'94 XP MPEM 278000305 vs 278000071, which one should be used?

[sledder12]

I've searched for hours on the net. Someone by ther name BILL86E seems quite knowledgable, however, I'm still confused. My ski has 278000071 in it, but info I'm finding on net says the upgraded/superceeded MPEM should be 278000305. I purchased a backup MPEM listed as a 278000071 and concidentally fellow sent 278000305, maybe this is a good thing?

What is the difference between the two? RPMS higher on one than the other?

 

[Minnetonka4me]

Theres prob a difference on the board...in other words nothing special. Either one will work just fine.

 

[Bills86e]

93-94 xp

A change in accessories changed the mpem.
In '93 the xp had the 071 with a separate module, then later incorporated the vts into the 305 as one module. It had two gauges, oil/fuel & tach. In '94 the same mpem module also operated a third gauge,a speedometer. Both years had a manual indicator. An SPX is last years XP with any added accessory designed late in the xp year.
'93XP = 657 engine
'94SPX = 657 engine
''94XP = 657X engine (larger bore, beefier cases)
'95SPX = 657X engine oil/fuel gauge changed, mpem upgraded to the 423 mpem(indicator lights added to gauge) Tach & speedo were not used, and the closed circuit start & stop switches were upgraded to an open axial single button switch circuit.

Bills86e

 

[Minnetonka4me]

A change in accessories changed the mpem.
In '93 the xp had the 071 with a separate module, then later incorporated the vts into the 305 as one module. It had two gauges, oil/fuel & tach. In '94 the same mpem module also operated a third gauge,a speedometer. Both years had a manual indicator. An SPX is last years XP with any added accessory designed late in the xp year.
'93XP = 657 engine
'94SPX = 657 engine
''94XP = 657X engine (larger bore, beefier cases)
'95SPX = 657X engine oil/fuel gauge changed, mpem upgraded to the 423 mpem(indicator lights added to gauge) Tach & speedo were not used, and the closed circuit start & stop switches were upgraded to an open axial single button switch circuit.

Bills86e

I am about 90% sure the incorporated VTS part of your reply is incorrect. Out of the 4 I parted, I did not see one that wasnt using the VTS module. I dont seem to have the pictures anymore as I sold all the eboxes a while ago to verify.

One other thing to remember when looking at your list is the XPs were the only ones to use the 5 wire ignition correct? All other 657 machines used the 4 wire.

 

[sledder12]

What makes it even more confusing is my '94 XP is all original. It came with the 071 and as for gauges has fuel/oil and tach, no speedo.

So based on whats been said, if I install the 305 everything should the same as the 071 correct?

 

[Minnetonka4me]

Just look at the both MPEMs...The wiring will be absolutely the same if I am correct. Gauges dont matter...they all pigtail off the same MPEM wires.