A Few More VM26 Carb Questions

[Anonymous]

Well, it's been awhile, but here it goes...

Here's the background info: 78' GS 1000, 4-1 exhaust, Uni pods, Dyna 3 ignition, DynoJet Stage 3 jet kit, new(ish) coils and wires with hot spark, & 54k miles!

Well, I did it backwards...I put in the DynoJet kit and was getting some backfiring and spitting, so I moved the needles to the next richer position. The bike was running better, but plugs 1, 2, & 4 were still fouling on occasion. So finally, I got it through my thick skull to check the valve clearances.
It ended up that I had 1 tight valve on #1, 2 tight valves on #2, #3 was within tolerence, & 1 tight valve on #4. SO after I purchased the $40 ($3 worth) shim tool and shims, all of my valves are within tolerence. I went back and re-synched the carbs and went for a ride. Fifty miles after the valve adjustments, #4 plug died...soon after, plug #2 died. Those plugs were wet...My garage smells like fuel...Seems like it's really running rich now. I've got hot spark and the carbs are in synch.

1. Am I right in assuming that getting rid of 4 tight valves is causing the bike to run rich?

A few more questions if you wouldn't mind answering...

2. On a 78 GS1000, where are the "Pilot Screws"? Are these the screws on the underside of the carbs (Mikuni VM26) that Clymer tells you not to mess with (that they're factory preset)? DynoJet never says anything about "pilot screws", so I have no idea how to go about adjusting them, or what will happen if I do, or even if I need to... Are pilot screws the same as a fuel mixture screw? (I know where the air mixture screw is. )

3. When I first pulled my carbs apart, I had a small nylon washer above the e-clip on my needle and a much thicker nylon washer below the e-clip. The guy at DynoJet said it sounded like the carbs had been rejetted before, and to put BOTH the thin and thick nylon washers on the needle below the clip. Is this right? It looks to me like it shouldn't make any difference below the clip, but i'd like to know for sure.

I'd love an answer to some of these questions, and always look forward to any other advice you can give me.

Thanks again guys...

[Anonymous]

Question #1
Probably.

Q#2
The pilot screws and the fuel mixture screws are the same, ie. under the carb towards the cylinder head side. Earlfor probably has the correct settings. If not him then someone else on the site will.

Q#3
The washers under the clip raise the needle, so they exacerbate the richness problem. You probably need to put the washers back the way they were. If the three-quarters throttle reading is still rich you could try swapping the washers - the thin one under the clip and the thick one on top of it.

There are a lot of excellent people here who will do everything they can to help.

Harrison

[Don Lobacz]

1. By getting proper clearances you now have the combustion working closer to optimum (what are your compression numbers). You may have overjetted to compensate for low compression.

2. The pilot screws are on the bottom. They are very sensitive and should be reset to their initial setting after cleaning. After they are reset they can be fine-tuned (write down the stock settings). The air screws on the side offer less sensitive adjustments.

3. It is my recollection that the thin washer starts out on the bottom and the thick one on top. That way you can flip the 2 and get more lift on the needle if needed. I would put it this way (small on the bottom) and set the needles on a middle setting. You also MUST synch the carbs after adjusting the needles.

[KEITH KRAUSE]

Spit IX. I replied to your earlier post, "Number 4"... Please check it out.