Re-jetting with a wideband

I'm new to the forum and street bikes, so forgive me in advance if this is a dumb question.

For the past 20 years, I've been messing with cars; most recently GM fuel injection. Tuning has become a real big deal, especially over the past few years as inexpensive wideband 02 units like the Innovate Motorsports LM1 have become available.

www.innovatemotorsports.com/products/lm1.php

The KZ650 I just bought has a Mac pipe and K&N filters, so I'm pretty sure the carbs'll need rejetting when I go through them. I've been surprised at the negative response from everyone I've talked to about using a wideband tuner to dial-in the A/F. I've looked around on here as well, and I haven't seen anyone doing it.

I figure a much higher percentage of motorcycle owners are interested in maximizing their performance, as opposed to car owners; most of whom just get in and go from point A to point B. I'm surprised that wideband tuning isn't more common. Am I missing something?

OK...I give up...what's wideband tuning? And how do you do that?

Bob

You place an oxygen sensor in the exhaust, just as every modern fuel injected car does. It reads the air/fuel ratio, allowing you to jet the bike to achieve the optimal ratio.

Wideband refers to processor speed and the oxygen sensor itself. Until very recently, fuel injected cars had computers with the processing power of an Atari video game. Those limitations necessitated "narrow-band" tuning. Aftermarket units like the LM-1 have much more powerful processors, which are capable of doing many thousands more operations per second, referred to as wideband tuning.

I'm not sure exactly what it is about the new generation of 02 sensors that makes them wideband rather than narrow band.

Post edited by: seanof30306, at: 2007/07/25 23:07

So you'd have to have a permanent oxygen sensor in the exhaust? AND an on board computer system to read it and make adjustments some how?

I'm guessing this would only work with fuel injected engines...right?

Guess that leaves my 79 KZ out. Sounds like a good idea though.

BobB)

I used a Dynojet Wideband Commander for monitoring and some basic mapping on my 750 turbo, although the bike was mapped properly using another wideband sensor linked to a dyno. Apart from the analysing hardware and software, the sensors themselves work differently from narrowband sensors. Wideband sensors used to be very expensive but as the price has come down they have become viable for tuning purposes. I can't see why anyone would be negative about them, they aren't the total solution (although combined with EGT they get close) but they are wayyyy better than nothing.

Bob_79KZ wrote:

So you'd have to have a permanent oxygen sensor in the exhaust? AND an on board computer system to read it and make adjustments some how?

I'm guessing this would only work with fuel injected engines...right?

Setups like the LM1 and WBC don't make any adjustments, you have to do that yourself, or use a programmable ECU in closed loop. Being only a sensor, it works equally well for carbs or EFI.

Bob_79KZ wrote:

So you'd have to have a permanent oxygen sensor in the exhaust? AND an on board computer system to read it and make adjustments some how?

I'm guessing this would only work with fuel injected engines...right?

Guess that leaves my 79 KZ out. Sounds like a good idea though.

No, not at all. The link I put in my original post is for an aftermarket unit. Take a look at it. You just place the 02 sensor in the exhaust stream while you are tuning.

In my opinion, it's too expensive for an individual to buy one solely for use on their own car. Most dyno facilities that offer tuning have them, though, and a lot of car mechanics I know get them as well.

On fuel injected cars, you can do a lot more tuning; adjusting the spark curve as well, but, I've seen tons of carbed cars tuned with wideband; it's pretty much standard procedure today. You can change jets accelerator pumps and springs, bleed holes and adjust the idel circuit so you're at the optimal air/fuel ratio at WOT for power, and the optimal A/F ratio on the idle circuit for economy. I don't know about bikes, but even well-tuned cars find 20-50 hp and significantly better fuel economy when tuned with wideband 02.

My point is that I'm surprised it's not more prevalent in the motorcycle world. Rejetting carbs is MUCH more common with bikes; Id've though bike tuners would've been all over it.

Post edited by: seanof30306, at: 2007/07/25 23:34

Post edited by: seanof30306, at: 2007/07/25 23:38

Yeah...I figured it would be expensive. But its a great tool.

Maybe KZRider can buy one and then rent it out to menbers?

Bob:evil:

Bob_79KZ wrote:

Yeah...I figured it would be expensive. But its a great tool.

Maybe KZRider can buy one and then rent it out to menbers?

