carb set up

[sa.racing]

Have a read of this site its by far the best explanation of how carbs actually work and how to tune them properly that i could find on the net.
http://www.factorypro.com/tech_tuning_p ... gines.html" onclick="window.open(this.href);return false;
Simon

[scratchin]

sorted it now its bang on this is how you set it if anyones interested
take the bike for a ride to warm it up.
When you get back home or to your shop, let the bike idle till the fan kicks on. We need to know that it is up to running temperature.

Shut the engine off.

One at a time, screw each pilot needle in till it bottoms (gently!). Then unscrew it 1.75 (one and three-quarter) turns. Do this on each carburetor.
This is a ‘known’ lean setting, but the bike will still start and idle.

Start the motorcycle and set the idle to approximately 800 rpm.

With your assistant watching the tachometer, SLOWLY unscrew the pilot screw on #1 carb till the idle starts to climb. Have the other person tell you when the idle starts up. At that point, start counting ¼ turns out. Your assistant is now watching for the tach to DROP a little. Once the rpm starts to drop, just screw the pilot needle back in half way to where it began to rise. You are setting the pilot circuit half way between ‘nearly too lean’ and ‘nearly too rich’.

Reset the idle back down to 800 rpm and repeat the adjustment on carb #2.
Repeat this process till you have adjusted all four carburetors.

Reset the idle speed back to where you normally keep it

Your pilot circuits are now set to optimum.

Take the bike for a ride and if you get popping on deceleration, unscrew each pilot needle an additional 1/8 or ¼ turn (just make sure that the additional amount is the same on all four carbs). Stop there. It’s as close as humanly possible to get it.

You have now set the pilot circuits correctly.

[marty400]

sorted it now its bang on this is how you set it if anyones interested
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You have now set the pilot circuits correctly.

Good work Scratchin!

As a point of interest:
1. How much have you turn't out the screw for each carb?
2. Does this affect the Carb syncronizations? Did you have to balance before, and after?
3. Is it something you only ever have to do once? Or is the Pilot Screws all part of setting the bike up for a new Exhanust can etc?


Hope you can enlighten me! 8)


Cheers
Martin

[marty400]

Have a read of this site its by far the best explanation of how carbs actually work and how to tune them properly that i could find on the net.
http://www.factorypro.com/tech_tuning_p ... gines.html" onclick="window.open(this.href);return false;
Simon

good find Simon!

I'll read when I have a moment!


Cheers
Martin

[scratchin]

hi martin all bikes would be different amounts of adjustment on the pilot screw, carbs should be balanced before any pilot adjustment and would'nt need balancing afterwards, its not realy something you should have to do, only reason i have is i adjusted them as the dyno jet kit states, which was a mile out

[marty400]

hi martin all bikes would be different amounts of adjustment on the pilot screw, carbs should be balanced before any pilot adjustment and would'nt need balancing afterwards, its not realy something you should have to do, only reason i have is i adjusted them as the dyno jet kit states, which was a mile out

Hiya Scratchin,

Cool.

Is there an element of a juggling act though? If one carb has more fuel goin into it, wouldn't there br more "umpf" per RPM - thus the carb would pull more air.... Or are the 2 areas really totally unrelated?

always got questions mate! :D

Cheers
Martin

[marty400]

Last question Scratchin!

I'm going to get the NC29 dyno'd this summer.

As part of the dynojetting - would the workshop be doing carb syncronisation, as part of the tuning optimization? Or is that a service item??


(I'm going to try doing the basic servicing myself, and treating myself to paying for dyno session! I'm happy with the oil and filter change, new Spark plugs, but not confident about the Carb Syncronisation this time around.)


Hope you can advise

Cheers
MArtin

[scratchin]

carb sync is realy easy all your doing is ajusting four screws but you would need the meter, any descent dyno would do this for you for not much cost, im booking mine in for a dyno run £30 hoping for just over 60bhp but more importantly a nice smooth curve you can learn a lot from the dyno especially from the air fuel mixture and a descent tester will give you advice on improvment, ive up't the main jets to 112's and dropped the dynojet needles down one notch from there instructions and the bike pulls really well and i cant feel any flat spots, i'll post the dyno sheet when i get it done in a couple of weeks see how accurate ive got it with just the feel of riding it

[marty400]

Hiya Scrachin,

Read the Haynes manual - says I need to remove the Carbs to get to the hose inlets!
Er... I'll leave it to the dyno guy this time around!

Good luck with your next dyno session! Hope its bang on mate

Cheers
Martin