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4 Stroke XPL?

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
Hey guys, i’ve been kicking around this project, i ride long distances and in lakes that only allow 4 strokes. i’ve seen a video of an XPL with a 4 stroke in it, I think it was in australia? I cant seem to find the video now:(

anyways i want to put a 155 engine into the XPL i just bought, any one tried anything like this before? Will it work?
 

DanSquires

Well-Known Member
Messages
403
Location
Blue Springs, MO
Water Crafts
More skis than brains.
Hey guys, i’ve been kicking around this project, i ride long distances and in lakes that only allow 4 strokes. i’ve seen a video of an XPL with a 4 stroke in it, I think it was in australia? I cant seem to find the video now:(

anyways i want to put a 155 engine into the XPL i just bought, any one tried anything like this before? Will it work?
It's been done a couple of times. An insane amount of work, so you'd better really love that ski to make it worth it.
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
I put a 4tec into a 1997 seadoo Challenger and can attest to the insane amount of work. I had the 787 in mine with the 140mm pump. With that setup, the 4tec output shaft was taller than what the boat would allow. I had to cut the pump tunnel and rear motor mount points and glass them into the boat hull. The XPL I believe has the 951 and a 155mm pump, so that may not be an issue. However, I also had build a custom fuel tank as the fuel pump needs to be secure, and LARGER, because I love to spend time out on the thing. The 155 will be more fuel efficient than your 951, but you'll still need a custom tank. Here's a link to my build: Challenger 4tec Upgrade - Page 2 - Seadoo Forums
PM me if you want to know who built that green masterpiece in the above video.
 

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
I put a 4tec into a 1997 Seadoo Challenger and can attest to the insane amount of work. I had the 787 in mine with the 140mm pump. With that setup, the 4tec output shaft was taller than what the boat would allow. I had to cut the pump tunnel and rear motor mount points and glass them into the boat hull. The XPL I believe has the 951 and a 155mm pump, so that may not be an issue. However, I also had build a custom fuel tank as the fuel pump needs to be secure, and LARGER, because I love to spend time out on the thing. The 155 will be more fuel-efficient than your 951, but you'll still need a custom tank.

PM me if you want to know who built that green masterpiece in the above video.
i've seen that green one online, it seems like it was way more complicated due to him having the supercharger and intercooler has to be placed. Hopefully the engine doesn't sit too high where the shafts won't line up as yours did on your boat as that would basically call it quits for me.


It's been done a couple of times. An insane amount of work, so you'd better really love that ski to make it worth it.
Yes I love the hull is the last smallish hull IMO that rides nice but still feel small and non boat like.
 

DanSquires

Well-Known Member
Messages
403
Location
Blue Springs, MO
Water Crafts
More skis than brains.
i've seen that green one online, it seems like it was way more complicated due to him having the supercharger and intercooler has to be placed. Hopefully the engine doesn't sit too high where the shafts won't line up as yours did on your boat as that would basically call it quits for me.



Yes I love the hull is the last smallish hull IMO that rides nice but still feel small and non boat like.
Then anything is possible with enough time, money, and knowledge.
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
Regardless of the height of the output shaft, I BELIEVE (might be wrong) that the 4tec XPL conversion requires a custom driveshaft.
 

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
That's not too big of a deal, I can get one made up probably, I still panning all of this, so it'll be a while before i post anything.
 

etemplet

Premium Member
Premium Member
Messages
2,933
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
That's not too big of a deal, I can get one made up probably, I still panning all of this, so it'll be a while before i post anything.
You're gonna weld on this thing or get a new one machined? 6K RPM. if the plan is to piece together a shaft YIKEs !!
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
I do agree 100% that this is the best hull before they turned into yachts. Best looking too IMO
 

etemplet

Premium Member
Premium Member
Messages
2,933
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
I have a 1998XPL and a 2003 XP DI. How are they to work on with the engines in the front. Are these better performers than the RX ?? I think the newly built engine that came with the 1998 is a BIG BORE. I'm gonna have to pull the head to verify.
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
I always hear horror stories about the DI models. They really have to be in perfect shape all the time or the top-end goes. Then again, I heard these 2 strokes need a top-end every 100hr anyway, so idk.
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
I want to say a 4 stroke xpl can reach 80 with some perform performance mods
 

etemplet

Premium Member
Premium Member
Messages
2,933
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
YIKEs..... no way. I need pavement and brakes for those speeds. LOL Good brakes.... good rubber, helmet and leathers. LOL
 

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
You're gonna weld on this thing or get a new one machined? 6K RPM. if the plan is to piece together a shaft YIKEs !!
if it needs to be short ill get it cut and re splined if it needs to be longer I'll get one made up, but that being said i've know people that cut and welded shafts without issues, so idk if its a big deal

depends
I always hear horror stories about the DI models. They really have to be in perfect shape all the time or the top-end goes. Then again, I heard these 2 strokes need a top-end every 100hr anyway, so idk.
yeah, the ski I picked up was a DI, idk what's wrong with it, low compression on one cylinder but has spark and cranks but won't start up, the guy I bought it from said no one wanted to touch it so I got it cheap.
The 951 engine is not very reliable imo, I've rebuilt mine at 100 hours to be preventative, but back in the year 2000, when I was racing, these things would blow left and right compared to the Kawasaki and Yamahas we were competing with, but its 130 horsepower out of two-cylinder with a big ass piston, you can't expect much lol
 

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
also, as long as i go 65 MPH outta this thing im fine with it, im staying N/A after all
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
I'd get the supercharged engine. You don't have to go as fast as it can go. Also, you can trade speed for insane holeshot. It's what I did on my challenger conversion as the extra speed made it chine walk.
 

etemplet

Premium Member
Premium Member
Messages
2,933
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
yeah, the ski I picked up was a DI, idk what's wrong with it, low compression on one cylinder but has spark and cranks but won't start up.
Check your air pump pressure. Also the injectors.... all 4 of them. I'd send them off for cleaning. I always do this before I start working on the skis. Good Luck !!
 

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
I'd get the supercharged engine. You don't have to go as fast as it can go. Also, you can trade speed for the insane holeshot. It's what I did on my challenger conversion as the extra speed made it chine walk.
I get that, but I really like the idea of an 87 octane build, I have a few other modified skis that I use to get my thrills on, this is really just gonna be my cruiser, plus if I get an intercooler version that makes a whole different issue with making room for the piping and cooler itself.

Check your air pump pressure. Also the injectors.... all 4 of them. I'd send them off for cleaning. I always do this before I start working on the skis. Good Luck !!
I have no intention of fixing this ski, I just wanted the clean hull for the swap $150 paid in full I'm not too attached to getting up and running.
 

IDoSeaDoo

Well-Known Member
Messages
3,056
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
Ah yes, 87 octane is definitely a factor. I agree. 155hp should be plenty. If you want more pop, shave the head and get a valve job.
 

WhiskeyD

Active Member
Messages
886
Location
Charlotte, NC
Water Crafts
96 XP & 97 SPX
IMO the 4stroke swap would only be worth the time and money if you are going to be boosted. According to google, the NA Rotax 155 weighs nearly 180 lbs more than the 951. I would imagine its no faster, possibly slower, than the 951 motor already in the ski.
 

RotaxBoi

New Member
Messages
12
Water Crafts
XPL, XP, RXP 155
IMO the 4stroke swap would only be worth the time and money if you are going to be boosted. According to Google, the NA Rotax 155 weighs nearly 180 lbs more than the 951. I would imagine its no faster, possibly slower, than the 951 motors already in the ski.
180 MORE? that can't be right? Is it? I'll have to check
 

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