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951 / 947 Break In

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amcreativ

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Hi Guys, what an amazing forum you have here. So many knowledgable folks!

I just had my 1998 GTX Limited with a 951 blow a hole out the bottom of the motor. It appears I had a failure in the counter balance crank, which sent debris flying everywhere inside the seadoo. I have a reman 951 coming from CV Tech out of Quebec, Canada tomorrow. They send a kit of new gaskets and some kind of break-in oil. Would I be smart to use this oil they send or stick with some type of 30w HD oil? What do the experts around here suggest? I'm sure you've you answered this a million times and I truly apologize if it's been beaten to death.
 
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Uhmmmm......10W-30? Is this what made your engine blow up. You have a 2-stroke so the only oil that should touch it is a API-TC rated full synthetic oil.
 
mikidymac said:
Uhmmmm......10W-30? Is this what made your engine blow up. You have a 2-stroke so the only oil that should touch it is a API-TC rated full synthetic oil.
Click to expand...

I have read that people have used 30w HD motor oil in the counter balance crankcase. I have always used Amsoil Interceptor oil in the Oil Injection Tank. It blew up because the seadoo took on water.
 
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Oh, that makes sense. For the balancer just use standard 30w HD motor oil. It's pretty cheap and easy to find.
 
Lol Miki,

When cv tech sends engines out they are usually dry so check the counterballance cavity if they did in fact put anything in there.
They sometimes send castor oil as well for break in.

For breaking it in set everything up as normal and do heat cycling.
Start, idle around, start going up in throttle and then back off amd repeat. Gradually increasing max throttle each time. 5 hours later you can reach full throttle bursts followed by cool downs.
After 10 hours of easy running you can start longer higher throttle runs.

The idea is to heat up the engine and get the parts to expand and if some parts expand to the point they touch and wear in, you want that process to be as slow as possible which is why the heat up and cool down cycles.
 
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Mekanix said:
Lol niki,

When cv tech sends engines out they are usually dry so check the counterballance cavity if they did in fact put anything in there.
They sometimes send castor oil as well for break in.

For breaking it in set everything up as normal and do heat cycling.
Start, idle around, start going up in throttle and then back off amd repeat. Gradually increasing max throttle each time. 5 hours later you can reach full throttle bursts followed by cool downs.
After 10 hours of easy running you can start longer higher throttle runs.

The idea is to heat up the engine and get the parts to expand and if some parts expand to the point they touch and wear in, you want that process to be as slow as possible which is why the heat up and cool down cycles.
Click to expand...

Do you believe in doing some gas/oil mix for the break in, which will run rich and foul plugs for at least a tank of gas. Or keep it just gas and oil injection as normal?

I'm not taking any chances on the counter balance cavity and filling it up with 30w HD motor oil. 40ml from what the shop manual says.
 
Mekanix said:
Lol niki,

When cv tech sends engines out they are usually dry so check the counterballance cavity if they did in fact put anything in there.
They sometimes send castor oil as well for break in.

For breaking it in set everything up as normal and do heat cycling.
Start, idle around, start going up in throttle and then back off amd repeat. Gradually increasing max throttle each time. 5 hours later you can reach full throttle bursts followed by cool downs.
After 10 hours of easy running you can start longer higher throttle runs.

The idea is to heat up the engine and get the parts to expand and if some parts expand to the point they touch and wear in, you want that process to be as slow as possible which is why the heat up and cool down cycles.
Click to expand...
Mel,,,you are right on,,,increasing the pressure/heat,,,gradually,,,on the rings/Pistons in the cylinders,,,
 
Keep in mind when you add oil you are making the (air/fuel) mixture leaner.
Oil is displacing the fuel for a given volume so when you say rich and lean that usually always refers to the volume of fuel vs air.

If you break it in slow it doesnt lean out enough to matter.
I typically break mine in hard when I build them purposefully for that .
I use the excess oil from harder acceleration to make up for not mixing.
 
For break in as long as you have carbs premix the first tank at 50:1 even with oil injection.

First 1/2 of the first tank no more than 1/4 throttle varying the rpm for 15 minutes then let cool for 30 minutes and repeat this until 1/2 tank. Next 1/2 of the first tank up to 1/2 throttle doing same varying throttle and heat cycles.

