JBM Industries has BS34 Carb Holders In Stock...

[501Spanky]

I just ordered a set along with new diaphragms.

Don advised me that they also now have tooling for the VM32 carbs with a 39mm spigot.

I'm not affiliated in any way - just giving you folks a heads up

 

[Cesiumsponge]

Thanks for the heads up! I wasn't expecting these until September.

What's the next easiest method to sync carbs since JBM boots don't have the little vacuum barbs?

 

[retiredgentleman]

On some years, the carbs have a small bolt that unscrews to allow a fitting to be installed. My 78 SE BS38's have that small bolt.

I've ben told you can use a grease fitting to screw into the access port on the carb. Need to remove the small ball from inside the grease fitting.

Many years ago, I needed a fitting to screw into the carbs, on my 1976 XS500C, to allow sycning. I found a bolt with the correct thread, and drilled a small hole down the centre of the bolt, and then ground off the head of the bolt, so that tubing would fit on. Worked quite well. Actually the fitting can be purchased these days.

 

[Cesiumsponge]

I'm not even sure where the access port of the carb is for and I've taken most of it apart and reassembled it when I checked my pair of BS34's for any broken seals or worn out parts, checked and upped a few jets to typical sizes for the mods to get it in the ballpark range as a baseline to start tuning from. I'll have to study some of the diagrams a bit closer to see if I can temporarily replace a bolt with a setscrew with a hole drilled down the bore. That's a clever idea, retiredgentleman!

Worst case scenario, I can sync with the factory boots, then swap out to the JBM boots when the carbs are good to go. It's kind of a pain to pull the carb units off. I can't seem to remove and reinstall it without taking apart the brace and boots completely and using a few choice words.

 

[retiredgentleman]

The BS34's may not have the access port that the BS38's have.

I have found that if you do a careful sync with the carbs on the bench, they are so close that you don't really need to use a manometer. A piece of paper is used as a feeler gauge. Adjust the center screw until you have equal drag with the piece of paper under the butterflys.

 

[501Spanky]

Thanks for the heads up! I wasn't expecting these until September.

What's the next easiest method to sync carbs since JBM boots don't have the little vacuum barbs?

I was looking at that myself. I'm going to do the bench top approach as suggested by RetiredGentleman. If all else fails, I'll ground a plug to do the dead cylinder method.

 

[Cesiumsponge]

RetiredGentleman, I was actually pondering if that would work. I considered taking it to work and using my feeler gages to adjust the sync screws until the butterfly valve openings were about that same. That or try seeing if I could load it on the optical comparator and seeing if I could get it to focus on the gap width and adjust that way.

I still feel like I need to get my money's worth because I built one of those yardstick manometers with small diameter aquarium tubing. I'm out a whole $4 and a lot of work trying to force the oil down the small tubing without air bubbles (then coming back the next day and seeing the bubbles evacuated on their own! @%&#)