moto guzzi le mans not running well with lafranconi silencers

[gil]

Hello All ,
I have a question concerning a Moto Guzzi ''Le Mans 1''.
The machine has been completely & recently restored ..........is now roadworthy and generally running well ,with all teething problems sorted out apart from CARB SET UP, for which I would appreciate more advice.
I need help to fine tune & find the correct jetting /carb set up based on the below information .
 
Mechanically everything is standard including points , chain timing & Dellorto PHF36B carbs with bell mouths . Only non -standard items are LAFRANCONI Comp.  silencers ( the ones with twisted fins )

The Standard Carb set up should be -
135 main
60 idle
K5 needle [2nd position]
265 AB. needle atomiser
60/3 slide
70 starter  jet
38 pump jet (5cc x20 strokes )
23/24 float height with carbs on their side (10 gram floats)

The Modified set up is -
140 main
55 idle
K5 needle [2nd position]
265 AB needle atomiser
60/3 slide
70  starter  jet
38 pump jet

Initially the bike was running badly using the standard carb set up ,so after testing with a variety of combinations I have found that a slightly larger 140 main jet ( 145 too rich ) and slightly smaller idle 55 jet ,give the best results .
i am still unsatisfied with result though and reckon that it is still possible to improve ,the main issue being  THE VERY BOTTOM END WHERE IT IS FLAT AND SOMEWHAT UNRESPONSIVE , making it difficult to accelarate  from low down .
The 55 idle jet gives more response though than 60 and 65 which makes running flatter and glitchy .
It is unusual that the smaller 55 is best  and I am considering buying even smaller jets to test .The larger size jets should theoretically be more suitable ?
When opened up things improve and I feel that the mid/top end is now accurate.

Has anyone the same set up as myself ?
Any help appreciated THX





 

[Stevex]

You havent mentioned accelerator pump set up and flow check.

[PeteS]

My setup on the ‘76 LeMans is slightly different but know it has a stock cam and head flowed by Manfred Hecht and lightened flywheel. Rennsport exhaust and K+N filters. Only mod to the carbs were going to a 143 main. This determined at the dragstrip comparing ETs and max RPMs.
It winds up like a two stroke but still has very little power below 4000 RPMs. This bike never had much low end power. I think the only cure for that is more displacement.

Pete

[2WheelsUp]

My stock LM1 with Lafranconis runs great with the factory carb jets/needles, so unless you have different internals I wouldn't think you'd have to mess with the jets/needles.  @GuzziSteve tuned by bike, so perhaps setting the valves, timing, and richness correctly may be all that you need to do. The only issue I've had was keeping the accelerator pumps primed. I fixed that by replacing a couple needles related the accelerator pump... forgot the part numbers but I can look it if up anyone cares. I still need to use the choke after it's been sitting for over a week but after it starts I release the choke and the pumpers work great.