Carburation problems. - Cali iii

Technical Big Block Tonti and Loop Frame models
1

Got back from three weeks in France a week or so ago. We’ve just been out on the bike again today and it’s definitely not running right.

It’s a Cali III FF with PHF30 carbs.

It misfires on low speed pick up from roundabouts.
There is a definite smell of petrol when running at low speeds.
It won’t idle correctly.
The fuel consumption is very heavy.

The misfire seems to be from the n/s cylinder but I’m not sure.

I’m suspecting either a choke valve stuck open (I’ve got lever chokes on the carbs) or some debris holding the float needle valve open causing it to flood. Anyone got any alternative theories?

I hope it’s not a result of the nasty E10 fuel in France. I did try to avoid it.

I’ve got a couple of gasket kits ordered from Eurocarb and when they arrive I’ll give both carbs a going over with the ultrasonic cleaner. I only rebuilt them about 6000 miles ago.gtmdriver2013-08-03 14:23:43

2

Have you tried turning fuel on and watching the carbs to see if any appears on the outside? If sticky needle valve or punctured float it probably would. Feel bottom of float bowls to see if ‘wet’. May not be a misfire but rather a backfire if too rich. Case of investigating properly rather than guessing (take it apart and see what’s what). Tip: you can test the needle valve by taking off float bowl, hold up float with a finger and turn fuel tap on, you should then be able to turn fuel on and off at will by releasing and raising float and see it running out onto the floor. You might have a sticky float hinge. Parts can fail despite being rebuilt not long ago. But could also be a sticky choke piston yes. Guzzibear advocates cleaning with white spirit. HTH

Mike H2013-08-03 15:10:59

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The problem with E10 fuel in France is that they are chucking E15 in the tanks and not telling anyone, there go the O rings.G.

4

Float filled with petrol? I’ve had that, nothing to do with E anything petrol.And in France they have both types in most places, normal and E fuel.You can even check the price of each grade on this website.

5

Might be stating the obvious but have you looked at the plugs to give a clue to which cylinder is running poor.

6

I wondered about a leaky float too.

I will investigate all these possibilities. Thanks for your input.

7

Have you got rubber tips on the float needles, could they have been eaten away by ethanol?Or old steel ones can wear a ridge over time and stop sealing.

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On my VHB’s the tips are plain metal. It’s a valid point though, hence my float-bowl-off-finger-under-float test mention.

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I remember seeing very handy see-through float bowls on Guzzis in the past. I wonder if they all dissolved…

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Yes I had them on the Spada. Thought they were really cool at the time, don’t think I’d bother now

11

I’m sure this has been fixed by now, but maybe split inlet rubbers?

12

Yes we are overdue for an update

13

Sorry!

I stripped, cleaned and rebuilt both carbs and re-fitted them with new rubbers. It made no difference whatever so I did a complete re-tune and re-balance. I managed to get it to idle OK eventually but the idle mixture screws needed a major re-set to get it right…

So I’m no wiser really. One day it was idling fine, the next it needs a serious retune to keep it going.

14

Ahhh twas just “Being Italian” on yer mate.

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maybe go through the ignition system and look for faults?

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Bum. This could be an ignition problem after all? Contact breakers is it? If misfiring would produce excess unburnt fuel yes.

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No it’s Newtronic contactless and since I re-adjusted the carbs it’s right as rain so it’s not an ignition problem.

I just can’t fathom why the carbs should suddenly need serious re-tuning to get the bike to idle again.

18

drop the taps out the tank and have a look at the filters. My t5 went through a phase of intermitantly running like pig and needing the cabs stripping and cleaning to get back to normalmodern petrol had ‘cleaned’ the tank and i ended up with a 1/2" layer of sludge that slowly made its way through the tap filter / inline filter and carb filter to block things up

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Could it just be a dodgy tankfull of fuel?

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[QUOTE=guzzi-t5]

[QUOTE=gtmdriver]No it’s Newtronic contactless and since I re-adjusted the carbs it’s right as rain so it’s not an ignition problem.

I just can’t fathom why the carbs should suddenly need serious re-tuning to get the bike to idle again.[/QUOTE]drop the taps out the tank and have a look at the filters. My t5 went through a phase of intermitantly running like pig and needing the cabs stripping and cleaning to get back to normalmodern petrol had ‘cleaned’ the tank and i ended up with a 1/2" layer of sludge that slowly made its way through the tap filter / inline filter and carb filter to block things up[/QUOTE]

I didn’t think of that but, having said that, there was no sign of any sediment or deposit in the carbs when I stripped and rebuilt them.