Hey guys, quick question. I have a Rotax 720 in my sea doo
sportster. I badly need more power. What is the best way to get
more power out of that engine? I am thinking of boring it out .5 and
cutting the head. But I dont know if that would mess up the
carb( same amount of fuel,but bigger firing chamber). Any idea's?

Thanks!

Justin Van Dyken

On Jul 4, 8:20 am, wrote:
Hey guys, quick question. I have a Rotax 720 in my sea doo
sportster. I badly need more power. What is the best way to get
more power out of that engine? I am thinking of boring it out .5 and
cutting the head. But I dont know if that would mess up the
carb( same amount of fuel,but bigger firing chamber). Any idea's?

Thanks!

Justin Van Dyken

A different exhaust (expansion chamber) would help a lot. rememebring
that from my old two strike motorcycle days.


Here's a quick search. that 720 is pretty beefy, and mod's are
relitivly cheap ,and easy:

http://www.rossiereng.com/tech_pwc4.html

On Jul 4, 8:59 am, Tim wrote:
On Jul 4, 8:20 am, wrote:

Hey guys, quick question. I have a Rotax 720 in my sea doo
sportster. I badly need more power. What is the best way to get
more power out of that engine? I am thinking of boring it out .5 and
cutting the head. But I dont know if that would mess up the
carb( same amount of fuel,but bigger firing chamber). Any idea's?

Thanks!

Justin Van Dyken

A different exhaust (expansion chamber) would help a lot. rememebring
that from my old two strike motorcycle days.

Here's a quick search. that 720 is pretty beefy, and mod's are
relitivly cheap ,and easy:

http://www.rossiereng.com/tech_pwc4.html

Justin Van Dyken wrote:

Tim,

Very helpful website!! I had been thinking about cutting the head as
well but I was not sure what was a safey level to raise the
compression too. This site lays it all out! Thank you

Justin Van Dyken

On Jul 4, 4:22 pm, Justin Van Dyken wrote:
On Jul 4, 8:59 am, Tim wrote:





On Jul 4, 8:20 am, wrote:

Hey guys, quick question. I have a Rotax 720 in my sea doo
sportster. I badly need more power. What is the best way to get
more power out of that engine? I am thinking of boring it out .5 and
cutting the head. But I dont know if that would mess up the
carb( same amount of fuel,but bigger firing chamber). Any idea's?

Thanks!

Justin Van Dyken

A different exhaust (expansion chamber) would help a lot. rememebring
that from my old two strike motorcycle days.

Here's a quick search. that 720 is pretty beefy, and mod's are
relitivly cheap ,and easy:

http://www.rossiereng.com/tech_pwc4.html
Justin Van Dyken wrote:

Tim,

Very helpful website!! I had been thinking about cutting the head as
well but I was not sure what was a safey level to raise the
compression too. This site lays it all out! Thank you

Justin Van Dyken- Hide quoted text -

- Show quoted text -

No problem, man. Actually raising the compression is good, but then
again, it's some "by guess and by golly" too

Bad thing about modifying the head etc, is that you would have to
change a lot of other stuff too. and getting the head right is another
thing. That's for the pro's, that is if you have the coin to go with
it.

Yes, there's a lot of easier bot-on stuff that will do the job without
having to do surgery....


good luck!