BS

[jefft]

Where is it on the BS 38 carbs that you can attach a manometer other then the intake boots? I have heard there is another place to do this but it seems like everyone uses the carb boots. My othere question is , does the center screw where the carbs are linked just control the movement of the right carb butterfly or does it moves the left one too.
jefft

 

[TeeCat]

I wonder if it would work on each side of the choke crossover tube? I think it's largely vacuum traveling across there. Maybe?

 

[jefft]

I remember reading that one or the other carb should be adjusted first but can't remember which one. I think it was the left. I bought some JBM carb boots and really didn't want to put barbs in them if I could check vacum somewhere else.
Jefft

 

[5twins]

The center adjustment screw on the linkage controls the position of the right butterfly plate only. Use it to sync the carbs by matching the right plate's opening to the left's. The screw at the left carb's cable arm controls idle speed for both carbs, moving both throttle plates in unison through the linkage. Match (sync) the plates using the center screw 1st, then set the 1200 RPM idle speed using the left carb screw.

'76 and newer 38s had a vacuum port blocked by a screw located above the butterfly shaft and below the mix screw. You can draw vacuum from it for using gauges if you temporarily replace the screw with a suitable hose nipple. The thread is a common M6 .....

 

[ontherocks]

You will need m6 X 1.0 mm hose barb. I had a hard time finding any. 650central sells them but not worth it with shipping charge unless you are buying alot of other stuff. I ended up drilling out some grease zerk fittings from ace hardware and it worked just fine. They are like 50 cents a piece there.

 

[jefft]

Thanks for breaking that adjustment procedure down. You should write manuals that was so much clearer the way you explained it. I think I am going to try and find a suitable fitting or drill some zerks. I want to use that vacum port rather then drilling holes in my boots.
jefft