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SH1/20 jetting guide

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SH1/20 jetting guide

Postby Storkfoot » Wed Jan 27, 2021 8:48 pm

I am trying to get my head around which atomisers and slides are the richest and where the bleeding starts between pilot/ slide/ atomiser/ main. Does a guide exist?

If no such guide exists, May I ask:

Is a 5914-2 slide richer than a 5914-1?
Should a 7895 slide only be used with an SH2/22?
5899 atomisers. Which is the richest?


I have obviously used SH carbs before but not on an engine that has been significantly tweaked. That’s why I am asking :)
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Re: SH1/20 jetting guide

Postby ladsdad » Thu Jan 28, 2021 4:33 am

Hi Paul
Hope you are well
If you search "jetex" on the forum or 22mm jetex, there's lots of info on atomisers & slides for SH carbs that should help you(on or around page 7)
Cheers Mark.

Btw the Vega looks good, nice work
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Re: SH1/20 jetting guide

Postby Storkfoot » Thu Jan 28, 2021 10:12 am

Thanks, Mark. I shall sit down and go through it later :)

All the best.
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Re: SH1/20 jetting guide

Postby HxPaul » Mon Feb 01, 2021 9:21 am

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Re: SH1/20 jetting guide

Postby Storkfoot » Mon Feb 01, 2021 10:17 am



Thanks for the reply. Yes, I have seen this. It is in Sticky’s and the Lambretta Workshop Manual. I am after a guide that would help you jetting a carb from scratch on a non standard engine.

I can see that the 5914-1 slide is richer than the 5914-2, for example. I can see this as the size of the cutaway is smaller on the 5914-1
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Re: SH1/20 jetting guide

Postby hullygully » Thu Feb 11, 2021 2:48 pm

message sent
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Re: SH1/20 jetting guide

Postby Adam_Winstone » Thu Feb 11, 2021 6:54 pm

What spec motor? I've played a fair bit with the SH range of components so may be able to help.

There may also be old forum threads available, in which I discuss the non-linear rich vs. weak delivery of the atomisers.

:)
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Re: SH1/20 jetting guide

Postby Storkfoot » Thu Feb 11, 2021 7:07 pm

Adam_Winstone wrote:What spec motor? I've played a fair bit with the SH range of components so may be able to help.

There may also be old forum threads available, in which I discuss the non-linear rich vs. weak delivery of the atomisers.

:)


Hi, Adam. It’s a 4 speed Vega with original barrel given a modest tweak by Chiselspeed. Exhaust with baffle removed and larger diameter tail pipes. Airbox has had usual holes drilled to increase airflow.
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Re: SH1/20 jetting guide

Postby Storkfoot » Thu Feb 11, 2021 9:55 pm

Thanks to Hullygully :)

Image
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Re: SH1/20 jetting guide

Postby coaster » Fri Feb 12, 2021 2:18 pm

Didnt the old Lambretta Tuning Guide cover jetting? it certainly covered the exhaust mod. I have a copy but not able to get to it until Sunday
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Re: SH1/20 jetting guide

Postby Storkfoot » Fri Feb 12, 2021 8:26 pm

coaster wrote:Didnt the old Lambretta Tuning Guide cover jetting? it certainly covered the exhaust mod. I have a copy but not able to get to it until Sunday


I have two copies. Can I find either though :roll:
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