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Another DR Fuel Injection project.... 1993 DR250SE

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After pouring over numerous EFI threads, and digesting the information, I am hooked on the prospect of EFI. Its contagious I guess. Much thanks to the FI pioneers here, Wild West Sidney, Capt Midnight, Msiddalingaiah and mx_rob.

I am going to Fuel Inject my 1993 DR250SE. Its a clean 9,800mi Las Vegas bike, that showed little abuse, but suffered a failed petcock and needed an engine overhaul and new(used) head. With LOTS of help from Jesse at Keintech, I got the motor completely rebuilt, with all the upgrades, etc. It thankfully runs like a top now, and I have a pumper and BST carb for it. Unfortunately, neither carb seems willing to offer both good economy and throttle response. That, along with my incessant need to tinker, led me to the decision to try my hand at FI on the bike. I have fuel injected Land Cruisers in the past, so I am not entirely new to this, but theres more than just a subtle difference between using all GM components, ECM and burning a new PROM when it comes to Microsquirt...

Hopefully, this will end as a success and help folks teetering on the edge to jump in and make the plunge. I can design the hard parts and figure a way to make them whether it’s a bunch of hours cursing at the lathe, or begging a friend to cut them on a CNC, but I am pretty much at the mercy of learning the hard way on the lathe and mill and have ruined more parts than I have successfully made so my average isn’t good. Down right bad infact. What I will show here is well past the begining of the learning curve, but is still not pretty or well machined.

The electrons are a touch more slippery for me, and while I can probably do a fine job wiring up a harness and working with the software involved, I know very little about what makes a transistor work and how to keep from letting the smoke out of certain things on the green PCB.

Keep in mind, I suffer from Analysis Paralysis and maybe OCD. You can be the judge... Despite some crucial advice about "just make it work" I tend to spend lots of time on little details.

With that being said, lets get started:

Any EFI project needs a few things for sure: ECM, Fuel Pump, Throttle body, Sensors and Wiring.

FRONT PAGE RUNNING TALLY:

(I am only going to tally the stuff I use on the bike, so others can get a feel for a cost. Manhours not included...)

Microsquirt V3: $339(still need to order)

Throttle body(TRX420 Honda): $70

TRX wiring harness(TRX680): $30

Fuel Pump(TRX700): $76

Innovate LM-2 WBO2: $220

Misc Sensors and Relays: $40 so far

Misc Wiring Supplies: $35

Edited by brettgarland

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Throttle Body:

I needed a throttle body. After reading a number of threads, throttle body selection seems to present a number of issues. Certainly many can be made to work, but I really wanted to find something that would work pretty much from the donor vehicle.

I knew the Trigger wheel for this setup was going to undoubtedly be the time and energy suck that would sap my willingness to continue, so I really wanted to find a TB that was nearly as direct a fit as possible, and allow me to focus energy elsewhere.

Something that looks like it will work is a tedious search process on ebay… really tedious. Hours upon hours of Mikuni and Keihin throttle bodies, Suzuki’s, Yamaha’s, snow mobiles, etc. I finally find a family of Keihin throttle bodies in Honda products that look like they will workout in terms of single bore, throttle cable, etc. After searching for hours on google and ebay, I figure the best donor is a TRX420. It’s a 34mm bore, looks like it will fit. Off to ebay, and $70 later I have one heading my way.(Don’t be shy about the “Best Offer” deal with ebay). Intake manifold will need a bit of massaging with a sanding drum on a dremel to port match, but nothing show stopping… TM33 pumper carb throttle cable fits perfectly if you use the in cable slack adjuster. It pulls from closed to open in less grip rotation than the BST. I am using the BST throttle tube with the pumper carb cable. It has MAP/TPS and IAC onboard. Despite having what appears to be an IAT probe in the bore, it does not have the thermister installed, and consequently doesn’t work.

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Details:

-Fits BST intake manifold. Its about 2mm bigger(44mm) than the BST bell OD, but does fit. Its got an off center bore much like the LTA throttle body mxrob had... So it will take a bit with a dremel and sanding drum to get the port matching dialed in but...beggars cant be choosers.

-4mm smaller OD(46mm) on aircleaner air boot side than TM33, so a good hose clamp will take care of that if you want to source a TM33 aircleaner airboot. I am working on getting an adapter machined for the BST air boot which is significantly bigger. Already got the design and CAD stuff done. Need to find a CNC shop to build a few. This will also help smooth out the blunt end of the throttlebody air flow wise, so likely a better option.