Bob:evil:

I don't think that's too likely, but, back when I was in Atlanta, this guy would travel around the country doing "dyno days" for late model Fords. In three pulls on the dyno, he could tune a lot more power and economy out of any of them. He'd set appointments and do 20 or 30 in a day.

I could see a carb expert with skills similar to wiredgeorge's (and who liked to travel) doing something like that for bikes and making a ton of money; especially since the market seems to be wide open.

Even if they don't like to travel, it'd only take a few tunes to recoup the cost of the wideband tuner; a local tuner could make a lot of money with one.

pingelonline.com has the set up for you. You can get a plug to put in the o2 sensor hole when your not tuning.

What timing! I was looking at Lorcan's site a few days ago and was going to post a thread just like this one.

My plan is to buy a sensor and design a readout system using LEDs. It would strap on to the tank for tuning purposes.

I currently use a stationary EGA which seems very accurate, but is really only meant to check idle.

I was looking at the mixture chart for voltage-versus-mixture and saw that 12:1 is stated as the desired mixture for power. But other sources I've come across mention 13:1 as the target. I guess one of my million questions for Lorcan is: Does the 12:1 pertain to turbos only, or is that for all gasoline engines?

Also, have you found any particular sensor to work better than others?

How stable does the mixture stay in the proper ratio? I occasionally put the bike on the centerstand and use the rear brake to scrub off the power while I accelerate the rear wheel in top gear at varying throttle positions. I notice when I go WOT quickly the EGA goes off scale rich (richer than 11:1), but if I go more gradually, the meter stays on scale between 11 and 12.5. The bike seems to be jetted properly by all other indicators. (I'm building the analyzer to use on other bikes to speed up the jetting procedure, mine took days of experimenting and tuning.)

Post edited by: loudhvx, at: 2007/07/26 02:36

loudhvx wrote:

What timing! I was looking at Lorcan's site a few days ago and was going to post a thread just like this one.

My plan is to buy a sensor and design a readout system using LEDs. It would strap on to the tank for tuning purposes.

I currently use a stationary EGA which seems very accurate, but is really only meant to check idle.

I was looking at the mixture chart for voltage-versus-mixture and saw that 12:1 is stated as the desired mixture for power. But other sources I've come across mention 13:1 as the target. I guess my question for Lorcan is: Does the 12:1 pertain to turbos only, or is that for all gasoline engines?

Also, have you found any particular sensor to work better than others?

I think it's overkill to permanently mount a wideband tuner on a non-efi bike. On efi (map-efi, that is, not maf), you are doing major tuning to the spark tables in the pcm, and making fuel adjustments every few rpms. On a carbed bike, once you have the jetting correct for WOT (Wide Open Throttle), it's not going to change unless you make a component (or altitude) change. For the idle circuit, a dyno would be great, but expensive overkill. I've always thought it would be cool to make friends with the guy at the speedo shop. His speedometer dyno would be perfect for part-throttle jet-tuning.

You don't need that, however. You can simply drive around for a time using the datalogger. You don't even need to weld in a bung for the 02 sensor; you can use a "sniffer" sensor that clips on the tailpipe.

The stoichiometric air/fuel ratio is 14.7:1. Stoichiometric is the scientific term that indicates the ideal ratio of air and fuel for COMPLETE combustion; all air and fuel is completely burned, yielding optimal economy and low emissions, while still producing adequate power. A lower number indicates a richer condition. Best safe power on a naturally-aspirated, carbed engine (no power adders) is normally somewhere between 12.8:1 amd 13.2:1. You can make a little more power by going leaner, but leaner is hotter, and you risk catastrophic detonation.

The beauty of fuel injection is, you can tune for an A/F in the neighborhood of 13.5-13.7:1 at WOT, yet still maintain safe combustion, as the knock sensors instantly warn of detonation, and the computer can richen the mixture, and the injectors' response is much quicker than carbs' Same with part throttle. The knock sensors, throttle position sensors and injector's super-fast response allow part-throttle tuning almost at that optimal 14.7:1. That's the main reason fuel injected engines make more power, get better mileage, and pollute less.

Wideband tuning for carbs is adapting fuel injection technology to carbed vehicles. You can't reach the level of precision fuel injection offers, but, you can still make huge improvements over the old methods of jetting and tuning.