Stuck slide

[twinegar]

Has anyone ever had a stuck slide? I have encountered this on 4 of my bikes, '79 CB750, "82 CB750 and both '79 CBX's. They all use a similar carb and in fact the carb tops and sliders are interchangeable. I just finished working the carbs on my good CBX (versus my money pit CBX) for the 3rd time because of poor performance. When I would take off from a stop it sounded like it was only firing on 4 or 5 cylinders but if I opened the throttle a little more it would smooth out. I could cruise at between 25 and 40 without incident but if I opened the throttle a little more the missing would return. If I opened the throttle full it smoothed out again so it seemed to be a particular throttle range where it occurred. I replaced the air cut-off valve and accelerator pump and cleared all ports and channels but still had the problem. Yesterday I pulled them off once again and saw that #1 slide was stuck open so I pulled all open and checked the slide operation by moving the slides in and out of each cap and only 3 were free with #1 being the worst. Upon close inspection a found a shallow dent in the cap and a rub mark inside so I swiped a cap off a set of 82 750 carbs. I put a light oil in the cap guide pipe on all carbs after first cleaning with spray carb cleaner and remounted. I checked each one to make sure they snapped back like they are supposed. I also lubed the carb to pump linkage as it wasn't moving freely. I reassembled the bike and went for a ride and it was still sputtering so I decided to take a longer ride to see if it would correct itself. After about 15 minutes and as many miles the problem stopped and the bike ran great for the rest of a 40 mile ride. I suspect that a slide had stuck again and freed itself.

Now.........after my long explanation I would ask if anyone else has experienced this and wound up checking the ignition and every other system before finally discovering they had a stuck slide(s)? I do know that owners like to polish the top caps and it is easy for them to fly out of hand while using a buffer wheel and it doesn't take much to dent or distort the circumference. I hope this post will help someone else figure out their sputtering bike.

[EMS]

Didn't someone a while ago posted a recommendation to NOT SWITCH carb tops???

[CBXRoger]

Somewhere in my pictures from the C2C ride across America, there are pictures of Rick Pope checking and fixing the same problem you describe. His yellow '79 CBX was in the trailer at the time and I believe we were in Illinois. I am sure Rick can elaborate on the subject. The repairs were made by flashlight.

[twinegar]

EMS.
It is always a good practice to keep parts segregated so they go back on the carb they came off of but as long as the slide moves freely I don't see a problem. I could have ground the high spot on the dented cap or ordered a new one but it was easier to scrounge one off another carb. Anywho, it worked out in the end.

Is there an email for Rick Pope?

[Soren Junker]

What you descibe is exactly the same problem I found on my newly bought Prolink. After changing ignition cords, which did not help I traced the problem to cylinder #1, and figured that this cylinder for some reason would run too rich as the problem leveled out at appox 4000 rpm.
I figured that the slide would be stucked due to stand still corrosion, but found a dent in the carb top as you describe and came to the same conclusion, that the previous owner had polised the top and dropped it. I spend 2 hours grinding the slide and top together using car polish and it works. All other slides were checked and worked perfectly.

[Rick Pope]

I'm here. And yes, I had a dented dome. Carb dome, not my head......

I finally fixed it by polishing out the dent. In fact, I had several domes that would work on one carb, but not another. I mixed and matched until I got down to the one with the dent.

As it turns out, the yellow bike Roger mentioned had several issues in the carbs, all minor, all frustrating. I took the whole rack to Jim Zemenek (he's local) and he found all the problems. It runs great now.