I recently got my engine working and idling!

But it only idles when I physically hold up the throttle linkage so the carbs are closed and are running on the idle system. The springs on the linkage return the throttle each time but not quite far enough so it leaves them open and the engine revs high.

Is this a case of the springs being too weak or the way I've connected it all up being wrong in some way.

The arrow indicates the way I pull the linkage for it to idle. When this is pulled the engine idles perfectly, however when the throttle is used and then released it doesn't return and the revs shoot up. No 3 screw is already screwed out so that's not stopping it close

1 and 2 are where the 2 linkage parts are bolted, could these be too tight? They don't seem to be

4. Could i fit a spring from here down below to return it?


Spanks for any help!

Isn't it just a case of shortening the linking rod, (the one with the two ball joints)?

Mick

Assuming the throttle cable isn't too tight and the carbs are somewhere near synched.

Remove the carbs turn them upside down, on the bottom of of each carb you will see a plate with 4 screws. remove it, below it you should seen a spring connected to arm that goes through the throttle spindle. Check the return spring and also check the roll pin isn't sheared.

[Edited on 23/7/05 by britishtrident]

quote:

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Originally posted by Mix
Isn't it just a case of shortening the linking rod, (the one with the two ball joints)?

Mick

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Slacken the nut on the cable adjuster 5 and screw it in. Is there a damping spring on the balance underneath the flat piece 6. Have you lubricated the linkage at all, try a spot of 3 in 1 or some WD on the joints and on the butterfly pivots and work them a bit to loosen it up. It'll be alright when the newness wears off
Rescued attachment linkage.jpg

without the throttle cable attatched,can you open the throttle fully and then will it close again?if so we had this problem.we changed the point where the cable was attatched to the accelerator pedal so it had a larger range of movement.works perfect now.

Try disconnection the rod from top end , if engine then idles correctly problem is with linkage . If engine still races problem is with carbs/adjustment/ balance . This should point you in the right direction

I had a similar problem with a set of old carbs and it was the throttle spindle bent. Did you tighten them up too tight?

What's the throttle spindle?

At the moment i'm using 2 bungees between the linkage and the engine mount below which is working, but I don't want to keep it this way

I'll try out these suggestions tomorrow, thanks

Under the white plastic caps I think you will find are air bleed screws , If all else fails try taking caps off , you will probably find screws with a lock nut , slacken lock nut and gently screw in bleed screws, until they just touch the seats . Count the number of turns in case you have to reset to base setting. start engine and check/ adjust idle .

The throttle spindle is the bar through the middle that holds the butterflies. Did you tighten the nuts on this shaft when you put the linkage bits on the end?

quote:

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Originally posted by Northy
The throttle spindle is the bar through the middle that holds the butterflies. Did you tighten the nuts on this shaft when you put the linkage bits on the end?

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But did you over tighten?