97 GP1200 - Should I fix it or let it go

[CJ River Rider]

Below are pictures from a 97 GP1200 of which I bought used in 2007.


The ski gave me nothing but trouble until Rudy @ R-Rated cleaned and adjusted the carburetors in the spring of 2008. The ski ran well (less a stator replacement in 2009) until last year. Compression readings were 60-120-120. As you can see below, piston 1 is beat up and missing part of one ring. Cylinder walls look OK and looking down into the crankshaft looks OK.


I'm debating to fix her or get rid of her as I ride my 2008 STX-15F and my kids don't ride with me anymore as they got older. Before I decide what to do, I have some questions that hopefully your answers will help me decide.


1. Do I just replace the front cylinder and rings or should I replace them all? If all, I would assume a top end re-build kit would be the way to go. Can anyone tell if these are the factory pistons by the markings in the castings? Yamaha's web site lists different pistons and rings and I'm not sure which one to order.


2. Is there a way to tell if there is additional damage to the crankshaft or lower engine before I do anything else?


3. Do I purchase a whole new cylinder head or can it be-ÔÇ£re-groundÔÇØ out? If a new head is required, do I keep the existing cylinder head top?


4. Will the carbs have to readjusted?


5. Is there anything else I should be doing or asking about (forgive me if I'm being a bit too naive)?


I should also mention the ski needs a new impeller (It's cavitating on takeoff) and the steering cable broke/rusted out in storage.


The ski has (installed by others) K&N flame arrestors with re-jetted carbs, Worx sponsons, shock absorbing steering, R&D ride plate/ intake grate, premix kit, and solas impeller.


Thanks in advance for your comments or suggestions. Here is a link to more pictures:

https://www.dropbox.com/gallery/37041497/1/Old_JetSki_ReBuild?h=76ca66

[Glenn Briglio]

Below are pictures from a 97 GP1200 of which I bought used in 2007.


The ski gave me nothing but trouble until Rudy @ R-Rated cleaned and adjusted the carburetors in the spring of 2008. The ski ran well (less a stator replacement in 2009) until last year. Compression readings were 60-120-120. As you can see below, piston 1 is beat up and missing part of one ring. Cylinder walls look OK and looking down into the crankshaft looks OK.


I’m debating to fix her or get rid of her as I ride my 2008 STX-15F and my kids don’t ride with me anymore as they got older. Before I decide what to do, I have some questions that hopefully your answers will help me decide.


1. Do I just replace the front cylinder and rings or should I replace them all? If all, I would assume a top end re-build kit would be the way to go. Can anyone tell if these are the factory pistons by the markings in the castings? Yamaha’s web site lists different pistons and rings and I’m not sure which one to order.


2. Is there a way to tell if there is additional damage to the crankshaft or lower engine before I do anything else?


3. Do I purchase a whole new cylinder head or can it be-“re-ground” out? If a new head is required, do I keep the existing cylinder head top?


4. Will the carbs have to readjusted?


5. Is there anything else I should be doing or asking about (forgive me if I’m being a bit too naive)?


I should also mention the ski needs a new impeller (It’s cavitating on takeoff) and the steering cable broke/rusted out in storage.


The ski has (installed by others) K&N flame arrestors with re-jetted carbs, Worx sponsons, shock absorbing steering, R&D ride plate/ intake grate, premix kit, and solas impeller.


Thanks in advance for your comments or suggestions. Here is a link to more pictures:

https://www.dropbox.com/gallery/37041497/1/Old_JetSki_ReBuild?h=76ca66

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Can't really tell from pics how bad cylinder is damaged . I would replace all pistons and hone block .25mm. Use oem gaskets when rebuilding ,not the WSM I see in pics. Go thru bottom end and change crankcase seals and use oem parts. Check for vacuum leaks after assembling. Recheck carbs for anything strange.

[CJ River Rider]

Can't really tell from pics how bad cylinder is damaged . I would replace all pistons and hone block .25mm. Use oem gaskets when rebuilding ,not the WSM I see in pics. Go thru bottom end and change crankcase seals and use oem parts. Check for vacuum leaks after assembling. Recheck carbs for anything strange.

OK, thanks. Getting at the crankcase seals requires quite a bit more dis-assembly according to the shop manual? What about the cylinder head, new or re-finished? Just the head or the head & top?

[Glenn Briglio]

You have a pm.

