Mikuni RS Carb and Petcock Question

RoyNor - thanks! I just came in from the garage to post an update. You are exactly right, I took the rod out and saw that both ball bearings were missing! The springs were still there and I was lucky enough to have 2 ball bearings that fit perfectly. All fixed!

George - you were right on with your earlier tip. I wouldn't have thought of that myself and I couldn't wait to get home to take a look. Sure enough, it was pretty simple once I knew what to look for.

Thanks to everyone for their input!!

BTW, the ball bearings that worked were from the clutch actuator assembly. I had just rebuilt mine will all new bearings and had a few left over. I'll take that kind of luck anytime!

Here's a shot from another angle. The red arrows point to 2 holes. Under the choke rod is a spring. You drop the ball through the hole onto the spring and when you slide the rod through it applies pressure to keep it locked. There is also a detent for one of the balls that keeps it really secure when fully open.



Post edited by: 79MKII, at: 2008/01/15 21:11

On the BS34, carb 2 and 3 have small holes in the castings where the starter rod goes through. There is a hole drilled in the casting and you first put in the small spring which sits in this hole. The ball drops in on top. You then fit the shaft in which has a tapered end and it pushes the ball down as well as the spring below it. The ball is about 1/2 the size of a BB I guess and the spring is very small. These things routinely are missing on the sets I rebuild. The detent function the ball/spring provides will work OK with just one of the two sets installed.

Now that the carb problem is solved, anyone have an opinion on the single vs dual petcock? Is one pingel valve enough to feed this beast??

One pingle works on mine. 77 KZ1000LTD. 1075, ported head, cams, under bucket, RS carbs, Vance & Hines, Accel coils, Dyna 2, and soon GS 1100 swingarm.

kenskz1000 wrote:

One pingle works on mine. 77 KZ1000LTD. 1075, ported head, cams, under bucket, RS carbs, Vance & Hines, Accel coils, Dyna 2, and soon GS 1100 swingarm.

Thanks for the input!

Anyone else have an opinion on using 1 petcock?

i lightened your photo for "GOODER" viewing lol!

Caution -- unadultrated BS follows --

So long as fuel will drain from the tank through the petcock at a faster rate than your motor can consume it, there should be ample fuel being supplied to the carbs. This presupposes that the petcock is clear and unclogged.

For example, it usually takes only a few minutes to empty a full 3 gallon tank by draining it through the petcock, whereas fuel consumption at even a dismal 10 mpg would require 30 miles to consume 3 gallons. And running at a steady 100 mph in first gear (10 mpg??) for 30 miles would take about 18 minutes.

So am guessing that very few if any motorcycle engines regardless of size are capable of consuming fuel at a faster rate than supplied by natural drainage from a properly vented fuel tank through any single normal size clean unclogged petcock.

Maybe the Boss Hoss huge V-8 engined bikes are capable of consuming fuel at a faster rate than possible through a single petcock (but probably use a fuel pump anyhow).

But I really don't know and am just BS'ing for the fun of it. :lol: And quickly agree that the dual petcocks look really cool and all business.

Perhaps the second petcock could be considered as a secondary or backup fuel supply in event of a clog or malfunction in the other petcock. Betcha roadracers like the idea of using dual petcocks.