KTy

Whoa.... I didnt know about these new (possible) issues.... Damn' f**** Zirri... :grr: :puke: That's why the other 4th gear we talked about should *much* easier to install !! :love:

Ok, so I think I got it. The gap between 3rd and 4th is already larger than between 2nd and 3rd, so I think it's the good side. I will try with a bigger bottom spacer to make the cruciform and the 4th gear almost at the same heigth...

Did I read that you have the same maximum achievment only that the 130-190 engine was shifted to more high revs ? :plemplem: I must learn german...

I did what you say, starting from 1st gear and making sure the cruciform rest correctly in the grooves of each gears... And I end up this way ! I should double check this... The problem is, I think, if I put a shim to minimize the play when the cruciform is in 1st, 2nd or 3rd gear, when I will try to switch to 4th, the cruciform will push on the shim... I think that the cruciform MUST NOT be higher than the gear... I would appreciate other comments...

Good night Two questions related to the following picture: 1. On the right: There is something like 1 or 2/10mm of difference height between the short 4th and the cruciform; The cruciform is higher... Does this means the bottom spacer (the one close to the 1st gear) is too thin ? 2. Left: I'm not sure you can see it well: The cruciform is only 500km (I had some trouble with my gears in 3rd and 4th) but already it is not "square" anymore, it's almost like a trapezoid now ! Poor quality pictures (blured :puke: ): http://ktylife.free.fr/vespa/KTy133/DSCN2483.JPG http://ktylife.free.fr/vespa/KTy133/DSCN2484.JPG http://ktylife.free.fr/vespa/KTy133/DSCN2485.JPG http://ktylife.free.fr/vespa/KTy133/DSCN2486.JPG 2.a. Should I change it ? 2.b. Is the "reinforced" zirri cruciform really worth it ?? Thanks guys KTy -

So, as far as I can tell, it is a totally different configuration, so I think it maybe related to your multimeter... If you have the chance to plug an oscilloscope, I would be interested in seeing some curves... As for the dyno, normally I have an appointement in 2 weeks time ! :sabber: I will have lots of stuff to measure !

Oddly enough, a friend of mine had the same issue... I can only think that this is caused by a weird signal (not sinusoidal at all) from the stator. What are the exact models of rotor/stator and CDI unit ? I will ask my friend to see if we can find some related facts ! EDIT: He has a PX200 from 1995 rotor and stator and the blue Ducati CDI...

Oki doki... 'will try !

Hey, I'm looking for target values for these parameters (and more !) for common application (like, road, enduro, cross engines...)... Thanks ! KTy - :wasntme:

What do you have to do to mount a cosa rim on a smallframe engine ?

HUm... Well, at first I thought tacho was exactly a speedo, but I read some definitions and a tachometer is the speed of a rotating engine, so this might have confuse you also ?! :wasntme: Anyway, sorry if this topic was about speedo...

Alloha I have (re)design a simple and cheap tacho with 20 LEDs display pdf: http://ktylife.free.fr/vespa/compteur/SimplestTacho.pdf Inspired from: http://ktylife.free.fr/vespa/compteur/CompteTour%20web.htm (Note, in this old circuit, R7 is useless and R1 = 2.2k) Now, you only need 2 wires connected to any working bulb of your scooter ! R2 is a variable resistor, it is used to calibrate the system. C9 and C10 are optional, only needed if LEDs are distants from the LM3914 or if LEDs are "flickering" too much even at mid-rpm. I have successfuly tested it on my PX and on a 6V Sprint Veloce. It should work with any engine that generate AC voltage, from 3VAC to 25VAC ! I'm pretty sure it will be rather easy to integrate below any speedometer or anywhere else ! Have fun KTy -

What are the cheeks width and shape ? (In order to be used with direct inlet into crankcase like on the following pic) Any previsional delay and price ? Impressive work :sabber: !

