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Post by djuganight on May 20, 2015 13:02:17 GMT
Hi Guys, I'm currently planning to upgrade my baby, a Vespa 50s from 1966  I have already ordered a Pinasco 102cc alluminium cylinder kit and a Carburator 19/19 full kit which includes a Malossi air filter. My only concerne here is regarding the primary drives. I know the recommended for this upgrade should be between 24/72 (3.00) or 22/63 (2.86). At closer look, I noticed that all 24/72 have straight teeths and the 22/63 has helical teeths. Which one should I buy for my Vespa or how can I know this without the need of openning the engine? Thanks guys |
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Post by tzsteve on May 20, 2015 17:04:17 GMT
straight cut if you can get the ratio that you want, would be my choice. though in theory the helical cut can last longer and should make less engine noise(i aint noticed a difference ever)
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Post by Juan on May 20, 2015 18:54:40 GMT
I'd use the 24/72, 22/63 is too long for most people unless you weigh about 7 stone wringing wet.
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Post by djuganight on May 22, 2015 13:26:39 GMT
yes they talk a lot about the engine noise caused by straight teeths primary gears.
I have left the "Old Lady" in the garage for the mechanic see what primary drivbe is installed.
I have ordered and all parts are on the way, including a primary gear of 24/72 but if by any chance the Vespa is still equipped with a stock transmission, 14/69 or 15/69, I think I will leave behind the primary gear kit I bought and just swap the primary drive 14 or 15 to a 16 teeths helical.
Wouldn't you think 16/69 would be better than 24/72?
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Post by henri on May 22, 2015 19:06:34 GMT
personaly on a 102 pinasco kit i'd go 22/63 , thats whats on my 130 dr kit an a guys 102 pinasco ive tested , seems fun enuff to me , for it to benefit a 24/72 the kit will need extra work to pull it ,an the right pipe , H
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Post by Tiberius on May 22, 2015 21:25:18 GMT
Sorry Henri but I'm struggling to grasp your logic here, why would a shorter ratio require extra work and "a right pipe"?
It's all swings and roundabouts as with everything, personal choice, put it how you will.
16 tooth added to the very short 50 ratios will be slightly better than normal but not enough for a 102cc in my opinion, okay for a better 50 or even a mild 75 kit, I'd be more looking at 18/67 even then.
Straight cut gears do add noise but it's not like it screams at you, at least whilst we're talking about kitted 50's.
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Post by tzsteve on May 23, 2015 14:42:06 GMT
straight cut in THEORY cause more noise but i`ve never noticed the differance
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Post by henri on May 23, 2015 14:51:27 GMT
i'm crap on the theory ,just in practice ive found the 22/63 to work, was thinkin on a 24/72 an asked my local scoot shop, allstyles in pompey , guy advised against it an pointed at kiddie nxt to me, he'd tried a 24/72 on a 102 an it wouldnt pull it ,was back in buying a 22/63.juans prob got loads more experience with them than me tho. H
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Post by djuganight on May 23, 2015 16:19:52 GMT
Yes, it's an hard choice, specially because for an intervention such as this, requires opening the engine. Not an easy, quick nor CHEAP job.
A guy that races and prepare vespas, also told me that was going to be a mistake installing a 24/72 in a Pinasco 102.
He told me that this is the primary transmission he install when tugging smallframes with 130cc cylinder kits. But he did not told me what would be the ideal ratio. I didn't bought the parts from him, if you know what I mean.... with this mentality I will never will so move on...
But although he told me that, the majority claims that a 24/72 primary is the right choice.
I'm on a dilemma Since I don't want to endup with the need to open the engine again.
Well, the primary gear is to be delivered next week along with the rest of the parts.
Imagine this, If I install the 24/72 and feel the gears extremely long and the 4th gear without power, I can always compensate by replacing the primary 24 by a 21 or 22cog, right?
