Carburetor HELP

[TripleXSive]

I recently got this bike running after re-ringing and cleaning up the head.
The bike starts on first try and idles smooth. But if you raise the rpm over 4000 and release the throttle everything returns to correct position except the idle speed which will stay up over 2500 or 3000 rpm. I have removed and cleaned the carbs 3 times checking and double checking all jets and adjustments. Carbs are very clean. Diaphragm's are good. Ispected and coated carb boot and resealed boot to head. In the am I have plans to start back to basic's and check all mechanicals. I am at a loss as to why I have this problem. I act Like a vacuum leak but the bike starts to easy, it idles fine as long as I do not get to aggressive. I really need some ideas that are more specfic to these CV carbs.

[xsivelybad]

Triple
I am in a pretty similar predicament but haven't quite figured out what the cause of the high idle is if i figure it out i will keep you informed and vice versa i hope
Greg

[randy]

Most times this problem is due to out-of-synch carbs OR a binding throttle cable.

[Czekus21]

If the carbs are sunk up and the throttle cable are fine, I would then check the vacume advance unit and vacume hose. But it sounds like mabee a sticking diaphram vacume slide or 2. I know you said they were good but your symptoms stear toward vacume keeping the throttle open. Are all the springs on the outside in tact?

[TripleXSive]

Carb HELP

Saturday PM have gone over mechanicals. Bike compression good valves good sparkplugs new, carb floats within .005 all vacuum lines plugged. Engine starts on warm up lever 3 rev idles smooth. throttle cable smooth and loose, Have airbox off and can watch slides all moving and returning to bottom. Increase engine speed and I still can watch the rpm climb even after releasing the grip. HELP

[rover]

Guys, check the clamps that hold the carbs to the manifolds, the rubber ones. It is quite easy to get one or two clamps positioned so that they will keep the throttle from closing. Get a small mirror and look at those inner clamps while actuating the throttle. Just a little drag will cause the idle not to return to normal.

[rover]

Also, just watching the slides inside the rear of the carb will NOT tell you if the throttle plates are closing. Those slides are operated with engine vacuum, independent of the throttle butterfly plates which control your idle speed.

[fxrer]

Hey Triple,

As pointed out by others in the past, you should continue your comments about your problem in the original thread, instead of starting a new one on the same subject. That way, the facts are all in one place, and readers can follow the comments by others that can help narrow the possible problems and solutions.

Anyway, the only way the rev's stay up is if the motor is getting more fuel & air. So, either the throttles plates are not closing, or you are getting more fuel through the enricher circuit.

Disconnect the throttle cable, where it connects to the carb linkage, and operate the carbs manually, see if that works.

If your throttle plates close, (and your slides lower to bottom), and it is still revving, then I would suspect something is wrong with the enrichers.

[TopCatGr58]

Hey there TripleXsive,

Although vacuum ports are plugged, you can still have vacuum leaks around the intake manifolds or even the carbs! Take some carb cleaner, WD-40, or starter spray, and while it's running, spray it around the intakes and the butterfly shaft seals, and see if the engine changes RPM. IF so, then you have a vacuum leak somewhere!!

If no change, then you can be assured of no leak. Now, take the carbs off, and look at the side that goes against the engine, there are 3 little holes in the top of the carb body, check to see if the butterflies are all covering part of the furthest exterior hole evenly! IF not, then adjust the synch screws to get them to all even positions...=BENCH SYNCH, then put them back on, and it should behave a bit better, and then you can get a vacuum gauge and perform a vacuum synch to get them more precisely even.
T.C.

PS, I merged the threads, YES, PLEASE CONTINUE TO REPLY TO YOUR ORIGINAL THREAD, WHEN IT'S THE SAME PROBLEM/SUBJECT.

[mn2346]

I had this problem on a SH and it was fixed by doing the carb sync over and over until I got it right.

Used the lowered RPM method, where you sync at the under the normal rpm range and then adjust it to normal after it is even.
Now runs like a kitten.

-M

[waterman5776]

I've been struggling with this exact same problem for some time now. I've taken my carbs off often enough I can now do it in less than 3 miniutes. I keep logging on here to see if I can gleen some new info that might just help me to solve the problem. I was excited to have seen a fresh string which might have some hints to follow-up on.

My bike had been in storage for >15 years when I bought it, so I rebuilt the carbs before I tried to run the bike.

It would start and run idle well for not having any adjustments done on it yet, but when I gave it throttle it would not return to Idle. Instead it settles to around 2800-3000 RPM and stays there. If I shut it down it will start at an idle (950-1000 RPM's) again.

I checked all the obvious things, throttle cable sticking, linkage hanging-up, vacuum leak, float level, slides sticking, etc., and could not locate any problems.

When I pulled the sparkplugs they were coated with heavy black soot, indicating rich fuel mixture. They even fouled to the point I had to replace them.

I replaced the carb holders, adjusted and re-adjusted the floats, and bought a synchronizer and made adjustments. I can get the four columes to equalize, but I don't know how I should relate the scale of the synchronizer to the RPM's. It was mentioned in one of the above replies that you should sync at lower than normal RPM first, but didn't mention a suggested RPM or RPM range (ie. 600 RPM or 600-800 RPM) This couold be helpful Info.

I've now invested in a Colortune. This little gem is supposed to let you see the color of the flame in your cylinder so you can fine-tune the idle mix. I'll let you know how or if this helps in solving the problem.

I'll follow this string for other helpful tips and follow-up on what I discover if I get lucky enough to stumble on to a fix.

[mn2346]

I believe it was initially at 1300+, then after the first sync I could get it to idle at 900, then somewhere around 700-800. That is when I stopped and and the idle would allways return fast to normal idle. Naturally the idle was raised to ~1100 when done.

Only drawback has been that now the engine needs to warm a bit more before it idles properly without the choke.

-M

[waterman5776]

Thanks mn2346 for the info on the RPM's you were working in, this will come in handy when I continue my work.