SeaDoo HX Factory Pipe Set-up - Opinions Please

[ohell]

I am trying to return a once hopped up HX to reliable recreational freeride ski and was looking for opinions (substitute for trial/error) on factory piped HX with 720 motor. i have lots of aftermarket parts, but bought without carbs.

Current State -
Motor 2nd overbore w/ recent rebuild, ported cylinders, stock Mikuni 38's with single fuel pump, stock intake, stock air box, stock head, factory pipe with ECWI, stock pump with solas 14.5/22.5(looks like) stock grate. most of the time used at 500' above sea level.

Carbs jetting - intent is to jet near factory pipe recomendations -
main jet 140, pilot jet 70, N/S 1.2, 65 gram spring - was thinking on running 145 main jet in pto carb.

I put stock air box on due to concern about water ingestion because of ride style, but was told flame arrestors with water sock run fine with FP jetting recomendations - true???

I have no experience with factory piped 720 - all opinions greatly appreciated - even if it recommends changing set-up with larger carbs, ect...

I have read a few similar threads on this site, but looking for somthing more specific.

THANKS

[Bill O'Neal2]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

I had a customer who raced his HX in the offshore racing series out here for about 5 years in a row (1995-2000). When he first showed up here in 1996, he had an HX with a very similiar setup as yours, FPP and stock carbs. He had tried all of FPP's recommendations about jetting, compression, impellor, ect.

He was on his last overbore after siezing time and time again. The races are long and they hold it wot most of the time.

I installed 2 aftermarket Mikuni 44 mm carbs, stock head, same prop as you have and he raced the next 4 years without a siezure and won the offshore championship each year. Since then, he has ridden it recreationally ever since.

[ohell]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

Thanks for the input Bill!!! Your time spent helping and sharing knowledge is greatly appreciated by everyone; you're the Mikuni Jet-u-lator that doesn't come with a jetting kit.

I keep hearing if you run the FactoryPipe recommended set-up and ride WOT a lot you will toast the pto cylinder fairly quick. I think I will look for some 44's as a little insurance.

Anyone else that is willing to share a proven set-up - factory pipe720 please reply or post in set-up forum. thanks

[David_HX]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

Bill,

I have a '96 HX Fully Ported 717 w/ ADA Head Shell and 39cc Domes running .055 Squish and 145 Compression.
Cal-Jet built Crank w/ RAD Flywheel and lightened OE PTO

Have Dual Fuel Feed // Dual Pulsed Mik 44's on w/ the following Jetting Specs.:

717 Fully Ported by Brian Thomas
In-Line Shaft to Shaft Mikuni 44's
Total Jetting==>240//245
Main=110 MAG 115 PTO
Pilot=130
2.3 P-Off==>18 w/PROK F/A's
95 Gram
LS=1 1/2
HS=1

I was getting extreme 'bogging' when trying to run in the water although it would rev. up crisply on the trailer w/o any load on the drivetrain.

I changed the Pop-off to approx. 23 w/ a 115 Gram Spring and dropped the Pilot to 127.5

New Total Jetting==>237.5//242.5
Main=110 MAG 115 PTO
Pilot=127.5
2.3 P-Off==>23/24
115 Gram
LS=1 1/2
HS=1

Am still getting some bogging in the water and hard starting when warm although a couple blips of the primer usually brings it to life.

Should I try a 2.0 N&S with a 95 spring ?
Will the 2.0 flow enough fuel at WOT for this ported engine ?
I believe it will, but would like your recommendation.

Thank You for the help, I know it's close, but would like to get rid of the 'bogg'. It's hard to tell if it's a 'lean bogg' or a 'too rich bogg'.

BR8 Plugs are very dark and a little wet after WOT chops.


David

[Bill O'Neal2]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

Dark and wet? Never run good if it's dark and wet.

2.0's provide plenty of fuel to feed that motor.

What ignition or stator are you using? Single or dual stator ?

It can be difficult to get a modified motor to accellerate without bogging if you have the single generating coil stator and ignition. It is easily confused with carbureator problem that seem to make it appear overjetted, espically on the bottomend accelleration.

[David_HX]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

What ignition or stator are you using? Single or dual stator ?


Bill,

I still retain the OE Single Magnet Stator unit. I know of no other aftermarket Ignition set-up avaialble for the 717.
Checked w/MSD and Micro-Torch, nada......
Do you know of another source ?

