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Throttle Sticking


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#1 davej

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Posted 06 February 2019 - 03:29 PM

I have a problem with the throttle sticking, when I come to a junction the revs stay at about 1800 unless I blip the pedal then they will normally return to normal (1000). I am running twin HS2's.

 

I have replaced the cable, all the linkages seem free and the dashpots aren't sticking. The only thing I can think of is the throttle adapter thing is fouling on the manifold. I don't know the make of the manifold (LCB) but I think I will put a Maniflow Freeflow on it over the summer.

 

Anyone have any ideas?

 

NF1fOYi.jpg

 

sK7kemO.jpg

 

Thanks

Dave

 



#2 KTS

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Posted 06 February 2019 - 04:22 PM

A few things to have a look at...

Trim off the excess cable at the carb to avoid it getting wedged and stopping the throttle returning

Try and get rid of the kink in the cable above the clamp

Check the accelerator pedal is operating freely and there's no bits of carpet or underlay getting in the way

Disconnect the throttle cable from the carbs and check the throttle spindle operates freely by itself

#3 Moke Spider

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Posted 06 February 2019 - 06:44 PM

The part on the Linkage that the Throttle Cable attaches to looks up-side-down.



#4 davej

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Posted 06 February 2019 - 06:58 PM

Ah ok, so if it was the other way it would bend away from the manifold? Anyway of changing it over without pulling the carbs off?



#5 Moke Spider

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Posted 06 February 2019 - 08:00 PM

Ah ok, so if it was the other way it would bend away from the manifold? Anyway of changing it over without pulling the carbs off?

 

Yeah, the other side of the 'triangle' rests just off the Choke linkage.

 

No way I know of, it's Carb's off !!



#6 davej

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Posted 06 February 2019 - 08:33 PM

Thanks Moke, I will take the carbs off and swap it around



#7 davej

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Posted 07 February 2019 - 09:23 PM

I can't get the buggers off, I'm trying to get them off on the manifold so all the manifold nuts are off and the cables disconnected and out of the way. The heat shields foul the bulkhead  >_<  I have removed the bolts out of the top two engine steadies to try and tilt the engine forward but it seems solid.

 

Any ideas apart from break my hands and undo the bottom carb to manifold nuts?



#8 KTS

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Posted 07 February 2019 - 10:39 PM

lower steady and exhaust manifold to diff case steady if fitted may be stopping you tilt the engine forward

Last resort might be to try and take out the manifold studs so you can lift the carbs straight up?

#9 Moke Spider

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Posted 08 February 2019 - 12:37 AM

I usually undo the Manifold off the head, with the Carbs in place. I can just do these with my 1/4" Drive set.

 

This is one of reasons I gave up on twins.



#10 Rorf

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Posted 08 February 2019 - 05:31 AM

I would say there is a spring missing - the throttle cable seems to have no tension in it.



#11 davej

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Posted 08 February 2019 - 09:26 AM

I usually undo the Manifold off the head, with the Carbs in place. I can just do these with my 1/4" Drive set.

 

This is one of reasons I gave up on twins.

 

They are being a pain but I don't plan on taking them on and off very often. Maybe next time the engine is out I'll have a good look at the shields and see if I can trim a bit to give clearance.

 

 

I would say there is a spring missing - the throttle cable seems to have no tension in it.

 

The spring is there but going off the right hand side as it was fouling on the manifold, now I know why.

 

lower steady and exhaust manifold to diff case steady if fitted may be stopping you tilt the engine forward

Last resort might be to try and take out the manifold studs so you can lift the carbs straight up?

 

Thanks, hopefully I'll get enough wiggle room with the lower steady and exhaust manifold bracket off


Edited by davej, 08 February 2019 - 09:26 AM.


#12 davej

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Posted 08 February 2019 - 07:52 PM

Well I finally got the carbs off, had to undo the bottom steady and diff to exhaust, I then had to remove the bolts through the top engine steady and thermostat housing, it seemed to be sticking on the stud. After that I had enough wiggle room to get the carbs out.

 

tfrinZa.jpg

 

Should it look something like this?

 

VSZguRE.jpg

 

 



#13 Moke Spider

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Posted 09 February 2019 - 04:56 PM

An apologise here, this is the type of Linkage it appeared to be

 

d2PJyZ9.jpg

 

I'll add though, that this linkage ^ is an easier one to set up correctly, as when in an idle position, the top of the 'flat' of the triangle should be set such that it is 0.020 - 0.030" off the Choke Linkage. This ensure that there should be the right spring tension and that the Linkage will move through the correct Arc Angle over it's total movement.

 

However, while you have them off, I'd suggest checking that they are assembles on the manifold as per they are when on the car and checking the linkages and throttles are totally free with free play in the linkage throughout it's range of movement.

 

Also, check you have reasonable spring tension with the throttle in the idle position, as the natural manifold vacuum tends to want open the butterflies.



#14 davej

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Posted 09 February 2019 - 06:58 PM

Right ok, so was it right for the linkage I have before?

#15 davej

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Posted 13 February 2019 - 07:58 PM

Well I finally got it all back together today and 3 new return springs, throttle is a bit stiff due to the new springs but its all sorted, revs drop back to normal  :D






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