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XR1800 4-Stroke MR1 Swap

Robb235

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Got the flat steel rails that I’m using for motor mounts drilled last week, and test fit them over the weekend. I’ve also attached the sketch I drew up for the rails.
You can see in the picture where I cut up the engine bay somewhat so that these MR1 motors will fit. I need to fiberglass that back in, but the temperature has been too chilly lately.


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Robb235

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Got some goodies from Amazon last week.
Epoxy paint for the steel motor mount rails. That Top Side boat paint scratches too easily. My wife used it to paint the bathroom wall tiles in our master bathroom from the 1950’s blue to a nice glossy white color.
Also got the epoxy resin to fiberglass in the holes I had to make in the engine bay. And the gel coat once the fiberglass is complete. Just need the weather to warm up a bit.
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Robb235

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I’ve done a poor job of taking pictures and posting progress.

I have fiberglassed in the port side engine bay and gel coated, so now the motor will physically fit in there. I’ve drilled, tapped, and painted the steel rails that the motor mounts will attach to. And last night I dropped the port motor into place in the engine bay. I have not hooked up any cooling, electrical, fuel, throttle linkage, exhaust, etc.

Don’t judge the yellow layer on everything. It was literally raining pollen yesterday.
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Robb235

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Where can I find some high pressure hose to lengthen the piece that feeds cooling water from the jet pump to the coolant inlet on the motor? What pressure does it need to be rated for? Either #1 or #11 in the picture.
 

Attachments

UnorthodoxCreations

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I went through this on one of my cars recently. You should be able to get hose at AutoZone or similar part of stores, just make sure it's rated for fuel injection.

"High-pressure fuel hose for clamp-type fuel-injection systems is also available. This fuel hose is SAE 30R9-rated and uses a fluoro elastomer inner liner that will withstand up to 180 psi and 300 degrees. It is approved for all fuel blends including straight methanol, and the outer coating is also ozone- and abrasion-resistant. High-pressure fuel-injection hose can also be used in low-pressure applications, but the difference in pricing may convince you to save it for where it is needed."

 

WREKS

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@Robb235 I would remove the fitting and clamp and match with whatever auto or marine parts can offer. Being once-through cooling there should be little pressure buildup.
 

Robb235

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Ok, I was thinking the inlet saw quite a bit of pressure since it was coming off the jet pump. Anyone happen to know the inner diameter of this hose? I’m out of town all this week, was hoping I could order online and have it when I got home. Was thinking it was 1/2” or 5/8”.
 

WREKS

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Robb235

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Been working on the motor swap in what little spare time I have. Mainly waking up early before work to spend an hour on the boat.

So both motors are in and aligned. Cooling hoses are all hooked up. Exhaust is hooked up on the port motor using some silicone elbows to deal with the offset. Haven’t installed exhaust for starboard motor yet.

Electrical so far had been pretty easy. The stock wiring harness from the boat mostly connects to the MR1 harness. And by that, I mean the kill switch and the start switch plug right in. The MR1 harness has a blanked off connector that supplies a signal to the tachometer. I bought the corresponding plug and connected it to the green and black wires on the boat wiring harness.

Next project for electrical is to utilize the stock XR1800 overheat warning lights on the dash. The new tachs also have warning lights on them. I’m going to wire the tach warning lights (overheat, low oil, check engine) back to the ECU. The stock XR1800 overheat warning lights I’m going to wire directly to the thermoswitches on the motor. This should offer some redundancy in case of an overheat.

On the boat wiring harness grey/yellow wire is for exhaust overheat, and grey/black for is engine overheat. I’m going to splice in the grey/yellow wire into the pink wire of the MR1 exhaust thermoswitch, and the grey/black wire into the MR1 engine thermoswitch.

A problem I’m currently having is the stock XR throttle cables. When installed on the MR1 throttlebody, there is too much slack in the cable. I need to figure out how to shorten this cable.

Some pictures from this morning:

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UnorthodoxCreations

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Robb235

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Robb235

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Woke up early this morning and made some more progress. Starboard exhaust is hooked up, port engine airbox is installed, ground wires ran from motors to negative battery terminal.

Waiting on some parts to arrive to complete my fuel pump build.

Some progress shots from this morning. And as I’m posting these pictures, I’m realizing I forgot to hook up the electrical plug from the airbox to the engine harness…

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Robb235

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Some parts showed up today, and I built my fuel pump assembly. It may look a little janky having the fuel pumps clamped to the sending unit, but I didn’t have a better way to attach them.

I sleeved the wires with 4mm PTFE tubing thatI bought off Amazon. I have this fear of the wiring insulation degrading, and causing a spark inside the fuel tank.

I don’t plan on reusing the stock plastic shroud that went around the sending unit. I’m not really sure what it’s purpose is? Only thing I can figure is to keep the fuel from sloshing around the sending unit, causing big swings on the fuel gauge. With both fuel pumps attached, the sending unit no longer fits inside that shroud.

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Robb235

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Fuel pump assembly is installed back in the gas tank. Fuel lines are hooked up, electrical is hooked up to the fuel pumps. No gas in the fuel tank currently, it’s 100% empty.

When I crank the port motor, the fuel pump primes. When I crank the starboard motor, fuel pump does not prime. It was late, so I didn’t start troubleshooting the issue. Trying to rack my brain on what I could’ve forgotten to hook up.

Will check fuses first, and if they all check out good, I’ll supply power directly to the fuel pump to make sure it works. If that test passes, I’ll hook up my laptop with YDS software to the motor to see if that tells me anything.
 
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Robb235

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And the verdict is…. bad fuel pump, straight out of the box. A little irritating, but at least it’s a simple fix. Luckily I have my third fuel pump that I used for bench testing that I can swap in.
 

Robb235

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Ok, so starboard motor fuel pump is good, but the motor no longer cranks. Not sure what I screwed up here since it cranked before. Turning the key and now there’s no sign of life, except that the fuel pump primes each time I attempt to crank the motor. YDS revealed nothing interesting. Lanyard is in, verified by YDS, so it’s not a kill switch issue.

Put gas in the fuel tank, port motor fires right up. Video below.

 
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Robb235

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Still not sure why starboard motor doesn’t want to turn over with the key any more. In the computer box, I can jump the Battery and Starter terminals with a screwdriver and cause the starter to crank. But I can’t get the key to crank the starter.

To verify there wasn’t something wrong with the key switch, I swapped electrical connections so that right key was hooked to the left motor, and left key hooked to right motor. No change, right (starboard) motor still wouldn’t turn over. Port motor cranks just fine.

I’m starting to think it’s an issue with this stupid Yamaha remote security system that the waverunners came with.
 
Last edited:

Beachbummer

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Do you get voltage to the little wires in the starting relay when you turn the key? The relays have gone bad before. (checking that would confirm your suspicion that the ECU is not sending power for another reason, or if the relay is bad) Good Luck!
 
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