Aborted Carb Sync

My JC Whitney four-way carb sync tool shows all four carbs, including the base carb, at 0. The reading on the dial says "Improper valve timing or intake manifold leak".

I think I knew that, but since I'm getting that reading on the base carb there's nothing to sync to.

Since the surging behavior (fluctuation of 500 rpm) is identical to before I cleaned the jets, I presume it is not the jets. However, I suppose it could be a leak somewhere in the carb system.

When the bike is cold, it idles at 1100 rpm. When it has been running for 15 minutes, it idles at 3,000. I end up adjusting the idle speed down after the bike is hot.

I did neglect the pilot air screws when I had the carbs off. I know: Me = Dumbass.

Do the symptoms I describe sound like a "remove the pilot air screws, clean the idle circuit, and adjust the pilot air screws" type situation, or does it sound like something else?

I pulled the plug wires one by one while the bike was running. (Never disconnected more than one at a time.)

I noticed that the bike would stall when I pulled wires for cylinder 1 or 2, but bike did not stall when I pulled the plug wires for cylinder 3 or 4. I do have strong spark at all four cylinders.

Carbs Cleaned, but it still surges

The continuing saga of my 1994 VF750C. Carbs have been cleaned.

Starts much easier, but this bike still surges. It surges at idle, fluctuating about 300-500 rpm, and it even surges under load. Surging is worse when bike was warm.

Still backfires under deceleration. Backfires more when warm. (As opposed to before cleaning the carbs, when it backfired more when it was cold.)

I did spray WD40 around the carbs when it was idling, looking for a correlation to surging. There was no surging related to the spray. I think this proves that there is no vacuum leak?

Any help would be greatly appreciated.

Carb Sync Help

Found a helpful site for Carb Sync information for my new Magna.

That's the next thing I'm gonna try.

http://home.broadpark.no/~ahagen/magna/tips.htm

Choke Cable Routing

The parts I was waiting for from Honda came in. Carbs had been cleaned and reassembled waiting for the last two parts. I seated the carbs on the Magna in about 2 minutes.

What was so hard on the V30 was a piece of cake on the new bike. I'm sure having rubber carb boots that are actually flexible makes all the difference.

Now I'm trying to locate the proper routing for the choke cable. (Of all things...)

The cable is oriented so that the cable end mounts to the carb rack running out to the right of the bike (as you sit on the bike). Yet I know that the choke knob mounts on the left side of the bike. Somehow this cable has to do a 180 turn and come out on the left side of the bike.

This is so simple that it doesn't bear mention in the Honda Service Manual. (All other cables and tubes -- fuel lines and throttle cables) appear on the "cable routing" pictures in the manual.

So far I haven't found a description nor picture of the choke cable routing. Not in the service manual nor on the internet.

Pilot Screws

I was reading information on Magna carbs that pertained to first generation, 1980's era, Magnas and Sabres. I was trying to locate the pilot screws, which on the earlier Magnas are covered with a plastic cap and need to be drilled out in order to be removed, cleaned and replaced.

Thankfully, before I started drilling, Dave warned me that the 3rd gen Magnas don't have plugs covering the pilot screws. Instead, they have a "D" shaped head (to make them tamper proof) and require a special socket to remove and/or adjust.

You will need to remove the pilot screws to fully clean the idle circuit.

Oops. Oddly there are a couple spots that look like plugs to me. It's a damn good thing I didn't start drilling. Of course Honda Manual says nothing about removing or drilling the pilot screws. I'll have to see about getting a special socket, or making one or something?

The slow jets (idle jets) have a slot head and are removeable. The pressed-in jets are for the choke circuit. The best way to clean them is to use a small wire (real small) as a probe. Also the clean the choke circuit properly, you should remove the choke plungers from the side of each carb so you can spray cleaner thru the circuit.

Pry Points

1994 VF750C carb removal is underway as the sleet and freezing rain falls in Indianapolis.

When I did this on the V30 they popped right off with hand pressure only. This bike is a little more stubborn.

Of course I have removed all the tubes and loosened the boot clamps. I can feel and see each carb sliding in the boot, so everything is loosened. I just don't want to damage anything.

The SABMAG FAQ and the MOOT FAQ mention maybe having to pry carefully. I'm trying with a piece of 1x3 hardwood as suggested by the FAQ but ... what am I supposed to pry against?

Junky Jets

Just like y'all said, the carb slow jets were clogged, not all the way, and I blew them out with carb cleaner and have them soaking right now.If I hadn't cracked that plastic fuel-line T on the way out, I'd be seating the carbs first thing in the morning after a good long soak. As it is I'll have to shop for an OEM part.All in all though the carbs really do not look that bad. I've seen varnished carbs on a HD that sat for 10 years after my father-in-law's death....these are nothing like that.I am not doing a complete disassembly here, just cleaning the jets.The pilot needles have never been drilled out. I don't suspect any problem with the float valves either. Do I need to mess with them at all?And those smooth so-called pressed-in idle jets that Honda says are removeable but everyone else says they aren't ... what do you typically do to them. I tried spraying with carb cleaner but cannot see daylight, nor any holes.

Carbs Removed

That was easy.

There is one casualty so far -- the little plastic T connector at the rear of the carb fuel-line is toast. I thought I had pulled the fuel line off the T but in fact I had pulled the T in two. I think on the last bike I did this on, the part was metal not plastic.

I may hunt for one at PepBoys in a minute.