My GPRXP build

[John's truck]

Took a small break from working on the ski to take care of the trailer, since it's gotta roll from CT to Louisiana this summer. Got some new rubber, ST145-12 radials. They're right between 4.80 and 5.30 in diameter, and they're 81 mph rated. Also, I've kinda been dreading working on the wiring harness in the storage unit while it's cold out. Storage unit doesn't have heat or even electricity/lights.

So my plan was to put new tires on the trailer and then pull the ski to work on do the wiring harness in the garage there. Well I finally realized something. Almost all of the splices I need to do are in the ÔÇ£AÔÇØ harness, the one with all the sensors and ignition coils. So I just went to the storage unit and pulled that one off the ski, and I'll take that harness to work and build the harness on the workbench first.

Then I'll bring the ski to work another day and pull the ÔÇ£BÔÇØ harness out since it needs the most work. I'm going to separate out the charging circuit in to its own harness since it doesn't need to connect to the ECU or fuse panel. I get that the stator and the VTS plug both go towards the back of the ski but they don't need to be wrapped in the same loom.



I'm really starting to lean towards de-pinning the SeaDoo connector and the Microsquirt AMP and just pinning the SeaDoo wires straight in to the MS amp if they're the same pins- there's no way I could get that lucky though.

[K447]

- new rubber, ST145-12 radials. They're right between 4.80 and 5.30 in diameter -

The wheel and tire fitment diameter would be 12 inches, I expect.

Those old-school tire numbers would be the width of the tire?

[John's truck]

The wheel and tire fitment diameter would be 12 inches, I expect.

Those old-school tire numbers would be the width of the tire?

Close, but not quite “The smaller 4.80-12 is 4.9 inches wide. The 5.30-12 is 5.6 inches wide”

They all fit on 12” by 4” wide rims though. 4.80-12 is a bias ply that’s 20.5” tall, st145/80-12 radial is 21.3” and 5.30 bias ply is 21.9”

[John's truck]

So I was sitting here wondering where power comes from for the ignition coils, since they're in the A harness which I just disconnected from the ECU. I didn't think their 12v+ power comes from the ECU. It's doesn't. It comes from this rectangle plug that crosses over from the A harness to the B harness (since that one contains the fuse panel). It carries 12v for ignition 1,2,3 and the cam angle sensor. Never knew what that one did until today.

[John's truck]

Well I finally did what I should have done a while ago, actually measured the injectors. I was wrong about the size of both the L96 injectors and the SeaDoo. I thought the SD were 60mm oring to oring, they're 65. I thought the L96 were 48, then I thought they were 46, measured at 45. So what I thought needed to be a 12mm spacer needs to be 20mm. My bad. So now the hunt is on. I'm probably going to grab some common 24mm spacer hats and then just put a washer between the intake manifold and fuel rail to correct the difference.

[John's truck]

Well I just ordered an 8 pack of the tall injector hats. I only need 3 but they weren’t really any cheaper if I bought 4 or 1. So 8 it is. These are the same height to turn Bosch 0289158040’s in to vt1100’s so I can always use the leftovers on one of the other skis. I might have a snow day tomorrow so I might make some progress on that wiring harness finally… we’ll see

[John's truck]

Started to un-wrap the wiring harness. The more black tape I take off, the more it's starting to make sense. I made it in to 3 connector groups. One is sensors I'm not using (oil pressure, exhaust temp), one is power and ground for coils and injectors, and one is sensors I am using (air temp, water temp, air pressure, cam sensor, crank sensor- might be it?). I also ordered a de-pinning tool kit so I can just pop the electrical contacts out of the SeaDoo connector and *fingers crossed* plug them straight in to the Audi ignition connector and Microsquirt connector. If that doesn't work, I have wire strippers and a crap ton of heat shrink solder joints. As far as oil pressure, the stock sensor is a single wire and the switch is open-close, it isn't a useable 0-5v pressure transducer. If I want to monitor oil pressure, fuel pressure, or anything else in the future, theres a few more remaining inputs and I can order an actual pressure sensor from Low Doller motorsports with a pigtail for like $35. That won't be hard to add in to the harness either. Just another splice to sensor ground and one of the color coded MS wires

[John's truck]

Well I remembered what the other 2 connectors are. TPS and IAC. I’ll be using TPS but not IAC, so that will get unwrapped and set aside. Idle will be controlled by timing.

