A/F Ratio...Dialing In

[DaMax]

Hey guys,
Just wondered your opinion since I am completely stuck here. I want to be able to effectively correct my a/f screws by using a portable tool without killing my budget. I've herd of things like the Gunson Gastester, or their colortune, yet I've herd some pretty bad reviews.
What about header temperature readings to dial in my screws using a laser. Or is that not enough?

Cheers

 

[wildweasel_pt]

All you need is a AF ratio monitor. I want to fit one as well to dial in the carbs i'll be installing.
Check http://www.innovatemotorsports.com/

 

[DaMax]

I was thinking about buying that, but then wouldn't you have to drill holes in your exhaust and weld some bungs to install an O2 sensor to get a reading? How would you go about setting it up? I've been researching these past few days and haven't got far at all.

 

[ninjaneer]

The thing with the GasTester is that you'll have to know the "recommended" CO (carbon monoxide) percentage. Not saying that it's unknown, but I haven't seen anyone ever talk about it, and think you'd have to do some research. Also of note is the following excerpt from their instruction manual

Multiple Carburettors
Where two separate carburettors are fitted, (not to be confused with a Twin choke carburettor) two extra complications arise. Firstly the air flow through the carburettors must be accurately balanced before any mixture setting can be undertaken. This can be done using the Gunson’ Carbalancer, or less accurately with a tube to listen to the air intake hiss. Secondly there will be separate mixture adjustments which must be synchronized. In the unlikely event that cylinders fed by each carburettor have totally separate exhaust, CO can be checked in each exhaust to set the respective carburettor. When the exhaust is common to all cylinders another method must be used. One method is to count the turns of the mixture adjusting screws from the fully closed position (or jet flush with the bridge for variable venturi types) and then ensure that the screws are kept to the same number of turns throughout adjustment. An alternative (and better) method is to use a Gunson Colortune to set the mixture strengths equal at some point, then to ensure that the screws are turned the same amount during subsequent adjustments.

Sounds like Gunson would rather have us use their Colortune. In that case, I would follow weasel's suggestion, which is something that I had thought about doing after seeing several other folks do it.

 

[Diablotin]

Did I read here that the colortune would be impossible to read due to the plugs location? Unless it's another one we are now talking about.
I was thinking about one of those AFR, if it's mounted you read only in one plug? Where should it be located?

Sent from my GT-I9100 using Tapatalk 2

 

[DaMax]

Yeah, I've heard on the forum where people bought the colortune finding out that it is almost impossible to fit in and get a decent reading out of it.

 

[ninjaneer]

so from what i understand, one could mount a O2 sensor on the #2 down pipe if limited to only one. i believe it is garrett who went balls out and had mounting points soldered into all four, maybe even six, locations.

 

[jfeagins]

I've got a gas sniffer in my arsenal from way back. It connected to the individual down tubes via Yamaha's premounted bungs in each on the OEM exhaust. Very PITA to use. Slightest breeze coming through the shop could affect the readout. Had to have a fan on Max for cooling purposes while adjusting. As I recall, the co2 numbers I'd see on that old tool was to be between 3-3.5. Don't remember what that was - maybe a % unburnt fuel?

Anyhow, in the end, it was far EASIER to just let the bike idle, set the synch, and at the same time, adj the A/F screws by ear. The lower the bike idles, makes it much easier to 'feel by ear' the difference between settings, and the synch tool will ensure all carbs are always kept close in settings. After adj, I'd idle the bike back up to 1k and test the throttle response.

I think doing the A/F by tool might give a bit more peace of mind, but in the end, it prolly won't get you down the track enough faster to make it worth the $$.

just my 2 cents.

 

[sdt354]

+1, the old ear works fine on the old Vmax. I end up 2 3/4 to 3 /14 out. Marks 4-2 pipes. Although from the factory they can be a lot different from each other. Go for a test ride with a proper size screw driver and you'll find the sweet spot. Stock pipes I ws around 2-2 1/2 turns out.
Steve-o

I've got a gas sniffer in my arsenal from way back. It connected to the individual down tubes via Yamaha's premounted bungs in each on the OEM exhaust. Very PITA to use. Slightest breeze coming through the shop could affect the readout. Had to have a fan on Max for cooling purposes while adjusting. As I recall, the co2 numbers I'd see on that old tool was to be between 3-3.5. Don't remember what that was - maybe a % unburnt fuel?

Anyhow, in the end, it was far EASIER to just let the bike idle, set the synch, and at the same time, adj the A/F screws by ear. The lower the bike idles, makes it much easier to 'feel by ear' the difference between settings, and the synch tool will ensure all carbs are always kept close in settings. After adj, I'd idle the bike back up to 1k and test the throttle response.

I think doing the A/F by tool might give a bit more peace of mind, but in the end, it prolly won't get you down the track enough faster to make it worth the $$.

just my 2 cents.