-TM33 Throttle cable(pull only) fits fine. Need to use the in cable slack adjuster(I hadnt in the above pic so in reality there wont be excessive slack as pictured), but it works just fine and opens the throttle body from closed to open in less rotation than the BST carb. The cable orientation is so good that I wanna think someone designed it to be swapped into a motorcycle.

-Has TPS, MAP, IAC, and Injector.

-Length is nearly identical to the BST carb at 98mm.

-As you can see the fit in the frame is easy and other than the IAC plug being near the wiring harness(Slight reroute of harness will immediately alleviate this issue), its made for the DR350.

-No funky fuel rail or other dangling bits.

-34mm bore. Not as large as I would have liked but should be fine for a mild 350, or the dr250 I am using it on.

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Keep in mind, I suffer from Analysis Paralysis and maybe OCD. You can be the judge... Despite some crucial advice about "just make it work" I tend to spend lots of time on little details.

:busted: If you start a support group, I will be the second to join :busted:

I thought I would never finish it, but after taking it one step at a time, it got done.

Do you have an idea of the injector flow rate?

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Short of taking in to get cleaned(been too busy to drive to the shop to drop off), I havent got any way to test it... would be nice to have something to control the injector. Ive got a second trx pump, graduated cylinder and a watch.

Could one make something with a 555 timer and a transistor? I just dont have a scope to set the pulse width.

Its a bit shorter than the orange one you have, but appears to be the same size as the 07 and newer CBR600RR injectors, and those are 199cc/min for the primary(orange) and 205cc/min for the airbox ones(gray), so if mine is too big(likely due to the 420CC engine compared to my 250CC engine, I might scoop a few of those up. Those are closer.

Some online calcuator said I needed something in the range of 135-150cc/min, but I have no idea how to find any info on motorcycle injectors.

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Short of taking in to get cleaned(been too busy to drive to the shop to drop off), I havent got any way to test it... would be nice to have something to control the injector. Ive got a second trx pump, graduated cylinder and a watch.

That's really all you need. Just hook up the injector to 12V through a switch. Turn it on for 1 min and measure how much fuel comes out.

Could one make something with a 555 timer and a transistor?

Yes. I've been meaning to measure flow rate as a function of pulse width. It does not appear to be linear at all. As far as I can tell, for my injector, pulse widths around 4.5 ms deliver twice as much fuel as I would expect. Others have observed something similar on msefi.

Some online calcuator said I needed something in the range of 135-150cc/min, but I have no idea how to find any info on motorcycle injectors.

There's a link on msefi that has a data on a bunch of TBs and injectors. I'll see if I can find it.

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Fuel Pump:

This was the start of the project for me. I spent some money here to test and figure out what would work, both with regards to size and power consumption.

I started with a Honda CBR600RR pump. I dissected it, and took out the Denso 291000 pump inside. The trouble with this pump is the fact that the check valve is not part of the pump. Bummer, so I forged ahead, wasted some time on the lathe and made an adapter to insert into the pump, hold the check valve and the regulator. After all that trouble the pump draws nearly 4.2 Amps at 50psi. Ouch. Couple that with the fact that my design for the check valve seat prevented it from seating most every time the pump was shut off led me to abandon that project for now. I will revisit it later for another project I am sure… Likely a Toyota Land Cruiser FJ40 Fuel Injection project that has been on the back burner for a while. Cost: $30 for pump, and lots of lathe time.

Next up was the LTR450 pump. I had an idea that this would be a good candidate for the swap because of the power draw and the fairly compact package. It draws about 1.55A at 50psi, so its right in the ballpark. Downside is it’s just not that small, and on an electric start DR350/250, there isn’t the room required to mount it in a fashion that would be relatively safe off road. (I tend to crash a lot, so hanging outside the frame or in the rear wheel well isn’t going to work for long. I’ll keep it for a bigger chassis, maybe a XR600 I would love to buy and fuel inject. $80 down.

Last up: TRX Honda 420/680/700 Series ATV pump. This little guy is not little. Even less room to mount in the chassis, as you can tell in the pictures. But, it has the same Type “S” Keihin pump in it that the LTR450 pump does, and while the can is large, the guts are what’s important. It’s got a check valve built into the pump body, not the housing, and a 50psi regulator and draws slightly more power at 1.78Amps. Both parts are easily removed from the can, and will be used in my fuel system… $50 down.

