Mag side piston running lean on 587

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La Verne
Water Crafts
1992 Seadoo SP
#1
Just pulled my heads off today as I’m prepping for the season and I noticed that my mag side piston is running a little lean compared to the pto side. There’s some minor carbon buildup and definitely not enough where I should be worried but I only have about 8 hours on a full engine rebuild so I’d like to prevent the possibility of any other problems. Any information is always appreciated.
Here’s a list of everything I did and some parts I installed/previously had

Sent cylinders to Fullboreonline.com
Wossner pistons
Ocean pro head with .043 squish
Ported intake ports on case
Advanced the rotary valve timing
Rebuilt OEM crankshaft
Mikuni SBN 46mm carb
Hot Products Air Filter
Mariner intake manifold
West Coast pipe and water box with Jet Works flow control valve
Rebuilt starter
Rebuilt jet pump
New solas impeller with a 15/20 pitch
Oil injection block off kit
Replaced all fuel lines and fuel filter
New spark plug wires and boots
I’m running 50/50 vp C14 and 91 pump
 


Messages
45
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Location
La Verne
Water Crafts
1992 Seadoo SP
#3
Image1554156393.327555.jpg
I did clean some of the carbon off when I originally inspected it. But as you can see there are a few hard deposits
 

mikidymac

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#4
That’s actually rich as the fuel washes everything off.
 

mikidymac

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#5
What’s your compression? Did you pressure test the engine? Carbs rebuilt with only genuine mikuni parts? Any fuel system air leaks?
 
Messages
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Location
La Verne
Water Crafts
1992 Seadoo SP
#6
Compression was around 180-185 while engine temp was up. I checked last season after a ride around the lake but I can’t fully remember which one had more than the other but they were close. Carb has all oem parts, never pressure tested the engine nor did I pressure test the fuel system. I clearly need to though... haha
 

mikidymac

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2001 XP
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#7
You need to be running at least 91 octane in that. Did you have the head milled or something to get that high of compression? It should only be 150 psi stock.
 
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Location
La Verne
Water Crafts
1992 Seadoo SP
#8
I run vp c12 with a 50/50 mix of 91 octane. When I posted this thread I listed everything that I did to this ski
 
Messages
45
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0
Location
La Verne
Water Crafts
1992 Seadoo SP
#9
The one thing I regret is not swapping engines and go bigger but I didn’t know any better. This is my first engine rebuild I’ve done and it was a fun one. I just wouldn’t want to do it again any time soon haha
 
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Location
La Verne
Water Crafts
1992 Seadoo SP
#10
A little update...I pressure tested the bottom end and checked the pop off on my carb. One issue that I found was that I previously hooked up the primer wrong. I T’d off the filtered fuel going to my carb instead of the reserve line but that was a quick fix
 

mikidymac

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#11
You are better off running the primer off the return line just run it a little longer so there is a dip in it and put the primer fitting at the bottom of the dip. This way you eliminate the chance of a bad primer leaning out your engine.
 
Messages
42
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Location
Texas
Water Crafts
1996 Seadoo XP
1997 Seadoo XP
#12
Compression was around 180-185 while engine temp was up. I checked last season after a ride around the lake but I can’t fully remember which one had more than the other but they were close. Carb has all oem parts, never pressure tested the engine nor did I pressure test the fuel system. I clearly need to though... haha
 

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