 

[jfeagins]

On a Gen II Vmax, the A/F ratio's are an entirely different animal... After modding the air box or exhaust, or both, you add a Power Commander V device and the sky is the limit. Dial the A/F in by RPM's at any given throttle %. You can do that in each of the five gears. You can also break it down by individual cylinders. Or...all the above. Enough to make you want to scratch your head in disbelief.....or tear it out, depending upon whether or not you get the bike dialed in correctly.

 

[ninjaneer]

On a Gen II Vmax, the A/F ratio's are an entirely different animal... After modding the air box or exhaust, or both, you add a Power Commander V device and the sky is the limit. Dial the A/F in by RPM's at any given throttle %. You can do that in each of the five gears. You can also break it down by individual cylinders. Or...all the above. Enough to make you want to scratch your head in disbelief.....or tear it out, depending upon whether or not you get the bike dialed in correctly.

perfect for your every day control freak unk::rofl_200:

 

[wildweasel_pt]

Im gonna weld one or two bungs on my exhausts so i can at least compare AF on both right and left carb bank. I have a 4-2 exhaust. On Injection systems this lambda sensor (O2 sensor) is paramount for AF ratio tuning by the ECU. With carbs everything is done by hand on the AF screws unless one is using a system similar to flo-commander where we can tune the AF ratio at the same time on all cylinders. My carbs are partially equipped with this flo-commander system so if i can get this running i will only need 1 bung.

http://www.flo-commander.com/how_it_works.htm

 

[ninjaneer]

Im gonna weld one or two bungs on my exhausts so i can at least compare AF on both right and left carb bank. I have a 4-2 exhaust. On Injection systems this lambda sensor (O2 sensor) is paramount for AF ratio tuning by the ECU. With carbs everything is done by hand on the AF screws unless one is using a system similar to flo-commander where we can tune the AF ratio at the same time on all cylinders. My carbs are partially equipped with this flo-commander system so if i can get this running i will only need 1 bung.

http://www.flo-commander.com/how_it_works.htm

How dare you keep this a secret up until now. :rofl_200:. I thought I had silenced my Monkey, but dude you got him all riled up now. :bang head: Damn that looks like fun to install. unk:Which model/application are you using?

 

[dannymax]

Yeah, I've heard on the forum where people bought the colortune finding out that it is almost impossible to fit in and get a decent reading out of it.

You may have heard that from me....I got a Colortune and dicked around with it trying to 'see' the flame until I eventually broke it! :bang head:

I've heard of some guys using and likeing it but it didn't work at all for me.

 

[wildweasel_pt]

How dare you keep this a secret up until now. :rofl_200:. I thought I had silenced my Monkey, but dude you got him all riled up now. :bang head: Damn that looks like fun to install. unk:Which model/application are you using?

I don't know the model. I bought a set of 41FCRs and they came with those nipples/spigots instead of the airjets (main and pilot) and that got me curious. I asked around and Sean was able to find out what they were. Then i contacted the dudes at flo-commander to know a bit more about this and this is certainly doable and a lot easier to get everything lined up. But im going to do this in order. Now im disassembling the carbs then i'll take care of the intakes and after i rig everything up i'll chat with them again to see whats the best applicable setup. The great thing with this kit is that all 4 carbs will be tuned equally because the jets are the same with the same tuning for all carbs at the same time...

 

[DaMax]

Thanks guys for all your input and time!! I'll try the method that jfeagins said. I just want to make sure I have the process right.
I have a Morgan Carbtune, so I'll hook that up after the bike is warmed up (Like usual when syncing).
1)Then I should lower my idle to about 600-700 after all four carbs are synced.
2) Adjust one a/f screw to just about the right spot (which I am assuming is slightly above the bike almost dying).
3) Try to match the other three carbs the same by looking at my Carbtune.
4)Check throttle response
5)Bring idle back up to 1k.

:ummm::ummm::ummm:

 

[ninjaneer]

For me, I cant get 3 & 4 to "die" when their screws are fully closed. So I raise my idle to about 2k, adjust accordingly, and then set back to 1k.

Regards from my Taptalking Hercules Android

 

[naughtyG]

I've tried and tried to adjust A/F using the idle raising/dying method and for the life of me I could not make it work. This is a method that prolly works great on a single cylinder motor, maybe even on a twin, but on a V4.. er, no. Not for me anyway.

I reckon you've got a better chance to get your A/F right by looking at the color of your spark plugs.

If you really want to adjust it properly - get the bike on a dyno with exhaust fumes sniffer. Shame that is expensive to do.

 

[mr.maxx]

i knew a guy in maine that could set em by ear. on any bike...

i cant do it:rofl_200:.....i reakon the only real benefit would be lower emissions... like THAT is our goal:rofl_200:..

ive allways set all the carbs to the same number of turns. after i get it tweaked where it runs good.....my plugs all look about the same....
dam close anyhoo.

 

[naughtyG]

Yea same here - about 2.5 turns out of all 4, then ride some. Next time the spark plugs are out, if they look a bit white the A/F screws are going 0.5 turn out, if black they go 0.5 turn in.