high idle

[glenn]

My bike starts without choke from cold revs at about 2000 rpm then climbs rapidly to around 7000. Opened up idle screw jets from 1.5 to 2 and then 2.5.
This lowers the rpm reached.
I should add that the throttle cable is not connected because I thought it may be fouling the movement of the butterflies Probably been done to death but I cant find anything.
Have cleaned carbs, new plugs checked all connections and done a pre synch as per thread.
Glenn Oz

[uk1.1s]

Runaway idle

Hi Glenn,

May be another cause, but my experience of this was when the mixture was set way too low once when I was playing with carb jetting.

Hope that helps or rules something out

[skids]

Re: high idle

It is a common thing to have to adjust idle as you make adjustments with either the idle screws or with the carb synch screws. If this is not the thing you are dealing with:

If you just cleaned the carbs (by soaking), make sure the "butterfly" shaft seals are not sticking. The cleaner makes the rubber seals swell. I think that if this has happened, the throttle linkage to the No. 3 carb (or others?) will not return to the stop.

Adjusting the pilot screws like you did might cause such rich mixture that the efficiency of the burn is dragging down the rpms.

I hope you didn't turn the synch. screws instead of the pilot screws! I ALMOST did that once!

Watch the action of the "ckoke" to make sure none linkages are slipping.

Originally posted by glenn
My bike starts without choke from cold revs at about 2000 rpm then climbs rapidly to around 7000. Opened up idle screw jets from 1.5 to 2 and then 2.5.
This lowers the rpm reached.
I should add that the throttle cable is not connected because I thought it may be fouling the movement of the butterflies Probably been done to death but I cant find anything.
Have cleaned carbs, new plugs checked all connections and done a pre synch as per thread.
Glenn Oz

[Ken Talbot]

You need to set the idle speed with the single, thumb-wheel adjustment screw located between carb #2 and #3. On later models, you have to slide your hand in between the cylinder fins and the carbs, below the intake manifolds. This is a good place to get burned if you're not careful and the engine is warmed up. I believe the earlier models have this adjustment screw sticking down towards the crankcase, aft of the float bowls, but still between #2 and #3. In this case, you get burned by the warm crankcase.

[glenn]

thanks for your replies.
Ken did that number with the idle adjust screw. Its ok.
But I think skids may be on the mark.
The throttle bar does stick but not through use. It seems like the vacuum draws the whole lot up, then it jams.
Will try again today. Take off carbs and just check over.
What is throwing me is that the throttle cable is NOT connected so the problem is carbie only
Glenn
Oz

[TopCatGr58]

The throttle bar does stick but not through use. It seems like the vacuum draws the whole lot up, then it jams.

Glenn,

There's no way that the engine vacuum should/could cause the butterflies to open!!!! IF they are opening, then your springs are not positioned properly, which are to keep the butterflies closed until you pull them open with the throttle cable!?!?

Are you truly talking about the butterflies opening, or the vacuum slides!?!? The vacuum slides also won't rise until there is a decent amount of vacuum imbalance, like whacking open the butterflies from idle, but once that imbalance is neutralized, they slide back down. I ran mine in neutral with the filters off to see how they behave, and if I just slowly increased the throttle, they actually didn't rise at all, but they bounced real well hitting WOT from idle!! I realize they act differently under load conditions. So, if it's your slides that are rising just at idle, then again, something ain't right!? HTH.
T.C.

[glenn]

Hi Topcat
I cant work it out. Seriously my medication addles my brain.
jimg1au is coming over to go through it for me.

Glenn

[uk1.1s]

Wierd stuff

Hey Glenn...hope you and Jim suss the trouble out...best of luck, Graham