66E Conversion

I feel like a wide band o2 would be extremely helpful if it gave meaningful readings, for developing the base map, probably tune 0-100% throttle tied to a trailer in the water, cruising down the lake and out of water(won’t hit 100% here) and interpolate between those three lines to fill in your base fuel map, then I think you have to take it out and tune accel enrichment by riding it. I had not heard of x-tau enrichment but it sounds great, I think for a two stoke you will end up with a large x and long tau because fuel isn’t just stuck on the intake port wall, it has the whole crankcase and transfer port area to stick to. I didn’t get that deep into it but I’m hoping the mega squirt can just correlate throttle position to a map at a certain rpm(I think that’s how it handles alpha-n to begin with) and then derive mapdot from that for faster response.
I did message @tyler breitweser but he didn't offer up too much info
 
I feel like a wide band o2 would be extremely helpful if it gave meaningful readings, for developing the base map, probably tune 0-100% throttle tied to a trailer in the water, cruising down the lake and out of water(won’t hit 100% here) and interpolate between those three lines to fill in your base fuel map, then I think you have to take it out and tune accel enrichment by riding it. I had not heard of x-tau enrichment but it sounds great, I think for a two stoke you will end up with a large x and long tau because fuel isn’t just stuck on the intake port wall, it has the whole crankcase and transfer port area to stick to. I didn’t get that deep into it but I’m hoping the mega squirt can just correlate throttle position to a map at a certain rpm(I think that’s how it handles alpha-n to begin with) and then derive mapdot from that for faster response.
I did message @tyler breitweser but he didn't offer up too much info

It has been a while since I've had my nose in megasquirt, but I think you are spot on all around, and I'm pretty sure you can do exactly what you are describing.

A more sophisticated approach that I'm pretty sure megasquirt is capable of (but not 100% sure) is to take a "map" reading from the actual crankcase, and time it for the reading to be taken at a particular point in the stroke, probably just before transfer ports closing. No idea if that would actually work, but it makes sense to me. I think the way simpler Alpha-n is a better way to start off though. I think you can have compensation based on temp and "atmospheric" pressure with a pressure sensor inside the hull, which seems to me like a good idea.

Very cool project looking forward to seeing how it goes.
 
Yeah they mention phasing the map readings in the x-tau explanation, but it was unclear to me whether ms2/microsquirt was actually capable of that. That would be the coolest way to go about if it could I think
 
I'm pretty sure it can or the xtra code can. Once upon a time long long ago I was interested in putting a Microsquirt on a single cylinder dirt bike, the challenge with those is that there isn't really any plenum to take a map reading from, only the very short length of port between the throttle body and the intake valves which obviously has hugely varying pressure throughout the stroke. I remember reading about a guy who used Megasquirt on a similar motor and did the timing of the map reading thing in the intake port and timed it to read just before the intake valve closed. This is a little bit more complex on a four stroke because you need to know both the position of the crank fairly accurately, and you need to know which stroke you are on, so you either need a cam reference sensor or to do your position sensing on the camshaft, I was debating between trying to do that or just going Alpha-N but ended up never finishing the project. I think his project may have even lead to a modification of the extra code to allow choosing the timing of the map reading, but this was about 10 years ago so my memory is very hazy. Also no idea what sort of evolution the whole thing has had since then, but I doubt any capability was taken away.
 
Got a little progress on this project, Pump Installed and some motor assembly:

Clearance PVs
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Adapter Bearing:

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Laser Cut Cylinder Spacers:
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Other stuff:


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Layed up two hoods this weekend, The first one was way too flimsy at only 4 layers. The second one I used the rest of the carbon I had, making it 9 layers and an extra strip under where the pole pad will land. I would still like it thicker, but I think once I add a chamber for breathers it will stiffen it up to where I think it should last for a while.

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Inching along, cut some headshells, hopefully will cut some domes and double check squish on the cr500 pistons by the end of the week. they changed a bit since I posted the cad image, I figgured these cylinders have a thick enough flange to not need girdle studs , so might as well save that weight.


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What I found was a suspension bearing for a Kawasaki 4 wheeler, 92046-1290. It’s also listed other places as a ta202725 and sometimes as just a ta2025. I haven’t looked super hard but if you can find one with an oiling hole im sure that would be preferable. 20mm Id 27mm od 25mm thick
 

Sparkplug

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Location
Red Bluff CA
So, I did exactly what you did with the drive shaft. My boss at the time, a self made machinist, told me it would not work. Mark Ericson told me it would not work unless perfectly balanced. And still probably not. I had it trued to less than .001 of runout. It broke in less than 2 hours of riding. Trying to save you the hassle.

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So, I did exactly what you did with the drive shaft. My boss at the time, a self made machinist, told me it would not work. Mark Ericson told me it would not work unless perfectly balanced. And still probably not. I had it trued to less than .001 of runout. It broke in less than 2 hours of riding. Trying to save you the hassle.

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lol, well its in so I'll try it I guess. Although may be moving this project over to an eme hull thanks to my local used hull dealer @Rushford_Ripper and the amp will sit for a while longer, space may be a concern in the eme though hopefully I'll get some time to work on it this week or next
 
My XFS lost spark, probably an easy fix but its almost July and I haven't worked on the eme or amp at all, so the 66e got shoved in the rickter in hopes of actually riding it this summer.
So good news is the motor is in the rickter and it ran, turns out there were still some packing peanuts in the chamber:

the pfp waterbox I bought for this project didn't fit in the rickter so I decided to make my own more compact one with a scupper to prevent water flowing into the motor:
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adult assembly required

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scupper flap, I glued a piece of eva foam to float the flap closed when the box fills with water

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Did you get to ride this thing?
I rode it in the rickter for a grand total of about 10 min. Started way to rich on the jetting, leaned it out on the trailer before ever hitting water, hit the water for a couple min was still too rich took it home and rejetted, took it out again putting around not going too crazy to break it in. It shot right out of the water the few times I whacked the throttle like it never had with the 701 based setup. Problem was I used pretty thin cooling line from mcmaster that ended up melting off pretty quickly, so overheated the motor and sprayed water everwhere, ski started to loose power, I limped it back to the launch. Pulled the heads to see if I melted those o rings too and found that some metal also bounced around between the piston and head. I had bought a 62t 850 already and it had come in and was sitting in a box next to all the parts I had just ripped out of the rickter. So back in all that went so I could ride it some last summer and I still have yet to tear into the 66e to see what all happened. Hoping the plating is still good and I can slap it in something before this summer.
 
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