It's probably easy to adapt. The pickup on vespa is a small positive signal of ~1V that is about 1ms long. You will maybe need to protect the input of this unit as the vespa pickup genrate also negative signals down to -4V. Interesting indeed, and not too expensive :) But if you want to go even cheaper and with the same functionalities, check here: http://transmic.net/gbindex.htm http://transmic.net/dc628.htm

Exactly It's a simple way to use the negative alternance of the signal ! No magic here... Dyno will tell

@kan_Kuma: First, it's beetween GREEN and WHITE (ground) , and yes, it was measured on two differents PX125E engines running for true :) Actually, the important thing is, what I measured was below 200VAC (about 170VAC), to ensure that after the modification, the engine won't deliver more than 350VAC (because there is a 400Vpp inside the Ducati CDI). Adding the diode and the condenser makes a voltage-doubler, but with only 3 periods (the flywheel has 6 poles) to charge the condenser before the spark is ignited, it is not really doubled, it's about 60% more. As I only increased the voltage of the capacity (I didn't change any resistance), the spark is probably longer while more than doubling the energy (E = 1/2 . C . V²)! I'm not saying it's risk-free, but for me, it is worth trying I think the main reason why this trick is working (at least for me !) is that the Ducati CDI was not design specificaly for vespa, so it is over-rated compared to the stator :wasntme: @minikin222: It has to do with my french accent...

hum... Yeah, the more I think about it the more I think it can actually do something :) It's like a condenser, indeed ! Thanks

Unfortunatly, I cannot guaranty that it will work perfectly :wasntme: BUT, as far as I know, the "only" thing that could happen is that you blow the CDI unit ! :haeh: And another important point; the voltage is *decreasing* with the rpm ! So there is nothing to worry for the CDI at high RPM. The maximum voltage is usually around 2500-3000rpm. Before mounting the circuit, it could be a good idea to measure the maximum AC voltage that you have between the white and green wire on your CDI unit. Again, if you have less than 200VAC, you're safe, you can try the modification without fearing to damage anything. I haven't made any picture but it's fairly simple, I'll make a drawing ! Have fun Edit: Here you go !

Yes, of course ! Anything that can give you a better spark is good for your engine performance, but it is also better to reduce emission ! I have now several other friends riding with "my modification", they all feel that the engine is easier to start, smoother to drive and it responds better at low rpm... Dyno-test will tell the truth How did you build your "Nology" cable ?

He's right. In normal condition the CDI unit is working "okay". But if one can improove spark energy at all rpm, then the engine will start better, have less emission and probably (we will see ;) ) be a little bit more powerfull...

I'm not sure I have understood what you meant, but I will have some dyno with and without condenser to see if it's really of *any* use...

Well, I guess so, but even if it's not exactly the same, it should be *very very* similar The basic idea of the condenser and the diode is to use the negative aternance of the charging coil. Because in normal operation, only the positive alternance is used, it's "a waste" !

Not so many people seem interested in this kind of project... ( Anyway So, I've made some datalogging with multiples configuration (condenser, vCDI or not,...); All blue curves are taken between the white (ground) and green point in the above schematic. What I can say is: * On a stock engine with *my* variable ignition timing module + a big condenser, spark energy is increased by 40% ! :) I'm looking forward to compare on a stock engine on a dyno without condenser, without a vCDI module, and after with vCDI module and with a condenser... There could be some nice surprise :wasntme:

Alloha, To make a long story short, 1. I looked at the specification of the ducati CDI, the important part is the maximum voltage of the condenser: 400Vpp (peak to peak) ! 2. I measured on my stock PX125E between the white (ground) and the green (AC voltage to charge the condenser), ~90VAC (=125Vpp) at idle, and a maximum of ~150VAC (=212Vpp) at mid-rpm (~120VAC (=170Vpp) at 8000tr/min) 3. I created a small electronic module 4. After this simple modification, I measured between green and white a maximum of ~190V (=270VAC) and ~160VAC (=225Vpp) at 8000tr/min far below the 350Vpp maximum input ! So, I've been driving with this little modification for hours, nothing to worry about ! A better spark gives better combustion, less emission, so an *overall* performance enhancement (do not expect +50% !!). Cheers, EDIT 2011: about 250 modules in use ! EDIT 2012: NEW version available ! Order it online www.kytronik.com ! Like us on Facebook

Alloha I was wondering if the bearing on the flywheel side of a PX can be too weak with a "big" engine (35BHP for example) with a light flywheel ? Or is it "just fine" as far as it is well assembled ? :grins: Thanks KTy