I'll try to get all the facts thus far up to date. Danny and Joe have been a huge help so far, but I still havn't narrowed it down yet. So here we go:
04' Kodiak 3-stage behind a stock Kodiak 350, currently 250ish original hours. Current impeller setup is 19,19,24, and seemed to be a well rounded setup for my application. Prior to any damage, I was doing right around 3500ish rpm for 35mph, and 4200-4500 for 40-45 mph. This April, I had some rocks get past the grate that shouldn't have. Bang smack and fireworks later, 3-stage was torn apart on the side of the Knik (thank you Danny), rocks removed, and reassembled. Immediately she had a good shake to her at idle, and hole shot was smoked along with much higher rpms etc. I think I was running 4000-4500 to stay at 30-35 mph, and 5,000 to run 40mph. Hole shot was 4500-5000 and took a country mile. I believe that my outer clearance was somewhere around .050 or less at that point, with leading edges and trailing edges looking awful.
A whole lot of money later, I have rebuilt impellers from Professional Marine (or whoever they send them to), along with new seals etc. Stators looked good, short of a few minor dings. Wear rings were acceptable. I re-assembled a couple of nights ago, very carefully... Here is a question for everyone, I've heard five million ways that different people determine the forward orientation of their impellers. I've also determined that there may be some people running them backwards. Looking at Kodiak's diagram and cutaway from their website, the base of the blades (where they attach to the hub?), which is the longest distance from the flat face of the hub, is the forward orientation. As far as i can tell, jet boaters refer to this as "short side", verses "long side". So the "long side" is facing forward, according to Kodiak. This matches how they were marked "leading edge" when I got them back from the rebuild. So for the sake of discussion, I'm going to assume that I have them facing the right way. Obviously the 24 is a no brainer, if you have it facing the wrong direction, you're going to chew up your stator in front of it. I have been asked if they re-piched the impellers during re-build, and I haven't the faintest idea.
During rebuild, replaced all the o-ring seals, new cutless bearings and sleeves, and used plenty of grease. My new outside tolerance appears to be .016 to .017 when all of the slack is taken out, and I'm checking one side (pulling the shaft down per say, until the impeller hits the wear ring, and then measuring the opposite side). Again, stators looked good. Prior to assembly, shaft play at the back of the shaft couldn't have been more than 1/4" up and down, side to side etc. I was told by proffesional marine to use 105 ft. lbs on the back nut of the shaft. Using a couple of screwdriver handles in between the last impeller and forward stator (to keep the motor from turning), I achieved 105 on the nut. I'm told this seems a bit excessive on tightness, and am open to any opinions.
Took it out last night for it's first run to Knik. Had a weird thing happen during fire up, it almost seemed like it took about 2-4 seconds, after the motor was running, for the pump to start pumping water (yes the boat was sitting in plenty of water). It's my understanding that depending on the angle of the ramp, as knik launch is steep, that people have had weird air pocket flukes, and the jet sucks air for a minute. Hoping that's what happened. Anyways, idle still has a pretty good shake..... I have no idea what's causing it. First hole shot after warm up (with approx 650 lbs of guys in the boat) was much better than before the rebuild, like worlds better. But still lacking from what it was before I feel like. With just me in the boat, it looks like about two boat lengths to get it on step.
RPMs are not what they were before the damage. I'm looking at around 4,000-4,500 for 35mph, and 4,500-5,000 for 40mph+. Top end feels really spungy/squishy to me, without a lot of response.
I've checked everything I know to check at this point and I'm out of ideas. Motor is having no issue getting to RPMS, so it must be a pump issue, and the shaking at idle has me worried...
Thanks in advance.