MS3 on polaris 650 triple 2-stroke?

[gndan]

As it says im looking to run fuel injection on my polaris 650 triple. I am wondering if I can use the original input coming from the engine or the output from the cdi box to the original coils. I want to use lsx coils and just single rail batch fire. For those of you who aren't familiar with polaris triples all the coils fire at once everytime so ignition should be fairly easy. Im just looking to use the factory pickup instead of the 36-1 wheel where I would need to build an adaptor.

Dan

[Matt Cramer]

Do you have any details on how the factory pickup is set up?

I doubt you'd be able to use the CDI box's output, but the input might be useful.

[frank_ster]

they have a magnetic vr sensor on the out side of the alternator with 3 magnets.

[gndan]

Thanks frank for your input, I have not been able to check it yet to see what it is since I have it in storage but if it where a "3 tooth" window that would be great! Ill check it when I have it home next.

Dan

[Matt Cramer]

they have a magnetic vr sensor on the out side of the alternator with 3 magnets.

That could probably work in Basic Trigger mode.

[gndan]

Matt that's exactly what im thinking! Especially since my car is a 3whore window and functions on basic trigger!

[whittlebeast]

Plan on going MAF as there is not enough MAP signal to get speed density to work and the exhaust system will drive alpha-n nuts. I lost 1/2 a summer trying. Once I went MAF, everything dialed right in.

AW

[frank_ster]

maf or throttle angle / rpm based. as the stock artic cats work

[whittlebeast]

maf or throttle angle / rpm based. as the stock artic cats work

The problem with watercraft is that the exhaust system has water in it that is used to control the speed of sound of the exhaust. This in turn controls everything on the power band of the motor. If you pass thru some section of the map wile there is plenty of pressure in the water cooling system and the next time you get there, and there is no water pressure yet, the fueling requirements are very different. MAF fixed all of this.

AS a side note: race watercraft with carbs do all sorts of electronic tricks to control the water in the exhaust to play with this power band. Once I went to MAF, none of that stuff worked and I remove it from the boat.

AW

[gndan]

What MAF are you running, and how did you go upon the tuning aspect on a 2-stroke? Tune it like you do with a carb and just watch the plugs or what?

Thanks, Dan

[whittlebeast]

What MAF are you running, and how did you go upon the tuning aspect on a 2-stroke? Tune it like you do with a carb and just watch the plugs or what?

Thanks, Dan

I was using a MAF from a v6 Ford Taurus that was designed for about 160 HP. Fuel flow is generally in mass / hour

([pulse width]-[opening time])*RPM

That can be compared to the lbs / hour that is coming off the MAF transfer function

The mass per hour of air / mass per hour of fuel is AFR by definition

Once you start seeing the pattern as to what the motor wants in fuel flow at a few points like idle, 3000 rpm (just on plane) and say 6500 RPM, the rest falls into place.

Andy

[gndan]

Andy, I sent you a PM about MAF install and tuning.

Thanks, Dan

[Mharvey1]

whittlebeast, I am hoping you are still following this post. I just registered so I am not able to PM you. A little about what I am wanting to do: I have a 99 Seadoo GSX RFI 787 that has given me problems from the start with the factory electronics. I found on the FSAE site that you had used a MS for an EFI seadoo 787 and then added a MAF to allow better tuning. I tried getting onto your website (www.ncs-stl.com/xp) but it keeps forwarding me to another site (http://www.nbs-stl.com/). I tried searching FSAE/msextra/shopsbt forums for more information on it but can not find any good details on it. This will be my first MS project and if all goes well I am hoping to fit some yamaha r6/gsxr600 efi throttle bodies to my 1988 FZR400 and then convert my '95 Seadoo XP 720 to EFI. A little about me, I am a Mech E. undergrad from U. of Utah, have rebuilt/swapped engines in cars. All cars I have dealt with are EFI but my two motorcycles and the XP are carbed. I have some decent machining/manufacturing experience. I was on an FSAE team at the U of U, and made a composite carbon fiber chassis. Really appreciate the help!