XR1800 4-Stroke MR1 Swap

[Robb235]

I think I’m far enough along on my 4-stroke swap that I can start sharing my progress.

I’ve owned my XR1800 for about 5 years, and while I like the boat, I’m just not a fan of either the obnoxiously loud, fuel thirsty 2-strokes, or the finicky carburetors that fuel them. I got to the point where I was tired of constantly having to tear into the motors or carbs, and decided to follow the lead of a guy on the YJB forum who swapped a pair of MR1 HO motors into his XR1800 jet boat. While I plan to copy most of the things he did, I also plan to do a few things differently. Such as, instead of running two fuel pumps, I liked the idea of running one pump into a dual port fuel regulator, and fueling both motors off that.

Due to the nature of being married with two young toddlers and a demanding full time job plus National Guard training, progress on the swap is sporadic, and often there are long stretches where I make no progress at all. But I will post updates if and when they happen.

 

[Robb235]

I sold both of my 1200 power valve motors and a carb rack to fund the purchase of an ‘05 FXHO and an ‘05 FX Cruiser. I found these gems in Texas while on a jobsite visit for work. The skis had about 45 hours on them, and had been sitting in the Texas sun not being used.

 

[Robb235]

I pulled the motors out of the skis, and realized I was going to need a new, beefier work bench. The bench I had before was left over from the previous home owners, and was much too small. I also built an engine dolly so that I could roll an engine outside and crank it to make sure it ran ok before putting it into the boat.

 

[Robb235]

I bypassed the Yamaha remote system by splicing together yellow to yellow, blue/black to black/blue, and blue to black. After those connections are made, need to run switched power to the yellow wires that are now spliced together. I used the Ignition pole of the universal key switch I’m using for bench testing to supply power to the yellow wires. So with Key On, the jet ski gauge cluster comes to life, and Key Off kills power (unless I’ve just recently bumped the starter, then it stays on on its own for a few seconds and then times out). Engine turns over when key is pushed to Start. Behaves just like a boat should, bypassing that Yamaha waverunner security BS.

 

[Robb235]

I rolled my engine dolly outside and cranked up Engine #1. What a beautiful sound compared to the 2-strokes.

I have the fuel pump removed from the pump assembly and submerged in the red gas can.

 

[Robb235]

So I went into this project not realizing I would have to cut up the engine bay a little bit to make these MR1 motors fit. When reading the other guy’s thread on YJB, I knew the motor mounts would have to move forward about 3”, but I failed to realize the odd ball XR1800 engine bay would need some cutting to make them fit.

Luckily I was able to study the guys photos a little closer and traced out the areas he had cut with a sharpie in my engine bay. After getting over the dread of cutting up an otherwise pristine engine bay, I went to work with my jigsaw and made the cuts for the left motor.

My original plan was to follow the idea of a guy on another forum who swapped in 1.8 motors into his XR1800 and use some aluminum angle and use those as rails, and bolt them down to the stock motor mount locations. Then bolt the motor to the aluminum rails.

Not my picture below, but the idea I was trying to follow:

I used angle because I figured the vertical leg would add rigidity, and aluminum to resist corrosion. But when I went to test fit the motor, the vertical leg of the angle conflicted with the exhaust manifold of the MR1.

So I scrapped the aluminum angle and went with 3/16” flat bar steel to use as my engine rails. My next step is to test fit the engine again, mark where I need to drill holes in the steel to bolt the motors down, and then paint the steel with epoxy paint to resist corrosion.

 

[Robb235]

Did some more test fitting this weekend using my 3/16” flat steel rails. That seems to be the perfect thickness for the rails; I was able to align the motor without any shims.

 

[Robb235]

Next step is to prime and paint the rails, since the rails are steel. I think I’m going to try this stuff.

 

[Robb235]

So I picked up a pair of a pair of SX230/AR230 HO tachometers. In addition to hooking up the tach signal, ideally I’d like to also hook up the three warning lights: Check Engine, Low Oil, and Overheat. Problem is, I’m not sure which wires to run from the jet ski ECU to the tachs to make these warning lights work.

