Carb rebuild service?

[JezzaPeach]

Hi, after in-situ cleaning, jet cleaning, fitting new correct float bowl seals etc, finding a float bowl screw seat thread stripped, and still leaking, I’m finally considering having them properly refurbished. Can anyone recommend a reliable tested service?
Advice appreciated as always.

[Laverda Dave]

Here you go. He comes very highly reccomended.
https://www.sohc.co.uk/index.php/topic,10075.0.html

[JezzaPeach]

Many thanks Dave

[Oddjob]

I've personally seen Gerbens work and whilst it looks great from a distance it's not so great close up. I'm being super critical though, however for what he charges I'd expect better.

[Menno]

It will be interesting to see how things will go - with trying to send a carb to the Netherlands to have is refurbished.
With being outside the EU and all that is...

[Nurse Julie]

It's easier to do that now Menno as there is a code that can be used for temporary export, repair and return of goods. But, we still have to pay duties on the value of the repair, unless it is under warranty, when no duty is payable.

[JezzaPeach]

Noted many thanks. I think I’ve worked out what the main issue is with mine. I had tested the float valves and they seemed good, and each bowl reaches 50ml, so I couldn’t understand why the fuel was reaching the bowl joints.
I think it’s because (on #3 & #4) the float pivot is binding very slightly on the brass rod. As it’s only 3&4, I’m going to try polishing those - the rod and the tubes it passes through, with very fine polishing paste, to get rid of any resistance. I’ll do the same with the gasket mating surfaces, and then test.

[Trigger]

Noted many thanks. I think I’ve worked out what the main issue is with mine. I had tested the float valves and they seemed good, and each bowl reaches 50ml, so I couldn’t understand why the fuel was reaching the bowl joints.
I think it’s because (on #3 & #4) the float pivot is binding very slightly on the brass rod. As it’s only 3&4, I’m going to try polishing those - the rod and the tubes it passes through, with very fine polishing paste, to get rid of any resistance. I’ll do the same with the gasket mating surfaces, and then test.

This should of been done as part of a full strip down and clean of the carbs. Any short cuts, you will be chasing your tail and getting more frustrated 

[McCabe-Thiele (Ted)]

Well done in finding the slight binding on the float brassware.
Hopefully when you have cleaned them up it will be sorted.

I soaked mine in vinegar overnight then washed off any residue with petrol that seemed to sort mine. Also I find the Brasso Wadding very good at removing surface tarnish.

[deltarider]

It's a common thing, realising how gentle the movement of the float is and how little it takes to disturb that soft force. I'd clean it with naphtha and use one of your grandad's pipe cleaners.
However, since it's both on 3 and 4, we cannot rule out an obstructed fuel flow. The CB500/550s are very sensitive to a correct tubing.
The correct dimensions for the fuellines are: for the CB500 and earlier CB550s: 18 and 30 cm length for the models with the bowltype petcock and 17 and 28 cm for models that have the newer style petcock. Do not be tempted to have them even one cm longer. For the tube that supplies carbs 3+4, use the soft metal clamp in the middle front side as shown in the pic (btw, horizontal is good enough) for proper routing. Ideal inside ⌀ of the fuel lines is 5,5 mm. Outside ⌀ will be around 10mm. Have this and the lines will not kink. Abstain from extra inline filters. Some have been lucky with them, but my experience is they can't be trusted. Often it isn't that filter itself, but the rerouting of the fuel line that - sometimes intermittent - impedes a proper delivery of the gas.

[JezzaPeach]

Many thanks Ted. I was thinking of vinegar as well.
Trigger and Delta all noted. I’ve done a fair bit to them all and agreed. This is the only real issue now and I may need to repeat with 1&2, and fuel flow I’ve sorted. If the polishing doesn’t work a full rebuild will be on the cards.

[Jond99]

Just bring this back up to see if anyone has any recommendations.

Mine, where supposedly done by the previous owner however it’s leaking from one of the bowels along with the suspect plumbing and a few other things leads be to think they’ll likely benefit from being done, that way I know they’ll have been done correctly.

Unfortunately I’m also in the middle of building work which I’m doing myself so have little time and space to tackle it myself, hence looking for recommendations.

There’s a few advertise on ebay, Greben being one but having read some posts on here possibly one to avoid?

[Nurse Julie]

Send them to Matt Harper at Harper Ultrasonics.
I could be wrong but I think Gerben may have retired.

https://www.harpers-ultrasonic.com/

[Jond99]

Send them to Matt Harper at Harper Ultrasonics.
I could be wrong but I think Gerben may have retired.

https://www.harpers-ultrasonic.com/

Thanks Julie, just down the road from me. I’ll certainly given him a call.

[JezzaPeach]

Jond99
I only just saw this still posting. I thought mine were leaking from the float bowls but it was the fuel pipe T pieces 8 o rings all along. Just in case.
PS carbs off tips: air filter box out. Clutch cable free (if 500/4) Back and front carb clamps off. Plenum back 1/2 inch. Strip of wood across the back of the head to use a big screwdriver to gently lever the front rubbers. Lots of wiggling. Reassembling, a touch of red rubber grease in the rubbers to help.
New fuel hoses from DS.
I also found lowering the floats slightly has stopped intermittent ‘soggy blip’ on down changes, and stalling, due to too much fuel being sucked through.