2001 RX Reboot Project – MPEM related question

[thejuice48]

Two reasons on the 951.
1. The carbs are mounted low in the hull and with open air filters they can and do suck in water which will ruin a 951.
2. They reduce the intake vacuum signal making the already lean 951 carbs even more lean. A lean 2-stroke is not a happy 2-stroke.

951 carbs explained by Group K....
Flame Arrestors – While the installation of aftermarket flame arrestors has been a very popular modification for many recreational pwc’s, we do not use or recommend them on our Swift Kit or Y2K Sleeper Kit. The technical reasoning for this choice is related entirely to the stock carbs used on the 951 engines. The carbs used on all 951s are the first generation of a carburetor that is designed as much for emissions friendliness as it is for performance. Among the most notable design features that make this difference, is the significantly increased distance between the butterfly and the “booster venturi” style fuel atomizer (aka “bombsight” atomizer). We cannot claim to know all the effects of this design departure, however we know a lot about one particular effect called “fuel delivery signal”.

In short, signal is the amount of vacuum within the inlet tract that helps to draw fuel from the metering circuits in the carburetor. The air restriction of the stock flame arrestor serves greatly to keep that vacuum very high. This high vacuum actually helps the quickness of throttle response at all engine speeds. When a free breathing flame arrestor is installed, this vacuum (aka signal) is reduced. The reduced signal means a slightly leaner fuel mixture through the entire range. This is normally not a dangerous issue for most pwc engines. However the emissions-conscious stock 951 carbs have an exceptionally weak signal at ¾ throttle opening. This means that a more open arrestor will cause the 70 – 80% throttle range become “a lot” leaner than the rest of the range. There is no jetting that can solve this problem (we tried). The “only” effective solution is to leave the stock flame arrestor (with the bolt on air horns) intact. Despite the restrictive appearance of the stock arrestor, it can easily pass enough air volume for excellent performance up to the 7140 rev limiter. The stock arrestor has received an undeserved reputation as “choking” the 951 into a bad rich condition. In truth, the rich condition is a correctable jetting issue, not an air access issue.

I have never ran into a lean condition issue or piston damage to due sucking water that I know of.

PPG milled the head, did the flame arrestors (Level I) in 2006/2007 with over 300 hours on the original engine. The top end then basically blew up and they blamed it on the number of hours. Then it blew up again during break in period, with 3 - 5 hours which they tried to say I was riding it too hard and I wasn't. Then they replaced top end and said the crank blew so they put in a racing crank. So the ski has a new top end, new crank. When I took it for the break in maintenance, I caught them doing an "oil change" on my two stroke engine which I had just filled with the fully synthetic bombardier oil at the time. It later changed to semi-synthetic so I drained and switched to Amsoil. I yelled, screamed, bitched moaned, and quit taking it to PPG. The engine gremlins seem to have disappeared after that.

I have had flame arrestors on it (rather than the factory airbox) since approximately 2007. I inspected the pistons and head in 2011 and again in 2016. No pitting or damage to the cylinders or pistons which would be indicative of a lean condition.

Generally though, I don't have water running through my hull. If I see an inch in there without me putting it there, I fix the problem. When I have put water in the hull to cleanse it, I never put any water in there past the center indent and even then it has been on a trailer where I could suck the water out with a wet vac and open the drain plugs.

I love CRC 6-56 rather than bombardier fogger and stuff like that. Seafoam Deep creep for really bad break loose quick stuff.

 

[etemplet]

It's your ski.

Two reasons on the 951.
1. The carbs are mounted low in the hull and with open air filters they can and do suck in water which will ruin a 951.
2. They reduce the intake vacuum signal making the already lean 951 carbs even more lean. A lean 2-stroke is not a happy 2-stroke.

951 carbs explained by Group K....
Flame Arrestors – <snip>

Most excellent informative post..

 

[JC-SUPERJET]

" I caught them doing an "oil change" on my two stroke engine which I had just filled with the fully synthetic bombardier oil at the time."

Seadoo Oil is worth stealing

300 hours on a 951 Seadoo Two Stroke is amazing, even for a Yamaha. But definitely too old & tired for any Engine Performance Upgrades.

951 Top End jobs almost always need a Fresh Crankshaft due to Crank Bearing contamination with Piston Pixie Dust. So basically, there is no such thing as a Top End Rebuild on a failed 951 Top End, just an Engine Rebuild, plus a Carb Rebuild...

Some "flush" the Crank Bearings to get a few more Hours out of their Crank, but there is no telling how long the Crank Bearings will last.

I'd say after 3 to 5 hours of easy run time, that fresh Engine is definitely past the break-in period.

And for some weird reason, the 951s do love to inhale Water. A Left Hand Turn. Maybe those big Pistons draw a big Vacuum. Maybe it's the Carbon Seal failures that flood the Engine underway. Low hanging Carbs. Or All of the Above.