You can see comparisons of the LTR and TRX pumps here and here

Now, heres where I deviated from previous fuel injection projects. I wanted something compact, and unobtrusive as far as pump mounting goes. I’ve never built a ship in a bottle before, but I now know exactly how much patience one must have... I am 90% done with the bracket and parts to mount the fuel pump INSIDE my Clarke 4.2 gallon tank. There is a bit of a leap of faith, since I had to drill the tank for the fuel exit, and mounting bracket studs. Thankfully it does not leak, and the CBR600RR pump housing donated the electrical bulkhead connector that allows me to run the wiring into the tank.

I made a bracket(.065" wall 4130 1.5" OD tube) and an arm(1/8" x 1.25" flat stock about 10" long) to mount into the tank to hold the pump and regulator from the TRX pump assembly. The bracket holds the regulator, and has a outlet for a 1/4" fuel line to be hose clamped on. A hose clamp holds the stock TRX pump and filter sock in the bracket. The fuel fittings to pass through the tank are not completed or pictured, because I havent finished them... The bracket bolts through the tank on the opposite side of the petcock fitting. I had to drill three holes, but since clark is gracious enough to make the tank uniform in thickness there(just over 3/16") and they sell extra petcock rubber gaskets, getting it to seal shouldnt be a problem.

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It takes a few correctly ordered steps to insert the assembly in pieces, and then assemble, but frankly, while it looks hard it takes about 5 mins to get the pump in or out.

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As mentioned earlier, I needed to have a bulkhead fitting for the fuel outlet, and another for the wiring. I chose to use the petcock mount to pass the wiring through, and was originally going to use a plate and tube, and jb weld the wires through it, hoping for a good seal. Just as I was about to toss the remainder of the CBR600RR pump housing out, I looked at the wiring connector, and with a lot of carving away plastic, I ended up with a bulkhead wiring fitting that works perfect, and doesnt leak a drop. It takes a regular petcock gasket, and had a connector on either side. So I bought some PTFE(teflon) insulated wire and will run wire from the left wing of the tank over the center hump down to the pump. Should work in theory...

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Lastly, since I wanted easy to remove fuel lines, I opted to retain the pushlock fittings. Luckily, I have a really nice Mastercool flaring tool that does all sorts of stuff, including, inverted flaring for my Land Cruiser addiction, but it also does push lock flares. So, I try the 1/4" and flare a piece of .250" OD .035 Wall steel tube I had, and it makes a PERFECT flare to retain the OEM honda pushlock fittings(the short steel tube with the bump in it). The bump retains the green lock fitting shown. There is one piece missing from the pic, but its going to be a round stock 90 fitting to make the outlet parallel to the ground. Will post pics when I make it.

DSC00381.jpg

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Forgot one pic:

This is a crude drawing on the outside of the tank showing where the bracket and pump are hanging. The pump filter sock sits about 1/2" above the bottom of the tank.

DSC00382.jpg

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Impressive, most impressive. I'm tempted to consider an in-tank pump myself. I have a plastic tank from a DR350 dirt model that might be big enough to fit a pump.

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Sorry for the delay, was in Baja for the Baja 1000, pitting for my friends Class 10 buggy. Alot of fun! If you like offroad stuff, it should be on your bucket list to at least watch/pit the race.

DSC00391.jpg

Anyway, back to the regularly scheduled program: Fuel Pump... Here are some final shots of the pump mounted inside the tank, and the other details, like the bulkhead fittings for the wiring and the fuel exit...

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Edited by brettgarland

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Hello!

As you have done som research for throttlebodys, i guess the trx700 has the same functions as your smaller throttlebody or am i wrong? As i can see from my research it has idle control valve, map, iat sensor and tps. Seems like a very nice fit for a xr650r instead of other bigger throttlebodys with adaptor-plates needed?

But i guess this type will need an additional fuel pressure regulator? or is this also built in.. hmm?

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Geaux: thanks! it was a painful, time consuming process, but worth it. Gonna hook it up and test the injector fuel flow rate this weekend.

martin t: As far as I can tell, the TRX420/680/700 are functionally the same. Bore size is the difference. I bought a trx680 one for cheap, and its 40mm. I think the trx700 one is 44mm?

As far as the EFI project is concerned, I have been behind schedule. Trying to source connectors/crimp terminals is not easy.

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I used Molex connectors, which are widely available. They make literally thousands of varieties, so it's a challenge to narrow it down. I used .062" (1.57mm) types, both two pin and four pin types.

