Setting all four A/F blindly to 2 1/4 turn. Is that OK?

[rabit1]

Setting all four A/F screws blindly to 2 1/4 turn. Is that OK?

Hi

Appreciate your comments and suggestions. I'm really not knowledgeable enough about carb. Anyway here's the story.

Stock carb, custom exhaust.

The PO messed up. Carb setting was way off. On idle the bike seemed to be running only 3 cyl (not sure). Exhaust on the left side seemed weak. Cyl No 3 stayed colder longer time when started up cold. Bike hesitated terribly on acceleration, sputters a little.

So first thing I did was synchronize them. But that didn't help at all.
Plug for cyl no 3 replaced. Didn't help either.
Check the resistance on coils (good) and swap plug cable (1 and 3), also didn't help.

I was about to do the shot gun, when I realize that the A/F screw setting seemed suspiciously wrong because on the no 3, A/F was 1.5 turn. On no 1 cyl A/F was 3.5 turn. I thought A/F is usually around 2-2.5 turn (not sure).

So I decided to test and return all setting to about 2 1/4 turn for all four cylinders.

Honestly, I chose 2 1/4 just for testing and I kind a remember I read on some posts that some vmax owners optimally set their A/F to 2 1/4 (I could be dead wrong tho).

And voila, the bike runs sooo much better, almost perfect. Easy start, No hesitation, good acceleration, smooth idle.

I'm so happy with how the bike runs. I'm really not sure if I need to do the shotgun anymore or change and tune the carb again. I don't really know how to tune each carb. and I haven't find anyone here in my area with the expertise to tune vmax.

I know that setting all four A/F to 2 1/4 turn is no way correct. I have no idea if the bike runs rich or lean, but is it ok and safe to just leave it there until I find someone who can tune them correctly?

What do you think guys?
Thank you for reading this rather long post, and surely
appreciate any suggestions....

Regards,

 

[Rusty McNeil]

It good to try to tune them individually but over a period of time I have gotten to where I know what works for me and don't over stress the process too much, just setting them all the same.

Synch needs to be pretty close too to even try to set them individually, and sometimes one cylinder just won't seem to respond at all,

 

[[email protected]]

2-3 turns out is pretty average. If it runs good, don't worry!

 

[rabit1]

Thanks...

As of right now.. I'm happy with the performance. What I'm worried about is whether I'm actually running to rich or too lean in the long run...

 

[Diablotin]

Maybe ride it a bit and just check your plugs. A quick check will tell you if it's too lean or too rich (which I doubt).
Your optimal could be around 2.5 turns.

Sent from my GT-I9100 using Tapatalk 2

 

[rabit1]

Maybe I should change all plugs first?



Those plugs now had been used for a while with previous settings. So I dont think they reflect current setting. Right?



Thank you

 

[MaxMidnight]

So long as the electrodes are in good condition that the most you would probably need to do is to clean then up with a wire brush.

That said, if the bike is running OK then I probably wouldn't bother.

 

[jfeagins]

If I remember correctly, those A/F carb setting only control A/F ration from idle upwards until the other needle assy's begin to take over, then the main jets do all the mixing in the upper RPM's. So, if you have the A/F settings good enough to idle properly, and they seem to transition into the midrange w/o significant hesitation, you won't be doing any damage by not setting them with a 'fine toothed comb", so to speak. Get them too lean, and you'd know it. Get them too rich, and fuel econ might be down a bit - if you idled around for the whole tank of gas.

When I set mine, I will have the sync guages set up at the same time, and normally will adj my idle down to around 800rpms. Makes it so I can "hear" each cylinder as I tune. I turn that cyl's A/F screw in slowly until that cyl begins to cough & want to kill the bike. Then I turn it back out approx 1/4-3/8 turn. I go through all 4 cyl that way, all the while double checking the sync. When I'm done, I will reset the idle back up to 1000rpms, rev it a couple more times - testing the transition from dead idle upwards. If it's slightly sluggish, I will back all 4 A/F screws out an even amount (1/8th turn) and retest the transition. When the transition is it's smoothest, I know I've got all 4 cyl A/F's the same, and the sync is spot on, and the bike is good to go.

 

[rabit1]

thank you guys..

jfeagins, thank you for sharing. I'm going to try your method, not sure if I can do it correctly but I'll try. Nice trick with lowering rpm to "hear" each cyl as you tune.

Well, I spoke a little too soon. I guess I was a little too excited. The bike still has problems.

This morning when I started the bike from cold, I still notice that cyl no.3 still stayed cool longer, and left exhaust was still weaker on idle. But if I increase rpm to about 3k, the left exhaust is actually stronger. (newbie question: both are supposed to be equally strong, right?)

And today I can still feel just a little hesitation during acceleration (just a little, but I didn't have hesitation yesterday). So I think the bike still has some way to go.

As for the plug, heck I can't even take the plug out, I can't find the right tool yet. My socket wrench and spark plug wrench don't fit on vmax.

I'll try to tune the A/F again. Do you guys think shotgun is still necessary?
Appreciate any suggestion on how to go from here.

Thank you,
Regards,

 

[jfeagins]

Try doing the "peashooter" with an eyedropper & seafoam. Might just clear it up. Otherwise, doing the shotgun isn't all that hard to do. Just be sure to follow the directions and NOT spray the carb cleaner indiscriminantly down every passage you see.

Fine tuning your A/F mixture prolly isn't going to make enough difference in what you are describing.

 

[DMAN999]

You might want to check for a vacuum leak also.

 

[rabit1]

Thank you,

Peashooter would not be necessary if I've done the shotgun, right? Or should I?

Dennis, are you suggesting there's a vacuum leak even if my carbs are all sync'ed and balanced?

With aftermarket exhaust (everything else is stock), what should I do with the stock A/F? Is it still 2.5 turns?

Thanks
Regards,

 

[DMAN999]

It's definitely a possibility.
You should check for cracks/leaks at ALL the rubber boots associated with the carbs and VBoost intakes.
Also make sure the airbox is properly/firmly seated.
Spraying starter fluid/WD-40/Propane (from a hand held torch) at them with the bike running is a good way to check.
IF THE ENGINE REVS UP AFTER SPRAYING AT THE BOOTS, YOU HAVE A LEAK/CRACK.
There are threads here somewhere with more info on checking for a vacuum leak.