Four Wheel Forum

Hi, the carb on my '62 (Rounded bowl) tends to stick at WOT when cold. It's not the cable, it's the slide itself. I know the slide is pretty worn (nicks, worn plating), and I've tried to carefully smooth it down without damaging the remaining plating, but it may need replacement.

Any ideas?

I have to ask...Internal throttle control at the handlebar? I have had sticky throttle's due to worn slides.

Spokes wrote:I have to ask...Internal throttle control at the handlebar? I have had sticky throttle's due to worn slides.

It's the external throttle. The reason I blame the (carb) slide is that after it sticks, if you push it back, the cable goes slack and pushes back inside the carb.

Ok. Yes, I have to agree that a rough slide will stick. You may have to source another slide or have yours machine polished.

Spokes wrote:Ok. Yes, I have to agree that a rough slide will stick. You may have to source another slide or have yours machine polished.

Any idea where I could find a carb slide?

Perhaps another member might know. Regrets on not having an extra.

Spokes wrote:Perhaps another member might know. Regrets on not having an extra.

No worries. Oh, I forgot to ask, is "machine polishing" some sort of special process, or am I overthinking it?

Maybe a little. You need a buffing wheel and gold or green rouge. You "burn" a finish into the aluminum, which gives it a smooth mirror finish. Thus a "machine polish". You can send it to me and I will do it and send it back.

Postage only. LMK

Spokes wrote:Maybe a little. You need a buffing wheel and gold or green rouge. You "burn" a finish into the aluminum, which gives it a smooth mirror finish. Thus a "machine polish". You can send it to me and I will do it and send it back.

Postage only. LMK

Wow, thanks. Tell you what, I'll pull the slide out and take some pictures of it. I'll post them here and we'll see if I can keep from wasting your time on it - or maybe there's another issue I've overlooked. It's been a while since it's been off the bike, so I can't recall 100% how it looked.

I'll pull it off some time over the next few days.

Okay, good news:

While the slide is a little worn, it wasn't entirely the problem. The bore on the carb was rather rough and slightly out of round. A little pressure on the outside and the slide would go right in.

So, I carefully cleaned and polished the scratches and pitting out of the bore , as well as the rough edges of scrapes on the slide using a dremel and autosol. Now, it's working better than ever. Return is immediate and firm.

Thanks for the advice, had you not mentioned polish I probably would've spent another hour staring at it before I got up the courage.

Great, I'm glad it works. I knew about applying pressure to the carb slide tube, but was reluctant to suggest doing it. I am afraid of damaging the carb if too much pressure is applied. (just me)

The polish with the dremel is a great idea to smooth out the bore and slide. Happy Trails!

I had similar problems form over tightening the carb flange. The slide would stick but release when I took 1/2 turn off of the flange bolts. Also a little Scotch brite in the slide bore could help.

The carb on my early Benly is doing the same thing. It is really annoying and makes the bike unridable. The slide is plated so I was thinking the sticking was a result of the finish being worn down. But deforming of the carb body also is suspect so I'll have to give them both some attention on the bench. This is a good subject as these are valuable components.