Here are the part numbers from Jameco.com:

Four pin housing:

224434

224514

Two pin housing:

224485

229956

Connectot pins:

224557

224565

Jameco has stranded CAT-5 cable also, the part number is 645749.

I was really looking forward to fitting the pump in my tank the same way you did. Unfortunately the GSX-R pumps I have are 1.5" OD, which just don't fit in the opening for stock tanks. I tried both the street and and dirt model plastic tank. It looks like your pump is about the same size, so unless I cough up the money for a Clarke tank, I'll have to run external. :bonk:

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msiddalingaiah:

The TRX Keihin pump is substantially smaller. I will post a pic of that compared to the 1.5" CBR pump. MUCH easier to snake into the filler neck.

Thank you very much for the information regarding the connectors. Will be looking into it!

As far as connectors holding me up are concerned, I am working with a sumitomo distributor to figure out what each of the TRX throttle body connectors part numbers are(two on the ebay harness I bought were damaged :bonk:. Also gonna use the sealed TRX fuse block, so I needed to order the correct crimp terminals for it.

Found a good waterproof twin 15 amp relay as well, and its got a specific sumitomo connector as well, which happens to be the same as a Honda WBO2sensor. so had to order that as well.

Tomorrow project is gonna be testing the intank pump, and flow testing the injector. I have two TRX420 throttle bodies, so I will get a good avg flow rate I hope.

On a side note, this regulator runs at 50psi. Is the standard flow rate for MS Tuner at the normal 43psi?

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msiddalingaiah:

The TRX Keihin pump is substantially smaller. I will post a pic of that compared to the 1.5" CBR pump. MUCH easier to snake into the filler neck.

Yeah!! :bonk:

On a side note, this regulator runs at 50psi. Is the standard flow rate for MS Tuner at the normal 43psi?

MS Tuner? Do you mean TunerStudio?? They really don't care about pressure, only injector flow rate. Measure the injector flow rate at whatever pressure you plan to use and you'll be OK.

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airboot.jpg

I have been slacking a bit, but finally got some motivation to get after knocking out some parts I was dreading making. A friend owns a CNC shop, so I decided to draft the throttle body air boot adapter and the trigger wheel in CAD and just get them cut out. While the air boot adapter wouldnt be too hard on a lathe, the trigger wheel requires alot of lathe and mill time, and the prospect of a dividing head is very time consuming, based on the confines I decided to box myself in with.

For the trigger wheel, I wanted to use one of the two stock VR sensors, since they seem to be pretty reliable, and I can leave the second one in there, and have a "spare" with a bit of swapping locations. Redundancy, I guess.

Furthermore, there is not an easy way to machine and install a true toothed wheel on the DR350 flywheel that would allow for a completely "under the cover" installation. Combine that with the fact that the flywheel is not true dimensionally in its outside diameter, means chucking it on a mandrel and turning it down to accept a std toothed wheel would compound the nearly .015" variation in OD, resulting in significant balance issues. So, I devised this trigger wheel, that will be about 2mm thickness, and once I grind down the short stock tooth on the wheel, will press onto the wheel. It should just clear the VR sensor pickup, and with a bit of honing, fit any DR flywheel.

If anyone out there is reading this and happens to have a flywheel handy, measure the OD of it, and let me know. I am planning on making the ID 5.120" which is about avg for mine, but I can trim the dims if needed to it might fit others... Planning on making a few of them, since the programming, not material is the real cost of this simple a part. My flywheel ranges from 5.127" to 5.110" in diameter, and its not a simple oval shape.

Some of you out there might wonder what happens to the weight removed with deleting the stock bump. I calculated the volume of material, and will drill balance holes on the wider edge of the ring, opposite the original bump.

Of course the OD of the ring will change with the OD of the flywheel its pressed onto, but I hope I will still get a decently smooth signal with regards to the peaks it produces as the VR sensor detects the "teeth"

triggerwheel2.jpg

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Dusting off the project... sorry for the long delay!

Got the V3 Microsquirt in hand(sad that they call that waterproof!) and some BIP373 drivers for ignition coils...

Installed sensors: Baro, Inlet Air Temp, and Coolant(cylinder head).

Been working on mocking up some wiring and utilizing some fancy splice connectors found in Honda TRX harnesses. These will allow me to easily access certain ciruits with a scope to troubleshoot.

No pics for now, but next week I will be back in town and punch ahead on it...

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