Mercury Sport Jet 2.5 L Conversion.

I Have a Toasted 175 XR2 Sport Jet In a Regal 1700. The boat is in good condition Engine is Junk.
2 Cylinders destroyed,
4 Con Rods
6 Pistons
Crankshaft Gone.
Hole in Crank Case.
To name but a few problems.

I'm In England so parts for these motors are none existant.

A freind of mine who has a machine shop races NS2000-F2 Power boats with 2 litre XR2 2 stroke engines, tuned to 200 hp he's suggested using one of his engines and converting it to run on the jet pump.

He's suggested machining the end of a standard merc drive shaft (8 spline) onto the end of the sport jet drive shaft (13 spline) to enable me to use the standard V6 crank rather than a replacement expensive sport jet crank.

Question is has anyone ever tried this aproach ??

<!-- loop replys -->The casting s on the 2.0 ltre race engine are almost identical to the 2.5 sport jet<!-- /reply loop --></TBODY><!-- /onionskins -->

If the weld is good, it should work just fine.....

i puchased a used jet pump to use on my 200 merc the shaft was 5 inches to long i took the shaft out of the pump and to a local machie shop they cut off what i didt need put new splines on it and i havent had a single issue out of it

Actually the jet crank is much less cost than the outboard one from mercury,although I agree they aren't as plentiful.I'm not convinced the 2.0 will have the torque required to turn the pump,a 2.0 making 200 hp is probably turning 7000-7500 to do it,that wont work on a jet pump to my knowledge,I don't know if smaller impellers are available,etc.Even if they are I don't think it would be good for a pleasure boat,i expect you would trash the pump and gearbox quickly,Chris

The jet pump is limited to 5800-6200 R's with any motor, and I agree the 2.0 will be a disapointment on power compared to a 2.5...... been there, and the 175 makes more bottom end power than the 240 EFI, I proved it more than once.

Thanks Guys,
So basically the converted drive shaft shouldnt be a problem,

But the feeling is the 2.0 ltre motor will have a lot less bottom end than the 2.5 sportjet even though it has been ported and tuned to 200HP.

The porting and tuning is to increase hp by increasing rpm,not an option on your jet pump,you need torque that comes from the increased cubes in my opinion,Chris