Crazy high idle!

Hey guys and gals, Im trying to get this bike running again and when it turns over it quickly goes out of control and idles at a screaming 5,000 rpm!
carbs are clean, i just had them off and went through them throughouly, they are synced with just a sliver of light showing at the bottom of the butterflys, the boots are on tight and all the way! so idk what the deal is but as soon as I turn it on it goes out of control.
Anybody run into this before?
the odd part is that at one point the engine went down to normal for a miniute or two, but then went out of control again..

I tried it with the choke on and off,
*and with the vaccume line coming out of cylinder two capped and uncapped (in the video it is seen uncapped),
these things didnt seem to make a diffrence.

link to video where it idles out of control:
https://picasaweb.google.com/1149019478 ... 8803633394
and then the poor baby backfired after i shut it off. (first and only time).
I afraid to run it again without a plan first.

Link to video where it briefly idles mostly normaly:
https://picasaweb.google.com/1149019478 ... 9445110018

 

I take it that you've turned the idle adjustment screw down.

 

Mine was doing this and I tore the carbs off for the 5th time and cleaned and blew out every passage, checked all seals and re bench synched it the same way. Found one of my enrichment shafts (?...the seat for the enrichment "choke" plunger) way loose and a lot of them not tightened all the way down. Reset the mixure and after warm up it idled nicely (sans a proper vacuum synch) with barely any choke applied. I guess my point is that although that might not be your problem its worth looking the carbs over another 20 times. Check that your floats aren't stuck and that the float needles are freely moving also. Or that your choke cable isn't hung up. It's usually something stupid like that too ha.

 

The simplest fix would be to take your throttle cable completely off the carbs, then turn the bike on. If it screams, then your cable isn't stuck on anything.

Turn the idle mixture screw ALL the way out, then start the bike again. If it still does it then you know its not the idle mixture or the throttle cable.

Next, check to make sure there isn't anything holding the throttle lever up and that it is completely down. If something IS holding a throttle lever up, move it out of the way and start the bike again.

If you haven't gotten the bike to not scream into the high end of the rpms after those 3 checks, then more than likely your going to need to do as mentioned above and clean those puppies out.

Keep in mind while on this little journey, the engine itself has NO WAY of increasing the rpms. Increasing rpms is controlled by the carbs, and they are controlled by you.

So make SURE you check those three things before you freak out. I just had this problem after pulling my engine and splitting the case. It was a combination of one of my throttle levers getting stuck on something, so they were open, and my idle mixture was ridiculously high. Damn thing revved into 8k in half a friggin second.

Scared the shit out of me the first time.......

 

thanks guys, and ill keep that in mind HirsuitHeathen.
This afternoon I went in the backyard before work and for the heck of it tried starting it again to see whats up, and low and behold, it didnt skyrocket. I even got on it and took it around the block once. but.. while riding it and the clutch was pressed in while switching up and down gears, the bike started to slowly climb in rpms until put in the next gear. i took it back in, parked it, and the rpms started to want to climb again so i shut it off. then started it back up, and it idled normal again. something is obviously still not right, as its touchy and wants to climb. but, at least it didnt do what you saw in the video, which is just crazy. im afraid itll do it again at any time.
Yes, i did check for slack in the throttle and choke cables, those are good, not putting any extra tension on while released, so that cant be it.
I fiddled with the idle screw and it did change the idle a tad so that must be working, right? I set it at about 1k.
I took the carbs apart a few months ago and boiled in lemon juice, i had one cylinder not firing so i took it to a shop that had some sort of ultrasonic cleaning machine so they could do it better, they did, so it must be pretty clean right? this is the first time trying to run it after the carb cleaning, and I will consider taking the carbs apart again, Im just perplexed by why this thing happens most of the time but twice now it has decided to run semi normal for a bit.

 

This is so common.
The Throttles are stuck OPEN.

Probably by the Throttle Cable Attachment impinged at the rear of the Head.
If so,... dont pry it loose. Move the carbs.

Improperly fitted Hose Clamps holding the Linkage OPEN.
Clamps upside down.
Not in Manifold locating channel.

Substitute Hose Clamps holding Linkage Open.

Linkage stuck or being held open.

 

Also very common:

Then the truth comes out... :roll:

You didn't clean the carbs if you didn't fully disassemble them, take EVERY little piece, spray carb cleaner through every little hole, visually verify (like jets, emulsion tubes, and enrichment well). Just boiling, or ultra sonic cleaning isn't going to get the gunk that clogs the tiniest of passages. You need to chemically break down the residue, and FORCE it OUT! While your at it, replace all of the orings to prevent air leaks (enrichement, pilot circuit, throttle shaft, fuel pipe, and float bowl for good measure).

Finally, MAKE SURE YOUR SLIDES GO CLUNK! Your idle will hang even if your butterflies are set right if your slides stick open. RickCoMatic thoroughly goes over this in his "Whole 9 Yards" and many subsequent post. Don't forget to measure your float heights, and check/adjust your valves.

Maybe you've already taken some of these steps, but you need to do them all, or you'll be chasing multiple symptoms of multiple problems.

 

Rickcomatic! Man, i feel dumb. I guess I never tightened down the clamps on the boots and the throttle linkage was getting caught up on one of the clamps that was sticking off the boot too far. Well, it seems to be much better now and so the project goes on. Thanks alot guys, also for all the great info on cleaning the carbs 'old-school style'.