4-Stroke GP1200R / VX Conversion Project

[boudin]

Picked up a clean 2002 GP1200R hull a couple of months ago for $400, and decided to do a VX conversion. I've read up other threads (not many exist) and came to the conclusion it should not be too difficult. I love the GPR hulls, but don't like the poor reliability and finicky 2-stroke motors. I had a donor 2009 VX110 I also picked up cheap (about 290 hours), and put about 10 hours on it to be sure the motor was healthy. Compression and leak down tests are good.

[boudin]

Stripping the VX and cutting up the hull to take to the dump. Local dump charged just $5.25.

[boudin]

Test fitting the motor in the GPR hull. Motor mounts line up, and there is 4" between the mid wall and PTO.

[boudin]

Mounted the throttle controller on the left side; e-box is mounted on the right side (both are close to the locations in the VX so the electrical harness reaches).

I also picked up a GP1300R fuel tank, and had the VX 2.5" nipple welded to the GPR water box.

Sealed up and bolted the pump shoe back in, fitted the VX pisser on the left, and plugged up the 2nd pisser on the right.

[boudin]

Original plan was to use a FXHO pump and 2" spacer, however, the 28" driveshaft is too long. So that won't work. (I don't want to move the motor mounts.)

Using the 2009 VX pump, the VX driveshaft is 20", but still too short. Note that on the VX driveshaft, the bearing housing / rubber donut could be replaced by a mid wall bearing housing; both the FXHO coupler and the VX driveshaft around the VX bearing housing are both 25mm. However, still 2 3/4" short.

After some research, I figured out that 2010+ VXs have a new driveshaft design that eliminates the bearing housing / rubber donut in favor of the traditional mid wall bearing housing. And the new 2010+ VX driveshafts are 24 3/4". Perfect! Nothing changed about the pump on 2010+ VXs, so my 2009 will work.

So I found and bought a 2011 VX driveshaft and bearing housing off eBay; and will use the FXHO 2" spacer, stock VX pump and impeller, and 2" trim and steering extensions from WFO.

More pics to come next weekend...

[boudin]

2013 VX 24 3/4" driveshaft and bearing housing.

[swlamarshrunner]

Nice work

[boudin]

I was able to finish the GPR conversion this past weekend, but was not able to water test due to rain. All in all a very straight forward conversion. I was in assembly mode most of the day Sunday so I didn't take many pics. I will try to get a bunch of pics this weekend.

A few highlights:

• Stock motor mount location--just bolts right up
• 2009 VX110 pump w/stock 18/22 impeller
• FXHO 2" pump spacer
• 2011 VX110 24 3/4" driveshaft w/2011 VX110 mid-wall bearing housing
• Resealed pump shoe with silicone
• 2" steering and trim cable extensions from WFO
• Use the VX throttle and start/stop switch

No seat mod or hull cutting necessary; only fabrication is 2.5" nipple on the stock waterbox, and Dremel the dash for the 2009 VX110 gauge cluster. I'll probably also step the sponsons this weekend.

My total cost was about $1925.

• 2002 GP1200R hull w/title: $400
• 2009 VX110 donor w/290 hours: $1150 (very beat up hull)
• 2011 driveshaft and bearing housing: $125
• 2" cable extensions: $50
• SBT seat cover, traction mats; 1300R fuel tank; K&N air cleaner; exhaust couplers; hose barbs; other misc. items: $200

I did have a little trouble with the ribbon delete; I had left out the rubber ring that seals the throttle body and it was revving to 4k at idle. Figured out that the coupler from a 2" pvc pipe cut to the proper length and then inserting the rubber ring fixed the issue.

I'm looking forward to the water test!

[macGruber]

Noice!

[swlamarshrunner]

That's awesome that you didn't even need any kind of special plates to adapt the engine. Did the stock vx110 pump also just bolt right in or any mods needed to make it fit?

[boudin]

That's awesome that you didn't even need any kind of special plates to adapt the engine. Did the stock vx110 pump also just bolt right in or any mods needed to make it fit?

That's right, no modifications. Everything just bolts right in. Once I figured it all out, a super easy conversion, and should be a very reliable GPR that can go 100+ miles on a tank. I still have to water test, and hoping the stock 18/22 VX impeller is the right pitch. It's the impeller that came with the VX and has a few dings, but not too bad of shape, and I did put in a new wear ring. Figure I'd try that first.

After talking to Rich/WFO yesterday, I will probably put on an aftermarket grate for safety, but only if I can hit 63+ mph. Honestly I'll be happy to hit 60 and leave it as-is for now. 63-65 is pretty close to a bone stock 2-stroke GPR, but far, far more reliable.

I can see this being an easy 4-stroke conversion instead of spending the $$$ rebuilding the stock 66V 2-stroke. If you watch Craigslist, you can pickup decent VXs for $2500 or less.

Ready to move on and get my Kawi 15F back on the water.

[steelerz65]

Following! Awesome thread, thanks for posting! I just recently was gifted a 2000 GPR from a cousin. I think it has a bad cylinder, not sure 'cause I haven't picked it up yet. I already own a nice running GP1200 so this build intrigues me. I would love to have a 4 stroke engine in a smaller ski like the GPR...seems like the best of both worlds to me. Please update with performance info as soon as you have had it out on the water and have a chance.

Nice work!

Tim

[boudin]

Runs and rides great, but could only hit 53 mph (basically like a stock VX). I am planning on getting a new Solas prop and pitching it down to 18/24. I'm also having a problem getting the nose out of the water--got to work on trim and the ride plate. Will let you know progress.

[boudin]

Got a new Solas 18/22 prop, and new wear ring. Still low 50s, but a heck of a good holeshot. Really handles well. Calling bunk on it ever getting close to 60 with 110 hp, 8000 RPM and the reduction gear.

Still a great easy build and a reliable GPR that starts instantly even after sitting for a week. I would not hesitate to take this on our 130+ mile river runs (just need to figure out how to carry extra fuel).

My son has two speeds: full throttle and no throttle! Should I be worried about future builds?

https://youtu.be/0VViPsxurtw

[GP123]

Looks good.... does that mean a SHO conversion would also be easy for you to work on ?