TOPIC:

Thanks.

There is a bend on your choke link, and in the manual, that I don’t think is in mine. I’m reluctant to bend it unless I’m certain it’s the right thing to do. What are your thoughts about the performance of the RHS carb if, when the choke is on, there is a gap betwixt valve and internal chamber? i.e., I leave it as is?





 

What I'd do is first separate the carbs, leaving the choke linkages where they are.  Then, working on the side with the choke lever, actuate the linkage, making whatever adjustments are needed, to get the choke flaps to open and close properly.  You might want to loosen the butterfly screws slightly for this part, and only tighten them after you have the butterfly properly centered in the carb throat.  Once you get the choke lever side working well, move to the other side and again, play with the choke flap alignment before snugging the screws back down.

It's possible that the choke flap shafts are bent.  So if you can't get the mechanism to work smoothly, I'd remove it and roll those rods on a flat surface, to assure they are not bent.

Is it possible to start up the bike with the carbs in place a using an auxiliary fuel tank, without the main tank in place? I’m wondering whether it can be done without the vacuum hose being connected to anything. Is that possible?

I’d rather check the carbs are working ok before the tank is reinstalled. 

A bit gutted to find a split in the top side of the  plastic diaphragm holder on the vacuum piston. The bottom side is fine and the integrity of the diaphragm appears ok. 

Any suggestions? A replacement piston is £300. I can’t afford that. So it’s make do, or mend. 

I was thinking of a couple of G clamps and glue, but that risks cracking the holder further. Or some silicon sealant, simply to fill any possible breaches in the air-tightness. 

 

Jimbo68 wrote:

Is it possible to start up the bike with the carbs in place a using an auxiliary fuel tank, without the main tank in place? I’m wondering whether it can be done without the vacuum hose being connected to anything. Is that possible?

I’d rather check the carbs are working ok before the tank is reinstalled. 

Yes. That is the usual way to do the final adjustments. The vacuum line must be plugged, else that carburetor will have a wickedly lean mixture. I use an old, plastic lawnmower fuel tank. I have an appropriately bent wire shirt hanger through the two mounts, designed so I can hang it on one of the hand grips. I also installed an inexpensive on-off valve in the new fuel line. It was very cheap and works like a charm.

P.S. A golf tee, small bolt, or even a pencil can be used to plug the vacuum line. I reckon vice grips will do the job as well.

All these photos of your carbs show them to be so dirty, it's hard to understand what you have.

This slide seems to be a match, and isn't overly expensive...
I may have a spare too, but shipping is expensive...

https  ://www.ebay.com/itm/    145305084676  (remove extra spaces)

Thanks Nessim. 

That is as clean as I could get them with carb cleaner and a brass toothbrush. I guess they have been neglected for some time. 

Cheers for the link to the reproduction piston. It’s a pity there isn’t more detailed photos but the description is certain about the fit. 

Jimbo68 wrote:

Thanks Nessim. 

That is as clean as I could get them with carb cleaner and a brass toothbrush. I guess they have been neglected for some time. 

Cheers for the link to the reproduction piston. It’s a pity there isn’t more detailed photos but the description is certain about the fit. 

You photo shows that the pilot screws weren't removed.  Or did you do so and put them back already?  

Honestly, the best thing is to remove all the soft parts, ungang the parts, then soak the bodies in carb dip solvent.  That will clean the internal passages.

Thanks Nessim. 

yes, I have removed everything and cleaned all metal parts with carb cleaner, and replaced all o rings. Now reassembled. 

I didn’t remove the piston diaphragms to wash them. Reluctance due to the split in one of the plastic diaphragm holders (see earlier picture). I thought I might make that worse. The pistons themselves were very clean and slide well. 

I'm almost ready to reinstall them on the bike and test with a remote fuel tank. Just waiting for new spring bands for the air cleaner ducts. 

Hi folks. 
Carb rebuild is complete and appears to be a success so thank you everyone that contributed here. Much appreciated. 

Salut!