Wiring 717 engine without mpem

[BUCKTRAN]

Hello everyone,

I was reading one of the post and it look like I may be able rewire the 717 engine with out using the Mpem , just loose function such as neutral, rev.


I have a 1998 Sportster 1800 with twin motor, i think the Mpem is burned and I would like to rewire the motors so it can be run without the mpem. would that be possible? have any one done it. Any info would be a great help. or if you have some lead on the replacement mpem.

 

[Isaac-1]

Take a look at http://www.seadoosource.com/1996speedstermpeminst.html it is my understanding that this same type of conversion can be done on the 1998 and 1999 717 boats, the only problem is that in 1998 Seadoo went to a proprietary wiring connector so it is not as plug and play as it would be with the 1997's as you would need to do a lot of wire splicing. (I think there is another aftermarket MPEM out there for the 1997 twin engine boats that talks more about using them on the 98's but I can't find it at the moment)

As to bypassing the MPEM completely, I have read multiple accounts of it being done, but no specific details, the bits I have been able to find suggests the use of connecting the ignition relay to a common start switch / key switch and adding an aftermarket 2 stroke rev limiter to each engines CDI, this does loose the lower neutral rev limit, which I suspect you could get back with a bit of creative wiring and 2 rev limiters per engine.

If you google seadoo 717 CDI wiring you can find a starting point to this process assuming you are good with electronics.

ps also see http://www.usedseadoompem.com/#!jetboat-conversions/cee5

 

[Mekanix]

Yes you can bypass the mpem on a 717. No you can't on a 787 since the mpem is responsible for detecting crank position, required advance and triggering the coil.

You can replace the all in one mpem with two single mpem's but loose neutral functionality without some custom work.

If you want to add the low rpm rev lime you will need a Dynatek DRL400. OR rather two of them. It has two rev limiters. One for high and one for low rpm's.

 

[Dr Honda]

The 720's CDI is built into the coils. All you need to safely run the 720's is an aftermarket rev limiter, set to 7000 RPM. Then, just wire in a key, and 2 starter buttons. (Use the rev limiter wiring diagrams to rig it up)

 

[BUCKTRAN]

thank you so much your all your respond, that is a great new for me.

Let say that I only just want to get it started and run first before installing others option such as rev limiter or neutral sw. By leaving the Mpem in it original location and snip of these wires and join them with switches and start button. would this work? is the mpem output a + signal to the magneto?

https://drive.google.com/file/d/0B9OL2aqABPDSRmpvaTh5UXh3WWM/view?usp=sharing

 

[Isaac-1]

One other issue you will likely run into is tachometer operation as I think they get there input signal from the MPEM.

 

[Mekanix]

Tack will work as well. Just wire it to the signal wire going to the coil with a 10k resistor in series.

 

[BUCKTRAN]

thanks Mekanix,

what do you guys think about that wiring diagram re work? would that be work?

link below:

https://drive.google.com/file/d/0B9O...ew?usp=sharing

 

[Dr Honda]

thank you so much your all your respond, that is a great new for me.

Let say that I only just want to get it started and run first before installing others option such as rev limiter or neutral sw. By leaving the Mpem in it original location and snip of these wires and join them with switches and start button. would this work? is the mpem output a + signal to the magneto?

https://drive.google.com/file/d/0B9OL2aqABPDSRmpvaTh5UXh3WWM/view?usp=sharing

Dont' do it.

you need to isolate the high voltage from the MAG. You don't want that going into the helm. (Water and electricity don't mix) Also... if you are running hard, and one of the engine come "Unloaded"... you can quickly over-rev the engine. And in turn... you could throw a rod, or cause other damage. Trying to save $100, could cost you an engine.

 

[BUCKTRAN]

Good point on Rev limiter,
how would I isolate the high voltage from the Mag?

 

[Dr Honda]

Good point on Rev limiter,
how would I isolate the high voltage from the Mag?

The rev-limiter will do it. It's basically going to be the "Kill" in the system. So, the switch you will wire into it... will be low voltage.

 

[BUCKTRAN]

I have been busy lately with families and work, will try to work on it this weekend and keep you updated.