Revs slow to drop between shifts.

[hankgood]

There were several discussions on the old board about clogged pilot circuits causing problems with revs not falling when closing the throttle. I used the threads for instructions and did a thorough carb cleaning and had all of the tiny ports spraying nice streams of cleaner into the throat. When I got the bike back together it ran fine - smooth as butter.

Now, less than a year later it's doing the same thing. I don't ride it much but it never sits more than 3-4 weeks. I've added a half a can of B-12 Chemtool with every fill-up.

Anybody got any suggestions? I don't relish tearing them down again. I have thought of installing a Pringel stopcock and running the bike dry each ride but I wonder if that will clear the pilot circuits of fuel.

Thanks

[MAN OF BLUES]

B12 is pretty strong stuff, but simply adding a can without running thru the whole tank is not a cure.
Running completely thru the tank is a better temporary fix. No chemical on the market will disolve minute rust particulates tho, and if this is what is blocking the circuit, it's pretty much a pull the rack and re-do thing when the bike sits.
As for running the bowls dry, that really doesn't work either, it just allows "lowering" the fuel level in the bowls to a point no more fuel is picked up, and there will still be lots of gas there, with the sad understanding that it will evaporate sooner, leaving the particulate matter there in the end, only to be carried into the circuit on the first usage again, in even higher concentrations...blockage is emminent.
Start by completely removing the fuel from the tank, and sucking all the fuel from the bottom corners using a turke baster with a hose attached to it...repeat flushing a couple times till you are sure there is no more rust. you will still need to clean the circuits tho, there is little you can do to prevent clogging when the bike sits so long. Sorry
if storing, always make sure the tank is completely filled with fresh good gas, to prevent condensation. Do not open the tank unless you are filling it, this just allows more moisture in there if it's a partially filled tank.
In lieu of adding B12, start adding a marine stabilizer if it's gonna sit, use the Marine grade Stabil product, it's designed to work better with ethanol laced fuels.

oh, and no matter what you add to the gas, do not add multiple "combinations", this just exacerbates problems, and causes bad results as each additive needs to be run completly out, before adding a different one....don't play chemist with the fuel, the outcome is never good.

[hankgood]

I don't think that  rust or tank crud is the problem.  It's a 2004 with a very clean tank and NAPA 3006 filter installed - the bowls are very clean. I'm thinking that the fuel is degrading. I will add Stabil in the future.

Guess a rebuild is in next - a chance to add over flow tubes.

[midnightrider]

I learned this trick from Steve-in-sunny-florida. Put 2 oz. TC-W3 2-stroke oil in every tank. Keeps things clean and helps keep the gas from going stail so fast.
I've noticed lately in this heat we've had that without the 2-stroke oil my gas would smell and look stail in less the a week of non riding.

[Mettler1]

 

   +1 You can get at Walmart for about $12 per gallon. About $.19 per fillup! Look for Super Tech TCW-3 in auto dept.

[Cybercraig]

The slides could also be sticking from sitting around varnishing up. That's one thing the TC-W3 will help with. How is your idle? Are you turning the adjustment screw in?

[jklhill]

I am guessing that you have already eliminated everything external of the carbs like throttle cables.

[hankgood]

B12 is pretty strong stuff, but simply adding a can without running thru the whole tank is not a cure.

Maybe I wasn't clear on the B-12 - I've added a half of a can at every fill-up since the last cleaning.

I am guessing that you have already eliminated everything external of the carbs like throttle cables.

The throttle cables seem to snap back nicely.

Are you turning the adjustment screw in?

Idle adjustment is hard to regulate and the choke/enricher is harder - very high RPMs and impossible to set for a decent warmup.

[Karl]

All the other folks had good advice.               Just a thought, before you pull the carbs, did you check for vac leaks?
A spray can of starting fluid, or WD-40 can work.     I had a tiny (very tiny) crack in a boot once that gave me some problems.
Good luck.     

[Steve in Sunny Fla]

Yeah, it's crudded up pilot circuites. The problem is that unless they're open enough to flow some fuel laced with cleaner, they won't clear on thier own.

 I have 2 bikes I ride right now, a voyager and shoodaben. The carbs are virtually the same. I have been doing the tcw-3 trick consistently, and have have had absolutely no issues with the voyager, which sits more in a VERY hot shop (steel building in florida). I mention the heat because the ethanol evaporates like crazy here. Shoodaben is parked next to it, but gets ridden more. Anyway, a few months ago I forgot to add tcw-3 to the concours, and the bike sat for 18 days. 18 DAYS! would you believe it - the pilot circuits were blocked, and nothing short of pulling the carbs for cleaning helped. Meanwhile, the voyager, which has always had the tcw-3 has had absolutely no issues. I think that pretty much confirms the tcw-3's usefullness - Steve

[MAN OF BLUES]

Maybe I wasn't clear on the B-12 - I've added a half of a can at every fill-up since the last cleaning.

No, I understood you clearly....

I also read this:

Now, less than a year later it's doing the same thing. I don't ride it much but it never sits more than 3-4 weeks. I've added a half a can of B-12 Chemtool with every fill-up.

My comment was based on, putting the stuff in the tank is half the equation, unless it is being run thru the system, it ain't doing anything for the circuits, just sitting, and getting stale.
I'll also add that both Steve and I have mixed emotions on B12, and we have discussed the higher incidences we both have seen, with regard to float needle tip degradation on carbs where B12 was allowed to sit for extended periods of time.
The stuff is a treatment cleaner, and does not need to be continually present in the fuel.

besides, nobody will want to ride behind you ...that stuff does have an odor to it....

the best prevention to blocked circuits is to run the bike (distances) and cycle the fuel.

[hankgood]

Could someone please explain the reason why clogged pilot circuits cause the motor to be slow to return to idle?

[George R. Young]

Wild-ass guess, did you have to turn the idle speed up to compensate for poor low-speed mixture?

[hankgood]

Wild-ass guess, did you have to turn the idle speed up to compensate for poor low-speed mixture?

The idle adjustment didn't have much effect after the problem started.

I'm just curious what about clogged low speed jets causes a motor to be slow to return to idle.

[midnightrider]

The idle adjustment didn't have much effect after the problem started.

I'm just curious what about clogged low speed jets causes a motor to be slow to return to idle.

The engine is starving for fuel because of the clogged jets, the mixture is too lean in the low speed range. If it were too rich it would bog down then return to normal idle.