• Welcome to Jetboaters.net!

    We are delighted you have found your way to the best Jet Boaters Forum on the internet! Please consider Signing Up so that you can enjoy all the features and offers on the forum. We have members with boats from all the major manufacturers including Yamaha, Seadoo, Scarab and Chaparral. We don't email you SPAM, and the site is totally non-commercial. So what's to lose? IT IS FREE!

    Membership allows you to ask questions (no matter how mundane), meet up with other jet boaters, see full images (not just thumbnails), browse the member map and qualifies you for members only discounts offered by vendors who run specials for our members only! (It also gets rid of this banner!)

    free hit counter

Winter Project Seadoo 720 Build

Seadoo4me

Member
Messages
20
Reaction score
2
Points
12
Boat Make
SeaDoo
Year
2001
Boat Model
Challenger
Boat Length
Other
I've started collecting engine parts from Ebay to build a replacement engine for my Challenger. The PO threw in a WSM crank rebuild kit and a WSM Platinum piston kit when I bought the boat. I plan on installing a WSM rotary shaft since my engines are leaking from the shaft seals. Both motors have new carbs already. I've read up on performance mods (Group K) and Mr. Bill and aside from port matching all intake and exhaust surfaces I'm likely to have Group K mill the heads and call it good. Since my pumps have stock impellers I think upgrading to Solas props will give me better performance w/o affecting reliability. The PO did liners and pump rebuilds 2 years ago. Does this sound like a good plan or is there something I'm missing ? All rubber hoses are being changed out now and I'm replacing the starter cables also since they're corroded...
 

tdonoughue

Jetboaters Captain
Messages
2,290
Reaction score
1,544
Points
242
Location
The Woodlands, TX 77381
Boat Make
Yamaha
Year
2012
Boat Model
AR
Boat Length
24
You are taking it in salt water, I assume, as you have corrosion on the cables? Replacing the hoses is good--you may consider replacing the clamps with stainless ones while you are at it.

Have any pics?

Not too familiar with the SeaDoos. What is the condition of your impellers? If they are still good, you may be able to re-pitch them and save a buck there.
 

Seadoo4me

Member
Messages
20
Reaction score
2
Points
12
Boat Make
SeaDoo
Year
2001
Boat Model
Challenger
Boat Length
Other
Boat came from Florida originally so I assume it saw salt down there. The guy I bought it from used in fresh only he claims. I've put new-ish oil pumps on both motors, replaced a rotary valve and cover. This thing is a hot mess, both engines had mismatched hardware and some very rudimentary "repairs" done incorrectly. I havent even looked at the pumps yet sort of afraid to honestly. I'm going to change the oil in them and run thru this season unless I find something really bad. Both motors have good compression thankfully.
 

tdonoughue

Jetboaters Captain
Messages
2,290
Reaction score
1,544
Points
242
Location
The Woodlands, TX 77381
Boat Make
Yamaha
Year
2012
Boat Model
AR
Boat Length
24
Good compression goes a long way. When you check the impellers (eventually you do have to look), also be sure to check the intake path--that it is smooth. At that age, caulk and stuff may fail and leave gaps and things resulting in cavitation. It will have you thinking your impellers are bad when really you just need a little silicone caulk...
 

Seadoo4me

Member
Messages
20
Reaction score
2
Points
12
Boat Make
SeaDoo
Year
2001
Boat Model
Challenger
Boat Length
Other
I plan on dumping the pump oil and checking for metal. I read up on Group K website about the pump shoe and shaft protector issues. PO did say props had some nicks so I will pull both pumps this fall and replace with Solas. New carbon shaft seals as well while everything is apart. I've lost some water time getting everything these guys botched up repaired correctly. Hopefully nothing too hacked up under her but the ineptitude of prior 'mechanics' repair work has been glaring and disturbing so who knows...
 
Top