I sure would like to have an Ignition I could vary the timing and curve w/o having to remove the RAD Flywheel while in the Hull,, but all I can do is turn the OE Stator Plate.

It is currently in the "Full Advance" position as per instructions from Bob @ RAD.
I am using their 'older' "Gold Anodized' F-Wheel which requires this Stator Plate position because of the internal Ignition Trigger Magnet placement.

[Bill O'Neal2]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

David,
I always swapped the 720 ignition for a 1994XP ignition, stator and RAD charging flywheel and used a Micro Touch rev limiter when building a modified 720 powered ski that was not using total loss.

There are no store bought fully adjustable aftermarket charging ignitions other than the MSD enhancers. MSD does not make a 720 Enhancer.

I have heard of adapting a stator/charging oem system on a 1996 XP in conjunction with a total loss ignition box to get the advantages of a charging fully adjustable ignition. Maybe you could do that to your 720 ?

I think the easeist system to adapt would be an Advent Tempest 2 ignition box, spliced into the oem system to run the ignition and coil.

[David_HX]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

Is that the '94 XP or XPi Bill ?

I'll look into the '94 XP(i?) set-up. Is that a 3-phase charging magnet system ?

1994 XP Stator Plate: 290995104
1994 XPI "" "" : 290995103
1996 HX Stator Plate :290886726

Why would the single phase electrical of the 1996 HX 717 cause a bog condition ? What is deficient with it ?
They appear to "look" the same in the diagrams.

1996 HX (717) is a single phase I believe so would I have to exchange the Grey MAG Cover Deusche connector (4-pin) for a 6-pin variety.


""" I have heard of adapting a stator/charging oem system on a 1996 XP in conjunction with a total loss ignition box to get the advantages of a charging fully adjustable ignition. Maybe you could do that to your 720 ? """
Not practical IMO,,, The Inductive pick-up of the 787 set-up has nowhere to mount inside the 717 MAG Cover

The M-touch rev. limiter is part of the FPP ECWI solenoid controller already,, and it rev limits @ 8000rpm so I have no problems with that but there are no DIP Switches or Jumpers for advance, retard or curve control.

[Bill O'Neal2]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

XP, not XPI.
The single generating coil system uses a coil with the CDI built into the coil. The dual system uses a capacitor and a normal coil.
The problem with adding modifications that consume large doses of fuel ( 130 low speed jets vs 75 low speed jets in a stock HX carb) at low rpm with a single stator setup is that it has much less energy at the sparkplugs at low rpm to light the fuel for combustion. The dual stator and coil setup lights the fuel much better at low rpm.
You would need the whole grey box, magneto, and stator from a 1994 XP. Not an XPI, which has the same basic setup as your 720.

I did not mean to put a 787 ignition into your 720 HX. The ignition pickup has nothing to do with my suggesstion to try to splice in another ignition system to adjust the timing mapping and advance/retard. If you can figure out how to do it, you might want to try it.

[David_HX]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

So basically,, I need more Spark Energy, Correct ?

I tried MSD for an "Enhancer" a long time ago, but it wasn't available for the OE 717 set-up.

Is there any way to adapt the one that MSD sells for the 787, or are those only using the non-CDI type coils ?

I have ALOT of extra wiring in my Grey Box supporting twin bilge pumps (relays), blower fan, '96XP Fuel gauge and supplemental LED indicators as well as a S-D stand-alone DESS module.
This has all run before, albeit with a much less "efficient" engine.

Swapping out all this to a new Grey Box would take a huge effort for re-wiring all the wire harneeses I built through every available watertight connection hole on the present Grey box.

An external Ignition enhancer seems the most direct route to a larger spark kernal in this situation. Any suggestions in that direction ?

Also, I may be visiting the west coast (folks live in O.C.) next month.

What is your street Adx. ? Still in beautiful Glendora ?

David

[David_HX]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

........ I apologise for hi-jacking this fellows thread. :o

[Bill O'Neal2]

Re: SeaDoo HX Factory Pipe Set-up - Opinions Please

David, When we raced HX's back in the day, we ran 787 engines. Since then, I built some of the World Finals winning SS HX's with 720 big bore engines. All of them used total loss ignitions.

I suggest you get ahold of George Gabroski. He said he set up his XP with a charging ignition and an MSD T.L. ignition box ( unless he was lying about it).
Maybe ole George can guide you through it, as I have not done it myself.

I'm still in the same building I was in last time you came here.