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First start after rebuild

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#1
Hey guys,

Finally getting back to my ski. Engine was fully rebuilt a couple months ago. So I'm just wondering how you guys would go about a proper startup?

I'm on premix, so I've gone to 32:1 for the tank. I did pour quite a bit of oil in the cylinders as well a while ago. My main question is, is should I pour some gas I. The cylinders to get her fired up? If so, how much?
 


AKnarrowback

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94 xp
94 sp
94 gtx
#2
If it is going to work it should go without any extra gas down the cylinders. Start it like you would any other day,

The big question is did any extra oil get dripped into all the bearings before closing up the case halves? Is the rotary valve shaft resevoir full? (just do a double check of the two big lines to make sure they are full). Did you bleed the oil injection pump?

Just make sure the oil gets to where it needs to in that first minute of the first start I always hold the oil injection pump arm wide open by hand for the first minute to make sure any bubbles are bled out of the lines between the pump and manifold. If no oil got dripped onto the bearings don't worry just use that oil pump for the first minute. I have never seen an rv shaft resevoir fail to fill on it's own but I always do a double check to be sure. Premix in the tank is good. Take it easy for the first tank full, let the motor break in.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#3
I have no rotary (951 engine). Also not on an oil injection.
 
Last edited:

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#4
The bearings have some oil. Just enough to keep them spinning until normal operation takes over. Other than that, and the oil I poured in the jugs and down the carbs a month ago, she's bone dry.

This is why I'm having trouble starting it. I've got the gas cycling thru the carbs - I just pull the flood line returning to the tank and blow in it until gas come out the carb flood outlet. She still isn't getting the engine wet enough for combustion.

I was also not trying to not keep engaging the starter. Was hoping there's a quicker way to juice it up
 

AKnarrowback

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94 gtx
#5
Do you have gas in the filter/water seperator after cranking the motor over? That will give you an indication that fuel is being drawn out of the tank into the fuel lines. Pull the filter apart and dump any fuel in it, then crank it and see if it fills back up.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#6
Have not tried that. Will give it a whack tomorrow afternoon and report back.
 

mikidymac

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#7
You don’t need any oil down the carbs or cylinders and can actually cause a problem with the rings sealing. Some of the best engine builders suggest cylinders being dry even. I like just enough oil spread by finger to keep them from rusting.

Oil in the counter balancer?

The only thing you need for it to fire immediately is to leave the return line off the carbs. Then blow air into the tank check valve by mouth to pressurize the tank and fuel system. The moment fuel starts coming out of the return fitting on the carb put the return line back on. The ski will fire immediately after that. If it doesn’t something is wrong.

From there check for spark, compression, flooding carbs, etc.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#8
Yeah, gear oil in the CB.

I do exactly what you described to "prime" the engine as well. Maybe I'm just not letting it turn over enough to start catching.
 

mikidymac

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#9
There is no turning over to catch. It should fire immediately.

Did you rebuild the carbs with genuine Mikuni kits and needle and seats. Check popoff and leak down?
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#10
Yes carbs we're rebuilt. Top end only had 10 hours when the crank failed, so I didn't replace anything there.

Just went out to try and fire it up. Gas is cycling thru everything fine. Accelerator pump is squirting well. She won't fire up. She has small blips of combustion won't won't catch to stay running. The head is also warming up after 3 minutes. Does this come down to spark issues?

I trimmed both plug wires also. Didn't touch anything else related to it before/during rebuild. Plugs are new br8es gapped to ski specs.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#13
I don't believe it's flooding. Nothing is getting very wet, no significant gas smells.

It was spitting smoke out of the exhaust earlier, but still wouldn't catch. Waterbox is a bit wet, she was spitting some water out of the exhaust too (think it's old stuff from the waterbox - that's the only piece that didn't come out of the hull during rebuild).

Spark is great. Pulled the plugs and everything is dry, just a small amount of oil on PTO plug. Cleaned them off anyways and dripped 3ml of premix in each jug before firing. Turned it over for a sec before reinstalling plugs as well. That's when it smoked as stated above.

I've tried all variations of choke/throttle as well. With choke/no throttle. With choke/WOT. No choke/no throttle. No choke/WOT. I also pump the accelerator a few times before each try.
 

mikidymac

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#14
You need to check compression. If that is ok then it could be your reeds.

With compression spark and fuel it will run so something is missing.

Are you sure your pistons and rings were facing the correct direction?

Is it cranking over fast, battery good and strong?
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#15
Yes I triple checked piston direction. Also made sure the piston rings were facing the correct way so they wouldn't catch on the holes in the head. (Edit - now that I think of it, I couldn't move the rings, they only had one way to go in around the protrusion on the ring fittings. But I did make sure it wouldn't catch on the cylinders)

I cleaned the old reeds extremely well before reinstalling. Made sure all the flaps were in good shape. That seems to be okay, but I don't know what a defective reed looks like.

Compression is the only thing I didn't check yet. Will do that tomorrow. I just thought I read somewhere it's pointless until after everything is broken in.

I can't think of anything I did differently during the rebuild to hinder it from starting. Front flywheel was lined up according to the markings I made, as well as the marks it left by the holes when removed. This was also aligned differently than the manual had, but I made a post about that here and confirmed they had two different alignments on the 951s.

The carbs had been sitting, even after I rebuilt them. Didn't plan on it, but my day-to-day kept me from getting back to the ski. So let's just say a needle is stuck somewhere, would it keep this thing from starting even after putting some fuel in the jugs? Even if only firing for a second or two?

Was also mentioned to me that oil can sit in the crankcase and cause issues? Is this a possibility after having sat for a while?

Cylinders seem quite dry. Turned her over without plugs in and nothing. When I pulled the plugs today, from after trying to start yesterday, like I said PTO had a drip of oil on it, and the MAG plug was clean. I'm wondering if clean is a bad thing in this case.
 

Ryan727

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Water Crafts
1999 Seadoo GTX Limited 951 (x2)
#17
Some sort of combustion took place, because smoke came out of the exhaust. But no, it would not fire up.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#18
I don't know how much people normally dump in there to get it running. I did 3ml in each jug, then turned it over without plugs in just in case. That's when I reinstalled the plugs and it combusted whatever was left in there I guess?
 

mikidymac

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#19
Dumping a little fuel in each carb should get it to fire for a couple seconds if everything is correct.

Did you actually take the flywheel apart?
If you don’t have the cup clocked correctly with the ring gear of the flywheel it will not be sparking at the correct time causing your exact symptoms.
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#20
That's what I'm talking about. I reassembled it the exact way it came off, which was different then the manual. Really good ski shop told me to reassemble it the same way it came off, as well as someone here when I posted about it. They said if it worked when it came off, put it back on the same way
 

Ryan727

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1999 Seadoo GTX Limited 951 (x2)
#21
@mikidymac here was my flywheel. You can see the tiny hole on the flywheel is far more clockwise from the knob on the cup compared to the manual. The cup I marked with a Sharpie during removal, you can see below. There was also a large imprint from the holes in the cup exposing that part of the flywheel for the last 20 years, and the rest of it wasn't. Therefore, it was very easy to line it up as it was for the last 20 years.

IMG_20180929_202340.jpg
 

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