Triumph Rat Motorcycle Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Bike of the Month Challenge!

1 - 6 of 6 Posts

·
Registered
Joined
·
165 Posts
Discussion Starter · #1 ·
Hi, Just installed an Innovate LC-1 with a G2 Gauge to my 2006
790cc Bonneville and I'ts up and running, the bikes set up is no snorkle, stainless steel race header which has no cross over balance pipe and a set of classic TR6 silencers which I have fitted baffles to to keep the sound down. The main jets are 125 and thats it, I can't adjust the idle mixture screws at the moment as they are seized and I am awaiting an adjusting tool from the states before attempting to alter them, the gas sensor is fitted to the L/H side header at about where the cross over pipe would be on the std headers.
The readings I am getting at about 1/4-1/2 throttle on the A/F gauge is showing between 12-13, at full throttle it drops to 12 would this show I'ts running on the rich side also once you shut off the throttle the dial nearly goes off the gauge up to 18 with a lot of popping, would this be on the lean side what should I be looking to alter once I've managed to free up the idle mixture screws, Also does the dail normally fluctuate much when the throttle is kept steady.
Thanks.
 

·
Registered
Joined
·
2,741 Posts
I suggest tuning it under load & for steady cruise. It is normal for the a/f to show way lean on decel. 12:1 is on the rich side.
 

·
Premium Member
Joined
·
629 Posts
I've got the G5.

Yes, the needle does fly around alot especially when changing gears, but when holding a steady hand it should be pretty solid.

You are rich, I'm not familiar with your pipes, but maybe 120's would work better for you.

If you have a Dynojet needle, (or any other adjustable brand) you could try raising the clip which will lower the needle, leaning out your mid-range a bit too.

The advice about tuning for midrange and cruise is sound, most of us don't spend much time at wide open throttle, even when passing or being a bit rowdy.
If you can find jetting that gets you 13:1 at 1/4-1/2 throttle, with 13:1 at idle, you will be pretty happy overall.
-K
-K
 

·
Premium Member
Joined
·
629 Posts
I was also going to say, that if you've removed the airbox and are running pod filters, your AF readings are going to be much more effected by the wind direction and any gusts.
On my bike I've noticed that I can be at 13:1 cruising in still winds, and 12:1 with a headwind and 14+:1 with strong sidewinds.

That's one thing the airbox IS good for, is calming the effects of the winds.

-K
 

·
Registered
Joined
·
95 Posts
Hi, OB. Welcome.

Firstly, the numbers:
When your dial says x:1, the x represents the amount of oxygen molecules to each fuel molecule. Therefore, 13:1 is richer (less oxygen) than 16:1. (Apologies if you're aware of this.)

Ideally, you should be tuning your carbs so you cruise (idle to 1/4 throttle) at about 15:1 (slightly lean for fuel economy) going progressively richer as you open up the throttle, to a figure of about 13:1 when you've got the throttle wide open. Due to their nature, carbs do lean out when you close the throttle but you should be getting a little popping, not lots.

There is a diagram showing you which parts of the carb system affects the fuelling at various throttle openings. Unfortunately, I can't find one at the moment. :S If you can get a copy of Jenks Tuning Notes, it's a great resource and specific to our carbs. Basically, main jet dictates 1/2-full throttle openings, needle affects midrange and idle circuit=small throttle openings. (Have I missed a stage??) You dial the main jet in first and then work your way down (mains, needle-taper and height, pilot)

There are plenty of websites that show how to properly tune a carb-just choose the one you understand best. :)

Hope this helps.

Jetting instructions for CVK carbs: http://www.dinqua.com/Triumph/carbs1.html
 

·
Registered
Joined
·
1,687 Posts
Well done on fitting the A/F gauge OB53!

The first thing I'd suggest to anyone fitting one is not to get too hung up on varying readings while riding.
It will vary quite substantially as the conditions vary (revs, load, throttle position, acceleration, deceleration etc etc etc.)

Ive found that the most accurate means of determining actual A/F for set-up purposes is taking the reading under gentle acceleration thro the gears, all the way from minimal speed up to WOT.
Set up the carbs using the readings obtained by this method and you wont be far wrong.
In my case this was backed up when I dyno'd the bike and got pretty spot-on A/F readings across the board.

During general riding you'll find that when jetting is correct you'll get a variance +/- around 13:1. The narrower this variance band is, the better, showing your jetting to be optimal for your set-up.

Dont take any notice of readings in extreme conditions such as mad acceleration or deceleration, and yes, you will get a super-lean reading when shutting the throttle off under all conditions.
I also get a momentary lean reading as I go thro 70mph in top gear which Ive never been able to dial out. Doesnt effect performance and didnt show on the dyno readings, so it there to stay!!

I did a test to see just how badly off the jetting needs to be before it starts to effect performance badly, and could be obviously felt with the SOTP.
Readings richer than 11:1 or leaner than 15:1 can definately be felt, and surprisingly the symptoms are very alike.
When I purposly under-jetted to obtain a 16:1 ratio the bike hardly revved over 3000rpm and felt like the engine was full of cotton wool!!
On the dyno it seemed that my bike would produce optimum HP figures at about 12.7:1 but obviously thats slightly detrimental when it comes to fuel economy. Everythings a compromise!

Oldbiker53, if your getting 12:1 readings under the above conditions then I'd consider stepping down to 120 mains, or better still, leave the jets alone and open up the intake a little.
Thats an easier option and you'll certainly get better results!!

NB....... If you havent read it already, there is a very interesting, informative, contentious, contradictory, entertaining and sometimes very amusing thread on this very subject here.....

http://www.triumphrat.net/twins-technical-talk/107628-what-is-the-perfect-f-ratio.html


V.
 
1 - 6 of 6 Posts
Top