- Location
- Hudson River Valley, NY
A PWC is the proof of "rode hard, put away wet"-so how long does an engine last ? Assuming, of course, that you don't sink it or blow it up with mods.
In 1996, I bought the new twin carb SJ 701. I live near water, so since that time, it has been used on average twice a week, often more, in season. I run May-October, water temps willing.
The engine is totally stock except for primer kit. Hull has plate/grate/prop, and a UMI steering kit. Most of my riding is on a river, with some salt. I've ridden surf, but that's a rare treat. The ski has been offshore in New Jersey at Barnegat Light (huge, huge swells), and to Daytona Beach. Even rode with the Mauler, a legit racing champ off Matansas Inlet, Fla. - This toy has not been babied.
I used Mercruiser or Evinrude oil for most of the ski's life, recently going to Amsoil. The Mercruiser is sold at my local boat store...ran 50:1 per instructions. I'd flush after rides, but other than occasional fogging spray and yearly plugs, not too crazy.
Like many of us, I got the dreaded 'bog' two seasons ago. It started only when in a trough of a wave, where you needed to blast over the top. Started and ran fine everywhere else.
We rebuilt the carbs-second time in 20 years...bog still there, got worse over time. This year, Jetski Solutions re did the electrical...the plug wires had turned into carbon at some point....
Bog still there and getting progressively worse...but only when the engine came up to full hot. Rebuilt the Fuel Pump. No change.
Really frustrating, I'd splash, ride for 30 minutes, all good, right up to rev limiter now that the carbs and the sparks were in the right place....but when hot, it would "grab" as if it was fuel starved, or soft seizing. Kinda like you get a 30 minute ride and go home
The engine is OE bore. Third set of pistons....every few years we'd pull the block, see the bores still had the cross hatching, and replace the piston and rings.....so stock bore, stock sized pistons.
Still, the bog. Having literally rebuilt everything in line, we went to SBT and ordered a short block. The folks at SBT called and confirmed everything, and a "new" engine appeared in my driveway three days later.
Now, when I say "we", I mean my brother, who while not a professional mechanic, runs a beautiful X2 and trained with a motorcycle shop who drag raced-let's just say he adjusts his own valves on a Ducati Desmo. I'm a helper who keeps track of the 10 mm wrench and buys beer.
It took four hours, but the engine swap was mostly uneventful - We discovered the back left engine mount was in three pieces after hammering it for 20 years. The back lower exhaust manifold bolt is tight to get to, and we got lucky in that the coupler came off with little problem. The air tools were MVP for fly wheel removal.
Working on break in now, did one session yesterday at easy-easy riding. The SBT short block looked good and everything went together OK. The engine fired immediately. It feels good on the break in ride, but of course WOT and the search for the dread BOG will have to wait.
We didn't do an autopsy, but there was no sign of seizure on the pistons...but we could turn the whole thing over by hand. Compression may have been an issue. Our theory is that when the engine came full warm, the rings didn't seal properly and everything else went out.
Some pix of the process. 20 years on one crank. Yamaha builds junk.
In 1996, I bought the new twin carb SJ 701. I live near water, so since that time, it has been used on average twice a week, often more, in season. I run May-October, water temps willing.
The engine is totally stock except for primer kit. Hull has plate/grate/prop, and a UMI steering kit. Most of my riding is on a river, with some salt. I've ridden surf, but that's a rare treat. The ski has been offshore in New Jersey at Barnegat Light (huge, huge swells), and to Daytona Beach. Even rode with the Mauler, a legit racing champ off Matansas Inlet, Fla. - This toy has not been babied.
I used Mercruiser or Evinrude oil for most of the ski's life, recently going to Amsoil. The Mercruiser is sold at my local boat store...ran 50:1 per instructions. I'd flush after rides, but other than occasional fogging spray and yearly plugs, not too crazy.
Like many of us, I got the dreaded 'bog' two seasons ago. It started only when in a trough of a wave, where you needed to blast over the top. Started and ran fine everywhere else.
We rebuilt the carbs-second time in 20 years...bog still there, got worse over time. This year, Jetski Solutions re did the electrical...the plug wires had turned into carbon at some point....
Bog still there and getting progressively worse...but only when the engine came up to full hot. Rebuilt the Fuel Pump. No change.
Really frustrating, I'd splash, ride for 30 minutes, all good, right up to rev limiter now that the carbs and the sparks were in the right place....but when hot, it would "grab" as if it was fuel starved, or soft seizing. Kinda like you get a 30 minute ride and go home
The engine is OE bore. Third set of pistons....every few years we'd pull the block, see the bores still had the cross hatching, and replace the piston and rings.....so stock bore, stock sized pistons.
Still, the bog. Having literally rebuilt everything in line, we went to SBT and ordered a short block. The folks at SBT called and confirmed everything, and a "new" engine appeared in my driveway three days later.
Now, when I say "we", I mean my brother, who while not a professional mechanic, runs a beautiful X2 and trained with a motorcycle shop who drag raced-let's just say he adjusts his own valves on a Ducati Desmo. I'm a helper who keeps track of the 10 mm wrench and buys beer.
It took four hours, but the engine swap was mostly uneventful - We discovered the back left engine mount was in three pieces after hammering it for 20 years. The back lower exhaust manifold bolt is tight to get to, and we got lucky in that the coupler came off with little problem. The air tools were MVP for fly wheel removal.
Working on break in now, did one session yesterday at easy-easy riding. The SBT short block looked good and everything went together OK. The engine fired immediately. It feels good on the break in ride, but of course WOT and the search for the dread BOG will have to wait.
We didn't do an autopsy, but there was no sign of seizure on the pistons...but we could turn the whole thing over by hand. Compression may have been an issue. Our theory is that when the engine came full warm, the rings didn't seal properly and everything else went out.
Some pix of the process. 20 years on one crank. Yamaha builds junk.
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