rds
2nd Class Ticket
Posts: 30 
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Post by rds on Apr 13, 2019 17:58:36 GMT
I have been "lucky" enoug" to dismantle a number of Dellorto SI carbs recently and to compare the jets to the Haynes Manual. Few of the carbs have jets that match the listings, naturally.
I have looked in several places but not come up with what I would like, which is a unified resource (eg a spreadsheet table) listing clearly in order of ascending (or even descending) "richness" (I do not mind which way it goes, as long as it is clear and foolproof, nothing fancy) the idle/slow running jet, the main jet (all three pieces separately) and choke jet.
Eg
is 142 richer or leaner than 140?
Is B1 richer or leaner than BE1? etc etc
Can anyone point me in the right direction or have the table to hand please?
Cheers
RDS
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Post by mijapxman on Apr 13, 2019 21:56:49 GMT
rds, if you Google 'Vespa si jetting chart' and look at 'images' you'll find everything your looking for.😉
Mij☺
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del
1st Class Ticket
Still riding a 125. 200 still on bench.
Posts: 82
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Post by del on Apr 15, 2019 18:08:23 GMT
Hello. Main jets are numbered in 100ths of a millimetre. So a 106 jet is 1.06mm bore. A 115 is 1.15mm bore. Sometimes catalogues and my Haynes manual will have it written as a fraction just to confuse the issue so a 106 = 1.06mm = 106/100.
I assume all the other jets air correctors etc are the same measurement. The emulsion tubes however are a law unto themselves as are throttle slides.
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Post by mijapxman on Apr 15, 2019 19:17:12 GMT
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Post by mijapxman on Apr 15, 2019 19:21:17 GMT
Si carb slides here 👇.😉
Also worth a look is Mista freak mopeds YouTube site, in his playlists , under, " carb tricks."
Mij☺
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rds
2nd Class Ticket
Posts: 30
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Post by rds on Apr 16, 2019 0:24:52 GMT
Many thanks to you both there; i did originally do a jetting search. I had hoped the info i would find would be in a simple table for each parameter, in one place, like i have seen for Amal and SU carbs, so that i could easily order eg one or two steps up or down as required. The info on the "image search" results that i did turned out not to be as simple as i had hoped and seems to be a resource for performance tuners rather than getting a dodgy bike back working! Still, the links on the last two posts are much appreciated!
cheers
RDS
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Post by mijapxman on Apr 17, 2019 14:55:30 GMT
rds, what problems are you having? I forgotten your engine and carb and exhaust specs, can you let us know those too?
If you were meaning is a 142 Main jet richer than a 140 main jet, the a 142 is richer .
Don't think I 've used a B1 so can't say.
The charts do have the answer to the BE1, BE2 , etc the confusion maybe WHERE the make it richer or weaker etc? The chart shows this too, can appear very complicated I know, but have a look again and mista freak moped has many carb videos in his playlists , that are well worth a look. Here's one that may help 👇.
Jim/mij☺
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rds
2nd Class Ticket
Posts: 30
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Post by rds on Apr 18, 2019 22:42:32 GMT
Hello Mij
many thanks for that. I have a 150 super with no performance items on it at all as far as i can see.
However the bike has not been treated too kindly by previous owners and I am left to pick up the pieces to get the thing running properly.
As the carb looked knackered and was impossible to set idle or mixture (several gaskets were missing, needle valve was damaged etc) I considered a refurbish kit but the price was not too far off a new SI20/15 from Willenhall Scooters, so that's what I bought. At the same time i stripped and cleaned a few friends' carbs that had been superseded by their other needs (ranging form 20/15 to 20/20) and temporarily fitted an SI 20/20 which might be over fuelling the bike in its low state of tune.
Anyway comparing all the jets part numbers form the various carbs none actually matched the Haynes manual list but between all the carbs there are a few variations and it was my hope to lay out a selection of each jet in richness order so that i could test which felt better on the bike (without dyno!!). This is especially the case as i foresee the need for a new exhaust soon.
In other words, i have been trying to think ahead re the carb to be fitted to match a new non-performance exhaust. However this has been put slightly on hold until i deal with the issues that arose over the last few days (see separate posts coming up!).
Is this a wasted exercise though and i should get the bike going with the current set up however bad and make changes incrementally (which costs more....!)?
cheers
RDS
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