Pilot circuit mixture screw adjustments, tempurature relation...

[acammer]

Hey guys. I have been riding the VMax since March of this year, after buying the bike in January. Bike has run very well, starts great, excellent power. I have noticed some drivability issues in the pilot circuit that have become markedly worse as the temperatures have climbing above 90* recently. Yesterday, after my 30 mile ride home from work, sitting in traffic, I was able to clearly hear that I was loosing 1 and then even both cylinders at idle on the left bank. I have super-trapps with 5 discs and open end caps, and could clearly hear that just idling both cylinders would roughen as soon as I let it idle, and then quit all together. A blip of the throttle would relight them. If I kept it open a bit, they were there, but a bit rough. Once underway and over 1500rpm things were fine. Also, if I let the bike lug down to near idle in second or third gear and then apply maybe 30-40% throttle, I could get the left bank to instantly quit, a bit more throttle, or as soon as the revs came up a bit more, and they both cut right back in. I have a very rich smell, both on cold starts and any idle condition. Also, my cold starts are SUPER easy. This morning it was 70* out, I started the bike and immediately cut the choke back off completely, and could idle, and hold the 1800rpm rich pilot check. FYI carbs synced with home made manometer 2wks ago, and peashooter completed.

So, I think it's pretty clear that I have a rich pilot circuit. I don't have any black smoke that I can find, but is it possible that the pilot circuit is so rich that it would cause this cutting out when things get really warm - I would expect in the heat that things would be going rich. I guess the other possibility is an air-leak that gets worse as things warm up, but I don't notice any lean popping.

My screws have been uncovered by the previous owner, I just looked this morning before I rode in. I am planning to try some adjusting when I get home tonight. Am I correct that the adjustment is to a fuel circuit, and screwing in to seat the needle restricts fuel (leaner) and backing the screw will fatten the mixture? Whats a good base-line for a near stock max, just the open cap super-trapps, and a dyna 3000 on curve 4. I will take care with the screws, I've read the horror stories about them stripping, hopefully these will play nice.

I appreciate your input.

 

[SpecOps13]

Screw in, Leaner. Screw out, Richer... Base for me is 3 turns out. It depends a lot on your set up of jetting, mods and altitude...


Good Luck.....:clapping:

 

[[email protected]]

You might just have some schmutz in there....Peashooter and Shotgun help but don't always do the trick.

 

[SpecOps13]

Run the bike for a few minutes then drain each carb into a cup or jar. Check for fine black particles....

 

[acammer]

I did the carb drain when I did the pea shooter a few weeks ago, fuel looked good. If the screws will come out I will try a partial shot-gun while I am at it tonight. If they were gummed through, I think I'd be leaning, not going rich. If this was a lean condition, it ought to be at its worst when its cold, and get a little better as it warm up, this does the opposite, which makes me somewhat confident it's going rich.

 

[Rhoy Carter]

Check your Charging system, the voltage might be low at idle and the ignition requires good voltage

 

[acammer]

Check your Charging system, the voltage might be low at idle and the ignition requires good voltage

I would think this would result in some hard starting, and be prevelant at the cooler temps. I may go ahead and drop in some new spark plugs, I may find some clues there as well.

 

[Vmaxattacks]

When you are doing the "shotgun" correctly then you would have taken the screws out and would have been able to know the condition and the amount if turns they were out. Make sure you do the entire process completely and you will be amazed how much it helps. I do and I was!

Bud

 

[85vmax]

When you are doing the "shotgun" correctly then you would have taken the screws out and would have been able to know the condition and the amount if turns they were out. Make sure you do the entire process completely and you will be amazed how much it helps. I do and I was!

Bud

Buds right, you can't do the complete process without taking the A/F screws out.....those being clogged could be the problem......you sometimes have to do it all 2-3 times.

BTW...when you say almost stock, I hope you are running premium fuel and a jet kit.........setting 4 on the Dyna 3000 requires that....minimum.
That high advance may also be the reason you start and warm up so quickly, and could be also the reason you run a bit hotter and having those probs down low.

 

[sdt354]

You might just have some schmutz in there....Peashooter and Shotgun help but don't always do the trick.

+1, when I bought mine it only had 12,000 miles on it but had not been ridin for a while. A tear down and cleaning with thin guitar string was all that would unplug some circuits. I do a pea shooter as a maintenence meassure at least once a year.
Steve-o

 

[acammer]

Update: Left side carbs, easily adjusted, fortunately this was mostly the offending side. I was able to get a more stable idle from both cylinders, where as before the right side, 1 cylinder in particular, wanted to do most of the thumping at idle. The right side mixture screws, appear to have been fooled with before. I couldn't get my screw driver to slot in... upon some close flashlight inspection it looks like these must have been stuck at one time, drilled, still stuck, and then epoxed over (concern for air leak?) There is a hole in the middle of each screw, the slot for the screwdriver is still there, but there is definitelh something clearish and shinny coated over the screw. So, those will just have to do, maybe some day I'll pick up some right side carbs from somebody and swap them out.

The real bummer was I went to go recheck my sync when I was finished, and the nearly stripped screw for the intake mainfold cover became a definitely stripped screw. I will try slotting it with a dremel, I think I can make it accept a big straight bladed screwdriver pretty easy. But, I took a test ride any everything seems much better than before, just a little more fuel on the left evened things out.

 

[alorio1]

Sean Morley commented in a post that he had a high % rating on getting the A/F screws out and if he's not successful there's no charge. I think I have my story right......maybe he will chime in a give all the details.

 

[acammer]

I have seen something to that effect. I am going to seafoam it tomorrow to see if I can get it to where I am satisfied. If not, we will see about next step.

You are dead right about the ignition as well, I need to dial that back to curve 3, I reread the book and it does suggest curve 4 and over to be jetted up. Now, I have been very intentional about listening for any spark knock and I have none, but I would like the piece of mind. We will see if that settles it some.