IP II Carburation Issues ??

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draxdave
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IP II Carburation Issues ??

Post by draxdave »

Bit of background first: I've had the ex RAF Cyprus IP II (3366) for six months and 1900 miles: it has always smoked too much on start up and never idle'd smoothly – but on the open roads between Drax and Seaways Cafe she runs like a good 'un, howling along between 5 and 6k RPM. This my fourth Norton Rotary.

Today was different though, started instantly as always and ran very well on the open roads but soon noticed that the engine temp was reading low, and LHS indicator idiot light packed in - although the winkers themselves were OK - loose wires I guess.

Came to leave Fridaythorpe and the engine just died when I tried to pull away; I had to rev to 4 thou plus and a ton of clutch slip to get her rolling; and then she ran great as always and I managed to nurse her home. When home I noticed that the engine died when I took my thumb off the start button – ballast resistor anyone ?? Both sides of the engine were hot as usual, so not running on one rotor.

I will take the tank and panels off tomorrow for a good look around, and the carbs will have to come off for an inspect and clean session – any comments folk ?
Anthony Duffield
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Re: IP II Carburation Issues ??

Post by Anthony Duffield »

Dave,

My experience of the air-cooled rotaries is limited I have a water-cooled Commander, smoking on start-up obviously suggests too much oil so I would check the oil pump setting and try to measure oil consumption against mileage, I get around 1000 miles/litre. I have never heard of a rotary getting oil into the engine when it stands for a while and am not sure even if it's possible, someone on here might know. Poor idling: in my experience idling too high is air leaks around the induction tubes, poor tick over after the thermistor cuts in is low compression, I'm not sure if the air-cooled engines have a thermistor?

The engine temp was reading low, and LHS indicator idiot light packed in - although the winkers themselves were OK - do indeed suggest loose wires or bad earths.

Engine dying when pulling away could be fuel related, it would be worth checking the fuel filter and flow of fuel to both carbs before stripping them, engine stopping when releasing the starter button does sound like the ballast resistor, short it out for a test but I do not think it's a good idea to run the bike for any length of time with it shorted.

If you find out what's wrong, please let us know.

Tony
draxdave
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Re: IP II Carburation Issues ??

Post by draxdave »

Cheers Tony, wow 1000 miles per litre - that's amazing. I currently get around 300 miles per litre, and my other bikes returned around 350/l.
I have checked the oil pump setting a couple of times, the "C" stamp aligning with the indent at 2,000 rpm, but will check again. Thanks for your comments.
johnbirchjar
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Re: IP II Carburation Issues ??

Post by johnbirchjar »

If memory serves,I used to get about 300 miles to the pint(650 per ltr?) from my Classic,and looking at the silencer ends after a lengthy and fast motorway blast Very Happy (that lovely light grey colour cool )I always figured both oil pump and carb mixture were about right(usually about 45 to the gallon the way I used the old girl wink ),so sounds like your bike's oil pump is a tad rich. Water cooled rotorey owners I talked to on this issue allway seemed to use much less oil than there air cooled counterparts,J.B.
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Interpol2471
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Re: IP II Carburation Issues ??

Post by Interpol2471 »

Don't forget to check the yellow generator wires and make sure not overheating and beginning to burn as causes all sorts of funnies!
Various rubbish in various states of decay.....
draxdave
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Re: IP II Carburation Issues ??

Post by draxdave »

Hi Guys, I have at last got round to looking at the IP II, and I have a couple of points that need clarifying if any of you lovely chaps could oblige ??

The needles on the bike appear to lean toward the front of the bike; the manual says that they should be biased toward the rear ?? I cannot figure how to change this angle ??

I have checked the main jet heights and they appear to be set for a single rotor idle model at 2.7 mm ( LHS) and 3.1 (RHS). The twin rotor idle jet heights are both 3.2mm - any comments ?


It is entirely possible (probable) that I have misread and misunderstood everything of course – can anyone put me out of my misery please ?
draxdave
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Posts: 49
Joined: Sun May 08, 2022 5:16 pm

Re: IP II Carburation Issues ??

Post by draxdave »

Hi Guys, I have at last got round to looking at the IP II, and I have a couple of points that need clarifying if any of you lovely chaps could oblige ??

The needles on the bike appear to lean toward the front of the bike; the manual says that they should be biased toward the rear ?? I cannot figure how to change this angle ??

I have checked the main jet heights and they appear to be set for a single rotor idle model at 2.7 mm ( LHS) and 3.1 (RHS). The twin rotor idle jet heights are both 3.2mm - any comments ?


It is entirely possible (probable) that I have misread and misunderstood everything of course – can anyone put me out of my misery please ?
Anthony Duffield
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Re: IP II Carburation Issues ??

Post by Anthony Duffield »

Dave,

Type "Bias" into the search bar where you will find a lot of good info on this subject.

My workshop manual lists the main jet height at 3.10mm, that is what mine are set to and I have no issues with how the bike runs.

BTW my average fuel consumption is 47.36 MPG

Tony
draxdave
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Re: IP II Carburation Issues ??

Post by draxdave »

Many thanks Tony, I will keep you posted, regards dp
draxdave
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Re: IP II Carburation Issues ??

Post by draxdave »

Well, we are getting somewhere !! The carb pistons & chambers are spotless, both jets are set to 3.2mm down; she now has new battery – the voltage on the old one fell to 8v when the starter was buttoned. The large white multi-pin connector under the instrument cluster is now firmly clicked into place – it was loose before !!

She runs round the lanes very nicely; the only issue is that she “idles” at 2,000 rpm. I think I read somewhere that air leaks between carbs & rotor housings could be the culprit, and maybe also between plenum exit port and the “angle” casting.
johnbirchjar
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Re: IP II Carburation Issues ??

Post by johnbirchjar »

If you have had the carbs off it could also be the Choke Idle rod, (especially if one has moved the little locking nut wink ) it only has to be a Nats out to increase the revs on idle,J.B.
Anthony Duffield
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Re: IP II Carburation Issues ??

Post by Anthony Duffield »

Dave,

JB has a point about the fast idle rod and worth checking. With a good flashlight it's easy to check that when the choke is fully closed there is play in the lever that connects to the fast idle rod.

If found OK my experience of uncontrolled fast idle is air leaks at the engine end of the induction tubes, I lubricate the O Rings with a high temperature grease and make sure that the tubes are pushed all the way in.

Good luck
Tony
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