2015 superjet slow cranking

Joined
Jun 2, 2011
Likes
303
Location
seattle area, Wa
#1
I’ve been chasing an issue of slow cranking with my 2015 sj for a while now and I’d like to finally solve it.

It always starts, it just cracks over very slowly compared to all of my friends stock superjets and my previous 2013.

In chasing the problem, I’ve tried the following:

Tested multiple known good batteries from my buddies skis.

Replaced starter solenoid for new oem unit.

Verify all grounds inside ebox are perfectly clean.

Used MSD enhancer installed in ebox.

Battery cables are perfect, no fraying, corrosion, and connections at starter are clean. Brand new 4 gauge ground wire just installed tonight, no change in cranking speed.

Removed flywheel cover to inspect bendix and flywheel and verify correct bendix washers were in place. All checked out. Stator is lined up with original timing mark, not advanced or retarded.

This superjet is using an engine I had built for lites spec. It is approximately 180 psi, nothing crazy. Pump bearings and midshaft bearings turn extremely smooth without issue. The engine is not original to the ski but it is a standard 62t case setup that came factory on the sj.

I’m getting pretty tired of heading it crank so slowly compared to every other superjet I’ve heard, especially newer ones.

The last thing I could think of was the starter. It is not the original starter and I do not know where it came from. I took the starter apart and it was very clean inside. I do not know the proper amount of washers that are supposed to be on either side of the starter motor. Bench testing the starter it seems to operate properly but I do not have another one to compare on the bench.

Is there anything else I am missing when troubleshooting this problem? Do I pick up a used and unopened oem starter to see what happens?
 
Joined
Jun 2, 2011
Likes
303
Location
seattle area, Wa
#3
Pretty sure huh? It is about the last thing I do not know about. It’s black, not painted a factory engine color. It seems to spin ok but I have nothing to compare to. It’s been with the engine since day 1
 
Joined
May 2, 2011
Likes
26
Location
Alabama
#4
Yamaha starters are black. You said it was not the original starter so I assumed it wasn't. It turns over slow but starts points to the starter. You have pretty much ruled everything else out. I would have made sure all of the connections are good and clean and then jumped the positive of the battery directly to the starter. If it still turns over slow with a known good battery then it's the starter as you just bypassed everything else. That would be after you turned the motor over with the plugs out to make sure the motor turns freely and checked the compression to verify it's 180 lbs so that you have ruled out it can't be the motor.
 
Joined
Jan 8, 2007
Likes
251
#7
Excellent suggestion fx1mark, I’ll jump directly to the starter next. That should be the end all tell all.
Big Kahuna, do you mean hold onto the coupler and turn the engine over?
NO!!! Remove starter, hold bare starter attached to nothing, hit with 12 volts, should have pretty good torquing or twisting motion from dead stop.
 
Joined
Jan 18, 2006
Likes
357
Location
wisconsin
#8
NO!!! Remove starter, hold bare starter attached to nothing, hit with 12 volts, should have pretty good torquing or twisting motion from dead stop.
I do this while trying to "grind" the starter into a 2x4 piece of wood clamped into my vise. Try to stop the starter. A good strong starter will NOT stop, and will just grind into the wood. Starters do go bad, and will crank slow when doing so. (Even OE Yamaha ones)

Could also be incorrect washers/spring set up for bendix drive, alowing it to bind.
 
Joined
Mar 8, 2014
Likes
238
Location
Minneapolis, Minnesota
#9
Starters have 2 positive and 2 negative brushes so it acts like 2 electric motors in one. You can lose contact in 1 brush and basically lose ½ of the starter torque.
One thing I do when I check out starters is clean all of the carbon dust out, sand the commutator and the brush face and put it back in service. Rarely do I see the brushes wear out. Over time there can actually build up a corrosion layer on the commutator and the brush face that is not conductive and will prevent it from working correctly. If you take sand paper (non metallic ~100-200 grit) to the brush face, try to do it as the same curvature of the commutator to maximize contact area. Usually it’s a cheap fix, just some of your time.
 
Last edited:
Joined
Jun 2, 2011
Likes
303
Location
seattle area, Wa
#10
I do this while trying to "grind" the starter into a 2x4 piece of wood clamped into my vise. Try to stop the starter. A good strong starter will NOT stop, and will just grind into the wood. Starters do go bad, and will crank slow when doing so. (Even OE Yamaha ones)

Could also be incorrect washers/spring set up for bendix drive, alowing it to bind.
thanks for the suggestion, I can give that a shot today. In my diagnosis and troubleshooting I verified that that all bendix washers and their arrangement was in the proper order. Everything checked out for the bendix and related washer. I made sure no extra ones were in the case bushing or the front cover bushing and verified correct thickness of all washers as well.


Starters have 2 positive and 2 negative brushes so it acts like 2 electric motors in one. You can lose contact in 1 brush and basically lose ½ of the starter torque.
One thing I do when I check out starters is clean all of the carbon dust out, sand the commutator and the brush face and put it back in service. Rarely do I see the brushes wear out. Over time there can actually build up a corrosion layer on the commutator and the brush face that is not conductive and will prevent it from working correctly. If you take sand paper to the brush face, try to do it as the same curvature of the commutator to maximize contact area. Usually it’s a cheap fix, just some of your time.

I will give this a shot today while I have the starter out again. Thanks for the suggestion!


NO!!! Remove starter, hold bare starter attached to nothing, hit with 12 volts, should have pretty good torquing or twisting motion from dead stop.
Holding the starter in my hand it does seem to have decent torque, I'll be trying the wood test today like John Zigler mentioned, thanks!
 
Joined
Jun 2, 2011
Likes
303
Location
seattle area, Wa
#11
One thing I am not sure about is the exact amount and placement of all washers that are located inside of the starter. The only truly obvious one is the large washer with 4 prongs located at the geared end starter cap. I have not been able to find a diagram online showing the EXACT number and placement of the internal washers for a starter.
 
Joined
Jun 2, 2011
Likes
303
Location
seattle area, Wa
#12
Further troubleshooting:

I ran power from a jump box directly to starter bypassing all of the electrical box and components and the engine turned over at the same speed. I believe the starter is my culprit.

I also removed the starter and tried the wood test and could not get it to stop. Mixed feelings about the results of this afternoon. Perhaps my next move is to disassemble the starter and look for anything obvious inside and clean the brushes.

If that doesn’t work, I’ll track down a known good oem starter for comparison purpose.

EDIT: I just noticed that this is not an oem mitsuba starter. No markings anywhere on it. I think we can conclude the starter is most likely the culprit and I will track down an oem starter for replacement.

I’ll update with results when it’s all said and done.
 
Last edited:
Joined
Jan 12, 2013
Likes
2,259
Location
the jetski grave yard
#13
loosen the bolts a bit on the flywheel cover. if the Bendix is too tight, this will let it spin freely.
on a kawi based PV motor, somebody put a washer on back side of the Bendix where they don't go. another washer was put on the cover side and with the cover tight , it was bound up. it took a while to figure that one out.
 
Top Bottom