Sticking throttle/idle issue

Carbs are cleaned, synched.

Throttle recently reran from handlebar swap, and it's sticking just a little bit. When I rev it to about 3k after having ridden it with the throttle open a while (such as on the freeway) it'll be sticky, and not want to drop below 2500 or so. Then, when accelerating, I'll ride it up to 3k in 1st, shift, when I shift at 2500 in 2nd it revs to 3k as soon as the clutch goes in.

So my question is: how do I clean my throttle cable? I'm presuming it's just sticking in the housing.

Also, the bike can't idle. It idles with the choke on, but it will slowly sputter and die with it off. How do I adjust the idle to bring it up just a bit? I've got a 4 into 1 exhaust system, could that cause problems? unsure if the carbs were rejetted after the swap, but I'm assuming they weren't.

 

For starters if you're shifting at 2500rpm you're not accelerating and you're not doing the motor any favors. REV IT. I rarely have less than 4K on the clock; run it to 4000 or 5000 before you shift; 7K if you want to accelerate. (Redline it if you want to rocket into the distance.)

The best way to clean/lube cables is with a cable-luber. Any motorcycle shop should have them; it's a neat little "block" you clamp onto the end of the cable that accepts the straw from an aerosol can and you power-flush and lube the cable. I use Tri-Flow spray lube; a bit expensive but impervious to temperature extremes.

There is a big knob under the carbs in the middle that is the "master" idle adjustment knob; simply turn it in a few degrees.

 

Remove the Throttle Cable and pull on the Bullets to see how the Cable reacts to movement.
If the Cable binds during the "Movement" Test ... the Cable could have a broken wire making the Cable bind or move slowly.

Replace the Throttle Cable.

Bring the Cable to a Bicycle Shop.
They can make you a brand new wire Cable and use your Sheath.
Cable and Sheath? Whatever you need.
Far less expensive than a Dealer Part.

The problem might not be Cable related.
You might have Diaphragm Piston stiction. Very common.
Dressing the Piston Bores and refinishing them to prevent the Piston from sticking is very common after 15 years of service or more.

 

Thats an interesting idea. do you think it would be cheaper to just do this rather than the cost of a luber + lube not to mention the time spent cleaning the cables since bike shops can do stuff like that in a matter of minutes

 

IF ... the Cable isn't broke with a wire unfurling ... just clean it.

Douche it out with Carb Cleaner and then Oil it.

But, ... it there's a broken strand you can feel. Shit Can the Old one after you visit the Bike Shop.
A Broken Strand on a Throttle Cable will freeze-up the Cable with the Throttles open and that aint good.

There's nothing like the feeling of a Brand New Bike Shop made Throttle Cable made with stainless wire and lubed with silicones.

 

I'm not really hard on the bike. I only shifted that low when I was trying to figure it out. But I rarely shift above 4500. My engine hesitates from 8k to 9500 - but I'll deal with that later.

 

shops do it in a matter of minutes because they use the gadget Fitz is talking about
look at the throttle tube, maybe the grip is dragging on the bars
your sure it's not a vacuum leak
fix it now before sticking a little turns into stuck and bad things happen
chacal has brandy new ones

 

Gun lube works well, too.

 

It sounds to me, like you simply have a dirty and out of tune carburetor problem.

It sounds like you are associating the poor performance of your carbs with a sticking cable, when in actuality the cable has nothing to do with it.

 

Did you miss the part where I mentioned having taken the bike to one of the best shops in the area, and had the carbs cleaned/rebuilt/resynched?

no time to work on it until friday, but I'll clean it first, and work from there.

 

Egad, Watson, I do believe we're onto something.

The two things you mentioned (above) go together and give us a big clue...

Throttle shaft seals.

If the shop wasn't as good as you think, and didn't fully break the rack and strip the carbs but instead just "dunked" them they may have actually made the situation worse.

Throttle shaft seals don't always WEAR out, quite often they dry out, or start to split or actually split into a couple of rings, and still seal pretty good when the shaft is at rest or not turned very far. Then as you turn the throttle shaft more, they start to open up and leak (vacuum leak.) This condition is almost impossible to detect because they work ok at idle so they pass the propane test.

If the shop wasn't as thorough as you think and did in fact exacerbate the issue, you should be able to detect a leak using the propane test now I'll betcha. At least it's worth a try.

 

. . . Or try starting fluid for the leak test. At this point what could Ether hurt ??

 

Actually, you didn't say that at all. The only thing you said was "Carbs are cleaned, synched". Some people think that running fuel injector cleaner through their tank and turning the sync screws until the bike sounds right to them is a proper clean and sync. How was I to know you weren't one of those nitwits?

I will tell you what you have stated.

1. "and not want to drop below 2500 or so"
2. "the bike can't idle"
3. "My engine hesitates from 8k to 9500 "


All of those things together indicate that you have a carburetor cleanliness or set up problem. Since this is the first time you mentioned having had a shop professionlly do it for you, I recommend you go get your money back.

 

I've seen all sorts of stuff to keep the Idle high after a Cleaning.
Some even hook up the Carbs tp the Choke by mistake.

Mostly, its a Cable hook-up issue.
Something not seated or put-on wrong to begin with.
Then there's Air Leaks.
Manifolds leaking.
Holes in things.

Eventually, it all gets smoothed-out after discovering what's the matter.