Carburetor question

[RedDirtFarmer]

Okay, I have another question I hope someone can help me with. I have no service manual so I'm kind of in the dark here. I'm totally new to anything VW and although I got the trike running, it does not idle very good or take gas smoothly at low rpm when it's hot. It seems to be running lean because when I pump the carb a little it takes off like a house afire. It runs great at higher rpms.

Here's what I've done so far, I've checked the intake manifolds to make sure they are tight, checked the rubber gaskets, took the top off the float chamber to check for gunk or dirt (it was clean). On the right side of the carb there is what looked like an adjustment screw but when I removed it, it wasn't for adjustment, it's some sort of replaceable jet and it was clean. On the left side of the carb there is a big adjustment screw but I have no idea what it's for because it was turned out about ten rounds. It has no spring, just an o-ring. According to the papers I got with the trike it's a 2009, 1600cc, 80 hp motor. I don't know what else to check, I can't find an idle adjustment.

[peteg59]

Welcome to TrikeTalk James.

From your description of the way its running, it does sound like it might possibly be running lean.

Do you know what make/model carb is on your trike? If stock, it should be a single Solex.

The VW dedicated site The Samba, has various discussions on carb tuning for the various models of carbs that VW used over the years that I've found helpful.

[vwbug72501]

Pictures of engine, carb, and distributor will help. What is casting #s on carb?

A Bentley manual is a good reference to start with: https://www.amazon.com/Volkswagen-Se...tley+VW+manual

Some of the parts combinations from the '70 - '79 era Emissions engines will experience "stumbling off idle" conditions.

[DeathBySnuSnu]

Probably plugged up somewhere in the low speed curcuit of the carb.

Also check the distributor advance is not sticking or broken in some way.

[RedDirtFarmer]

Okay, I'm going to try to post a couple of pics along with this info off the carb:

34PICT-3

Bocar

Hecho en Mexico

113 129 021P (on a metal tag attached under a screw)

Any ideas?

[vwbug72501]

What kind of distributor? Picture would be good.

[rhino 2]

Okay, I'm going to try to post a couple of pics along with this info off the carb:

34PICT-3

Bocar

Hecho en Mexico

113 129 021P (on a metal tag attached under a screw)

Any ideas?

Shot in the dark here, Bottom of the carb, [Bottom picture] . Now I'm just going by memories from when i played with VW's...70 to 75..Theres a silver colored round cylinder with a wire going to it, That wire is hot with the ignition on, It operates a plunger that if it loses power will shut the carb off....I would check that part/wire... That drove me nuts on my 71 beetle....Like i said just a shot here...

[RedDirtFarmer]

Yes there is a wire from the distributor to that solenoid on the carb, not sure what function it has, it seems to be solid but I will check it for sure with a meter. Here's a zoomed out picture with the distributor.

[peteg59]

The carburetor solenoid switch stops gas from entering the idle circuit of the carburetor when the key is off, or when it fails.

With it disconnected or when it fails, the engine will still run but only at speeds above idle. It won't idle at anything close to "normal" if/when it fails or comes unconnected from its power supply, (typically from the + side of the coil).

Not 100% recommended but it can be bypassed once it fails, by removing from the carb & cutting the plunger end off with diagonal cutting pliers or similar tool & carefully reinstalling it back in its place in the carb. I emphasize careful on installation as the carb body is aluminum or other such soft metal, & the switch threads are steel & can easily strip out the carb threads if overtightened or cross threaded.

Personally, I'd only bypass this "safety" switch if I was on the road.

The switch makes a noticeable audio "click" when energized, & can also be tested quickly by disconnecting the only wire running it & trying to start the engine in the "idle" position.

If it started easily before & won't start unless using heavy throttle after disconnected, the solenoid is bad.

[vwbug72501]

Distributor doesn't look to have a vacuum advance. Probably a "009" mechanical advance only type. This dist / carb combination can be a bit quirky as I remember. Try some Internet research on this issue. I can't remember but it seems that there are some "non-stock" advance set ups that will fix or minimize this issue. Back in my shadetree dune buggy days we would just feather through the flat spot and put our foot in it to go but that was off road. "Drive it like you stole it" doesn't always work so well on the street!

Another "roadside" fix for the defective fuel cutoff solenoid was to unscrew it just enough to let the engine idle (usually about 1 1/2 turns) and leave the wire connected. The wire connected would keep the solenoid from vibrating out as you drive. I never had one leak or pose a problem.

[RedDirtFarmer]

Probably plugged up somewhere in the low speed curcuit of the carb.

Also check the distributor advance is not sticking or broken in some way.

Well, there you go. I checked the fuel cutoff solenoid and it was working perfect so I took the carb off, took out every screw and orifice and sprayed carb cleaner through it and compressed air and it worked like a champ!!! I also found the idle mixture screw just below that big adjustable screw (still have no idea what it is) and adjusted the idle mixture and speed. What a relief!!! Even though everything looked clean as a whistle, there must have been some gunk stuck in there somewhere. Thanks for all the suggestions guys!

[rhino 2]

Well, there you go. I checked the fuel cutoff solenoid and it was working perfect so I took the carb off, took out every screw and orifice and sprayed carb cleaner through it and compressed air and it worked like a champ!!! I also found the idle mixture screw just below that big adjustable screw (still have no idea what it is) and adjusted the idle mixture and speed. What a relief!!! Even though everything looked clean as a whistle, there must have been some gunk stuck in there somewhere. Thanks for all the suggestions guys!

All's well that ends well 👍👍

[stinger608]

That solenoid that everyone is talking about could sure be the issue.

Unscrew that from the carb and hook the wire back to it. Now turn on the ignition. The plunger on the end of that solenoid should slide back and forth as you turn the ignition on and off.

If it doesn't slide, then that is your problem.

If that's the case, there is one of two ways you can fix the problem.

(1) check to see if a local parts house has one and buy a new one

(2) take a pair of wire cutters and clip the little plunger off of the solenoid.

I've cut them off many times and had no issues with the carb.

[RedDirtFarmer]

Once again, google to the rescue. I found a step by step procedure for adjusting this carb and also found a youtube video. Surprisingly, the large screw is the idle speed adjustment and the small screw is the mixture. The screw you would think is the idle adjustment is supposed to be adjusted 1/4 turn past making contact with the stepped disc operated by the automatic choke. I adjusted everything and it worked perfect!