My Used 98 XP Ltd. came with Flame Arrestors plus Pre-Filters/Outer Wears, which are supposed to be Water Resistant/Repellent. But I only ride on Flat Freshwater.

Bone Stock Two Stroke Seadoos are awesome. So much Horsepower per Cubic Centimeter. The Cylinders are a Work of Art. Most HP of ALL Stock PWC Makers. Basically, a Sleeper Big Bore Stroker (that's why it comes with a Counter Balance Shaft).

 

[mikidymac]

I have never ran into a lean condition issue or piston damage to due sucking water that I know of.

PPG milled the head, did the flame arrestors (Level I) in 2006/2007 with over 300 hours on the original engine. The top end then basically blew up and they blamed it on the number of hours. Then it blew up again during break in period, with 3 - 5 hours which they tried to say I was riding it too hard and I wasn't. Then they replaced top end and said the crank blew so they put in a racing crank. So the ski has a new top end, new crank. When I took it for the break in maintenance, I caught them doing an "oil change" on my two stroke engine which I had just filled with the fully synthetic bombardier oil at the time. It later changed to semi-synthetic so I drained and switched to Amsoil. I yelled, screamed, bitched moaned, and quit taking it to PPG. The engine gremlins seem to have disappeared after that.

I have had flame arrestors on it (rather than the factory airbox) since approximately 2007. I inspected the pistons and head in 2011 and again in 2016. No pitting or damage to the cylinders or pistons which would be indicative of a lean condition.

Generally though, I don't have water running through my hull. If I see an inch in there without me putting it there, I fix the problem. When I have put water in the hull to cleanse it, I never put any water in there past the center indent and even then it has been on a trailer where I could suck the water out with a wet vac and open the drain plugs.

I love CRC 6-56 rather than bombardier fogger and stuff like that. Seafoam Deep creep for really bad break loose quick stuff.

Just answering your airfilter question as to why.

If it has been working for you for this long I would be hard pressed to change anything as well.
Just don't let your friends borrow the ski, that's how most of them ingest water it seems.

Also talking in general, nobody should have ever done any performance mods on a 951 with 200 hours let alone 300 hours, it is always the kiss of death. For the average rider nobody should modify a 951 just as @JC-SUPERJET indicated.

 

[thejuice48]

Just answering your airfilter question as to why.

If it has been working for you for this long I would be hard pressed to change anything as well.
Just don't let your friends borrow the ski, that's how most of them ingest water it seems.

Also talking in general, nobody should have ever done any performance mods on a 951 with 200 hours let alone 300 hours, it is always the kiss of death. For the average rider nobody should modify a 951 just as @JC-SUPERJET indicated.

It's funny you should say that. PPG moved from Fort Lauderdale to Lake City and I called up to get my invoices and Glen tried talking me into bringing my ski to Lake City to be completely worked over. No thank you.

 

[thejuice48]

Just answering your airfilter question as to why.

If it has been working for you for this long I would be hard pressed to change anything as well.
Just don't let your friends borrow the ski, that's how most of them ingest water it seems.

Also talking in general, nobody should have ever done any performance mods on a 951 with 200 hours let alone 300 hours, it is always the kiss of death. For the average rider nobody should modify a 951 just as @JC-SUPERJET indicated.

On a side note, I was watching the videos of the idiots at the 79th Street Boat Ramp, Haulover inlet, and Haulover marina the other day. It is no wonder so many skis end up sunk. It truly has gotten worse.

 

[WhiskeyD]

Delete the AP and rejet for the FA. I remove that bulky airbox on all my skis, especially 951s because it makes carb tuning a PIA. Stock skis it doesn't really matter, just leave it since you wont be tuning all the time.

 

[thejuice48]

" I caught them doing an "oil change" on my two stroke engine which I had just filled with the fully synthetic bombardier oil at the time."

Seadoo Oil is worth stealing

300 hours on a 951 Seadoo Two Stroke is amazing, even for a Yamaha. But definitely too old & tired for any Engine Performance Upgrades.

951 Top End jobs almost always need a Fresh Crankshaft due to Crank Bearing contamination with Piston Pixie Dust. So basically, there is no such thing as a Top End Rebuild on a failed 951 Top End, just an Engine Rebuild, plus a Carb Rebuild...

Some "flush" the Crank Bearings to get a few more Hours out of their Crank, but there is no telling how long the Crank Bearings will last.

I'd say after 3 to 5 hours of easy run time, that fresh Engine is definitely past the break-in period.

And for some weird reason, the 951s do love to inhale Water. A Left Hand Turn. Maybe those big Pistons draw a big Vacuum. Maybe it's the Carbon Seal failures that flood the Engine underway. Low hanging Carbs. Or All of the Above.