Next full tank straight gas and only oil injection. First half up to 3/4 throttle. Varying rpm and heat cycle. Last half of tank up to full throttle but never hold it wide open varying throttle and heat cycling.

Now break in is completely done.
 
Yup, I agree with Miki.

As opposition to this method I tried the motoman way as well on a machine I'm currently running. Pretty much full throttle from first start and no mercy. 10 hrs later no change in performance. This is intentional though just to see what happens. After another 10 hrs I'm pulling it apart to see what it looks like. (951 in an 98 xp)
 
I learned my method from Harry at Group K back in the 90’s and he built the winningist endurance race skis. Also Seadoo didn’t use Teflon rings like the Japanese so their break in for the rings takes longer.
 
So today's break-in mostly successful. It tends to bog down and stall if I push the throttle from idle. Its idling 1350 to 1400 in water. Checked the plugs and they look remarkable for running 50:1 and injection. The bogging down got worse as the day went on. Sometimes it would clear up at the higher end after a quick take off. Never hit faster than 45 kmh and not over 5200 rpm. I'm still only at a half tank after being on and off the water since 9:30 AM. Now keep in mind, it isn't all the time, more time running okay than not. I did find it would do it more on start after a cool down period sitting.

Out of water, it doesn't bog down whatsoever. It idles around 3300 to 3700 rpm and the throttle is snappy as ever. But as soon as it's in the water, it bogs down but as I mentioned above, intermittently.

I took it out of the water for the day to prevent any possible damage.

Any ideas what could be going on?

 
Sounds like the pump is not working, the low speed adjuster may be too far in or there is an issue with the carbs themselves being way too lean on low end.
 
Mekanix said:
Sounds like the pump is not working, the low speed adjuster may be too far in or there is an issue with the carbs themselves being way too lean on low end.
Click to expand...

Thanks for the reply! I took it back out again today and it seemed a bit better when it was cooler, but then as the day went on, it got worse. But that could just be me. I'm at a half tank now, so I was able to open the throttle a bit more. It certainly doesn't have the low end power the previous engine had before the counter balance shaft snapped and bearings blew out. But once it's up to speed and flattens out on the water, it wants to go like it usually does, nice and fast. However, Lake Ontario was about 4 to 5 foot waves and I was constantly bogging down before I took it off the water, but never fully stalled. Maybe worse when going against the waves. Again, could just be me being hyper aware or paranoid.

I did adjust the idle in the water to sit around 1500, but now if I let off the throttle, it hangs at 2100 for a good 5 seconds or more then finally settles back down to 1500. Before hand, it was down around 1350 to 1450. 3100-3300 out of the water. Now with the idle set at around 1500 in water, out of water it's up around 4000.

I did notice some smoke coming out of the tuned pipe where the two pieces come together at the big clamp. I will have to readjust that without a doubt.

I'm hoping I don't have to pull the tuned pipe out, the airbox, and rip the carbs apart. Or worse, I hope it isn't electrical. We didn't pull the carbs apart when we had them off the old motor and onto the new.
 
The tuned pipe leaking could be the cause of your problem. I did mine last year, pretty easy. For me it was way easier to remove the tuned pipe completely to get all of the old selaent off rather than trying it in the ski. Use permetex ultra copper RTV sealent. You may have to lossen the exhaust bolts to line it up. The torque pattern is in the manual. Make sure to put the copper ring back in after you get all old selalent out.
 
Mraw said:
The tuned pipe leaking could be the cause of your problem. I did mine last year, pretty easy. For me it was way easier to remove the tuned pipe completely to get all of the old selaent off rather than trying it in the ski. Use permetex ultra copper RTV sealent. You may have to lossen the exhaust bolts to line it up. The torque pattern is in the manual. Make sure to put the copper ring back in after you get all old selalent out.
Click to expand...

Thanks for your help! I will definitely give it a go again, scrape off the sealant we put on, put fresh sealant on and try again.
 
I took video of each carb, while pushing the throttle and Im getting fuel spraying into the carb. This is with the machine off, airbox off, etc... Is it a different animal altogether if it's running?

If the accelerator pumps weren't functioning, clogged, would I see no fuel coming out?
 
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