Loss of power.

Apologies if you've read this already, but I've come to consider it the Bible for tuning Weber carbs:

https://www.speedsterowners.com...-carbs---mark-harney

If you haven't already, take a half hour or so and read it all the way through.

Once you're sort of dialed in, the following part is, for me, the crux of doing routine 'touch-ups' when the motor starts to drift off-song. It's probably a good idea to clean the idle jets first to make sure dirt isn't the culprit.

"...Now go to each mixture screw one at a time and slowly turn it in (by slowly, turn it about 1/8 to 1/4 turn at a time and stop and wait for the response of the engine for a few seconds) until the engine begins to slow down (you'll be leaning out a cylinder).

Now slowly back the screw back out (same method you used to screw it in) until that cylinder starts to pick up again and run smooth. This is the critical point in the mixture adjustment. Slowly open the screw a little more at a time until you reach a maximum idle speed. Don't go any further!

If you're not sure, stop there, screw it back in until the idle drops, and then start to back it out again until you feel confident you have unscrewed the minimum amount that you have to in order to get max idle speed from that screw. Move on to the next cylinder. Do this until you have done all 4 cylinders..."

I saw and read Harney's writeup here:

http://www.thesamba.com/vw/for...b+mixture+screw+seat

Good stuff there.

This was my 3rd attempt, and success, at least until I take a test drive and confirm. I'll still readjust, just to make sure and for practice.

Another thing I've come to appreciate is just how dependent on engine temp the tuning process is. No matter how long I used to let the engine idle in the garage, it never got warm enough and would drift out of tune once driving.

Now, I take it out and drive it until it's fully warmed up before coming back in and messing with the carbs.

This probably has as much to do with the linkage as with the carbs themselves.

You've brought up a very good point, Mitch; you want the engine fully warmed up before adjusting the carbs, and it won't get to full operating temps idling in the driveway.

That's one thing I learned from owning a 914 in the past. These engines like to be thoroughly warmed up first.