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 Kommer
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| posted on November 24th, 2004 at 09:51 PM |
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Setting up Kombi carbs
I'm just putting my Kombi carbs together (it's a 2.0l aircooled) and there's a couple of things I don't understand after reading manuals:
1. The throttle butterfly is supposed to have .004" gap unless its a valve with a bypass drilling. What is a bypass drilling ?
2. How is the fast idle set up ? Is there supposed to be a different throttle butterfly gap when the choke is all the way shut ? What is it
supposed to be ?
Thanks,
Kommer
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Kommer
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| posted on November 28th, 2004 at 07:59 PM |
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OK I'll try something different:
The Kom is running like shgit on small throttle openings.
Not too good on idle, but I can cope with that.
Just off idle it makes this bomp bomp bomp bomp sound that sounds really rich, and makes it dead unpleasant to drive:
No black smoke
No amount of fiddling with the idle mixture screw makes any difference
Chokes are fully open
Timing is 7 degrees with the vacuum line off.
Spewin.
Sick of fiddling around with it: carbys off/carbys on/ carbys off etc etc etc
Any ideas ???
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Andy
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| posted on November 28th, 2004 at 09:50 PM |
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Hello Kommer,
For you first post, I don't have my manual handy, but my guess is some butterfly's have a hole through them, and they don't need the gap at idle,
as per the manual.
The fast idle is controlled by a stepped cam behind the auto choke (inside it). There is a bar that attaches a lever behind the choke to the throttle.
If your chokes close correctly when you let the throttle off you should see the butterfly is held further open. If not the bar that attaches the choke
to the throttle is adjustable. Check you manual for details.
As for the problem, could be a number of things. Firstly set the idle up as per manual, including the central idle, it's not that hard. A brief run
down (please check the details as I'm going from memory here) Check float level ~12mm, make sure there's not dirt in there while your at it. Set the
initial idle mixture on each carb (in throttle plate) to ~2.5 turns out. Set the central idle mixture screw to ~2.5 turns out, and the idle speed
screw to ~1 turn out. Check all the solenoids work (it will have 3 if it's all stock).
Also check the idle jets are clean as they are prone to clogging (if you have 3 solenoids it will be the two small solenoids).
If that doesn't help, send some more details, does it start OK, does it run OK once above idle?
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Kommer
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| posted on November 29th, 2004 at 04:33 AM |
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Thanks Andy,
I set the carbs up pretty much by the book as far as the initial idle, central idle mixture and idle speed screws are concerned. I tried doing the
float level, but it didn't seem to be working out with the carbs on the bench and the fuel flowing in from a motorbike tank suspended nearby. I used
different washers under the needle/seat but it didn't seem to make much difference. The float level is around 15mm on both carbs. The car runs OK
as long as youre accelerating with more than about 1/4 throttle.
What about this: when it's running at idle making it's bomp bomp bomp bomp sound, with the flat air filter connectors off, if you put your finger
over 3/4 of the central air inlet pipe (which is sucking like crazy and your finger feels like it's getting sucked in) the idling actually cleans up
nicely. That suggests to me that it's actually lean on the central idle system. I might pull the LHS carb off again and check to see that there
isn't a fuel blockage in the line from the bowl to the central system.
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 vw54
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| posted on November 29th, 2004 at 07:20 AM |
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Kommer
Where are u located ??
Did you fit or recondition the throttle body sections of the carbies.
These wear very easy and you will find a lot of slop and additional air suction / leak areas. Vintage have these throttle sections re conditioned / re
bushed if you need some.
By the sounds your describing you have a air leak and its sucking in additional air around the throttle shafts which makes the carbies pop and not
idle correctly. As you say its goes good under acceleration because you need all teh extra air possible
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Kommer
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| posted on November 29th, 2004 at 08:21 PM |
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I'm in the Blue Mountains. The throttle shafts are a bit sloppy, but the deterioration in the running happened a bit suddenly, when the car wasn't
driven for a few months because the gearbox was sick. So I figured I was looking for a blockage or something.
BUT tonight I actually discovered something wrong !! Hey that's progress ! But how to fix it ? Does anyone know what the IDLE MIXTURE ENRICHMENT
ASSEMBLY does ? (See Bentley1978- p3-22, item #2, or Gregorys 1989 reprint p.38) I opened mine up and all the bits were floating around loose inside
and not achieving too much. Do they make any difference to anything ? Can I just block off the holes or something ? Does anyone sell new assemblys
?
Thanks for any ideas.
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Andy
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| posted on November 30th, 2004 at 11:52 AM |
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Kommer,
I don't have my manual handy. Do you have an auto or manual? (carbs vary slightly)
I guess what your talking about is on the LH carb and is connected to power? I've never found a replacement OR seen a functioning one, they are prone
to falling appart inside with vibration. Just plug the ports, it's only for starting like the chokes and could be your problem, but it's probably
been like that for ages.
Just check again for blockages in the idle circuits/jets.
You can eliminate the central idle circuit if you like by screwing the speed screw (big brass one) closed. If it doesn't idle you can open the
butterfly's slightly, and slightly increase the initial mixture screws slightly to compensate.
Just another thought, check your plugs, the bomp bomp could be one cylinder not firing properly. Pull one lead at a time and see if the revs drop the
same for each one. Then see if one plug is a different colour to the rest.
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Kommer
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| posted on November 30th, 2004 at 09:09 PM |
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Andy,
Many thanks for your time in replying.
I again(for the 4th time in 24hrs !) took off the LHS carb last night and stripped the IDLE MIXTURE ENRICHMENT ASSEMBLY. One of the holes into the
carby behind it was thoroughly blocked. I cleared it out and replaced the Assembly with one from a spare carby. The replacement one was pretty dodgy
too, but not so bad. Anyway at midnight I took it for a spin and it ran as sweet as. Brought it to work today and iot ran smooth as silk. Well not
quite: I'll have to revisit the synchronisation and the initial mixture. But other than that, shes purring.
Thanks again
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Andy
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| posted on November 30th, 2004 at 10:51 PM |
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Cool,
It's frustrating at the time, but satisfying to find the problem yourself :-)
Glad to hear another bus is roaming the streets :beer
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Kommer
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| posted on December 1st, 2004 at 06:48 AM |
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Well, it's a ute actually.........but thanks all the same.
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vw54
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| posted on December 1st, 2004 at 07:21 AM |
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Kommer
I suggest that you talk to Boris at Vintage Vee Dub in Campsie, they have the bits you need and know the carbies 9789-1777
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