Guhl Motors ECU Reflash Donor Bike

[jasonc32amg]

From what I can see it doesn't look to be worth the effort unless you get a full exhaust.

[tbanzer]

Does anyone know if there are different fuel or ignition timing curves for the different gears. As I brought up before I have a low rpm stutter in 1st - 4th gear but not in 5th or 6th.

[lt1]

It is my understanding that there are separate, programmable ignition and fuel maps for each gear.  I have heard contradictory reports as to whether the maps are different from the factory. 

[Armyguns]

The attached dyno chart from TODAY might change a few minds about the validity and worth of the Guhl reflash. 

I dropped by Don's on my way back from ARC 2.  He had a short time available between customers and we got my bike back on the dyno.  He reflashed my ECU back to factory stock and we did a dyno run, but this time it was in 4th gear.  Recall that last time all pulls were done in 5th, which really didn't show what I KNEW was going on by my seat of the pants.  The stock run is the blue line.  He then reflashed the ECU back to what he originally installed on June 10th.  That is the red line on the chart.  THIS chart clearly shows what my ass has been telling me- this bike pulls MUCH HARDER than stock.  About a 10ft/lb gain at 3K RPM, plus 6 HP at that RPM.  Those differences gradually decrease as RPM increases, but the reflash is always higher than stock.

It would have been nice to do 1st, 2nd and 3rd gear pulls, but his time was limited today.  I have no question that the difference between stock and reflash will be just as dramatic in the lower gears.  I've been saying all along that the bike isn't any faster, but it is quicker with more grunt. 

I now have 1700 miles on the bike with his reflash.  It is absolutely SOLID.  I have not experienced a single negative aspect.

I hope this latest information helps to make an informed decision. 

[mikeboileau]

Does this flash address the flies?

[Armyguns]

Does this flash address the flies?

I'm not exactly sure what you mean by 'address the flies'.  This mod, as described within this thread leans out the fuel to varying degrees based on RPM (described within the thread) and opens the flies sooner (also described).   We believe (or at least I believe) it is an alternative to pulling the flies out.  Pulling the ECU has to be a lot easier to do than pulling the flies.  The map that has been developed is applicable to a stock bike- no aftermarket exhaust or air filter.  It would certainly work with aftermarket mods, but it is highly recommended to have a map developed on a dyno with those mods in place to insure that the correct air/fuel ratios are maintained.  To the best of my knowledge this is the first time we have data showing before and after performance in a side-by-side way. The fifth gear pulls were done on the same day and within 30 minutes of each other.  The fourth gear pulls, while done on a different day, were done within 20 minutes of each other.  You will see that the peak numbers differ between the data collected on June 10 and that of today.  This is easily accounted for by taking into consideration the variables we could not control- air temp and humidity, engine temp, and the fact that I got a new tire installed three days ago

I hope this helps.

[stewart]

The attached dyno chart from TODAY might change a few minds about the validity and worth of the Guhl reflash. 

Perfect this is just what I needed to see, now I just need to find some time between weekends to send the ECU in.

[Armyguns]

Perfect this is just what I needed to see, now I just need to find some time between weekends to send the ECU in.

Ride it down there on a Sunday, spend the night, get it reflashed on Monday and head home enjoying the added torque! 

[stewart]

Ride it down there on a Sunday, spend the night, get it reflashed on Monday and head home enjoying the added torque!

If only I could, nope I'll pull in a few weeks before I leave on travel for a few weeks.

[cablebandit]

We believe (or at least I believe) it is an alternative to pulling the flies out.  Pulling the ECU has to be a lot easier to do than pulling the flies.

So less than 10 minutes and twisting 8 screws that are easy to access is now difficult?     Just kidding.  It's nice to see a dyno run finally.

I still have to think that the gains you see on the low end are mainly from the flies being open early on. 

[Armyguns]

I still have to think that the gains you see on the low end are mainly from the flies being open early on.
[/quote]

Remember that the fuel was leaned out 5% across the board and more intensive leaning between 3-4K RPM and above 8K RPM based on feedback from the broadband O2 sensor. 

[Mister Tee]

Personally, I think that if you can lean out the fuel map 5% across the board and retain the original performance, much less increase it, you're way ahead.  Mileage will improve, and your engine will run cleaner.

[DocPigskin]

If I was thinking of doing a full aftermarket exhaust and the ECU reflash so would I install the new exhaust and then ship off the ECU to be reflashed?   I always thought that if I do a full aftermarket exhaust, that I would have to retune the bike in which case I would image the ECU would have to be reflashed again wouldn't it?

[Mister Tee]

If I was thinking of doing a full aftermarket exhaust and the ECU reflash so would I install the new exhaust and then ship off the ECU to be reflashed?   I always thought that if I do a full aftermarket exhaust, that I would have to retune the bike in which case I would image the ECU would have to be reflashed again wouldn't it?

Your bike isn't being "tuned" if you send the ECU in for a reflash.  It's being loaded with a map developed for that combination.  So you would install your exhaust, send in your ECU and ask for a map appropriate for your full exhaust system.

[DocPigskin]

Your bike isn't being "tuned" if you send the ECU in for a reflash.  It's being loaded with a map developed for that combination.  So you would install your exhaust, send in your ECU and ask for a map appropriate for your full exhaust system.

Thanks.

[mikeboileau]

We need to be able to update our maps as needed.  When we can do that, this reflash deal will be a huge success.

[Kazairl]

A handheld programmer like what is available for my truck would be wicked. Set it up so you can plug it into a computer and download new tunes that the tuner can send you through email. That would be cool.

 I don't know how easily flashed the ECU is however. A handheld flasher may not be practicle.

[Mister Tee]

A handheld programmer like what is available for my truck would be wicked. Set it up so you can plug it into a computer and download new tunes that the tuner can send you through email. That would be cool.

 I don't know how easily flashed the ECU is however. A handheld flasher may not be practicle.

The way to accomplish that is with a Power Commander via a laptop PC.  But, an ECU reflash does have one advantage a PC does not - you can change the timing curve.

[lt1]

FYI, Guhl is working on a USB/laptop/motorcycle programming interface, but it is still down the road a bit.  I'll be sending my ECU in for a reflash in a few weeks.

[DocPigskin]

Does anyone have the contact info for Guhl motors off hand?