Carb Balancing

tribonnie

New member
Location
uk
New to Laverda and just going to check Jota carb balance
Any advantage in running the centre carb slightly richer
Does the centre cylinder run hotter than the others
Richard
 

Paul Marx

Hero member
Location
France
Well old man, when you're caught off guard with that top heavy behemoth of a triple and that you topple over because your old legs can't stop it, you'll be happy that a young twin rider is there to pull you from under the thing before the situation turns into an on the spot cremation.
:sneaky:

Paul
 

Laverdalothar

Hero member
Location
Germany
Don't forget to
-balance the Choke sliders first and make sure they close tightly and move evenly
-set the float hight correct (18mm +/- 0,5)
-set the idle screws evenly
-make sure the components are not worn out or blocked (jets, needles, sliders
-check Valve clearance is set correctly
-check exhaust and inlet has no air-leaks

THEN start with balancing them, please... ;-)

Everything else just masks an issue.
 

CLEMTOG

Hero member
"New to Laverda and just going to check Jota carb balance
Any advantage in running the centre carb slightly richer"

balancing the carbs does not affect the mixture ratios of any of them, least of all the centre one. I don't think you confused balancing and mixture ratios but others might. There are dozens of triples around that have never or rarely seen any instrumentation to get the balancing correct, drill bits under the cutaway and listening for any slides "clicking" shut later than others is merely the starting point, not definitive balance, a well balanced triple will tick over for a fortnight with no "blipping" and start when hot by merely touching the starter button, (with a six foot pole if you like) no choke, no throttle movement, but most dont do that, it is very common to see a hot triple automatically get half choke to get the motor restarted.

I did at one time run a larger main jet on the centre pot than the outer two, ( I am getting preillously close to a recorded 250,0000 kilometres) this was a safety measure as I was trying desperately hard to make the thing economival (they are not economical full stop) it was a useless excercise, what is needed on one is needed on all three, because a certain amount of cooling comes in with the fresh charge, too weak can be very dangerous (ask me how I know) 14.7:1 air fuel it should be regardless of throttle slide position.

CLEM
 

Laverda SF

Hero member
Balancing Slid Carbs - 1st thing I do is place a stop like a 6 or 8mm Hex in the throttle bore (Mechanical Slid Stop) and adjust the throttle cables to sync on shutdown so that you hear "ONE CLICK" - Not one followed by 2nd or 3rd as with a triple.

Other words all carb slides hit the stop at the same time. Adjust equally for idle and play with the Air flow Idle adjustments for each carb.

Granted for Triples you may have to use a richer main jet for the center cylinder under full throttle ?

Never had a Laverda Triple ;o(

Air Flow Velocity Meters are a wast of time considering you have followed my instructions and perhaps dial in another 100 or so rpm on the top end.

Best to have your Breganzie run some what rich rather then lean at the expense of melting a piston ;o)
 
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CLEMTOG

Hero member
"Balancing Slid Carbs - 1st thing I do is place a stop like a 6 or 8mm Hex in the throttle bore (Mechanical Slid Stop) and adjust the throttle cables to sync on shutdown so that you hear "ONE CLICK" - Not one followed by 2nd or 3rd as with a triple"

not good enough Ron,

I did this for years until I decided to buy the right kit, which was later sold and even better kit purchased and that is about to happen again, times change, technolodgy improves, but when I first had vacuum guages I was using my SF1 as a daily ride and didn't own a car, once balanced using my new gauges the bike was a very different ride, it would tick over for a fortnight (never a good thing on a 750 twin to tickover for long periods due to oil circulation, my first cams from new only lasted 36,000 miles, I learned what is now common knowledge the hard way) it was a much easier bike to start, hot or cold, a bit more frugal, maybe, and would rev very cleanly all the way to and including WOT. The biggest gain was mid range vibration at motorway cruising speeds, in those day 80/85MPH, smooth as a Rollers bonnet polished with 3000 grit.
CLEM
 

Laverda SF

Hero member
CLEM: Well at least we are on the same track. Who's gonna win ?

At least you admit using the old method of balancing carbs - To me it's still the 1st practice of setting up multiple slider carbs (which dosen't exist anymore) - Guess after that, it's up to you - Intake, Exhaust, Timing, Jetting, Carb, Velocity Gauges (which I had no use for)... etc.

Would have been a pleasure to have known you and raced you back in the day ;o)

Shit! Even my 20 year old Jeep TJ straight 6 has a Lamba EFI, ECM, Fuel Injected, Bank Coils and Crank Trigger (No Distributor) governed by OBD2 Codes ;o(

I loved the old days when everything was hands on. Try to explain that concept to our Breganzie Puppies !
 
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mauricejota7604

Hero member
Ron there is one thing to consider on a standard bank of Dels on a triple, the slides don't rest on a stop they are all connected through a linked shaft assembly on top of the carbies, so I am afraid there aint no click hitting a stop.
 

Paul Marx

Hero member
Location
France
Ron there is one thing to consider on a standard bank of Dels on a triple, the slides don't rest on a stop they are all connected through a linked shaft assembly on top of the carbies, so I am afraid there aint no click hitting a stop.
Yes there is, when the slides hit the three 6mm drill bits you have stuffed up the carb throats to synch them.

Paul
 
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