sportster 717 rotary valve question

[teamziehm]

Okay my motor blew in my 97 speedster it was a 717, now I bought a low hour 96 gti with 717 I have motor in the boat now and runs decent but I believe valve is off, my big question is , WHY DOES THE 97 SPORTSTER SINGLE BOAT USE A 132 ROTARY WHEN ALL THE OTHER 717's USE A 159 PLATE?CAN I JUST USE THE 159 PLATE TIMED TO 147/65 LIKE WHEN IT WAS IN THE 96 GTI SKI? THIS SHOULD BE THE
LAST TIME I BOTHER YA GUYS FOR HELP I REALLY APPRIECIATE ALL THE GREAT HELP

 

[Dr Honda]

The smaller valve gives a smoother idle, and more traceable mid. So, it makes driving the boat a little easier.

BUT...

Yes... you can use the 159 degree valve. It may just be a little rough in the lower/mid RPM's.

 

[teamziehm]

Thanks for the answer buddy, so I have come to the conclusion that the old rotary valve that was in it was also a 159 valve, so valve DOES NOT make a difference in jetting or power when 159 is set to the 147/65??? There was a line scribed on the case where rotary was lined up with on the new motor, so just leave the 159 where it is? becuz I do not have the original 132 valve. The reason I say i thought it was timed wrong is becuz its pretty rich all the way around the throttle range .vtheconly thing then I can think of is the 96 gti air box lid must be different than the sportster causing the sportster to have a rich condition.thanks dr honda

 

[Dr Honda]

The 720 air boxes were all the same. With the exception of the single carb engines.

If it's rich... then something is up. (Like your pop-off is low, or the N/S is leaking a little. OR... you are sucking oil past the RV seals.

As far as position... don't trust any "Marks" on the case. They could be wrong. Just get a degree wheel, and set the RV properly.

 

[teamziehm]

Okay I took boat out today while it was beautiful on the river no rain or moisture not like the other day(rainy n cool),, I adjusted low speed to 2 turns out from lightly seated and set idle and high speeds are turned in all the way to lightly seated boat runs awesome after setting allcthe carb adjustments and the 159 rotary valve to 147/65, SO NOW what can I do to gain 2 to 3 mph on topend ,rv plate, impeller cut head 0.10 run better pump gas or?any suggestions would really be great, I would lovevtovput a 787 in it if I could find a donor ski for the exhaust n electrical anyhow i much apprieciate it and you guys have been a huge help on here for me I really prieciate it