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Glad you mentioned that. Carbs are simple in principle, but with their multiple circuits and lots of fine passageways inside, it's easy for minor contaminants to cause trouble. Doing a carb refresh isn't necessarily hard (I enjoy it) but a rack of four can add up to a couple hundred bucks in parts.

One important note: The small engine world has found that modern gas with the higher ethanol content seems to really cause problems in carbs. I'm not positive, but from what I read the ethanol draws in moisture, and that in-turn creates deposits in the bowls and even can corrode some of the fittings. As clumps move around, they can easily clog those tight passageways.

Some people seek out ethanol-free gas, but supposedly keeping the tank full (minimal air space) and running them regularly with high quality gas helps a lot.
 

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Well I'm in Phx, so inclement weather is never really an issue. Water in the gas type of stuff happens alot in new England where I'm from originally. Here not so much, maybe with winter gas up north?
 

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Sourced some R1 carbs, and ordered a flange online! Need to read back through this whole thread to find starting point for JET sizes.

Anyone want to chime in for jet sizes 1.8 8v little head work done?!?!
Automotive tire Motor vehicle Automotive lighting Automotive exterior Gas
 

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My Keihin CVK's (36mm) came with 148 mains, and I replaced them with 162's from Jets R Us which helped a lot. But I never spent much time dialing those in as I traded the car shortly after installing them. This was on a low compression '85 Golf 1.8L.

Using a wideband O2 I was able to get the idle circuit running fine on whatever jets it had, with about 3.5 to 4 turns out. I remember that at about 5 turns out the screws got a little questionable.
 

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Ok so after a long while I finally got my 16v with R1 carbs to start but only after spraying some carb cleaner in it. But the idle drops to 300-400 and then the car dies. I gotta stay on the gas to keep it running.

I know there’s an idle adj screw and I think it’s this screw in the pic below?


If I turn the screw one way the car won’t start, if I turn it the other way it doesn’t stay running. Maybe I’m adjusting the wrong thing?


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Do those carbs have a "choke" bar that activates a plunger on each carb? On my Keihins, it wasn't actually a choke in the traditional sense, but it was more like a two step cold starting enrichment circuit. If yours does have it, what happens when you use it?
 

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Do those carbs have a "choke" bar that activates a plunger on each carb? On my Keihins, it wasn't actually a choke in the traditional sense, but it was more like a two step cold starting enrichment circuit. If yours does have it, what happens when you use it?
I’m sure it does, there’s was another cable that came with this setup but I didn’t use it.


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So it seems like fuel is part of my problem. The fuel out here is turning the brass green and clogging stuff.



I’ve ordered a rebuild kit for them. I’m just wondering what size jets I might need as the kit will come with stock jets.

Pilot jet I pulled out was a 20 and the mains have no numbers on them so other than sticking some metal in them and measuring the diameter of the metal I have no idea what size they are.

Engine stuff
16v 2L
Port/polish head
Oversized valves
TT cams
TT 4-1 header


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Do you have a sonic cleaner? If-not, those things are amazing at cleaning up carbs and I highly recommend getting one. Just be careful what cleaner you use, as some stuff can end up being a bit too rough, or leave a weird finish.

For the mains, if you can get a set of fine drill bits you may be able to find a sizing chart that correlates them to a bit diameter. From there, if you are feeling daring you could drill them out.
 

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Do you have a sonic cleaner? If-not, those things are amazing at cleaning up carbs and I highly recommend getting one. Just be careful what cleaner you use, as some stuff can end up being a bit too rough, or leave a weird finish.

For the mains, if you can get a set of fine drill bits you may be able to find a sizing chart that correlates them to a bit diameter. From there, if you are feeling daring you could drill them out.
Not really trying to drill anything out. Just trying to figure out what size jets I should be running. The car these came off of was tuned for 100 octane if I remember right. So I think a 20 pilot might be to much and I’m sure the mains will be to big as well


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Not really trying to drill anything out. Just trying to figure out what size jets I should be running. The car these came off of was tuned for 100 octane if I remember right. So I think a 20 pilot might be to much and I’m sure the mains will be to big as well


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First of all, clean the carbs (deep clean, i mean DEEP clean), if the carbs was used in a car with similar displacement to yours dont change the jets, simply clean it and try also clean or replace the air filters.

Jetting depends on health of your engine so you must experiment with different jet sizes, you can get a mini drill kit (from 0.80 to 2.0 mm in stepf of 0.1 mm), fill the hole of the main jet with solder and drill it, test it, drill again to different sizes once you feels close to the right size, buy the correct jets.
 

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First of all, clean the carbs (deep clean, i mean DEEP clean), if the carbs was used in a car with similar displacement to yours dont change the jets, simply clean it and try also clean or replace the air filters.

Jetting depends on health of your engine so you must experiment with different jet sizes, you can get a mini drill kit (from 0.80 to 2.0 mm in stepf of 0.1 mm), fill the hole of the main jet with solder and drill it, test it, drill again to different sizes once you feels close to the right size, buy the correct jets.
Oh they got rebuilt. They where extremely dirty. Car runs now, just high idle and rich currently. Screws are turned out like 3 1/8th, so I’m gonna turn them in a few turns and see if that will bring the idle down and lean it out some.


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