Wideband tuning question What AFR's to shoot for?

[Hult250R]

Ok so I've got the 450R carb jetted close on my '00 400ex.
I've made an adapter pipe to go between the headpipe and the muffler to put my cars LM-1 wideband into. I'd like to fine tune it and make sure I'm spot on. Its a little rich right now.

I've got experience tuning my turbocharged E85 powered car with the wideband. I'm wondering what air fuel ratios to shoot for on an air-cooled quad motor on pump gas?
Idle, 1/4, 1/2, 3/4, wot?

I've searched but all I can really find is for liquid cooled EFI motors.

Anyone here that's dynoed or that's installed a wideband have any tips on afr's to shoot for?

[Budweiserebel07]

lol Im into turbo'd rotarys and a wideband is great, but i had no clue people put them on quads ! I'll ask my brother after bit I'm thinking he knows the ratio on a 400

[Budweiserebel07]

He said from what he remembered, at 3/4 throttle he was at like 13. 5, but its been like 4 years ago.. just an idea i suppose.

[honda400ex2003]

13:1 for an every day rider

14:1 for a race engine or higher performance one.

http://imageshack.us/photo/my-images/33/dynorun416ex.jpg/

the lower lines on there are the f/a from mine.

the spike at the front is the shot from the accelerator pump and will happen on all of the graphs so theres no need to worry about it.

I started down around 12:1 and ended right around 13:1 with about a 8 jet size swing. 175 to a 168. any lower on a main and i would have to raise the needle on the chart to get the mid to come back down a bit while still getting closer to 14:1.

I was told a 165 would work in the warmer stuff, that was a graph at about 50 degrees and raining. I ran a 165 a few times, it actually made a bit of difference in sotp riding, could feel it pull really nice when it was around 60-70 degrees or more.

hope that helps out a bit.
steve

[Hult250R]

So even tuning at idle shoot for about 13? 14 is a little lean for my taste. I'd rather have it safe.
I want it pretty much 13 all the way through the rpm range?

[honda400ex2003]

i guess if i was going to do it, i would go for just under 13:1 at idle to help it with cold starts. then go up from there as you usually would. it is easier to do a full run and see what you get if possible like on a dyno or something since you wont get a good estimate without a load on it. just revving it in place will get you close but imo is still pretty useless. at about a 1/4 throttle or so you will start to see the spike and you wont be able to do anything about it.

i wouldnt go 14 either, the most i would shoot for is 13.5:1 if it is cold outside. if it was 90 out and you were tuning then 12:1 would be where i would want to be since i dont ride that hot and will ride when its cold outside. that will just depend on your application. thats whats nice with around 13:1, it will get you "close" for alot of applications.

what are your current jet specs and details of the machine?

steve

[Hult250R]

Stage 2 hot cam
Ground welds in stock header with 06 450R muffler with the spark arrestor removed
11;1 (I believe) piston, it was in it when I got it. 175psi compression

04 450R carb, 178 main, needle in the middle clip, 45 pilot, 2 1/2 turns out on air screw

[honda400ex2003]

what bore?

178 is quite rich for anything at or under 416.

pilot is probably a bit lean also depending on bore.

steve

[honda400ex2003]

stock bore low 160s (160, 162), maybe even a 158

416 bore upper 165 to a 172

pilot i would say should be around a 50 or 52 on either setup. probably a 52 at around the same 2.25 turns out but its hard to say.

steve

[Hult250R]

I'm not sure of bore size. I'm assuming its a basic rebuild so like .040 or so over stock
It seems a little fat on the main. I didn't get to spend much time jetting it yesterday. I got home and figured I'd make a piece to fit between the muffler and header to use the wideband on it to get it dialed in.

[honda400ex2003]

hard to say what it will be then lol.

steve

[Hult250R]

With what you gave me ill be able to get it really close
Ill post back up when I get it jettet with where I ended up with.

Any tips on how to use the wideband jetting it by riding it? I was going to hold it at a certain throttle under a load and watch where the WB is sitting.

[honda400ex2003]

lol sorry i dont have any experience with doing that. I used a stick that went down the end of the silencer and was on a dyno when i had mine done. i would say that it will probably be pretty tricky to get it tuned while riding it around. See if it will record a run and then you can interpret it from there. let it idle, start the test, hop on, nail it through the gears and see how it looks over the whole rpm range.

good luck! thats def easier said than done. haha

steve

[Hult250R]

Got the idle set a lot better. Went up to a 50 pilot and it sits about 13:1 afr. It was sitting at about 14.5
I've gotta get out where I can ride it to set the rest.

Were the main sizes you mentioned for a stock carb or my 04 450R carb?

[JOHNDOE83]

Because of the aircooled motor and the charecteristics of this engine, Its my opinion that the only way to jett it correctly for most power is to up the main jett till it breaks up on topend from being to rich, then back down on jett sizes till the break up stops.

This allows the motor in the ever changing enviroment of full throttle, half throttle, gear shifting wildness during a trail ride or race, to accomadate for fuel defficiencies and motor heat.

Call me old fashioned, but it works really well on my motor and www.jetsrus.com reccomends that method also.

I really wanna get the wideband sensor kit, Im just a lil on the fence about it. Do some trial and error testing and put some ride time in between jett changes, see if it feels like more power at a different fuel ratio?

I want one just to play with...lol.

[honda400ex2003]

Originally posted by Hult250R

Were the main sizes you mentioned for a stock carb or my 04 450R carb?

it will work with either one. i find that the 450r carb and 400ex carb are usually within a couple of jet sizes.


steve