Rotary valve 787 Questions

[moto17]

I just put in an new SBT 787 in my (1997 Challenger with one 787) jet boat and new carbs as well! Sooo the timing seems to be still off....I learned how to do it on this site and put in a new rotary valve form WSM ? hmmm it wont line up exactly right? it seems to be off just a little bit. The new motor turned over hard but I got it to start,timing is still off!. Has anyone tried a Carbon Tech rotary valve with any luck? and how about trying a different pitch?The one for my boat is a 159 might a 163 work as well? or would it need to be used with a hi performance pipe? I would like more power... any ideas ? Thank you

 

[Seadoobuddy]

Try flipping the rotary valve over and see if it lines up better than before. Make sure you have the right one also.

 

[moto17]

yea I tried that but no better! wondering if anyone has tried a Carbon Tech one?

 

[Chester]

Stay away from any carbon fiber rotary valves. They will quickly wear out the surfaces on the RV cover and the cases.
It doesn't have to be exact. The valve opening spec is 147* plus or minus 5*. You should be able to flip it over to get it within 5 degrees of 147*. The valve is asymmetrical.

Chester

 

[moto17]

We tried for an hour! the WSM one is a exact copy on the outside but the teeth are not the same.This makes it come out about %7 off any way you turn it.
I have a WSM dealership and just got off the phone with them,I ordered a Carbon Tech one as it is stamped different. They will take the other one back! I will pick up a oem Seadoo one or get one from SBT that is stainless. Thank you Chester I will have to check it in a few weeks! But I will have a backup!

 

[Dr Honda]

Yep... like Chester said... get rid of the carbon valve. They don't last... and they wear out the cases. It's truly a product that shouldn't be made.

Get a factory 159 degree valve, and put it in.


One thing though..... Since you said you have "New carbs"... did you verify what's inside? (Jet's and pop-off) Also... are they the same size?