701 sudden loss of drive & shake off idle in water

[Joe Superjet]

I was riding a lake yesterday for about an hour, just making figure 8s around a couple buoys. Wasn't holding her wide for long, super choppy so I was just jumping the whole way between buoys like brap brap brap.

Come around the buoy one time and I lose drive in the corner, no sudden motor stoppage or any weird noises. Starts up and idles fine, but if i rev it at all it gets pretty shakey. Feels like really bad detonation sort of. I've had a lot of crank failures in motocross bikes, and there was always some kind of screeching noise or something to indicate that a main bearing had seized or whatever.

Last thing I did to this ski was replace the Bendix, so Im thinking maybe the flywheel spun on the crank a little and timing is off? Either that or the midshaft bearings took a huge poop all of a sudden. I grabbed the pump right when the issue started and it didnt feel hot at all.

Any ideas?

 

[augustaf]

Lay the ski on it's left side and inspect pump intake area and impeller for debris. If none found, remove midshaft cover and look at coupler.

 

[tipafew]

My first gut says driveshaft/midshaft splines.
As already mentioned though, make sure the prop and pump are clean.
Possible a couple blew apart but that would more likely make some noise.

 

[Joe Superjet]

Really wish I had started it again once I got home. I did start it in the back of my truck at the boat launch to get some water out of the exhaust and it exhibited the same issue, shaking after 1/8ish throttle.

Pulled everything but the motor last night and it is all way too dialed, pump bearings are tight and smooth, midshaft housing is very clean and doesnt appear to have seperated anywhere, really nice looking splines on the driveshaft, couplers are intact. I think the impellar and pump look pretty good but I dont have any pwc experience so idk for sure.

 

[Joe Superjet]

When I pulled the front cover to inspect flywheel I noticed that I did not have to remove the kenny keeper to get at that cover bolt, had to the last time. Seemed like engine moved a tad since I replaced bendix, <0.25"

Also, when I pull the spark plugs and turn the motor over by hand there is no noise whatsoever, seems like a really tight/dialed rotating assembly.

 

[aboarder]

Any chance that you're running on one cylinder at higher RPM? That would explain the shakiness and lack of power.

 

[Joe Superjet]

Yea it's TOTALLY possible. I have suspected a misfire the entire time I have owned this ski, I have raced motocross on 2 strokes my entire life and this thing does not sound right when Im running it on the hose. Sounds like a misfire, but it has been strong in the water, despite sounding like it has a misfire on one cylinder at certain RPM.

Really nice build and this thing has been cleaned and cared for it's whole life, very happy with what I have seen during the teardown. It has stock plug wires and caps though! Possibly stock from 2001, with nothing but Hawaii surf riding in between now and then. I have a new coil and wires in the mail from JM, and all I can think to do is put this ski back together and try once my coil gets here.

 

[JetManiac]

I would do a compression test, it is easy and you can rule out problems in top end.

How do plugs look? Even front to rear?
How are motor mounts?

 

[Joe Superjet]

Plugs are even and appear to be dialed, but I only limped it back to shore after issues began, took like 30 seconds, and it idled fine for this trip.

I'll grab a comp tester tonight from HF.

Any advice on reinstalling pump? Should I grease the rubber gasket where pump meets shoe?

 

[Storbeck]

Are you certain that you got the flywheel on correctly and torqued correctly (or at least tight) after the bendex? If the flywheel bolt is not tight it's really easy to shear the flywheel key (not that I've ever done that...)

 

[Joe Superjet]

Pulled the cover off, but not the flywheel bolt. Im gonna take bolt off tonight and make sure its on there right.

Issue didnt start until it had been ridden for about 6 hours since the bendix was replaced

 

[aboarder]

Check compression like JM said, but I don't think that would be the issue. It's usually harder for an engine to start with low compression than it is to run at higher RPM. I had a plug cap go bad on me. My misfiring was worse than yours (if that's the cause), because mine missed at low RPM most of the time, but it missed 100% of the time when I got the RPM up. I suspect that coil with wires and caps will fix your issue.

 

[JetManiac]

Check compression like JM said, but I don't think that would be the issue. It's usually harder for an engine to start with low compression than it is to run at higher RPM. I had a plug cap go bad on me. My misfiring was worse than yours (if that's the cause), because mine missed at low RPM most of the time, but it missed 100% of the time when I got the RPM up. I suspect that coil with wires and caps will fix your issue.

I don't think it is the issue either, just easy to rule it out as an issue.

 

[JetManiac]

Plugs are even and appear to be dialed, but I only limped it back to shore after issues began, took like 30 seconds, and it idled fine for this trip.

I'll grab a comp tester tonight from HF.

Any advice on reinstalling pump? Should I grease the rubber gasket where pump meets shoe?

I hear their low end tester is questionable, but their 'higher' end tester is ok.

Better to use silicone to seal that gasket, better yet to replace it and still use silicone.

 

[Joe Superjet]

Figured it out, bad crimp on fuse wire bullet connector. Ski works really good now, thanks for the help guys.

 

[Storbeck]

Do you have an oem cdi or something aftermarket like an msd enhancer?

 

[Joe Superjet]

It's an enhancer

 

[bellpeper1]

Hate to restart a old thread but my ski just started this same exact thing what exactly did you find wrong with yours which connector I cant seem to find any more threads on the site the exactly describes what is happening like yours does