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TFI Box

Joined
May 29, 2008
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Ontario, Canada
Does anyone have the Dobek TFI Box installed? Any negative experiences with it? Do the "2 - 1.5 - 2 - 5" settings that Dobek recommends work well with the Bandit?

I have no problems with adding a TFI box, I'm a little concerned about the 02 bypass. I know in the past some people had all sorts of problems with them.
 
14,000 miles so far with my Dobek installed..... yeah, it works. Although if all a guy is gonna do is install a K&N and a slip-on can, a TFI is not mandatory. The bike runs juuuuust fine without remapping.
- however -
Once you start modifying the air box, removing the throttle plates, do the 02 bypass, and/or replace the header system, you simply gotta modify the fuel mixture as well.

Problems?
I don't quite understand it but..... on rare occasions, my red fuel injection idiot-light comes on. It seems to happen when I'm on the freeway cruising at a steady speed in the heat of a hot HOT day(??). I would say that in 14,000 miles, this has happened to me no more than 5 times. I simply pull over, turn the ignition off, start up the bike again, and ride off.

Dale Walker of Holeshot (on-line) offers a Dobek. If you pay more for your Dobek through Dale, you benefit from his hours and HOURS of testing on the Dyno, and the resulting settings that he has settled on.

------ If I had to do it all over again, I would do NOTHING more than replacing the OEM air filter with a K&N, drilling a 1" hole in the air box lid, and adding any after-market slip-on muffler. Of all the mufflers out there, I would lean toward a Holeshot 17" muffler, adding Dale's (removable) DB reducer for another $40....., gving me the option to make more noise or benefit(?) from less back pressure
 
they key is O2 bypass.
the O2 sensor allows the ECM to see what the mixture is doing and adjust (within a mechanical and electronic range) the fuel flow rates so minor modifications don't need a add on controller. older systems have fixed maps and can't adjust.
 
------ If I had to do it all over again, I would do NOTHING more than replacing the OEM air filter with a K&N, drilling a 1" hole in the air box lid, and adding any after-market slip-on muffler. Of all the mufflers out there, I would lean toward a Holeshot 17" muffler, adding Dale's (removable) DB reducer for another $40....., gving me the option to make more noise or benefit(?) from less back pressure

It's been a LONG winter, and I'm getting itchy to start doing some work on the ol' Bandit .
I'd like to add the TFI box to richen up the fueling a little. The performance improvement is a bonus but by no means necessary. As I said, the 02 bypass is my only concern.

I'm also not sold on the K&N filter. Years ago a couple of friends of mine used to race cars, and K&N filters were the norm; after a few runs on the dyno, they discovered that the K&Ns didn't offer any advantage whatsoever over the stock filter. I have heard many conflicting reports about after-market filters.
 
My feeling toward the K&N is.....
They are best after being clogged with particulate, cleaned & oiled, then left in place for thousands of miles.... allowing to get dirty to stop the really little particulate from getting into the intake. I'll inspect them for insect wings, leaves, and larger bits & pieces, but generally allow them to get to dirty. They work MUCH better dirty than even a brand new OEM air filter. (just an opinion mind you....)

- and -

It easily did something for my BMW R1150R with it's Supertrap can,

in my Bonneville, the combination of my K&N, "bell-mouth" intake, and jetting, the bike transformed into a pretty mean little 70 hp toy,

it made my Yamaha FZ1 run too lean (and poorly), even WITH an after-market free flowing muffler,

it seemed to give my Bandit 1250 more low-end grunt with my MIVV mufler, but the bike ran MUCH better if I left my muffler's (modified) DB killer in place,

they have worked in many of my cars, seemed to make NO difference in a couple of my cars, and the combination of a K&N & free-flow muffler in my Toyota Tacoma made for an annoying resonance in the cab that I lived with for no more than 6 months.... I couldn't stand it any longer, but the little four banger LOVED the combo!
 
Well, I think I'll try the TFI box with 02 bypass but leave the air box and air filter stock. We'll see if that resolves the lean-running engine problem.
I'm sure I'll have to play with the TFI settings quite a bit - I understand it's mostly trial-&-error as every bike is slightly different...
 
Pesto,
before you buy anything.I see you are from T.O.,Give Ryan Gill a call at Riders Choice.He has tuned some of the top Canadian superbikes and should be able to answer your questions.He tuned my race bike and it's now a very smooth monster:trust:
 
Pesto,
before you buy anything.I see you are from T.O.,Give Ryan Gill a call at Riders Choice.He has tuned some of the top Canadian superbikes and should be able to answer your questions.He tuned my race bike and it's now a very smooth monster:trust:

I'll eventually get rid of the catalytic and that's probably when I will get someone - such as the guy you suggest - do some final tuning; but for the time being I want something that will let me tinker with the fuel delivery. I just want to make sure the 02 bypass doesn't cause any problems... I heard of so many people getting FI errors on their Bandits because of the 02 being bypassed. Hopefully whatever is causing the FI light to come on is not causing any permanent damage.
 
