CitroJim's AX, C3 Picasso, Cycling and Running Tales

[RichardW]

Solex PBISA 32 16 like This!!

[CitroJim]

Can you find the carb model number? There are a few NOS and reconditioned carbs available on this side of the ditch.

Thanks, that would be good Mike... It's a Solex 32 PBISA 16 PSA

It's unique to the AX11 and although the 32 PBISA used on the AX10 is similar it's not compatible...

The AX11 one is recognisable by having a vacuum capsule on the rear of it to pull off the choke under high vacuum. The AX10 one doesn't have this.

[mickthemaverick]

There is a new carb in France on ebay Jim, item number 403976410475 . A mere 270 euros will secure it!! Not an exact used one on there at the moment

[moizeau]

Have you got access to an ultrasonic bath Jim? If not and you have a lawnmower repair place anywhere near, they usually have them. A couple of 15 min sessions at 60 degrees with an air line in between should sort it. When putting it in the bath obviously completely strip it but put all the brass bits in a glass jar of petrol and tilt the carb so the crap can run out of the holes.

[CitroJim]

Thanks Mick and Pete I do know of an ultrasonic bath I might be able to use and that's got to be a good plan!

[xantia_v6]

Is this the correct one? said to be new: https://www.leboncoin.fr/equipement_auto/2225659916.htm
or a used one that has been refurbed? https://www.leboncoin.fr/equipement_auto/2258962065.htm
Or a new one direct from Shanghai?? https://fr.aliexpress.com/item/1005002534320956.html

You do have to wonder why these are made in China, there cannot be a vast market for them.

[Gibbo2286]

Good to see she still has a shine on here Jim

She shines like Bristol bacon Alasdair

I don't know the origin of that expression but I've known it since I was a small child when it was frequently used to describe something very shiny...

I've never heard it outside of the area of Somerset I was born and brought up in so it may be very local...

Bristol loves blue, Bristol blue glass and the local council has made all the taxi operators paint their cabs blue.

[CitroJim]

Bristol loves blue, Bristol blue glass and the local council has made all the taxi operators paint their cabs blue.

A good choice of colour Eric I like blue almost as much as bright red and yellow...

Speaking of blue, Bluebell's carb is now good I pulled it all to bits - without removing it from the engine - and gave it a good clean this morning..

This is the carb with the lid removed showing the accelerator pump delivery pipe...

Note there's a little sediment in the bottom of the float chamber... That was entirely the result of running about 15 miles yesterday with the filter bypassed just in case it was the cause of the flatspot. It wasn't as these little filters have more than adequate flow capabilities... The relatively tiny drilling in the float chamber float valve body bears witness to that...

The problem was indeed the accelerator pump and a good blast of compressed air blew out a lump of muck... I also have a suspicion the non-return valve - a ball bearing - in the bottom of it was a bit gummy... Cleaned with carb. cleaner...

Happily, the diaphragm was good.

The very end of the accelerator pump delivery pipe is swaged to create a very fine orifice... Only a few thou' so easily blocked.

I pulled out all the jets, cleaned them - although they were all clear - and gave the body and lid a good scrub with carb. cleaner. All passages and drillings were blown out with compressed air.

I replaced the float valve with a brand-new one as this was initially badly gummed and another cause of poor and erratic running at the beginning of recommissioning...

All the bits were reassembled with a nice new lid gasket...

With a new fuel filter fitted I took her for a test drive and all is now very, very good

There's a lot of sediment still in the tank. The new filter showed some had collected in the bottom of it after just ten miles...

I'll be giving the tank a good clean out next time I'm down in Somerset... Alasdair and I have a cunning plan

For now I'll carry a few spare filters with me on each journey...

After that I went for a bike ride to celebrate...

[mickthemaverick]

Great news for you there Jim, maybe not so good for the replacement carb suppliers!

[CitroJim]

Great news for you there Jim, maybe not so good for the replacement carb suppliers!

