Squirt W/ Jet drive... First time out!

About using jet ski motors to power small boats

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capt jake
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Post by capt jake » Tue Aug 28, 2007 9:01 am

Nice job. I thought that looked like Cushman, but it has more water in it than I have seen since I was there. ;) Only about 1 1/2 hours from here.

Speaking of automotive, I painted my sailboat over 6-7 years ago with and acrylic enamel. It looks as good today as it did when we finished painting it! I used Delstar, a bit pricey but I feel in the long run it was worth it.

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steve crawford
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Post by steve crawford » Tue Aug 28, 2007 6:42 pm

Matt here are some updated pics. of the boat.

I have this ride plate from one of the skis I bought last year. I haven't taken it out yet I am going to add trim plates to each side first.

Image

Here are pics. of the intake grate ,I cut out the center bar.

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The gap between the impeller and wear ring of the pump is verry close, need to come up with some old auto-points gages.

Image

The ride plate is an aftermarket. In combination with trim plates on each side this might prevent some sliding in turns.

I think if I were to do another boat I would put the pump all the way forward and that would make the ride plate even with the back of the transome.
You can get drive shafts that work on kawasaki 650 down to 17'' or 18 ''long. Their is a lot of combinations of this sort of thing that needs to be archived for other builders.


AGAIN THIS INFO NEEDS TO BE UNDER A JET-POWERED CATAGORY.

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M_Holmes
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Post by M_Holmes » Wed Aug 29, 2007 11:47 pm

Hey Steve,

It's kind of hard to tell from a photograph with any degree of accuracy, but I'd say the clearance between your housing and impeller is WAY too big. If I was to venture a guess, I'd say that looks like somewhere between a .025-.040 gap. I did some checking on the net, and from what I can find, the general theme I gathered is that there is no such thing as too little clearance, and anything in excess of .010 (per side) is considered real loose.

I'm really interested to see what you find out when you stick a feeler gauge in there. If there is really .025" or more clearance, I'd say that is definately the cause of your standing start cavitation problem.

I would pull the pump off, pull the impeller off, and remove all the shims. Put the impeller back on, and if it rubs, pull it back apart and repeat... adding 1 shim each time until you get it to where it just clears, i think that will solve your problem, and probably provide massively improved acceleration and top end in the process.

Later,
Matt

Oh BTW... Howdy Capt Jake.. I'm only 40 or so miles north of you.. up in Auburn. It's been several years since I've been to Lake cushman in the winter months, but I can recall back when I was a little kid, they used to lower the water level WAY down. There is some really fascinating terrain down beneath the surface.

I get real nervous when I am on that boat ramp that you see in the pics. If you walk down the ramp approximately 25 feet from where the truck is parked, you are swimming in 100 foot deep water, haha. I make sure to set that E-brake like I mean it!

My mother and father bought a cabin there back in 1980, and it's still in the family today. I have many fond memories of that place :-)
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capt jake
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Post by capt jake » Thu Aug 30, 2007 8:42 am

Yup, I used to go there in the winter and drive the truck down the boat launch. We drove all around the lake bottom. I used to service a development company there and in the 80's they lowered it enough to finish the logging that was stopped when the dam was completed. He told me there was a complete logging train and town at the bottom of the lake that they hoped to salvage. I missed it. ;)

I also used to go there to a buddy's cabin there. I have two co-workers who own houses at the golf course now, though it has been years since I was last there.

You are actually 34 miles North of me. ;) I work in Auburn, just live in Olympia. :)

terrymc
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Post by terrymc » Thu Aug 30, 2007 5:41 pm

Steve/Matt

On the impeller clearance thing, my Kawa m,anual specified 0.2mm as the "standard" and 0.6mm as the "service limit". The text says "if the clearance is less than the service limit, do not adjust it. If the clearance is greater than the service limit, and tthe pump case is in good condition, adjust the impeller clearance." (as Matt indicated, you do this by taking out the impeller and changing the shims.)

The manual also says that if there are scratches or gouges inthe case deeper than 1mm, you should replace the case.

(I'm boning up on how to rebuild a pump!)

TRM

LTGoshen
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WoW!

Post by LTGoshen » Thu Aug 30, 2007 6:22 pm

Dude! thats obe great looking project. And I too loke the lake,
Again nice work
Live right now. Live every day in the sun.

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M_Holmes
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Post by M_Holmes » Thu Aug 30, 2007 11:37 pm

Wow, capt jake, small world!

That's funny what you said about the logging train, because I've heard that too. I don't know about the train, but I do know that back when I was 10 or 12 years old when they drained the water out, it uncovered about a 50 foot long section of a super old wooden train trestle, just beyond that boat launch. It must have been cut down, or it disintegrated and fell down the rest of the way, because Last time I was there when the water was down, it wasn't there.



Hey Terry,

Did you check those splines out?

I rebuilt my yamaha pump and it took me literally one hour from start to finish, with no press. It is SUPER easy. I think your 550 pump is put together pretty much the same way. The key is: Freezer and torch.

Here's the method I used (impeller is off at this point...)

1. Rapidly and EVENLY apply Heat the outside of the bearing bore area of the housing with your propane torch (through the stator). you don't have to go hog wild or anything, just to the point where it's very uncomfortable to touch with your bare hand. The key is to make the bore expand slightly with the heat, before it has a chance to soak into the bearings and expand them as well. If done properly, the bearings/shaft will practically fall out of the bore (it may take a couple light whacks with a rubber mallet to jar it loose).

