Carb problems ?

Camel, Sahara, Kanguro, Coguaro

Carb problems ?

Postby 3potjohn » 01 Aug 2020 14:45

I am having an on going battle to eliminate a stutter which seems to begin at around 4000 in 6th on a 507 Coguaro which has been flowerpotted and has fairly brisk silencers.I think it seems to clear at 6000 rpm. Carb settings (PHBH ) are
Pilot Jet 45, needle X18 second notch, BC264 emulsion tubes, main jet 122, float jets are 250( I think).floats white 9. something grammes
I have swapped pilot jets down to 43 and up to 50, and for the hell of tried 128 main jets, which you will not be surprised to learn made no difference. I have cleaned the carbs in an ultrasonic bath and blasted a lot of carb cleaner and air through.
If I try pulling the chokes on I think there is a slight improvement for a second or so.
I tried immersing the floats in water for an hour but have not found a measurable difference. There was some slight corrosion on a needle.
All o rings and chokes are spot on or new. I have swapped out the cable chokes for new lever chokes but no difference. Inlet manifolds look good. Ign timing ok, rear valve clearances OK but have not checked the front as that brilliant air filter housing is in the way of the rearmost bolt unless I am being blind.Or stupid.
Given that I have not changed the needles, nor floats would that be a reasonable approach?
I realise needles are not cheap but this impression of the Bronte family is very irritating.
Still it is the only bike that has defeated me after quite a few. This of course number 13.
John
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Re: Carb problems ?

Postby haboola 72 » 01 Aug 2020 21:35

Flowerpotted? How much of the innner cone is left ?
The filter housing is the same as a 501 Camel . I took 6 inches off mine and I'm running 100 main jets with X2 silencers, 105 main jets with aluminium
trials silencers ( small and noisy ), the other settings you mention are the same.
The filter housing is prone to separating in the middle and letting in air. The giant jubilee fastener does its best to contain the poor mating overlap, I found a supplementary
8mm zip tie tethered to the frame stops any movement from vibration.
The horribly awkward allen screw to the rear of the front rocker cover can be loosened with a cut down allen key or a 30mm hex allen bit and a 6mm spanner, then swap to a 25mm bit to get it all the way out. It's a pig but better than dismantling the airbox and carb hoses to check the front valve clearances.
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Re: Carb problems ?

Postby 3potjohn » 02 Aug 2020 05:02

Thanks for your reply. That filter is a real pig. If only there was a flatter one with a rectangular filter element......
I will try your suggestion about the shortened hex key but it is very near the housing.
John
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Re: Carb problems ?

Postby 3potjohn » 03 Aug 2020 05:58

I tried collecting the fuel in each floatbowl in a ramekin dish borrowed for the purpose whilst nobody was looking. After failing miserably on the first occasion because some idiot left the reserve on, I find the rear carb has more fuel in than the front one. If that is not due to excess emptying via the fuel lines then maybe that is the issue.
I am pretty sure the bike runs OK to start with, which might tie in with a fuel height difference. But which is correct?
John
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Re: Carb problems ?

Postby 3potjohn » 03 Aug 2020 06:47

So I have 40mL on one side and 30mL fuel on the other.
I tried measuring the float height as per the Dellorto manual ( 24mm). Ideally if I had one good new one as a reference I might get somewhere.John
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Re: Carb problems ?

Postby mbmm350s » 04 Aug 2020 11:50

Hi John

You can get plastic clear float bowl for the purposes of comparing fuel levels, useful on two stroke such as tuned vespas/lambrettas
where the fuel level matters.
Not cheap.
search for clear float bowl PHBH or try a scooter tuning shop
I have bought parts from wasp performance before may be they will have it?

Mark
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Re: Carb problems ?

Postby 3potjohn » 04 Aug 2020 12:42

Hi I saw that item on the Eurocarb website. Think for the moment I will look at floats.I usually can sort carbs so this is a new experience.
There is plenty of acceleration however.
John
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Re: Carb problems ?

Postby 'It must be a .....' » 04 Aug 2020 13:02

Malossi PHBH clear float bowl 3014909.
Will be cheaper from a scooter shop.
Or cheaper still to get another standard float bowl and modify it to take a piece of clear pipe, to check the fuel levels.

Good luck, Ian
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Re: Carb problems ?

Postby Steve Brown » 04 Aug 2020 18:10

I also modified a brass float bowl/main jet holder to do the same thing. Drilled through the bottom and fitted a tail piece with a clear plastic pipe attached. You have to hold the plastic pipe up or make something to hold it for you. Works a treat.
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Re: Carb problems ?