Or the purveyors of ultrasonic baths Mick

[moizeau]

It was just a thought, I'll shut up now. But my 4 membrane (CV) carbs on the Zeph11 didn't like like a normal clean, they needed US. Bloke in the club spent 800 squids on some flat slides, brand new, US'd them, the filings that came out was scary.

[CitroJim]

It was just a thought, I'll shut up now. But my 4 membrane (CV) carbs on the Zeph11 didn't like like a normal clean, they needed US. Bloke in the club spent 800 squids on some flat slides, brand new, US'd them, the filings that came out was scary.

Yes, I've heard horror stories about slides jamming when inappropriate cleaning fluids are used in some carbs Pete. A slide jamming in a motorbike carb is a particularly scary thought...

What solvent did he use to cause the issues?

I think I'll be OK with how and what I used

[moizeau]

On the Zeph11 it was the very small holes in the front of the venturi. The bottom end mixture was impossible to set due to 'fuel tar' in the passage way that leads to the mixture screw.

The mixture screw hole can be seen on the far left with the jets removed.
A common problem on these CV carbs with modern fuel.
After stripping twice, carb cleaner, air line etc. they were getting better..... In the end I stripped them again and US'd the carb bodies. Still now I can't get the mixture screws to factory setting but can get the mixture right.
The photo also shows a clear tube that is used from the carb drain hole to set the float height. Turning them upside down and measuring the float height resting on the float valve isn't reliable due to the spring weakening and seat/float valve not being in perfect condition.
All 4 of the float valves also got replaced due to the carbs flooding no matter how I adjusted the tang on the floats. (at £30 each)

The chap in the club's carbs that emptied machining swarf into the US bath were brand new from the factory at a cost of £800. They will have been cleaned but he US'd them anyway and was quite pleased he did.

[CitroJim]

That's most interesting Pete Thanks for that and it goes a long way to long held suspicions about how much damage modern petrol can do... Especially if left to hang about for too long and go 'off' and go all gummy...

Methanol, I understand, can play havoc with carbs and cause slides to jam. I'm wondering just how much modern petrol weakens off the mixture and if we should be upping out main and idle jet sizes to compensate? Not compatible with brass floats either I believe... And given it's not good on brass maybe it'll erode our jets and emulsion tubes too. Float valve erosion is very worrying as a flooding carb is a good way to set an engine bay on fire...

We really are heading for some 'fun' times...

I'm sure, given my fuel tank and pipes are all plastic, the sediments in the tank are old fuel residues... I've no idea for how long Bluebell was off the road and hibernating in a barn but I reckon a good few years...

The chap in the club's carbs that emptied machining swarf into the US bath were brand new from the factory at a cost of £800. They will have been cleaned but he US'd them anyway and was quite pleased he did.

Gosh That's not good. Cleaned at the factory maybe but clearly not well enough...

[moizeau]

Float valve erosion is very worrying as a flooding carb is a good way to set an engine bay on fire...

We really are heading for some 'fun' times...

I won't cause an engine bay fire on a bike but was it does do is causes the petrol to flow into the airbox, from there onto the swing arm, frame discolouring it or worse, flow forward into the cylinder(s) and fill the sump up. The Zeph was doing both. When I drained the oil when I first picked it up I got 7.5 litres out...... it should only hold 5.
I think if I hadn't have bought it it would have died at some point because the PO wasn't mechanically minded.

Those of us running old carb bikes that aren't daily runners are already having lots of fun. I use an additive in all my carb engines, some in the club use a special ready mix at £5 a litre and brim the tank for over wintering, some drain the fuel system completely but this also has it's drawbacks if the bike is stored in a not absolutely dry environment. Rust in the fuel tank, corrosion in the carbs etc. Replacing a rusty tank could set you back £300 for a 70's Z, if you can find one, them another £200 to have it painted up to match the rest of the bike.
One chap lives near a small airfield and runs his bikes on 100LL Avgas. There are certain areas of the country (UK) where ethanol free fuel is still available, it's marked up as 5% ethanol (SP98) but these figures regarding the % are 'no more than' as opposed to an exact quantity.