2. Once you have the shaft/2 bearings assy. out, Put it in a plastic bag and put it in your freezer for about an hour. (I take no responsibility for what might happen if your wife catches you doing this, esp. if you don't have the courtesy to follow the plastic bag step, haha ;-) After the shaft/bearings are good and icy, work quickly to heat up the bearing all the way around with the torch, being careful not to allow time for the shaft to warm up to the same temp as the bearing. Hold the bearing and tap the shaft right out of the bore with your mallet.

4. Clean up all the parts, and get everything ready to reassemble. *Make sure there are no burrs or scoring of any kind on the bearing bore of the pump housing, or the OD of the shaft! Use an ultra fine scotchy or steel wool to touch them up if necessary. Pack your bearings with grease now... it will be harder to do once they are back on the shaft.


5 To re-assemble the new parts, throw the shaft in the freezer, and let it get ice cold once again. Once it's cold, (WORK QUICKLY HERE!!) bring it out to your work area and clamp it in your vise. heat the inner bore (ONLY) of the bearing with the torch, DO NOT overheat the bearing/grease at this point. Just get it up around 130-150 degrees or so. That's good enough to expand the bore significantly, without risking damaging the bearing or the grease. position it SQUARELY atop the chilled shaft and you should be able to push it right on there with nothing more than your fingers. (Have a clean deep socket that matches the diameter of the inner race, and a mallet on stand by though, so you can give it a couple love taps just in case. *To do the 2nd bearing, it may be necessary to throw the assembly back in the freezer to cool the shaft again from the heat it absorbed from the first bearing. Once it's cooled back down, repeat the same procedure for the second bearing.

6 Throw the shaft/2 bearings assembly back in the freezer for the last time, and let it get ICE cold. Once you're there, bring it out to your work area. *WORK QUICKLY HERE!! apply EVEN heat to the bearing bore area (only) of the pump housing until it's good and hot. ~150-200 degrees or so. Not smoking hot, but hot enough you wouldn't want to grab it with your bare hand. Square the bearings/shaft over the bore, and tap it down with your mallet. it should slide right in there. Again, work quickly on all of these procedures because you can feel it begin to tighten up almost immediately as the temperatures of the two parts start to equalize.

Viola!

I studied this thing for hours, and there is simply no way that you can use a press to reinstall the assembled shaft/bearings in the housing without exerting force directly through the balls and races of one of the two bearings. That is a definate no-no. We used this method back in the days when I worked at the engine rebuild shop... We had a rod heater machine that got the end of the connecting rod nearly glowing, then you positioned the piston at the end of the rod, and shoved the pin through by hand. once it cooled, it took several tons of force to press it back out.


Take it easy,

Matt
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leakcheck
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Post by leakcheck » Fri Aug 31, 2007 4:39 am

Matt missed one very important step...

Each time you go to the freezer open the refrigerator and grab a beer (or two) you can calculate the time needed in the freezer by the number of beers consumed.

Tell wife this is an old yankee method tried and true, tell her you saw it on This Old House...people believe everything they see there !!


Steve

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steve crawford
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Post by steve crawford » Mon Sep 03, 2007 10:57 pm

Matt the pump in the pic. was checked at .o14 and I took it out and adj. the shims and now it is .009 .
I got another intake grate in from eBay and i'll take the boat out this week.

If I get cavitation now I will take the grate off all together.

If that don't work, I'll be playing arround with the ride plate and trim plates to get more seperation from the back of the boat and the jet intake.

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steve crawford
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Post by steve crawford » Wed Sep 05, 2007 7:29 am

Matt my cavitation problem is fixed, I have zerro. It dosen't need an extended ride plate as in the pic. Just a combination of impeller clearence and the intake grate.

The intake grate should not be overlooked, that is the first thing to be removed to see if that solves the cavatation problem.

The ride plate with the fins does add alittle more grip in the hard turns.

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M_Holmes
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Post by M_Holmes » Sat Sep 08, 2007 10:15 am

Glad to hear it's working better. Did you notice any gains in acceleration or top speed as a result of the clearance adjustment?


I was having some poor steering response/skidding issues in mid/high speed turns the first time out, so I made a couple of little .75 X 1.25 X 36 strips for the bottom and epoxied them under the outbd battens prior to my last trip out.

Not only did it not have the effect I was looking for, it made the boat act really scary when crossing wakes and waves diagonally. I think I made them too long, or too deep, or mounted them too far back or something. In retrospect, it seems to make more sense to have the "pivot point" more toward the middle of the boat. I know many people have done the wood strips approach with great results, so my execution must have been flawed, haha.

Nevertheless, I'm going to plane these strips all the way back off, and try a single center mounted skeg this time. I'm going to my workplace to make the skeg right now. I'm also kicking around the idea of bolting a little dinky rudder to the steering nozzle.

The max. speed I was able to attain last time out, with only me in the boat was 37 mph. This was according to the twin speedos in my brother's ski boat. I was battling big waves from all the labor day weekend boaters the whole time, so I think 40 is still not out of the question if I can get some smooth water.

Take care!
Matt

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steve crawford
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Post by steve crawford » Sun Sep 09, 2007 6:24 am

We need to take this teck stuff to the jet ski section.

I notice more take off power but no more top end.

lone Duck
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squirtmwith jet drive 1st time out

Post by lone Duck » Mon Sep 10, 2007 4:33 pm

Just adding my pennys worth on the subject of impeller clearence . All the jets I have delt with specifi 3 thou. clearence 2 is even better as loong as there is no contact with the liner.
bush bunny

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