Postby 3potjohn » 04 Aug 2020 19:11

Right , a new float made no difference in either carb.Swapped float needles from my Sport no difference. Pretty sure the carbs are not tight against the underside of the tank.
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Re: Carb problems ?

Postby 3potjohn » 20 Aug 2020 14:05

After a lot of carb cleaner and prodding with a strand of copper wire on the rear carb I have made it worse. I am leaving the carb body soaking in thinners for 2 days. Then another session in the ultrasonic bath.
I tested as best I could all the ignition components.Still think rear carb as bourne out by the current findings.
This is the 28th carb I have had so guess one had to be really troublesome sooner or later but 28 seems like a coincidence.
If anyone has a PHBH 28BS carb or carb body I could try etc that would be VERY useful. Don’t think my 40mm Bings would cut the mustard.
John
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Re: Carb problems ?

Postby 3potjohn » 24 Aug 2020 18:33

Right, poked the idle and progression orifices on the intake side, felt some resistance on one carb.Good.
Lots of cleaning( ultrasonic,vinegar, boiling water, detergent, toilet duck even) but not resolved bogging at 1/4 ish throttle. I removed my pilot jets 45, and tried again with my old 50 jets. These did not work last time but now much better.I think then that I had blocked carbs and weak idle going onto progression. Not 100% fixed but now rideable. I went leaner on my Sport to cure an off idle stumble so this seems counter intuitive. Maybe I could go 55 pilots?
It’s only taken me 2 months.
John
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Re: Carb problems ?

Postby Steve Brown » 24 Aug 2020 18:57

Sorry you're still having trouble. A couple of things that occur to me, when going over carbs that might be blocked I check the passageways by spraying through them with what ever aerosol is to hand. Car cleaner is an obvious one but I've also used WD40 and others. The point being I look at what is coming through. On everything I've tried so far you should see a good clear spray coming out of the other end of the passages. Obviously block off the various ends in turn where it is a passageway that bifurcates. (my word of the day) and even more obviously wear eye protection!
After everything you've already checked as ok then if it still hasn't fixed it I'd suspect the ignition. You say you've checked that as far as you can but sometimes the only way to prove it is by substituting parts. I've had similar slight misfires that wouldn't go away till I fixed the ignition. The coils are getting old now and many of them are degrading slowly. My Kanguro had a hot starting problem that was cured by replacing the flywheel LT coil. (the one on the end of the green wire that should be at least 180/200 ohms. As others have proven before, you can still have an acceptable resistance there but with a weak or even intermittent output.
Keep at it or chancers like me will be offering to do you a favour and take it off yer 'ands Guv. :wink:
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Re: Carb problems ?

Postby 3potjohn » 24 Aug 2020 22:14

I must admit I was beginning to think that the CDI unit was on the blink, I cleaned all the Molex plugs earlier. I also was worried in case a coil was failing as it warmed up. I had a transducer fail once at the bottom of a long hill on my Sport. I had a spare back at the ranch but it was wince inducing getting home.Have to look at Suzuki and Kawasaki ignition parts I guess if I ever need a CDI unit or a stator for this bike. Anyhow won’t be riding tomorrow, the windy season has come early this year.
John.
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Re: Carb problems ?

Postby 3potjohn » 07 Sep 2020 06:28

The saga continues. Bike will start and tick over, and will run but as you go up to 3rd onwards the hesitation and stuttering becomes apparent. It seems to rev all the way with a big handful of throttle. It is such that when throttling back for example as you approach a tight bend the motor can actually cut out. This unpleasant in the dry and grim in the wet.I found that it subsequently starts up if the choke is on briefly, which I think should indicate a fuel starvation problem, however the new (black)floats are at the right level, the fuel pipes are new, the float needles look good , both taps open and it makes no difference if the petrol cap is loose nor the vacuum pipes blanked off. The manifolds don’t have air leaks.
I am thinking therefore of renewing the atomisers and needles ,x18 type, as one did look a bit corroded.This may account for poor running at the sort of throttle openings one typically rides at most of the time.However the 264BC atomisers are NLA.
Am I right in thinking a 264 is 2.64mm id. Would it be better to get e.g. a264T then drill out the extra holes with a 0.8mm drill?
Better d/w Eurocarb later on.
After all this I will know it is the CDI or dodgy coil! Or worn slides.....
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