Fun possibility that’s probably never going to happen. The FIDLE wire (normally PWM idle valve) can be repurposed for boost control for a turbo application. But I’m not a welder so that’s never going to happen.

[John's truck]

Injector hats showed up. These are the tall boys. They make the injector 73mm o-ring to o-ring which is a little ridiculous but it'll work. I made some 10mm spacers out of scrap to stand off the fuel rail. Then I stopped and got some nice nylon ones on the way home. As a bonus, I have 5 extra hats so I can put LS injectors or Bosch/VT1100's in one of the other skis in the future.

[John's truck]

And I’m starting to get the hang of this wiring harness. Once the depinning kit shows up, it’ll start moving pretty fast. But for now I’m taping up the sensors/connectors that don’t need any splices with that Tesa tape stuff. It’s WAY better than vinyl electrical tape. Not quite as nice as a fully heat shrink covered or wiring loom covered harness, but pretty close to factory

[John's truck]

Fancy spacers on the fuel rail and thermal paste on the Audi ignition

[John's truck]

Well I got some motivation and started de-pinning the SeaDoo connector and labeling wire numbers. I used a paper clip, and the pin kit I ordered got delivered afterwards. Oh well, I can use it for the Microsquirt pins. But I also realized that the SeaDoo, Audi, and Micro are all different. So the wires I took out of the SeaDoo wouldn't pin in to the Audi. So I just went ahead and spliced them, and taped up the harness.

[John's truck]

So here's the finished ignition and injector harness, just needs round pins put on the 3 injector grounds and 2 cam sensor wires to insert in to the Microsquirt ECU connector



heres all the sensor connectors. Most of them need to be spliced to a common ground and then pinned in to the ECU connector



and the growing pile of extra connectors. Oil pressure, exhaust temp, and IAC but more will end up here



closeup of the Microsquirt connector. I'll de-pin one of them and match it up to the round pin assortment and then try to pin as many SeaDoo wires in to the connector as I can, minimizing splices.

[John's truck]

Starting to remember things I knew last week. On the ignition harness, I only need to pin the Cam sensor wires in the the ECU. The 3 injector wires will be crimp spliced and waterproofed on the green common inj bank 1 wire, since I’m using batch fire. The Knock sensor isn’t being used so that one more connector I can pull out of the harness. The crank sensor is the twisted yellow and blue so it’s by itself. That’s really narrowing down the 4 sensors that actually share a ground to the ECU (CLT, IAT, MAP, TPS), making it much simpler.

[John's truck]

So I'm always taking 2 steps back to make a step forward. Or something like that. So I wanted to crimp pins on to the SeaDoo harness wires and stick them right in the MS connector. I couldn't find crimp on pins unless I bought a whole new ampseal 35 connector with crimps. Well- I got to thinking. There's 22 wires I'm using and 12 wires I'm not using in the Microsquirt harness. If I buy a virgin connector, I can swap over just the wires I need. Once you pull a wire out of an amp seal connector you're left with a hole. So I might as well just start with a virgin connector and build a smaller 22 wire harness. I probably should have just bought one of these to begin with. If anyone else is considering adding Microsquirt to a small engine, this is what I would suggest doing.



The wiring harness I got with the micro is a really nice piece but this is the list of wires I have no use for and can strip out of the harness. If I want to do some crazy turbo boost control stuff in the future I can always just add FIDLE back in to the amp seal with a push. But I won't. I promise