[vomitspot]

if you part it ill take the carbs
pm me if so
jason

[Adam]

This is a relatively easy fix, first check the fuel pump on number 3 carb. Check valve has failed causing a lean seizure. The aluminium will sand off the bore with some fine wet&dry sandpaper and some wd40 to lubricate it. New piston and rings and cleanup of the pitting in head with a dremel tool with a sanding disk. Thats the cheap way, you could get another head pretty cheap on ebay and replace all 3 piston's and rings ,new gaskets and replace the check valves in all 3 carbs ! Most important or will happen again first time out.

[97GPSLEEPER]

I have 340 hrs on my Group K motor, same rings & pistons, everything is untouched. They are very reliable when built and set up right.

[big raider]

I have 340 hrs on my Group K motor, same rings & pistons, everything is untouched. They are very reliable when built and set up right.

you forgot to tell them you have spent another 340 hrs laying underneath sleeper figuring out how to make it go faster and that's why you are the master

[crashhard]

The cylinder looks pretty good but you need to have the cylinder checked and honed at a machine shop. Then 3 pro-x piston kits and a gasket kit and oem crank seals. Tear down the complete motor clean everything and re-assemble. Get a new head its $100. Then rebuild the carbs. All said and done your looking at right around $800-850 for a good reliable ski for someone else to ride with you.

[CJ River Rider]

Thanks guys, changing the crank seals concerns me a bit. Is taking the engine out that hard? The shop manual shows it in 1 page and according to the SBT R/I, it does not appear to be too bad. Am I already half way there in what i have removed so far?

I've re-built carbs (automotive) before, but back when I was a kid many moons ago but never a triple carb set-up.

I've got to get the ski back in the garage again and re-evaluate.

Thanks again everybody for your advice and help.

[moo_r32]

verry easy to pull motor mate!! your pretty much done alreaddy! undoo the electrical box and sit it on top of ur motor and unplug the 3 (maybe 4) plugs near fuel tank that lead to electrical box (ull see them) pull thepostive and negitive battery teminal through and sit on top of mator (they are attatched to elec box) then just undo the engine mounts (i undo the 8 bolts at bottom of the mounts so all the shims stay in place or you could just undo the 4 bolts but if you do make sure to keep shims where u found them and dont mix up)

hadest bit is working out if u bolt the boars back on so you can put head on to use the hook on top to lift it out or give a mate a beer or two to come help you lift it ()bottom end is verry light!!)

[CJ River Rider]

verry easy to pull motor mate!! your pretty much done alreaddy! undoo the electrical box and sit it on top of ur motor and unplug the 3 (maybe 4) plugs near fuel tank that lead to electrical box (ull see them) pull thepostive and negitive battery teminal through and sit on top of mator (they are attatched to elec box) then just undo the engine mounts (i undo the 8 bolts at bottom of the mounts so all the shims stay in place or you could just undo the 4 bolts but if you do make sure to keep shims where u found them and dont mix up)

hadest bit is working out if u bolt the boars back on so you can put head on to use the hook on top to lift it out or give a mate a beer or two to come help you lift it ()bottom end is verry light!!)

Thanks Moo, Crash, Adam, Glenn, & GP Sleeper. Got her out yesterday, it was as easy as you said moo. I assume the next step is to get the flywheel and pump coupler off to open the case and change the seals?

A friend of mine suggested replacing the bearings. What do you think, or do they have to be seen first? I see the front bearing is over $100.00. I'll post some pictures when I get the case apart.

[Glenn Briglio]

Thanks Moo, Crash, Adam, Glenn, & GP Sleeper. Got her out yesterday, it was as easy as you said moo. I assume the next step is to get the flywheel and pump coupler off to open the case and change the seals?

A friend of mine suggested replacing the bearings. What do you think, or do they have to be seen first? I see the front bearing is over $100.00. I'll post some pictures when I get the case apart.

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Get it apart and see how the bearings spin and if there is trash in them. Definetely change the seals and pressure test after reassembly.

[moo_r32]

one thing i have learnt is that pressure testing a fresh motor is a must!! it prevents ALOT of headaches! wish i had done it on my first re-build!!!

[CJ River Rider]

Thanks guys, I definitely intend to test it after everything is done. Now I just have to get a hold of a flywheel puller, hopefully borrow not buy. I can get a pipe wrench to get the coupler off from where I work.