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'86 Brat won't idle - quick fix question.

idle idle control brat hitachi carb

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6 replies to this topic

#1 belacane

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Posted 09 August 2013 - 08:47 PM

Hello all,

 

So as of a few weeks ago, the idle on my '86 Brat dropped so low (to less than 100) that she'd stall after a couple of seconds at idle. However, when driving, performance is normal.

 

I Imagine I'm going to have to take a look at the carb, there are various leaks, and I'm sure it's got a lot of gunk stuck in emulsion tubes...etc.. While I've never rebuilt / cleaned out a carb before, I know someone who's very good at it, and that will be helping me.

 

Until then though, did some experimentation and developed a little quick fix that I'm not quite sure about being legit, but the result is an idle of about 1000.

 

Here's what I did:

 

IMG_20130809_011358_zpsdb6c515f.jpg

 

In the picture above, noticed that there's a vacuum hose attached to some kind of thing-a-majiger (circled) that when the car is on, opens the throttle a bit. 

 

To get the car to idle again,  basically fooled around with this, so that it opens the throttle more. Ended up moving the washer (orange arrow) to the other side of the bracket holding it and loosening the nut to shorten the arm that pulls on the throttle. Now it idles at about 1000.

 

So my questions are:

... what is this thing?

...Is it part of the idle control? It was just a wild guess to adjust it like that.

...Is it safe for the engine to do this until I'm able to clean out the carb?

...and are there any other reasons why that would be causing her not to idle, but perform fairly well when driving? 

 

Thanks guys!


Edited by belacane, 09 August 2013 - 09:29 PM.


#2 aba4430

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Posted 09 August 2013 - 09:30 PM

That is the AC idle up vacuum unit.  When the AC is on, it increases the idle by pulling on the throttle arm on the carb.  I have one on my 87 Brat, but it does not work.  Would you be able to post the vacuum hose arrangement to this vacuum unit.  Separately, it should not hurt anything to leave it adjusted like you have until you can sort your carb out.



#3 djellum

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Posted 10 August 2013 - 02:49 PM

a lot of stuff could cause it, vacuum leaks, fuel filter/pump problems, carb problems, ignition problem.  if its not had a tune up in a long time, check the basics, fuel/spark.

 

you can turn up the idle with a screw near the bottom passenger side of the carb.  it will do the same thing as the ac unit but its just mechanical and that is exactly what its used for.   



#4 belacane

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Posted 11 August 2013 - 01:05 PM

That is the AC idle up vacuum unit. When the AC is on, it increases the idle by pulling on the throttle arm on the carb. I have one on my 87 Brat, but it does not work. Would you be able to post the vacuum hose arrangement to this vacuum unit. Separately, it should not hurt anything to leave it adjusted like you have until you can sort your carb out.


Yes, I will take pictures this evening for you when I get home.




a lot of stuff could cause it, vacuum leaks, fuel filter/pump problems, carb problems, ignition problem. if its not had a tune up in a long time, check the basics, fuel/spark.

you can turn up the idle with a screw near the bottom passenger side of the carb. it will do the same thing as the ac unit but its just mechanical and that is exactly what its used for.


Did do a tune up recently.
Also tried the idle adjust screw, which did not help, which is why I went the a/c vacuum up route.
Does that indicate that it is perhaps more carb relayed than not?

Thanks much for the replies! Will update with what I find as I continue working.

Edited by belacane, 11 August 2013 - 01:06 PM.


#5 AKghandi

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Posted 11 August 2013 - 08:24 PM

rev it to around 4k and close the throttle and choke, it will suck the crap through the carb. it's happened to me a few times on the older carbs. some will say this is bad for it, and they would be right, but it sounds like you will be rebuilding the carb if it doesnt work so whats the harm?



#6 belacane

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Posted 12 August 2013 - 11:21 AM

rev it to around 4k and close the throttle and choke, it will suck the crap through the carb. it's happened to me a few times on the older carbs. some will say this is bad for it, and they would be right, but it sounds like you will be rebuilding the carb if it doesnt work so whats the harm?



Ah the poor man's tune up :) did do this already. It didn't help unfortunately :(

#7 belacane

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Posted 13 August 2013 - 08:02 PM

Aba4430, here are photos of the vacuum arrangement from the a/c idle up.

 

 

 

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Also tagged with one or more of these keywords: idle, idle control, brat, hitachi, carb

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