Ive got my cat gutted, snorkel out of airbox, stock air filter, secondaries out and a scorpion slipon and my bike runs friggen awsome,no surging or overly lean spots in power band. Ive checked the plugs and they look great, bike gets lows 50s for mpg when out on the highway and really pulls better than stock across the rpm range. Ive put over 15k miles since making these changes and have had zero problems. With all the issues with the 02 bypass(crappy mileage,fi lights) Ill pass.
 
I have a TFI on board and used it initially to get around the initial snatchiness of the FI when you first open the throttle. It also helped smooth out the low speed surge that was probably caused by the throttles not being balanced properly. They are now!

I did some experimenting and found it really didn't need a lot on the pots to get the results I wanted AND it worked in conjunction with the O2 sensor still hooked up, so fuel burn didn't suffer.
I had about 1-1-0 and somewhere around 2.5Krpm cut-off set.

After balancing the TB's (need to know the IAP valve trick), I now have it turned off, but am considering adding a bit to the mid range.

Changing settings is easy - remove seat, remove rubber cover, use small screwdriver to adjust the pot you want and put it all back, less than 2 minutes and can be done on the road.
 
After balancing the TB's (need to know the IAP valve trick), I now have it turned off, but am considering adding a bit to the mid range.

So to shut the TFI off and keep it at factory settings without completely disconnecting the box all you have to do is set all the pots to zero?
 
Well, after an exhaustive trial and error on the TFI box, I finally have my bike running the way I want it - obviously I don't have access to a dyno to see if it's 'as good as it can be', but it feels real strong and smooth.
I modified the air box but kept the stock filter (I'm not a big fan of K&Ns), added the O2 bypass and have a Yosh slip-on.

Surprisingly enough I didn't have to add nearly as much fuel as originally suggested. The bike seems to run better with the lower settings.

I have a JIS screwdriver on order and will remove the secondaries once it comes in, which will probably force me to start all-over and readjust the settings. Anybody have any idea how much influence the secondaries have on the fuel settings?
 

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Sorry, I haven't been keeping up.
I have heard that taking out the secondaries has no effect on the A/F ratio, they just allow you to open the throttles instead of the computer deciding how much to open them if you give it full throttle.
And putting the pots to zero does turn off the TFI. I see your settings are quite low also. I too found it didn't need a lot to cover issues.

If you are having just off idle glitchiness and low speed surge issues, then I recommend balancing the thottle bodies. If you have done this before on a carbed bike, it is similar on the bandit, with an important difference. Have to pull a vacuum on the IAP valve.

Some pics and story here for guidance
 
If you are having just off idle glitchiness and low speed surge issues, then I recommend balancing the thottle bodies. If you have done this before on a carbed bike, it is similar on the bandit, with an important difference. Have to pull a vacuum on the IAP valve.

Some pics and story here for guidance

Thanks Rich.
Wow, that's quite a set up you created... very impressive! Unfortunately I don't think I have enough knowledge to tackle such an intricate task.

I removed my secondaries over the weekend; haven't had a chance to go for a ride yet, but hopefully it didn't affect the fueling all that much. If need be, I'll have to take the bike to 'the pros' to have the throttle bodies balanced; but if it runs as well as it did before, I'll leave it as it is...
 
I don't think removing the secondaries will effect the mixture... but it sure does effect the performance :rider:
 
Well, I removed the secondaries (had to drill out the little suckers!) and so far it doesn't look like I need to tweak the TFI settings. It runs smoothly with no hiccups or surges.
I don't know if I've gained much HP or torque, but the major power dip I had at about 7K RPM seems to be gone, and it sure runs a lot more smoothly throughout the whole RPM range.
 
Re: TFI box

Has anyone with a p/commander or TFI box, secondaries removed and modded airbox with K&N re -connected their bypassed 02 sensor and if so how did affect running and did you get better fuel economy whilst cruising.Fuel in the uk is now $8.26 gallon and forecast to hit $10 soon! As i understand it the 02 sensor only works up to around 4k (my commuting rpm) so should not affect top end and there is no surging issues with the secondaries removed. any thoughts on this ?
 
I'm running my TFI with the O2 sensor attached. In bypass mode it felt rougher, but not necessarily any more powerful. And I think there were some bangs during decel from speed. Fuel burn dropped to around 44mpg (US).
With the idle cutout at 2500rpm and O2 attached I get 47mpg regularly and it seems smoother cruising.
I don't think we realize how lucky we are in the states to have cheap fuel.
 
Okay, gotta ask.....

What does the first pot control, the second pot, third, and final fourth control???

I may want to mess around with my stuff; I know that it's running rich, but runs GOOD!

Just curious how I might set it for better (more economical) fuel mileage when commuting, then return it to Dale's settings when I wanna RIDE the hail out my bike....!
 
