Pilot jet sizing - 82 1200 stock carbs

Paul LeClair

Paul LeClair

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Location
Calgary, Alberta, Canada
Hi all

with the wonderful challenge of exercising all 8 licenced and insured bikes presently in the garage, the 1982 1200 TS Mirage Series 2 has only done about 600 kms since total rebuild. I had it out for a wonderful run today on Father's Day, it is really running well and is a real joy to ride, except for stalling at stop signs.

the engine is totally stock other than Red's ignition. A11 cams, fresh bore hone and new rings, stock quiet exhaust

at the moment I have 55 pilots in the carbs. Once the bike warms up for a while it stalls at stops. The choices for pilot jets sitting on my work bench at the moment are 58's, 60's, and 65's.

my hands stink of fuel, I have another bike in the way on my lift at the moment, and I really would like to swap pilots only once if I can.

for the purpose's of this discussion, needle jet is AB 265, K1 needle, the choke plungers are new and seat properly, etc., and all internal parts are brand new and very carefully assembled and balanced. I am at 3,250 feet above sea level, roughly.

I am thinking 60's, as on my other 1200 65's make it stinky rich, but the other 1200 is high compression, 4C's, 3 into 1, etc.

What did Laverda use for pilot jet size on these 82 1200's when new?

Suggestions?

Paul LeClair

 
Any stock 1200 I have seen had 65 pilot, 118 mains, K14 needles. And restrictor plates in the airbox.
I used to live at 3000ft and jetting did not have to be changed.
55s are way too small for a 1200.
 
Hi Paul

I'm reasonably sure the original settings were:

Main Jet 115
Needle Jet AB265
Jet Needle K14, 2nd notch
Slide 60/2
Pilot Jet 65
Starter (choke) Jet 70
Float Valve   250
Float Height 17.5-18.5
Idle mixture screw 1.5 turns
Pump 4cc/20 strokes

(Mirage engines were the same except for 55 idle jet and 145 mains)

I reckon the best approach is to go back to the stock setting (65) and work from there. I've found that Dellortos tend to work better with a slightly rich idle mixture, but not so rich as to foul the plugs with soot. If the idle is stoichiometric or leaner, you get a bit of hesitation on the transition from idle to the first little crack of slide opening.

I tried using a colortune plug to set the idle mixture on a couple of bikes (Jota and bevel Ducati) but if you adjust the idle screw as advised by colortune (to get a blue flame with occasional licks of yellow) it's way too lean. A constant yellow flame is closer to the mark.  If you adjust idle screws for maximum revs at idle, it's ends up richer than the colortune recommendation and the carbs work better. My conclusion is that the colortune is interesting to play with, but not much use for tuning.


PS: Grant beat me by a couple of minutes. I type too slowly.  ::)

PPS: I reckon you have a set of carbs off a 1000cc engine on your 1200.
 
Paul, 

I run 60 pilots on my 1200 TS Mirage.    Needle jet is AB265 and needle is K1.  Open silencers are fitted.  The airbox is gutted and uses an aircon mesh filter.  All this at sea level.  Bike runs and idles well.

Tom
 
I am using 60's in TOG (1200TS)
lovely even tick over, standard excepting Jota pipes and also retaining, internal baffles and trumpets in air box.

the Colortune, may well be a Mickey mouse type tool, but I find it very useful for checking what is happening at tick over, is absolutely useless if you even crack the throttle open.
CLEM
 
Hi Paul,
In the first instance I'd re-check the mixture setting for each carb, anything more than 2.25/2.5 turns out then  fit slightly larger pilot jets.
At the same time balance the carbs.

Andy
 
Paul
Go the 60's say do you have a spare set ?? just kidding ..........I ran 60's in the Cico with the Dell's and A11's. 55's were too small and 65's it was fuelly.
 
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