My Used 98 XP Ltd. came with Flame Arrestors plus Pre-Filters/Outer Wears, which are supposed to be Water Resistant/Repellent. But I only ride on Flat Freshwater.

Bone Stock Two Stroke Seadoos are awesome. So much Horsepower per Cubic Centimeter. The Cylinders are a Work of Art. Most HP of ALL Stock PWC Makers. Basically, a Sleeper Big Bore Stroker (that's why it comes with a Counter Balance Shaft).

I don't think the oil was worth stealing more than it was just some "tech" they told to a 3 - 5 hour check on and the person didn't know it was a 2-stroke rather than 4 stroke.

I had a carbon seal fail on one of my SPX's. Ever since I keep a really good eye on the grease, position and general area.

Good thing about smaller skis is you can actually lift up the seat under way in calm water and check on what you have going on in the hull.

 

[thejuice48]

Delete the AP and rejet for the FA. I remove that bulky airbox on all my skis, especially 951s because it makes carb tuning a PIA. Stock skis it doesn't really matter, just leave it since you wont be tuning all the time.

You mean delete the Airbox? Airbox has been gone. All that was performanced tuned eons ago. At this point, I just want to get it on the water again, and then MAYBE I'll play with settings.

 

[mikidymac]

You mean delete the Airbox? Airbox has been gone. All that was performanced tuned eons ago. At this point, I just want to get it on the water again, and then MAYBE I'll play with settings.

He is saying to delete the Accelerator Pump and rejet the carbs to work with the Flame Arrestors.
PPG should have done all of that as part of their "Performance Package".

 

[thejuice48]

He is saying to delete the Accelerator Pump and rejet the carbs to work with the Flame Arrestors.
PPG should have done all of that as part of their "Performance Package".

Ok.

 

[thejuice48]

Well, I really don't have much faith in any shop at this point. After the top end went 3 times and PPG tried to blame me, I came out one morning to smell gas really strong. Searching around, I found a fuel elbow in the fuel line where it was not supposed to be after them charging me for all new fuel lines. The elbow had popped a hole in it and was leaking fuel. See pics below on my google drive.

fuel elbow – Google Drive

When I asked them where on the parts schematic this came from, they denied installing it. I certainly didn't.

At that point, I would merely pick the ski up from their shop, take it to the boat ramp, and return it to my floating docks.

 

[JC-SUPERJET]

Did they install new Tempo Lines? Replaced Old Tempo Lines with New Tempo Lines?

Amazed that the Tempo Fuel Lines weren't eliminated.

Tempo Lines are a well known defective Product that breaks down internally into a slimy sticky goo that clogs Carburetors, Fuel Lines and kills Engines.

That Plastic Elbow Fitting looks like the Anti-Siphon Elbow used in the Bilge System. It comes with a Pin-hole...

 

[thejuice48]

Did they install new Tempo Lines? Replaced Old Tempo Lines with New Tempo Lines?

Amazed that the Tempo Fuel Lines weren't eliminated.

Tempo Lines are a well known defective Product that breaks down internally into a slimy sticky goo that clogs Carburetors, Fuel Lines and kills Engines.

That Plastic Elbow Fitting looks like the Anti-Siphon Elbow used in the Bilge System. It comes with a Pin-hole...

I know I was charged for new fuel lines. Not sure they (PPG) actually installed new fuel lines. They also added that elbow as well, or it came factory because I surely didn't install it, and it was there. Obviously I removed it upon finding it. I was pissed. That's one of the reasons I called tot ry and get all my invoices. The copies I have are no longer readable.

 

[thejuice48]

Just got a call back / message from Glen. All of a sudden they don't have any receipts from that far back. If SBT has them from my 1997 ski for a new engine (2000), how do you not have receipts in your computerized system? Anything I could sue for the statue of limitations has long run out.

Hmmm.

 

[thejuice48]

I was looking back through pictures today and realized I had this pic when PPG first did the level 1. This was how I got it back....notice the writing in marker on the head including compression for each cylinder.

 

[mikidymac]

I know back in the day some builders used to lower the compression in the rear cylinder because the crank would actually twist and cause detonation in the rear cylinder so lowering the compression would help with this. Yamaha even did it on the OEM 760 engines but I have not seen anyone do it on a Seadoo.

 

[thejuice48]

So as of today, got the VTS all back together. Reinstalled the reprogrammed MPEM. Installed the newly replaced battery. Used key that didn't work before. Got the double-beeps. Meaning the MPEM recognizes the key on the DESS post. So if you need the DESS feature removed and/or reprogrammed to accept any key, the guy in MN is your person.

I need to go buy another key shortly.

Because the bracket for the rear electrical box was toasted, I tie wrapped it the electrical box to the top of the FIBERGLASS hull just to see if I could get it started.