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Post by henri on May 23, 2015 21:00:29 GMT
not sure on the ability to drop/gain a tooth on the small gear , i'm just use to the advise that gears are always matched pairs , tho i have heard people talkin on doing just that with straight cut gears , i think the deal is on a short stroke crank if just bolting a kit on the engine wont pull a 24/72 , but if more in depth tuning ,matching/gas-flowing/porting/head work is done an a revvy pipe that allows max torque available to be obtained the 24/72 is the best choice ,
its a standard tuning dilemma ,6 of one,half a dozen of the other ,
if only wanting to split engine once n buy 1 primarys ,i'd say stick with the one piaggio found best for a 90/100 cc ,22/63,an a 4 speed box ,thats what i did an it hasnt disapointed me ,yet??. H
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Post by djuganight on May 24, 2015 22:00:14 GMT
Regarding the 16tooth primary, smallframes stock gear, used to be 14/69 or 15/69.
Its general procedure change the primary to a 16 cog primary (helical) for speed gains. Normally it's a gain of 10kms/h in stock engine with 75cc.
Therefore changing this primary gear, for one with less/more cogs will, in theory, make the gearing shorter or longer.
Regarding the 22/63, isn't this a longer gear ratio than a 24/72?
If yes, If won't pull with 24/72 it will be even worst with 22/63...
This is a controversial subject I know.
The parts I bought are as mentioned in my first post.
I don't want a vespa for competition, I want one that rides well and nicely balanced.
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Post by madmax on May 25, 2015 23:52:13 GMT
DRT do a selection of small cogs for the 24/72. However, the 102cc kit should pull them easily.
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Post by djuganight on May 26, 2015 15:57:00 GMT
Thanks.
You meant pull the 24/72 easy?
Also, since I will also be changing the carburator for a 19/19 with malossi air first, what jettings should I use?
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Post by djuganight on May 28, 2015 14:02:14 GMT
just received all the remaining parts today and when straight to the garage to hand them.
Parts looking very good and I'm keen to get that installed to enjoy.
I also received an email from SIP and they have recommend the primary gear 2.56 (27/69)...
I am now even more confuse lololo
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Post by henri on May 28, 2015 17:42:36 GMT
join the club , theres too many variables to say "this primarys" the best , H
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Post by madmax on May 28, 2015 20:18:39 GMT
Thanks. You meant pull the 24/72 easy? Also, since I will also be changing the carburator for a 19/19 with malossi air first, what jettings should I use? The 102 kit should pull the 24/72 easy. The 27/69 are more suitable to 130cc etc... Try a 90 main jet and see how it goes. |
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Post by djuganight on May 29, 2015 16:19:55 GMT
thank you very much. I will keep this updated  Meantime here is a photos of the primary gears 24/72   Don't have photos of the other parts as I took them straight to the garage. |
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Post by djuganight on Jun 4, 2015 15:07:38 GMT
Today I went to the garage to see how the works were going my old girl was like this already:     Prevision is that on Tuesday is already rolling. I can now confir that this Vespa was equipped with the short gearbox version, therefore it as a primary gear of 18/67 and the Input Shaft Assembly is 10-14-18-22. I'm now more confident that the new primary gear 24/72 will work just fine and will pull all 4 gears, yes? |
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Post by djuganight on Jun 8, 2015 14:11:58 GMT
Today I went to the garage to know how are things going. The engine was already washed and cleaned and looking rather nice. I don't know the right word, but the admission was already wider. The mechanic had done this already. Its going to take other new parts inside, since the original ones were too outworn Here some pics of new items.   [URL=http://s1374.photobucket.com/user/Djuganight/media/Varias/IMG_08062015_124511_zps0gignfj   The front shock has 4 or 5 adjusting positions. Most probably is ready to be delivered tomorrow Sorry for my english, but I often don't know the technical terms for things. Regards |
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Post by Juan on Jun 8, 2015 20:17:51 GMT
I've never had a Cif front shock but all the other adjustable types that I've had, SIP apart, have a piss weak spring tension that's easily outperformed by a standard item. I'd advise you to get it off now to test the tension load and put on whichever is the strongest.
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