I was finally able to get the tips unstuck! For anyone out there that this happens to this is how I did it:
- Carefully file off the tips of the fuel screw flush with the carb throat (mine were sticking up into the carb a little)
- Freeze the carbs
- Break off the tip of a sewing machine needle, about 1/2" or so.
- Clamp the tip with some needle nose vice grips as tight as you can with only about 1/16" of the sharpest point of the needle sticking out the bottom. I tried to clamp the sewing needle in at a angle at first but I kept breaking the tip of the sewing needle off so I found that clamping it in at 90 degrees worked best.
- Line up the clamped sewing needle right on top of the brass tip that you filed flush
- Now squeeze the clamped needle straight down with your fingers being careful not to twist or you'll break the sewing needle
- Mine were all stuck pretty good but they all popped out. I couldn't get them out until I froze the carbs then they came out with some heavy pressure from my hands
Thanks for the help Doctor D, you got me on the right track!
Does anyone know how to remove the broken tips from the carb??? I have the exact same issue...not good.
It wasn't until I got to the idle fuel orifice, a tiny hole on the bottom of the engine side of the carb body, that I noticed an issue. The guitar string only went through one of the ports.
Seems someone, odds are it was me, over tightened the pilot fuel screws on 3 of 4 carbs causing the delicate tapered tips to jam in the idle port and shear off. In my defense, the springs and o-rings on the screws create some resistance, making it hard to know exactly when the screw has bottomed out.
Never having had all the screws off at the same time, I didn't notice that the tips of the screws looked different. Pretty obvious once they're on the table together though.
It's not an unusual problem, so I'm not beating myself up too badly. However, getting the broken off tips out of the carb bodies isn't the most fun I've ever had.
In any case, this explains some of the problems I was having, and new screws are on the way.
The other issue was one of the accelerator pump sticking. This was solved by using a felt polishing bob on a Dremel, and some Mother's to clean out the pump piston bore. Much nicer now and it returns fully every time.
As for jetting, the needles that come with the carbs might be fine for a stock GS750, but on a modified 836 they're too lean. 9DZH03's are much better, curing the huge lean-out that was occurring right after the end of the accelerator pump stroke finished. 127.5 mains were too lean with my open 4 into 4's and 50mm velocity stacks, but with balky pilots and a lean needle it's not an accurate measure. As soon as the new screws are in hand, we'll get back on the dyno and try again.
It's a PITA to fix these. I used sewing needles that I had snapped in half (to give them a flat-ish working surface) clamped in needle-nose vice grips, which I then rapped with a small deadblow. Be careful as you can actually peen the brass tip into place.
