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pdfruth's DIY Exhaust Servo Replacement Module (ESRM)

227K views 898 replies 309 participants last post by  PuffTheMagic  
#1 · (Edited)
Several of you have been asking for a solution that allows the exhaust servo to be removed/discarded. Not so much for the weight reduction, but for the space savings.

Well, here ya go...
I took up the project a couple days ago, after having a look at the signals involved, with my trusty old-school o-scope. Turns out the signals between the ECM and the servo are somewhat more involved than one might imagine. While it's not exactly straight forward, it turned out to be a fairly simple task. I decided to use an inexpensive PIC microcontroller (a single chip computer). With space savings the primary objective, I went for a small footprint package, and used an 8-pin PIC12F683.

For those that are interested in making their own, and have the materials & ability, I've attached;
- A schematic for the circuit
- The PIC micro assembler language source code
- A couple pictures of my assembled prototype (to give you an idea what's possible)

I just finished a fairly thorough series of tests (on the tread mill in my garage). Although I have yet to do some real-world tests, out on the track (darn snow), I'm confident the design is solid.

The finished circuit could be made much smaller (maybe %50) by using SMT components, and a custom PCB. But, I think this is "small" enough.

There are those who will wonder "What is the benefit of this mod"?... Simply put - space savings. For those building track-only bikes, and are cramped for space, this is the ticket.
I can foresee no reason that there will be any performance improvement. For the normal street rider, this would be a waste of time (unless you need the space of course).

This was designed specifically for the 2008 - 2010 CBR1000RR. It may work on other models & years, but I haven't tested it. The design is general enough that it should work on other bikes, tho. If you test it on other makes/models/years, and find it works, let me know. Or, if you find the design needs to be altered to accommodate others, let me know that too.

Note: The source code provided here is licensed under the GPL. Use it as you will. I expect anyone that produces replicas based on this code (or derivatives there-of), either commercially or otherwise, to provide a copy of the source code (or access to it) and a copy of the schematic, to anyone they supply it to.

Edit 12/22/2009: Currently researching the feasibility of making a bunch of these. See post #24 below.

Edit 12/27/2009: I believe I've located a source for the OEM connector for the 2008-2010, as well as the older 2004-2007 models, thus making it possible to build a plug&play solution. Also in the process of locating someone locally, with an 04-07, to do some tests (it should work as-is, just need to do some sanity checks).
 

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#2 · (Edited)
Not a plug-n-play solution

Probably the biggest road-block to making this a plug-n-play solution, is the 6-pin connector that Honda used for the servo sub-harness. To-date, I'm not aware of a source for the connector.

So, I used the connector from the original/factory servo. Just take the servo apart, unsolder the wires, and then use the factory sub-harness & connector.

I'll attach pics, showing the steps;

Step 1 - Remove the screws, holding the back cover on.
Step 2 - De-solder the 5 wires
Step 3 - Solder the factory sub-harness to the Exhaust Servo Replacement Module (ESRM)
 

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#11 ·
I gotta be honest to ya, awesome job!

I wish i had some semblance of knowhow when it came to making this stuff, but I would be willing to pay you to make me one. I would be able to make a nice little housing for it and would most likely forego the connector and trace the wires as close to the source as possible and splice them there to get rid of the extra wiring.

Once again kudos to you for solving this issue, if they had some kind of award for general ingenuity for forum members you would be my pick.
 
#13 ·
nicely done. PICs are a hobby of mine.. its good to see nicely commented code, pics, everything. looking at your solution, im fairly confident that it will work for the other honda bikes as well...

now theres only one step further i wanted to do.. thats cast a urethane mold of the OEM plug, so you can replace the plug/socket with a resin one that encapsulates the PIC circuit.
with that done, you would have a plug in solution that you could easily sell.
 
#15 ·
now theres only one step further i wanted to do.. thats cast a urethane mold of the OEM plug, so you can replace the plug/socket with a resin one that encapsulates the PIC circuit.
with that done, you would have a plug in solution that you could easily sell.
If someone comes up with that put me on the interested buyer list. Although I can solder a circuit board I do not have any way to program the chip.
 
#16 ·
I had to take one programming class to graduate and that was enough for me to learn one thing:I can't program. I admire anyone who has the ability to write a program let alone something like this.

Two questions:
Can you suggest a good program (free would be nice) to burn the program to the PIC?
Is there such thing as a plug and play device that will allow me to transfer the code from my computer to the PIC?

As others have said, great work!
 
#24 ·
Would you buy one of these for $15

Ok... the "Will you sell me one" queries continue to come in.

So... I spent some time working up a custom PCB today. Using SMT parts I can get the size of the whole circuit down to about 0.7 x 0.6 (inches). Slightly smaller than the prototype pictured in my opening post.
I checked with my favorite board-house (ExpressPCB). Using their miniboard service, I can get 60 boards made (to meet their minimum order size) for just over a $1 ea.
A quick check on prices for the rest of the parts... it looks like I could make 60 of these things for a couple hundred bucks.

Would y'all be willing to pay $15 each for one of these things (taking into account it's not plug & play, and it would still need to be soldered into your harness)? Anything less than that, and it's a waste of my time. The parts aren't a big deal. But it is labor intensive. I don't want to spend the money, and a bunch of time, if they aren't gonna sell. Considering there's others out there, who may also be building these, there may be competition. Not to mention the commercial vendors, who may be coming out with a plug-n-play solution in the near future.
 
#26 ·
Ok... the "Will you sell me one" queries continue to come in.

So... I spent some time working up a custom PCB today. Using SMT parts I can get the size of the whole circuit down to about 0.7 x 0.6 (inches). Slightly smaller than the prototype pictured in my opening post.
I checked with my favorite board-house (ExpressPCB). Using their miniboard service, I can get 60 boards made (to meet their minimum order size) for just over a $1 ea.
A quick check on prices for the rest of the parts... it looks like I could make 60 of these things for a couple hundred bucks.

Would y'all be willing to pay $15 each for one of these things (taking into account it's not plug & play, and it would still need to be soldered into your harness)? Anything less than that, and it's a waste of my time. The parts aren't a big deal. But it is labor intensive. I don't want to spend the money, and a bunch of time, if they aren't gonna sell. Considering there's others out there, who may also be building these, there may be competition. Not to mention the commercial vendors, who may be coming out with a plug-n-play solution in the near future.
I think that is a great price and you would be able to sell quite a few.