Bandit fueling advise

[Jdeac]

Got the bandit in the dyno today. It's a little lean lowdown and top end. Advise on what I should do next appreciated.

Setup so far

160 main 

5th clip on needle plus 5 washers

Mixture 3 turns out

Everything else stock

[Jdeac]

[Jdeac]

Not the best pics

[TonyGee]

3 turns out is pretty much max out on the mixture screws, go up one size on the pilot jet and retune the screws. 

[Gixer1460]

From what I can make out on that AFR trace (which isn't much!) the engine is rich at top and bottom and lean to ok in the midrange! Smaller numbers means rich! Can't see what any of the output numbers are but nice curves - not earth shattering looks stock!

[Jdeac]

The dyno guy said its lean lowdown and up top. On 4 pulls the average was 133 odd bhp. and just shy of a 100 ft/lb. 

My first time jetting. He said it was a good graph. But as above could do with being a little richer low and high

[Wagola]

I always thought the idea of a run on the dyno was for the operator to sort the fuelling out to the optimum or at least the best compromise. Forgive me if I'm wrong but shouldn't the adjustments be made by the operator and then another run to confirm settings going in the right direction ? Seems strange to come away and still be 'guessing' where to go with settings.

[Fazz711]

Probably depends what you pay for. 

If you pay for set up you will get set up if you pay just for a run to see where its at that's what you will get 

[Jdeac]

It was just a power run. To see what was what. No tuning.

[MeanBean49]

56 minutes ago, Jdeac said:

It was just a power run. To see what was what. No tuning.

Sounds like dyno guy doesnt actually know what hes on about.

Take it somewhere that does know and have them do the setup too would be my advice

If its a stock motor, the 133bhp figure is most likely an uncorrected crank figure

Edited April 16, 2021 by MeanBean49

[Jdeac]

Any recommendations in somerset then.

[Jdeac]

Is it right that the Afr should be between the red and green lines?? This is all new to me. Never had a bike on a dyno. And have done the jetting myself through lockdowns etc.

Edited April 16, 2021 by Jdeac

[Jdeac]

When I say stock. I'm on about the carbs. Bike has full system and filters 

[MeanBean49]

2 minutes ago, Jdeac said:

Is it right that the Afr should be between the red and green lines?? This is all new to me. Never had a bike on a dyno. And have done the jetting myself through lockdowns etc.

Yeah wants to be about 13.1 right through which should be centre of the red and green, within that band is close enough. 

Looking at how rich yours is going main jets are far too big as a start.

[MeanBean49]

1 minute ago, Jdeac said:

When I say stock. I'm on about the carbs. Bike has full system and filters 

With no engine work, 133bhp is not a genuine rwbhp figure.

[Jdeac]

Please excuse my lack of knowledge. 

So the lower the number on afr is rich or lean??

[MeanBean49]

5 minutes ago, Jdeac said:

Please excuse my lack of knowledge. 

So the lower the number on afr is rich or lean??

Lower the number the richer it is.

Its the ratio of air relative to 1 part fuel.

14 :1 14 parts air to one part fuel

11 :1 11 parts air to one part fuel

[Jdeac]

So from what your saying.  I need to lean out the lower and top end??

[MeanBean49]

1 hour ago, Jdeac said:

So from what your saying.  I need to lean out the lower and top end??

Yes. Putting smaller mains in will lean it all out.

You need to get tbe top end fueling right before you think about trying to sort anywhere else out.

[badger]

Tim Blakemore is in Bristol for dyno. Who I intend to see with mine at some point 

4 hours ago, Jdeac said:

Any recommendations in somerset then.

 

[Gixer1460]

17 hours ago, Jdeac said:

Is it right that the Afr should be between the red and green lines?? This is all new to me. Never had a bike on a dyno. And have done the jetting myself through lockdowns etc.

I wondered what they were ? ? ?  As I couldn't read the side bar numbers they were meaningless - below the bottom line just looked like regular AF trace!

[Gixer1460]

17 hours ago, Jdeac said:

Please excuse my lack of knowledge. 

So the lower the number on afr is rich or lean??

 

16 hours ago, Jdeac said:

So from what your saying.  I need to lean out the lower and top end??

That was mentioned earlier !

[colinworth79]

So with carbs your never going to get it perfect all the way through the rev range but should get it near enough. 

The main jet 3/4 to full throttle 

Needle/slide   1/4 to 3/4 

And pilot jet and screw , idle to 1/4  

Just a rough guide but there is a slight overlap  . So if you reduce your mains by a measurable amount it will then have a slight affect say over half throttle . 

As the previous replies the top end is rich you want to reduce the mains and then work from there .

From memory my bandit with pod filters and a full Akrapovic system was 150 mains .

[Spazpecker]

On 4/16/2021 at 5:51 PM, Jdeac said:

Any recommendations in somerset then.

JHS racing in Keynsham.