over-revving

[woodytwoshoes]

Hi, so I rebuilt my carbs, installed em and fired up the bike. It sorta runs for a while at idle then revs up and up and up till i turn it off. Any ideas?
Thanks,
Woody

[MisterCinders]

Air leak.

Please put your model and year in your signature, so folks can help you better. A location in your profile is good for this as well.

[BigD_83]

Woody,

I think we're going to need some more information to help you out here as there are a number of things that could be going on.

What bike? What's its history? New to you?

How was it running before you rebuilt the carbs? How did you clean/rebuild them?

Tune the mixture screws? Readjust the idle?

Did you go through the rebuild process as per the tutorial on the GSR? Did you replace the internal o-rings? Intake manifold O-rings replaced?

Did you:

bench synch the carbs before putting them back on?

Check your throttle cable tension ? (my personal favorite- the cable tends to pop out at the throttle tube)

[woodytwoshoes]

over-revving

Hi, ya sorry bout that, my bike is a 79 gs400. twin cv carbs. I used the manual to spec the carbs after and while rebuilding. Could this be a float issue? When the bike is off and sitting, gas is leaking out of one of the tubes off the bottom of one of the carbs.
Woody

[tkent02]

Do you have the choke on when it revs up?

[BassCliff]

Hi,

I just wanted to remind you that you can reply to your own thread. There's no need to start a new thread just to add more information about your bike's symptoms.


Thank you for your indulgence,

BassCliff

[woodytwoshoes]

over revving

No, choke is off, when i try the choke it kils the engine. Its not a choke but an enricher on these carbs.
Woody

[BassCliff]

Hi,

Did you bench sync your carbs before you put them back on the bike? Is the airbox installed?


Thank you for your indulgence,

BassCliff

[keman]

IF you bench synced, did you remember to turn the idle back down to close the throttle plates after you synced??

[woodytwoshoes]

over revving

Good morning and thanks for all the help, you guys are great!
By bench syc, you mean getting the slides to open the same ammount? They were very close if not perfect in that respect.
Woody

[woodytwoshoes]

more info

The bike will idle when started, i can adjust the throttle screw up and down and it works fine, then if i rev it up a bit it will just take off and I have to turn the key off to shut it down.?????

[Steve]

Good morning and thanks for all the help, you guys are great!
By bench syc, you mean getting the slides to open the same ammount? They were very close if not perfect in that respect.
Woody

A "bench sync" is the process of getting the THROTTLE BUTTERFLIES very closely synchronized while the carbs are still on the bench (hence the name) when you are done working on them. The slides on the BS-series (CV-type) carbs have nothing to do with synchronization.

After you get them back on the bike, you will need to follow up with a "vacuum sync", where you use vacuum gauges to make sure the carbs are fully synchronized.

The bike will idle when started, i can adjust the throttle screw up and down and it works fine, then if i rev it up a bit it will just take off and I have to turn the key off to shut it down.?????

When it "takes off", can you tell if the throttle mechanism is returning to the idle position?

It is possible that something is getting caught in the mechanism, preventing it from coming back down.

However, if the throttle is returning to idle position and the engine speed is still "hanging", you have a mixture problem. Specifically, a lean mixture problem.

When the bike is off and sitting, gas is leaking out of one of the tubes off the bottom of one of the carbs.
Woody

I was not aware that your type of carbs had a tube on the bottom, but I usually try to stay away from the twins, as they are just a little different. If you still have fuel dripping, you need to address that issue, as it will mess up anything else you are trying to adjust.

I used the manual to spec the carbs after and while rebuilding.

What manual and what do you mean by "spec the carbs"?
If you have PROPERLY cleaned the carbs (we still have not seen confirmation from you that you have done so), replaced all the o-rings in the carbs and intake boots, and are using jets that are appropriate for your intake and exhaust systems, then performed a bench sync (very easy on a twin), set your idle mixture screws to 3 turns out from lightly seated, your bike should start and idle quite well.

Until you can assure us that all of that stuff has happened, all bets are off.

.

[woodytwoshoes]

overrevvin

Hi, again and thanks for all the info. Ok, the butterflys. I did nothing to them. I had the carbs on the bench all apart and cleaned them. I have a soak soulution meant for carb cleaning. Must be as you say, bench syc. where is the adjustment for the butterflys? I put the carbs back on and used my carb sync , just bought new one, as best I could with the bike running intermittently. The sync was in spec, that is both carbs had equal vacumm. I will now check the butterflys and see whats happening there.
The local ace bike guy is going to come over soon to have a look as soon as he gets the roof on his trailer Almost winter here!
I really appreciate all the help, this is a great resourse, the best ive seen anywhere.
Again thank you all,
Woody