uh oh... idles low, throttles high....??????

OK this might be info overload but I have a problem:

Background: I rebuilt a set set of carbs i got off ebay. I tore them completely down and cleaned everything. new o-rings and gaskets. I did not replace the jets.

**i have not yet used a gauge to sync the carbs while on the bike**

I am able to get the bike fired up very easily even with the choke lever down (is this a problem?)

The problems:
When i start the bike i will adjust the air/fule mixture so its idling around 1.5 rpm. the bike sounds pretty good. No revving then dropping or popping. No white smoke, no black smoke.

BUT when i take the bike around the neighborhood it rides great for the first half of the trip (maybe 4 blocks) but then out of no where the RPMs start to creep up every time i pull the clutch in. it gets to the point where the only way to get the RPMS down is to turn back the air/fuel mixture again...

Im thinking i did not set up the throttle cable correctly but at this point im just looking for any thoughts or suggestions.

thanks a lot

kz.chris wrote:

I rebuilt a set set of carbs i got off ebay. I tore them completely down and cleaned everything. new o-rings and gaskets. I did not replace the jets.

Part of a good carb rebuild is making sure the fuel heights are all correct, and a good manual sync.

**i have not yet used a gauge to sync the carbs while on the bike**

This is a must, and makes a huge difference in the idle, cruise, and power output.

I am able to get the bike fired up very easily even with the choke lever down (is this a problem?)

Not necessarily. You could be a little too rich, but a nicely tuned bike will start without choke if it has been sitting in the HOT sun on a real hot day.

When i start the bike i will adjust the air/fule mixture so its idling around 1.5 rpm. the bike sounds pretty good. No revving then dropping or popping. No white smoke, no black smoke.

BUT when i take the bike around the neighborhood it rides great for the first half of the trip (maybe 4 blocks) but then out of no where the RPMs start to creep up every time i pull the clutch in. it gets to the point where the only way to get the RPMS down is to turn back the air/fuel mixture again...

OK... so... when you say air/fuel mixture... do you mean the large idle control knob, or are you adjsuting the small screws (4) on each carb?

Sounds like either air/mixture screws not properly adjusted, or an air leak at one of the carb holders.

Try: adjusting the idle control knob so the bike idles at 1000 rpm. Then starting with all the mixture screws at 1.5 turns out from lightly seated, turn all of them out another 1/4 turn. If the idle rises, then continue to turn further. If idle drops, turn them all the other way.
Youre trying to find the highest idle point.
At some point turning the screws either way some will result in the idle dropping if everything is setup good.

This is a rough way to tune the screws, but it will get you running/close.

Let us know!

Im still waiting for the sync gauge but heres some more info.

Today i started the bike and turned the air/fuel mixture screws (one by one) on each carb inward. The bike starts to die if i dont back out the screws quickly.

I backed each screw out 2 1/2 turns.

Took the bike for a spin and ive pin pointed whats going on.

The rpms climb and then stick every time i pull the clutch. when i release the clutch the rpms slowly drop if at all. by the time i got back to the drive way they were sticking at 4k

I double checked all connections and from what i can tell every thing is tight to the engine and airbox.

any ideas??

Air/fuel mixture crews should be adjusted only after engine has attained normal operating temperature. And not right after it's started.

The inconsistent idle may result from an air leak at wherever.

At idle, would spray WD40 all over suspected leak areas, such as carb holders, clamps, vac plugs, and look for smoke from the exhaust due to ingesting WD40.

Good Fortune!

Patton wrote:

Air/fuel mixture crews should be adjusted only after engine has attained normal operating temperature. And not right after it's started.

The inconsistent idle may result from an air leak at wherever.

At idle, would spray WD40 all over suspected leak areas, such as carb holders, clamps, vac plugs, and look for smoke from the exhaust due to ingesting WD40.

Good Fortune!

Thanks ill give that a try

So it turns out one of the boot holders was not as tight as i though. The good news I think that has fixed my sticking high RPMs.

I wont really know if everything is working properly until i get the sync gauge.

Yeah, basically EVERYTHING from the airbox snorkel tip, to the exhaust end tip, has to be completely airtight in order for it to run properly.

Fortunately, making things air tight is pretty easy. Especially if you use some permatex Moto-seal.

Once the bike is hot and running with no choke, use the idle control knob to get it down to around 1000 rpm.
Then turn all 4 mixture screws at the same time/the same amount, and you will hear a deffinate change in the rpm. it will go up or down. Just keep turning them all in succession till you pinpoint the highest idle point, then leave it.

Vac sync once this is done, will make a big difference.

GL.