720 exhaust pipes

[cameron da river rat]

i am interested in purchasing an aftermarket pipe for my 96spx w/720 and was wondering which to get?? a set of twin pipes i saw for sale or a factory pipe, r&d dry pipe??, not sure if coffmans makes one or not, but would like some input on the pros and cons of the different pipes, and how much real hp?? engine is new fresh! :D

[Bill O'Neal]

Cameron,
Forget the twin pipes. Only one company (PSI)ever made production twins for the 720, and that was 6 years ago. They didn't work well then, and they work no better now.
The best 720 pipe by far is the Factory Pipe Products 720 pipe. It definately makes the most power. Figure about an 18 hp gain, in conjunction with moderate carb mods.
The Rossier pipe is the second best choice. It makes decent power. But, be careful. There were different model Rossier pipes that fit your motor. Only their race pipe makes good power, The rest are not worth bolting onto your motor.

The R&D 720 pipe is somewhat of a nightmare and only makes marginal power gains.

When modifying the 720, there are several pitfalls that you must avoid. For a reliable package, I suggest that you do all of these mods to the motor when installing an aftermarket pipe.

Install some 44mm Mikuni aftermarket carbs and a stronger intake maniflod setup.
Install a "case brace" onto the side of the motor and change to pre-mixing the gas.
Do not raise the compression if you plan to use pump fuels.
These three modifications are very necessary to ensure long life. They will cost you about $700.00
extra, over and above the price of the FPP exhaust system.

After you change pipes, it will be necessary to lower the pitch of the impellor some.

For further information, call me M-F 9am to 4pm PST at 626 914 9509

[cameron da river rat]

thanks bill!!!!! :D

i currently run a pre-mixed 40:1, stock sea doo 720 and have had very good reliability out of it. or coarse i go through the preventive maintnance list in the repair manual almost after every ride but i like doin that sort of stuff anyway. gotta have somthin to take care of besides wife and kid.

i can understand the compression issue but why the carbs, intake and case brace????

i remember when i rebuilt it last spring that i measured the ports openings on the cases and they were only 40mm, why go to a 44mm? or is a 44 carb only 40 in reality? i've never herd of a case brace??? i read your carb boring statement about the effects of bored mikunis so i'm a little leary of doin that. do you recomend spicket mount or carb brace? any recomendations on carbs, intakes, f/a's???

thanks for your time [img]graemlins/winkanim.gif[/img]

oh yeah, found some ve big bore cylinders and cylinder head kit. i think somthin like 760cc. it was 300 for cylinders w/fresh bore and new pistons. any pro or cons??? [img]tongue.gif[/img]

[ November 01, 2001: Message edited by: cameron ]</p>

[Bill O'Neal]

Cameron,
I recently wrote about this same subject to another fellow. You may try the fourm search feature to dig up the artical.

The short of it is that the 720 cases are very thin and prone to cracking right across the RV face on the cases. The case brace is a 1/2 inch thick plate that fits between the manifold/rv cover and the cases. It bolts onto the side of the motor and provides the case strength necessary to sustain the higher rpms that will be made when using an aftermarket exhaust system.

OEM 720 manifolds have a tendency to crack, causing siezures. As long as you are swapping out the manifold, you may as well put some better carbs on it. I suggest 44 or 46 mm ( I like 44's best). The 44mm Mikuni's work very well with only proper jetting. It is not necessary to spend really big bucks on modified carbs, like Novi or Buckshots. The reason I like the standard carbs is that they are very easy to tune and they idle well without loading up the motor with excess fuel while going through no wake zones. With oem case porting, they matchup fairly well in size to the motor. With a case brace and aftermarket intake manifold/rv cover, you do not need to add a carb brace.

The VE kit is a cheap way to gain CC's. $300 is very reasonable. That kit sold for around $1250 new. A new set of pistons, rings , pins, circlips and gaskets costs about $300. So, you can see that it is a good deal.

[cameron da river rat]

yep! sea doo 720 ve kit, 760cc tripple exhaust ports, complete w/pistons, only $295.00 :D

but is it gonna give me any hp
it also has three coolant fittings on it
is heat gonna be created
should i get it instead of a pipe
tell me watcha think

[Bill O'Neal]

Cameron,
Instead of a pipe ? No.
A pipe will give you the most gains.

Will a 754cc motor make more power than a 720 ? yes. But not alot more, unless you do the pipe and carbs too.

Three coolant fittings ? Yes, to better cool the head and domes. If you look at the VE head closely, it is marked to tell you which fitting is "in and which fittings are "out". Also, there is information at www.rev-limiters.com about these VE products, or call Gary Fries at Micro Touch in Fountain Valley Ca. directly. Gary owns VE.