When I study the FXHO service manual, it looks like there are basically three bundles of wires running to the jet ski’s multi function indicator: the remote control box, the speed sensor, and the fuel level sensor. The jet ski multifunction indicator seems to get its information by ECU>Remote Box>Multi Function Indicator. I think the Blue/Black and Black/Blue wires control the buzzer. That leaves the Blue/Yellow wire as being, what I believe, the sole data connection telling the Multi Function Indicator the RPMs, engine trouble codes, low oil warning, and overheat warning. Which is information all coming from the ECU, through the Remote Box.



When I look at the AR230/SX230 HO service manual, there’s no such electrical diagram telling me how the tachometer receives its information for engine trouble codes, low oil, or overheat warnings. The only thing that’s in the manual is what appears to be the assembly instruction for the guys at the factory putting together the gauge cluster panel. It just shows 3 wires, Blue (check engine), Green (overheat), and Purple (low oil). Where those wires go after they leave the tachometer isn’t clear.



So how to go from the one wire feeding the jet ski’s Multi Function Indicator, to the three wire setup going to the AR230/SX230 tachometer isn’t immediately obvious to me. Would love to hear if anyone has any insight.

 

[UnorthodoxCreations]

Cool build. Following as I would consider going a similar route if something ever happened with my LS2000.

 

[Robb235]

So I went browsing on the tach manufacture’s (Beede) website, and found what appears to be the pin out for the exact Yamaha tachs I have, pictured in my previous post. From what I can tell, it’s a different tach than what’s shown in the AR/SX230 HO manual that’s also in my previous post.

The AR/SX230 HO manual shows 6 pins at back of the tach, with a harness and connector coming off the tach. What I have is an 8-pin connector, integrated into the tach (no harness coming off of it). These 8-pin tachs I have appear to match exactly to Beede model # 548012. Interestingly, the manual for that tach is labeled as being for Suzuki and not Yamaha.



So now I know which pins trigger each alert lamp (check engine, low oil, and overheat). My question is, where do these alerts come from?

For example, the Low Oil alert. Is there a wire that should come from the ECU to that pin on the tach? Or do I splice into the wire coming off the oil pressure sensor and run that wire to the tach? I wish there was a better diagram in the AR/SX230 HO manual that told me.

 

[Robb235]

Spent some time this weekend building my fuel pump assembly to accommodate the MR1’s fuel injection system.

I slid the fuel pump down a little bit further after I snapped the pictures.

I have a diode installed at the top of my assembly so that either engine can activate the fuel pump. I followed this thread as a guide: Yamaha Jet Boaters • Login

Not pictured: The dual port fuel pressure regulator. The “F” feed port will go to the regulator. Unused fuel goes from the regulator back to the tank via the “R” return port. What I haven’t figured out yet is where to mount the fuel pressure regulator. Ideally I’d like to mount it under the seat on top of the fuel tank so that I could easily check the fuel pressure gauge. But it’s not quite fitting there.

 

[cybuch]

So I picked up a pair of a pair of SX230/AR230 HO tachometers. In addition to hooking up the tach signal, ideally I’d like to also hook up the three warning lights: Check Engine, Low Oil, and Overheat. Problem is, I’m not sure which wires to run from the jet ski ECU to the tachs to make these warning lights work.

When I study the FXHO service manual, it looks like there are basically three bundles of wires running to the jet ski’s multi function indicator: the remote control box, the speed sensor, and the fuel level sensor. The jet ski multifunction indicator seems to get its information by ECU>Remote Box>Multi Function Indicator. I think the Blue/Black and Black/Blue wires control the buzzer. That leaves the Blue/Yellow wire as being, what I believe, the sole data connection telling the Multi Function Indicator the RPMs, engine trouble codes, low oil warning, and overheat warning. Which is information all coming from the ECU, through the Remote Box.

View attachment 125730

When I look at the AR230/SX230 HO service manual, there’s no such electrical diagram telling me how the tachometer receives its information for engine trouble codes, low oil, or overheat warnings. The only thing that’s in the manual is what appears to be the assembly instruction for the guys at the factory putting together the gauge cluster panel. It just shows 3 wires, Blue (check engine), Green (overheat), and Purple (low oil). Where those wires go after they leave the tachometer isn’t clear.