This is taken directly from the Dobeck website:

"GREEN FUEL POT - (functions like a fuel mixture screw on a carburetor) adjusts for the motorcycle's fuel requirement during light throttle operation from idling through highway cruising and steady throttle...

YELLOW FUEL POT - (accelerator pump feature) adds fuel on top of the green fuel pot setting whenever the throttle is opened rapidly. You should start with this pot at the same setting you found worked best on the green...

RED FUEL POT - (functions like a main jet on a carburetor). Adjusts top end fuel to maximize performance when air intake or internal engine modifications have been performed. Most manufacturers of current bikes get the top end fuel right and most settings will require no additional fuel to be added in this area unless modifications have been done.

RPM SWITCH POT - adjusts at what R.P.M. the green and yellow fuel addition stops, and the red fuel setting takes over. This adjustment can be achieved by either picking a R.P.M. that is 800-1000 above where you normally cruise at on the highway, or take redline, divide by 2 and add 1000 (i.e. 9000x.5+1000=5500). Each o'clock position of this pot equals 1000 R.P.M., so 5,500 rpm is half way between 5 and 6 o’clock... "
 
Re: TFI box

Has anyone with a p/commander or TFI box, secondaries removed and modded airbox with K&N re -connected their bypassed 02 sensor and if so how did affect running and did you get better fuel economy whilst cruising.

My understanding is that the 02-sensor's job is to keep the engine running as lean as possible to meet strict emission standards; if you add a TFI and keep the 02-sensor connected, it will keep on trying to make the engine run lean... which defeats the purpose of having a TFI to begin with.

With that said, there are a few people on this forum that have done some of the standard mods (air box, secondaries) without adding a TFI or bypassing the 02 sensor, and still had good results.

I do quite a bit of city/traffic commuting, so my main concern was the bike running too lean and getting too hot - especially after doing all the mods. To me the 02sensor removal is just peace of mind, and it definitely affected the way the bike runs and feels.
 
Thanks.... been awhile since I looked at 'em,
but I don't remember them as color coded(???).

Seems kinda complicated,
think I'll read this again after a couple cups of coffee.....
 
Thanks.... been awhile since I looked at 'em,
but I don't remember them as color coded(???).

The colors refer to the little lights above the adjustment screws. First one is green, second is yellow and third is red. The last one (on the right) I don't think has a light, but it's the screw that adjusts at what RPM the settings switch from green/yellow to red - set it at 5 and at 5000RMP the bike will start using the red setting, below 5 it will use the green/yellow.

The only light that stays on at idle is the green. If you crack the throttle open you'll see the yellow light go on, and if you rev the engine to where you have the last screw set, you'll see the green go off and the red go on....

Clear as mud, isn't it?
 
Hi Pesto boy/all ,
I suppose what i thought ( in my limited knowledge ) was that most surging issues were caused by the secondary butterfly's and that a power commander/TFI would add fuel in the lower rev range to help cover that up. Now as you said lot's have removed the butterfly's and some added a k&N with no fuel adder and are having good results, which would indicate the 02 sensor is managing to compensate. so i thought possibly removing the bypass would retain fuel economy up to 4k when i believe the 02 sensor stops working and a power commander/TFI would richen up the mixture from 4k onwards when not influenced by the 02 sensor. In theory giving good economy cruising and retaining power increases in the mid range and top end. ( i live in the north of the uk 19 - 22c max summer temps ). what i have just said may be a load of ******** :eek2: as i said my knowledge is limited.

Comments please
 
Hi Pesto boy/all ,
I suppose what i thought ( in my limited knowledge ) was that most surging issues were caused by the secondary butterfly's and that a power commander/TFI would add fuel in the lower rev range to help cover that up.

I don't think the secondaries have any effect on fuel economy. I would say they simply control how well the bike responds when you open and close the throttle; much more responsive and less lag.

... so i thought possibly removing the bypass would retain fuel economy up to 4k when i believe the 02 sensor stops working and a power commander/TFI would richen up the mixture from 4k onwards when not influenced by the 02 sensor. In theory giving good economy cruising and retaining power increases in the mid range and top end...

You are correct, apparently the 02 sensor is active at lower RPMs (below 4000 or something like that), which is where I spend most of my time while commuting.
One thing I can tell you is that once you get used to riding with the extra air/fuel and no secondaries, you'll most likely not want to go back to stock... much stronger and smoother, less of a power dip.

Overall I think people notice a loss in fuel economy because when you have better response and slightly more power, you would tend to use it... that's where the extra fuel goes. With that said, I haven't had much time yet to compare the before-and-after, so I'm not sure how my mods have affected fuel mileage. ALSO, I did all the mods at the same time (air box, TFI, O2 bypass and secondaries), so I am not sure which mod had the most impact... I figured while I'm at it, I might as well do it all!
 
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