Go to start it and I get one clunk from the starter, and that's it. One time I got two chunks.

Since I've already replaced the starter relay. I'm thinking I have a bad starter.

 

[thejuice48]

Video here:

20230324_161514.mp4

 

[mikidymac]

Verify you can turn the engine over by hand with the sparkplugs out.
Could be a locked up pump or crank, verify before messing with the starter.

 

[thejuice48]

Verify you can turn the engine over by hand with the sparkplugs out.
Could be a locked up pump or crank, verify before messing with the starter.

Did you listen to the video?

I was never able to turn the engine over by hand. 951s are a much harder to turn over than the smaller 787s. Even when I greased the PTO. I would have to turn the engine over till I had clear access. I have very weak hands. I tried with a pipe wrench the other day but didn't seem to do anything but damage the bolts around the PTO because I couldn't get a grip with a pipe wrench and broke off the zerk fitting.

The freaking thing was running when I rode it to the dock to put it in the garage. It even ran after. The pump would have less than 10 hours on it.

 

[mikidymac]

I have always been able to turn my 951 over by hand with the plugs out.
With a wrench it should be no problem at all. I think you have something mechanical wrong.
Stuck pump, stuck starter bendix, bad crank or bad balancer are some suspects. The starter clunk is a clue too.

 

[etemplet]

Yep should turn over by hand with the plugs out even with the pump attached. If it doesn't something is binding.

 

[thejuice48]

Here's my line of thinking:

At this point I'm opting for the non full ballistic route and feel I'm making forward progress.

I'm getting a kachunk. If I remember correctly back from my days with the 787's that one heavy kachunk meant bad starter. Which would make sense. The starter is original. The ski top end and crack were replaced around 325. Over 6 years, it was used about 54 hours per year. At 325 hours, the "upgrade" was done, which caused the top end to be replaced 3 times, crank once. I stopped having problems with the top end when I found that elbow in the fuel line and swapped out the fuel line.

The guy I sent my MPEM to, indicated the MPEM has 490 hours. So in between the initial build and break-inS, its had key on 165 hours. An engine should not blow up / lock up in that time. I originally had 325 hours on it and nothing was wrong with it when I took it for a performance upgrade.

Our riding style was take it out, ride it to an island to meet friends, hang out on island, ride to another area with friends, etc. We spent maybe 3-4 hours riding and key on per day out. I would also take it out during the week just to relax. So 55 days, of 3 hour use since 2007? That's 10 hours a year. I don't even think I broke a motor mount while using it.

The pump I replaced in 2011, and didn't ride it much after that. Old pump pics: 2011_05 – Google Drive

Replacement pump: 2011_05 new pump – Google Drive

The pump, the pushers, the cone, etc. were all new. I used Klotz oil and even changed it after 5 hours to check it. Again, it sat on a floating dock but did run when I moved it from the dock to the trailer to the work dolly and then to the garage. I could have mussels up in the pump area which are stopping it from turning and causing lockup. 382408_4216984631803_1378315200_n.jpg The canal I was living on was ridiculous for mussel growth on the pilings, my floating dock, and even on the lip of the floating dock to pull up. I still have a few on the ride plate. So it's very possible the jet pump is locked up.

When I worked on the VTS in 2016, was the last time it started and ran. Right after a storm which completely swamped the dock, broke the floating dock off causing me to move it from the floating dock to the garage . Again, sat in garage, so it would give a chance for the mussels to die and turn into hardened fossils.

Yesterday, as the sun was going down and the battery was dying in my flashlight/stun gun I took a peak in up the back of the pump and saw what looked like blood but that's not possible. So perhaps something rusted really bad in the pump somehow. I know I didn't over tighten the allens in the pump cone.

Perhaps I'll pull the pump first rather than the starter. If I pull the pump and can turn the engine over, then it's the pump that's locked.

If I do have to replace the engine, it would be common sense to replace the starter as well anyway. At least I can remove and test it. What's two allen bolts and a bunch of acrobatic maneuvers at this point anyway?

However, I know I cannot lift a 951 engine in and out myself, so I would need to borrow a friend's engine lift and I'm not sure if he has it in use or not nor how long I would need it. I'm also working in an outside environment so I have to be weary of rain. Right now I'm organizing by mini bolt bins and storage bins as I take it apart and put it back together, and even now I sometimes second guess myself.

I can pull the head and inspect the pistons again, but more gaskets.

BTW, does anyone know of the VTS should go up/down with the key on the DESS or only when running?

 

[etemplet]

VTS will operate normally within the 33 second time frame when you hit the start button without the key. If it doesn't insert the key.
As you say, I'd pull the pump first thing but I disassemble every starter for the skis to make sure the internals are clean and working.

I was not able to view the video.