Kit for balancing IP2 carbs

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BlackIP2
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Kit for balancing IP2 carbs

Post by BlackIP2 » Sat Mar 03, 2018 9:01 pm

Does anyone know if the Carbtune 2 kit can be used to balance my IP2 carbs, or can it only be done using the paraffin-filled manometer described in the factory workshop manual? I've used the Carbtune kit successfully on other bikes, so would assume it's also OK to use on the Norton. I know the rotary has a totally different intake system, but it still operates the vacuum fuel tap as other bikes do off the intake pipe.
The Carbtune kit uses dampened plastic pipes connected to tiny metal rods moving in calibrated glass tubes, so the principle of operation must surely be the same?

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Richard Negus
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Re: Kit for balancing IP2 carbs

Post by Richard Negus » Sun Mar 04, 2018 12:11 am

I still have pieces of equipment that work on every Norton rotary and are far less hassle than gauges and manometers and absolutely reliable - my ears!
Screw the idle adjuster screws out until the head faces are level with the face of the casting.; this will give a fast idle around 2000 rpm even with the choke knob pushed fully in. Allow the engine to get hot (at least 100C for an air-cooled or the fan(s) on at least twice for a water-cooled).
Then turn each screw in 1/4 turn at a time until the engine speed starts to drop and then turn in by 1/8 turns at a time. As the speed drops the exhaust note will become irregular so experiment by turning one screw more than the other. You may eventually need to turn one out rather than in. You should aim for a regular purr from the exhausts at an engine speed around 6 - 800 rpm.
The usual provisos of course:
.an IP2 with Sparkrite ignition will not idle well below 1200rpm without the dreaded retard box working (black box under the seat, usually).
.the carbs should be in good health, jet heights correct, AEF fuel metering needles.
.throttle butterflies both to be closed when the throttle is shut, and open at the same time when the throttle is opened.
.the engine is in reasonable condition.
It takes a little practice at first, but gauges and manometers only tell you the depression in each induction tract rather than what the engine is actually doing with the fuel/air it's getting.
R.
Slower slower, no faster faster - the joys of old fogey mode to hooligan mode at the flick of a switch

johnbirchjar
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Re: Kit for balancing IP2 carbs

Post by johnbirchjar » Sun Mar 04, 2018 12:16 am

I tried a similar sort of Carb tune device that we used back in the day on SU's before fuel injection,It didn't work evil,mainly(I think)because the induction system is so totally different on Rotories, cool,J.B.

BlackIP2
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Re: Kit for balancing IP2 carbs

Post by BlackIP2 » Sun Mar 04, 2018 6:34 pm

Thanks Richard. I do indeed have the Sparkrite but no retard box and it ticks over at around 1200 so that looks like it's as good as it's going to be.
Cheers all.

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