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Nelsthebass
Firing on two.
Joined: October 5th, 2009, 8:22 pm
Posts: 1415
Location: Stone, Staffs
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 Re: Re-jet it? Be careful that the new gasket has the right holes in it as many of them don't match the original drillings in the carb....
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1987 2CV Special
2014 Suzuki Swift Sport
2015 Lexus NX300h
1966 Ami Break
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| November 17th, 2016, 10:40 pm |
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ken
Agony Aunt - You have a car problem? Speak to Ken
Joined: March 6th, 2009, 1:40 am
Posts: 3675
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Re: Re-jet it? Dennis, I'm not too sure where that 100 jet came from, since you only need one jet, a 107, as a replacement for the original 102.5 primary petrol jet? p.s. Don't forget a supply of cocktail sticks, very handy when removing and reinstalling those small 'grub screw' primary jets...  Dennis wrote: Thanks for the help - especially Ken, and particularly for the explanations and the picture. My carb is marked CIT 225 so it's the later 18 & 26 mm venturi type.
I'll order the bigger jets (100 and 107) and see how it goes after that. Putting in a new carb top gasket that isn't torn in a couple of places might help too.
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| November 17th, 2016, 10:48 pm |
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Dennis
Firing on two.
Joined: March 24th, 2009, 9:18 pm
Posts: 248
Location: 15340 Mourjou France
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Re: Re-jet it? Ken - ECAS sells the larger secondary venturi jet (the 100 size one, but several larger sizes too), with the warning/suggestion:
"Jet setting is a fine art, do not move far from original."
And although at a very basic level I have absolutely no idea why a twin choke carb is better than a single choke one, I did notice that the performance on my 2CV was better when I removed a small piece of grit from the secondary venturi jet.
It's an easy change to make, and the jets are cheap, so I don't mind experimenting a little. It makes me feel as if I know what I'm doing.
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Dennis usually in the Cantal
1964 HY 72 (Type H, campervan) - LHD
1969 AZU 250 (formerly French Post Office van) - LHD
1982 Red Special - RHD
1983 Burgundy/Black Charleston - RHD
2017 Skoda Octavia Estate 1.4 DSG - LHD
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| November 18th, 2016, 9:20 am |
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Nelsthebass
Firing on two.
Joined: October 5th, 2009, 8:22 pm
Posts: 1415
Location: Stone, Staffs
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Re: Re-jet it? Glad to see Ken must be drinking on a school night too - the 100 jet is the secondary jet you wish to replace - correct?
_________________
1987 2CV Special
2014 Suzuki Swift Sport
2015 Lexus NX300h
1966 Ami Break
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| November 18th, 2016, 10:41 am |
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ken
Agony Aunt - You have a car problem? Speak to Ken
Joined: March 6th, 2009, 1:40 am
Posts: 3675
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Re: Re-jet it? Don't think so, Nels. The original secondary petrol jet in an 18-26 version of a 26/35 Solex would have been either an 87.5 or a 90. Bearing in mind that the flow rate is proportional to the "jet diameter squared", replacing an original jet with a 100 represents an increase of 23% to 30%. Fine, as long as you're happy to waste fuel, since that will have pushed the mixture beyond the "10% richer than stoichiometric' which gives peak power...  Nelsthebass wrote: Glad to see Ken must be drinking on a school night too - the 100 jet is the secondary jet you wish to replace - correct?
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| November 18th, 2016, 1:13 pm |
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Dennis
Firing on two.
Joined: March 24th, 2009, 9:18 pm
Posts: 248
Location: 15340 Mourjou France
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Re: Re-jet it? Ken -
I see that ECAS also have a carb re-furb kit, which includes secondary 95 and primary 105 jets. The 95 jet apparently isn't sold separately - my existing secondary jet is 90.
So I'll get that re-furb set (and also the 107 primary jet) as I need the gaskets anyway, and I suppose that should be a better approximation?
_________________
Dennis usually in the Cantal
1964 HY 72 (Type H, campervan) - LHD
1969 AZU 250 (formerly French Post Office van) - LHD
1982 Red Special - RHD
1983 Burgundy/Black Charleston - RHD
2017 Skoda Octavia Estate 1.4 DSG - LHD
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| November 18th, 2016, 2:04 pm |
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Sean
Firing on two.
Joined: April 22nd, 2009, 11:06 pm
Posts: 3684
Location: Ecosse
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Re: Re-jet it? tears in the lid gasket can make a marked difference
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Kissing the Lash
"Any advice of a technical nature is given on the understanding that I've actually done this shit, not just read about it in D*lly club mag some time ago.
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| November 19th, 2016, 5:24 am |
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Dennis
Firing on two.
Joined: March 24th, 2009, 9:18 pm
Posts: 248
Location: 15340 Mourjou France
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Re: Re-jet it? Ken - if I've got it right about flow rates, then going from a 90 jet to a 95 one is an increase in flow rate of 11%, which is about right isn't it?
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Dennis usually in the Cantal
1964 HY 72 (Type H, campervan) - LHD
1969 AZU 250 (formerly French Post Office van) - LHD
1982 Red Special - RHD
1983 Burgundy/Black Charleston - RHD
2017 Skoda Octavia Estate 1.4 DSG - LHD
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| November 19th, 2016, 10:37 am |
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tek
Joined: December 13th, 2014, 5:00 pm
Posts: 19
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Re: Re-jet it? Dennis,
see Part Number JPP02_95 for the secondary venturi jet.
Hope this helps.
Cheers, Thorsten
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| November 19th, 2016, 9:12 pm |
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Nelsthebass
Firing on two.
Joined: October 5th, 2009, 8:22 pm
Posts: 1415
Location: Stone, Staffs
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Re: Re-jet it? Out of interest Ken, how do you tell when a carb is at or near stoichiometric? I guess some expensive piece of analysing kit is required or do you just experiment with different jet sizes until it seems right?
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1987 2CV Special
2014 Suzuki Swift Sport
2015 Lexus NX300h
1966 Ami Break
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| November 20th, 2016, 11:46 am |
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