Adjusting the Sammy's Carburetor and a new leak presents itself

Not related, mind you, the two events mentioned in the title!

Today, under guidance from RichardM who once again explained the concepts involved with Carburetor Secondaries in a manner which led to my enlightenment, I "adjusted" the setting screw for these on the Sammy.

Background: I had, you see, in my early days of Samurai ownership, messed about with this particular screw, thinking it was the idle adjustment screw, which it was NOT.

I realized this a long time afterwards, while discussing things via messaging with Mike W.  Mike is the Samurai Guru I go to as he's rebuilt several and owns two!  In the below picture, Mike is using a spare carburetor of his to point to the screw in question.  

The above screw actually affects the opening of the Secondaries, aka secondary Venturi's or butterfly valves within the carburetor.  These are the ones used when underway, under load and at speeds higher than just idle or low speeds.  They enable bigger air volume for the carburetor as more fuel is required for higher loads/speeds.

View of bottom of Carburetor's top half

The two round disks are the butterfly valves

image courtesy again of Mike W.

Then, just for reference, here's a pic of the correct idle adjustment screw, again courtesy of Mike W.

OK, that's the background, I had turned that wrong screw thinking it was the idle adjustment screw way back when, while troubleshooting idle speed.  Of course, I lost track of how many turns and direction, and failed to note how many turns from soft seat it was at.  Stupid.

Anyways, back to today.  I had thought/felt that there was an acceleration "slowness" with the carburetor or as RichardM aptly put it: "it seemed to run out of breath" under load.  After a failed attempt to look up "initial configuration" settings for this screw; I decided to just try turning the thing and test it while driving.

Got the engine nice and warmed up, and using same route each time, noted performance first without any changes to that screw.

Then, driving the same route after I had turned the screw outwards/counter-clockwise two full turns, I noted that she seemed slower in terms of acceleration response.  I saw that the RPMs would climb very slowly as I shifted into higher and higher gears.

Backed out the changes by turning the screw inward or clockwise two full turns, then turning further inward by two more turns.

Same route but now I noticed better performance!  No more slow acceleration or climbing of RPMs!  The Sammy felt faster when accelerating from a standing stop, I was able to keep up with traffic easier and pull away from the guy behind me at the light much better than before.   Before, I would sometimes be so slow while shifting from 1st gear to 2nd gear that I feared the idiot behind me wouldn't notice and ram me.  Now, I don't think that'll be an issue, unless of course its an asshole driver but nothing I can do about that eh?

Feeling optimistic, I stopped and turned the screw a half turn more inwards/clockwise.  Ran the route again but noticed a return of slight "bogging" under acceleration.  I know, very subjective, with no real objective measurements involved, but that's what I got.

So, I returned the screw to the two turns position and will call it good for now.

A New Leak

So, later on today, I noticed a new small puddle of what turned out to be brake fluid under the Sammy.  Dammit.

It was easy to see where it was coming from, the P & B Valve or Proportioning and Bypass Valve for the rear brakes on the Sammy: 

This part, is also called a Pressure Metering Valve and has a manufacturer p/n of 51910-83110. After much searching of the net for the wrong p/n's; I fortunately stumbled on the right p/n and the picture at the website verified I was correct!

image source: roadlessgear.com

I've ordered the part, hopefully it'll be here in a couple of days and I'll be replacing it.

I suspect, the internal seal(s) in this valve had been steadily deteriorating over the years.  I'd been noticing air leaking into the rear brake circuits for no apparently reason since I replaced the rear brake cylinders over the summer trip.

So, though pricey, in a way I'm glad this valve finally leaked enough that I was able to notice it.  I am pretty sure it's the source of air in the brake system of late!

The way she's leaking now at the valve, the Sammy will have to sit until I get this part replaced.  Not worth taking a chance of the leak getting worse while driving the car and losing my rear brakes!