That long allen screw and the lock nut serving as the slide's adjustable upper stop on it weren't designed with easy adjustment in mind its seems..

I guess my problem is magnified because it's impossible to find an open end wrench smaller than 6mm in this Philippines city, but regardless - the nut is very close to the big bracket it's next to and even taking the big bracket next to it off wouldn't help matters

I've cut the small end off a 5mm socket and will even have to grind the OD of that down so it will fit into that small space and slide onto the nut, then have a piece of tubing welded to it or something (or just make my own wrench out of steel)

Luckily I haven't even started putting it on the bike yet, so it's not causing any downtime.




- I haven't read any comments yet about anyone adjusting their slide's upper stop next to the return spring, but the bottom of my slide goes up quite a bit above the upper edge of the venturi.

 

Do you have the downloaded instructions from Mikuni for the 36/40 series pumper carb? I may have missed it, but I don't recall any info or recommendations for changing the throttle stop from its factory position.

http://www.mikuni.com/pdf/hs40_manual.pdf

I think I'd only be concerned if for some odd reason the slide wasn't rising all the way to clear the throat. Still, I can't see any harm in adjusting it to where it stops exactly at the top of the carb throat. I did a quick search on the topic, and what little I found only mentioned insuring that the slide does clear the throat completely. Did you find a source that described more detail about the slide going slightly past the top of the throat? If so, please link it here, as it might be good info to pass on.

 

No I just looked into the carb as I cranked it all the way open and see the slide a bit higher than the venturi and the needle kind of cocking off to the side as the slide rose into the too-high position.

No sense having a great flowing hi-tech carb if the slide's overtraveling and effecting air flow thru the venturi

I just now took another look at it, and I'd say it's 3/16" too high at WOT. Pulling the needle further out than intended may throw off main jetting as well

I remember years ago Cycle mag did some carb flow bench testing and found that even a small amount of slide hanging into the airstream effected cfm numbers more than you'd guess

- Just can't recall if they tested with a slide rising up too high, but I think it's certain your flow would be better with the slide no higher than necessary



I'll get jam nut loosened one way or the other

 

You definitely do not want the needle pulling through the main.

 

I think it's probably super common for the slide to travel further up than the top of the Venturi. Mine was that way. Another user here - David R maybe - had it too. It's probably not something most people would notice, but it very well might impact jetting consistency at WOT. Anyway, I adjusted mine; can't recall the details exactly. I may have used a 1/4" open end wrench...which I suppose is not ready available in the Philippines.

 

flush + or - 1mm is what my non pumper TM manual says.

Syncing multiple cable operated carbs you might have one flush, one down a little or up a little.

 

So far there isn't one in this small town. Since the carb's a Mikuni wouldn't everything on it be metric?

Mikuni went to the trouble of including that long set screw and lock nut; I'll get it loosened up one way or the other

Nothing but time over here

 

Let us know how it goes. I have one to re-jet and install next weekend.

 

Probably it would be metric but when in a bind sometimes a standard wrench is "close enough" to get the job done. Just as long as the fastener doesn't get damaged.

 

I'll get it eventually.

Sometimes a 1 minute adjustment that turns into a week long adventure as you plod along is what you need here in paradise (9°18'38.55"N 123°18'37.13"E)


I already tried just giving the allen screw a twist to the left, but the set screw is doing its job and holding fast

After I grind down what's left of the 5mm socket's OD a bit I'll probably have a piece of rod welded to the side of it so I can give it a little twist.