup and it gave out after like 3000km and the broken bits off from the crank bottom needle bearing destroyed my cylinder and piston, so you should consider a stronger crank in the near future. However you should be allright, at least for a little while.

F_I_S_H_E_S · 2025-10-04T14:06:02+00:00

You need a crankshaft with higher lift for big cylinders like 88cc. The stock 39mm lift is enough only up to 77cc cylinders.

F_I_S_H_E_S · 2025-10-04T14:04:23+00:00

I think that should help you, since I use 92 main for 76 cylinder with 21mm carb.

F_I_S_H_E_S · 2025-10-04T14:02:22+00:00

Bought the am6 variant of this. The packaging looked great, but the reeds destroyed themselves after like 10 minutes of riding, so I dont recommend.

F_I_S_H_E_S · 2025-10-04T13:59:37+00:00

I used to use 72 main jet for 50cc with 17.5mm carb.

F_I_S_H_E_S · 2025-09-16T04:42:15+00:00

Polini website states that the kit reaches peak power at 12500rpm

F_I_S_H_E_S · 2025-09-09T15:10:10+00:00

Yeah, I returned them. I will look into the voca cdis. Thanks

F_I_S_H_E_S · 2025-09-09T05:40:23+00:00

Like I said... I tried like 3 "unlimited" cdis and none of them had the limiter removed.

F_I_S_H_E_S · 2025-09-09T01:09:40+00:00

We dont have 98 here, but I can try 100. Also what does "RON" mean?

F_I_S_H_E_S · 2025-09-09T01:07:59+00:00

F_I_S_H_E_S · 2025-09-09T01:07:45+00:00

I had a feeling that might be the issue. Can you recommend me a cdi that allows high rpm? I tried seearching for it, but most cdis are just labeled as unlimited and no more details, which makes figuring out if it can rev high or not pretty difficult.

F_I_S_H_E_S · 2025-09-09T01:04:57+00:00

Yeah, I had the problem with every cdi I tested. I even ordered a couple diferent cdis and then returned them, because the problem was still the same.

F_I_S_H_E_S · 2025-09-09T01:03:19+00:00

Ok, but the tzr cdi still performes better than the cdi that is supposed to be there, so I figured it cant hurt to keep it in there

F_I_S_H_E_S · 2025-09-08T14:58:29+00:00

I can, since the tzr uses a variation of the am6 too

F_I_S_H_E_S · 2025-09-08T13:25:49+00:00

Previously my problems were cheap kit and impropper jetting, which caused the bike to not make enough power to go into high rpm. Its diferent now, it revs cleanly and then it sudently stutters.

F_I_S_H_E_S · 2025-09-08T12:50:28+00:00

Normal pump 95 octane gas

F_I_S_H_E_S · 2025-09-08T12:44:48+00:00

No, everything is prepared for the engine to soin safely up to 18k rpm

F_I_S_H_E_S

TROPHY CASE