Hayabusa powered Subaru Micro Van project

Ben Modified

Registered
Hi, I am new to the forum and am looking forward to learning a lot more about the Hayabusa engine etc. My project is a 1970 Subaru 360 Van. The previous owner chopped the top about 8 inches (a bit too much) but it still needs a lot of work to finish it. My donor bike was a running 2007 with 8,000 miles. The engine is mounted in the van and I am nearly ready to fire it up for the first time. I may need to fabricate a custom gas tank for it. My understanding is that I can use the pump from the stock tank, though I am not quite sure about the venting requirements. I had to extend the header tubes about 10 inches for clearance purposes and am using a stock Buell Lighting muffler just past the 2 into 1 transitions. I will be parking under my apartment building and will need to be able to drive in and out at all hours so I will need to have a way to keep the noise to a reasonable level. I also incorporated a variable exhaust dump valve for when I am out and about. Also, when the engine was in the bike frame, it smelled as if it was running rich. I would like to ask if anyone has a suggestion for tuning the stock ecu to correct the rich mixture and also a tune that will work with a bit more back pressure than stock. Thanks so much!
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Wow! Looks serious... how did you calculate the final drive ratio?
Busa wiring harness?
Beefed up clutch?
Can you tell us more about the mods and the problems you encountered?
With 8 inches off the roof height you’ll have your head out the sunroof lmao!!
 
Wow! Looks serious... how did you calculate the final drive ratio?
Busa wiring harness?
Beefed up clutch?
Can you tell us more about the mods and the problems you encountered?
With 8 inches off the roof height you’ll have your head out the sunroof lmao!!

I am using a jackshaft so that I can get the engine as low in the compartment as possible. I used stock gearing from the diff to the jackshaft and then increased rpm by 20% from the engine output to the jackshaft. This was an arbitrary number to compensate for additional weight without going too high on highway rpm. Easy enough to make changes to the ratio if needed.
Yes, busa harness, extended with mods for second headlight and wipers.
Stock clutch. I have used this engine in a 1400lb reverse trike before w/o any problems. The van will come in lighter by 100lbs or so.
So far, only a couple of problems to overcome. To run the chain downward, I had to space out the drive sprocket to clear the water pump and then support the arrangement with an outboard bearing. Currently, I am trying to squeeze a fuel tank in somewhere.
Although severe, the chopped top will work fine. I am using two Mazda minivan 2nd row bench seats mounted directly to the floor. I am 6' tall and have 4" of clearance over my head. I just had to keep the rollcage hoops out of the way.
 
I started connecting the wiring today. Does anyone have any idea what this pigtail might be for? One of the wires is tapped into an ecu existing wire. The others appear to be pinned into the ecu.... Thanks!
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Sorry for the short answer last night. Not walking too good right now because of a slipped disk but managed to get you some pics this am

This is the flash tool from BoostBySmith
EBD41B68-0C45-4F60-B340-EBD2066E3A01.jpeg


This is where it plugs into
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I have mine run in the tail area
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Plug together and follow instructions
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You will needs a computer with windows. Does not work with Mac. Connect the usb cable and use ecu editor. Easy peasy

...




Got pie?
 
Sorry for the short answer last night. Not walking too good right now because of a slipped disk but managed to get you some pics this am

This is the flash tool from BoostBySmith
View attachment 1608596

This is where it plugs into
View attachment 1608597

I have mine run in the tail area
View attachment 1608598

Plug together and follow instructions
View attachment 1608600

You will needs a computer with windows. Does not work with Mac. Connect the usb cable and use ecu editor. Easy peasy

...




Got pie?
Thanks! So are you thinking that the previous owner would have installed this?
 
The harness is usually owner installed. Some shops will I guess but I’ve not known of it as often. It’s easy to flash the ecu if you have the tools. That allows it to be done in place.
 
The Van is almost ready to run! I connected most of the electrical and tested out the lights etc. I have not re-installed the gas tank yet. Nothing happens when I press the start button. I took a look at the wiring diagram and it looks like one of the wires is routed thru the ecu. Does anyone know if having the wiring harness disconnected from the gas tank will prevent the starter from functioning? Also, I have one connector left unattached. Does anyone recognize this connection and know where it might go. I have already bypassed the kick stand switch. Thanks so much!
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The Van is almost ready to run! I connected most of the electrical and tested out the lights etc. I have not re-installed the gas tank yet. Nothing happens when I press the start button. I took a look at the wiring diagram and it looks like one of the wires is routed thru the ecu. Does anyone know if having the wiring harness disconnected from the gas tank will prevent the starter from functioning? Also, I have one connector left unattached. Does anyone recognize this connection and know where it might go. I have already bypassed the kick stand switch. Thanks so much!View attachment 1612819
I think someone had an issue awhile ago where a bad connection st the fuel pump was keeping his bike from starting but im not 100 percent on it.
 
The Van is almost ready to run! I connected most of the electrical and tested out the lights etc. I have not re-installed the gas tank yet. Nothing happens when I press the start button. I took a look at the wiring diagram and it looks like one of the wires is routed thru the ecu. Does anyone know if having the wiring harness disconnected from the gas tank will prevent the starter from functioning? Also, I have one connector left unattached. Does anyone recognize this connection and know where it might go. I have already bypassed the kick stand switch. Thanks so much!View attachment 1612819

It will still crank, but you’ll get an FI light for the fuel level sensor being disconnected.

There’s a few things that will keep it from cranking.
1. clutch not pulled in
2. Kickstand switch not closed
3. Fuse on the starter relay is blown
4. Tip over switch is tripped.

You cannot bypass the tip over switch by just jumping the wires together. There’s a resistor in it that sends a specific voltage to the ecu. If it sees more then that voltage it will not crank as it thinks the bike is on its side.

You can jumper the kickstand switch. You can jumper the clutch switch FOR TESTING PURPOSES ONLY. The ecu uses 2 different fuel and timing maps depending on if the clutch is in/starting or if it’s in gear.

How far away from Houston are you? I’d love to tune this thing. Very cool project.
 
It will still crank, but you’ll get an FI light for the fuel level sensor being disconnected.

There’s a few things that will keep it from cranking.
1. clutch not pulled in
2. Kickstand switch not closed
3. Fuse on the starter relay is blown
4. Tip over switch is tripped.

You cannot bypass the tip over switch by just jumping the wires together. There’s a resistor in it that sends a specific voltage to the ecu. If it sees more then that voltage it will not crank as it thinks the bike is on its side.

You can jumper the kickstand switch. You can jumper the clutch switch FOR TESTING PURPOSES ONLY. The ecu uses 2 different fuel and timing maps depending on if the clutch is in/starting or if it’s in gear.

How far away from Houston are you? I’d love to tune this thing. Very cool project.

Thanks so much for the information! Very far from Houston unfortunately..Georgia. Really good to know about the clutch switch. It is currently properly connected, but it had been acting up in the past and I had put a jumper wire in to bypass it. The exhaust smell made me think the bike was running really rich. I will try a jumper again just to see if it will start. Hopefully just needs a little work on the switch. The tip over switch is just resting on a flat surface for now. It is positioned with the arc facing down towards gravity. Items 1,2,3 are all good. I need to check on the black/white wire in the second photo. I will post what I find. Thanks!
 
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