1959 Corsaro carb tuning

Singles built before the Lambertini era
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hotfoothowell
Posts: 15
Joined: 17 Dec 2012 09:53
Location: Alcester, UK

1959 Corsaro carb tuning

Post by hotfoothowell »

Just bought a "fully restored" 125 Corsaro, with a Dellorto carb, marked U8F20BS (but the 8 could be a B, and vice-versa). After cleaning the carb (which the vendor tells me came off a Corsaro Veloce), it will only run on full choke, suggesting that it is running lean. Can anybody say what the correct jettings and settings are? Main jet is 92, with a 6.5gm float. I have checked out the ignition system, and it seems OK. Thanks
morini500dave
Posts: 75
Joined: 30 Dec 2010 20:20
Location: Waterlooville U.K.

Re: 1959 Corsaro carb tuning

Post by morini500dave »

Hi.
Check your pilot jet is 42,above main jet atomiser,8mm spanner,main jet 98 or 100.The carb is ub20bs,float is correct,do you have a filter? may be a Dellorto F18/20,if so is it clean internally.I've some experience with these engines,Corsaro/Sbarazzino,currently have both types running well.

Hope this is helpfull,post reply as to your results!
Regards Dave.
morini500dave
Posts: 75
Joined: 30 Dec 2010 20:20
Location: Waterlooville U.K.

Re: 1959 Corsaro carb tuning

Post by morini500dave »

Hi.
Forgot to say,also airscrew set at around 1/2 turn out from closed.
Dave.
hotfoothowell
Posts: 15
Joined: 17 Dec 2012 09:53
Location: Alcester, UK

Re: 1959 Corsaro carb tuning

Post by hotfoothowell »

Thanks, Dave
That suggests that my main jet is too small, but where do I find the numbering on the pilot jet? There is a filter on top of the float chamber, which has been cleaned, along with the rest of the carb.
Patrick
morini500dave
Posts: 75
Joined: 30 Dec 2010 20:20
Location: Waterlooville U.K.

Re: 1959 Corsaro carb tuning

Post by morini500dave »

Hi Patrick.
If you go on to the Eurocarb Reading web site,www.dellorto.co.uk and on their home page put part number 1488,the jet will be pictured,in reality this jet is quite small and I have to use a magnifing glass to read the numbers clearly!
Hope this helps/
Dave.
hotfoothowell
Posts: 15
Joined: 17 Dec 2012 09:53
Location: Alcester, UK

Re: 1959 Corsaro carb tuning

Post by hotfoothowell »

Dave
That's a really useful site, many thanks. Unfortunately, the pilot jet won't shift without ruining it entirely, so I might buy a spare, and try drilling it out. Before doing so, I note that the some carb tops as advertised on that site have a built-in choke and lever. My carb top appears either to have been blanked off round the choke cable thread, or the old adjuster has broken off, not sure which. Anyway, the throttle slide has a space for a choke slide - would its absence cause over-lean running (as in my case)? I would have thought not, but would welcome your views. At the moment, the only method of choking the carb is via the sliding strangler on the air cleaner. Thanks again, Patrick
morini500dave
Posts: 75
Joined: 30 Dec 2010 20:20
Location: Waterlooville U.K.

Re: 1959 Corsaro carb tuning

Post by morini500dave »

Hi Patrick.
The Eurocarb site is very useful,does your carb not have a tickler on the top of the float bowl? it's used to flood the carb a little for cold starting,I doubt a chock slide would cause weakening if anything just causes the mixture to become richer? Both my bikes have tickelers and are all I use for cold starting.try using a stud extactor instead of drilling out as you may loose the size stamping and so be no better off with regards to the jetting!

Regards Dave.
hotfoothowell
Posts: 15
Joined: 17 Dec 2012 09:53
Location: Alcester, UK

Re: 1959 Corsaro carb tuning

Post by hotfoothowell »

Dave
I had a word with the chap at Dellorto, and he very kindly sent me all the specs for Morinis. While I don't have the correct carb for my actual model, it should be close enough. He suggests that at the throttle seetings I was using, the fault was more likely to be with the idle jet and needle. What I propose to do is borrow a friend's sonic cleaner, and make sure there is not a problem there, especially in the idle jet, before changing the jetting. The main jet was well and truly blocked before I even tried. Thanks again for your suggestions.
Patrick
morini500dave
Posts: 75
Joined: 30 Dec 2010 20:20
Location: Waterlooville U.K.

Re: 1959 Corsaro carb tuning

Post by morini500dave »

Hi Patrick.

They are helpful at Eurocarb,I'd be interested in the specs they give you if you could post them here that would be interesting to compare!

Dave.
hotfoothowell
Posts: 15
Joined: 17 Dec 2012 09:53
Location: Alcester, UK

Re: 1959 Corsaro carb tuning

Post by hotfoothowell »

Dave
Not sure how to post an email with pdf attachment on this site - if you give me your email address, I will forward the specs. to you.
Patrick
morini500dave
Posts: 75
Joined: 30 Dec 2010 20:20
Location: Waterlooville U.K.

Re: 1959 Corsaro carb tuning

Post by morini500dave »

Hi Patrick.

Pm sent.
Regards Dave.
hotfoothowell
Posts: 15
Joined: 17 Dec 2012 09:53
Location: Alcester, UK

Re: 1959 Corsaro carb tuning

Post by hotfoothowell »

Dave
Can't find any message, please email me at hotfoothowell@hotmail.com
Thanks
Patrick
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