View attachment 125731
View attachment 125732
So how to go from the one wire feeding the jet ski’s Multi Function Indicator, to the three wire setup going to the AR230/SX230 tachometer isn’t immediately obvious to me. Would love to hear if anyone has any insight.
View attachment 125733

View attachment 125734

This is AWESOME!!
I was having the same issue when I did my dash rebuild on my AR230. After doing some research, I know the sensors are wired to the ECU (because it monitors the RPMs to check for low oil pressure, before activating the warning light) and the ECU puts out a negative signal for each of the 3 warning lights. I hope this helps a little.

 

[Robb235]

It’s getting warmer outside. Time to pickup where I left off with this project.

 

[Robb235]

EDIT: I’m an idiot. I spliced together the wrong wires while doing the security bypass on this motor.

Ok, so I’ve got Engine #2 on the dolly now, hooked to battery and fuel. Fuel pump is kicking on when I try to start, and the engine is turning over, but it’s not firing up. No trouble codes indicated (multi function meter shows 01 when I check for codes).

If I spray carb cleaner down the throttle bodies, it will fire up briefly. So I have spark and compression, but the injectors aren’t firing for some reason.

 

[dabomb6608]

Are these engines out of mechanical (cable) throttle skis? I was just thinking last night about 4 stroke swaps and that was something that crossed my mind. I know the later MR1 motors were fly by wire.

 

[Robb235]

Are these engines out of mechanical (cable) throttle skis? I was just thinking last night about 4 stroke swaps and that was something that crossed my mind. I know the later MR1 motors were fly by wire.

Both of my engines are 2005 and are mechanical cable. No fly by wire on these.

 

[Robb235]

I still can’t get Engine #2 to fire up. I have it on the engine dolly hooked to fuel and battery. It will fire up briefly if I spray carb cleaner down the throttle bodies, so I know I have spark. Fuel pump is pumping and building pressure. But the injectors are not feeding the motor.

I hooked up the Yamaha Diagnostic System, and found nothing out of the ordinary. Through YDS, I turned on the fuel pump to put the fuel system under pressure. I then activated each injector individually via YDS, but even though they all made clicking sounds, none actually sprayed any fuel.

I’m thinking I have an obstruction in the fuel rail somewhere that is preventing fuel from reaching the injectors.

 

[Yamabro]

If its the same fuel pump that fired the other engine then I would agree with you about the obstruction. But if I’m not mistaken... check the throttle body and make sure the throttle isn’t slightly opening the butterfly. Cause I think it has a safety to prevent run off and keeps it from firing up.
Love what you are doing by the way with your XR1800!!! I recently acquired a XR1800 from a customer due to the port side engine having threw a rod and destroying the cases. I also have 2 Waverunners with the MR1 engines... This build looks very tempting.

 

[Robb235]

If its the same fuel pump that fired the other engine then I would agree with you about the obstruction. But if I’m not mistaken... check the throttle body and make sure the throttle isn’t slightly opening the butterfly. Cause I think it has a safety to prevent run off and keeps it from firing up.

Yeah, I found out that YDS wouldn’t even let me activate an injector if I held the butterflies open. I was hoping to peer down and see if the injector was squirting any fuel, but YDS got mad that I had the throttles open. So took the air box and throttle bodies off and flipped the assembly upside down and set that down on top of the engine. The idea was that, with fuel system under pressure, if I manually activated an injector, I should theoretically see a puff a fuel being fired. Instead I got clicking sounds from each injector, but none ever shot any fuel.
So now I’ve got the throttle bodies sitting on my work bench, and I’ll try to mess around with it some more tonight if I get a chance. I plan on pulling the injectors and cleaning them up a bit to see if that helps. The motor sat for years unused, so it wouldn’t surprise me if old gas has stopped up these injectors.

Love what you are doing by the way with your XR1800!!! I recently acquired a XR1800 from a customer due to the port side engine having threw a rod and destroying the cases. I also have 2 Waverunners with the MR1 engines... This build looks very tempting.

Thanks, I appreciate that. It was pretty much a project born of necessity, as I grew to hate the 3-cylinder 2-strokes. I rode a Yamaha R6 for years, and loved the sound of that motor, so I’m looking forward to having these MR1’s in my boat.