Thread: Modding the WJ500
07-05-2007, 10:32 AM #1
Modding the WJ500
(I am moving this discussion from the classifieds. Thought it was appropriate to continue this in the proper section.)
Originally Posted by w/rpm500
Last edited by afcblink; 07-05-2007 at 03:43 PM.
07-05-2007, 10:48 AM #2
HEY THAT'S MY SKI!!!.. pretty neat looking morph there... I was thinking a bit lower on the steering as then you could scoot back with a lower center of gravity and put more weight out back to get more speed... just have to find a hull...have about all the speed stuff ever produced already..
07-05-2007, 03:38 PM #3
BTW, "scoot back with a lower center of gravity" doesn't sound like the right approach to me. Have you spent much time riding a WJ? Mine rides best when I'm standing as far to the front as I can, leaning as far forward as possible.
Last edited by afcblink; 07-05-2007 at 03:43 PM.
07-05-2007, 04:20 PM #4
the wj/blaster i want to build will be a streight line ski ... the flat bottom on the wr/wj skids out too easyly in a turn ...you have to 'nose' it down otherwise and this scrubs alot of quickness you cant loose with this under powered motor... you just have to ride em with alot of body 'weight' shift ...(HERES WHERE BULL RAIDER WILL CHIME IN AND SAY DROP A 701 IN TO THIS) ... DING!!!.... as for the steering, the cable connections will be easy to adapt(should be compatable anyways, just shorter)... the head itself... you could graft the wj's 'head' into a cut down wr hatch and then glass the cut down unit into the WJ's hatch .. the early stuff is all fiberglass so epoxie will work fine with good glass work... mine is all rough drawn stuff so your morph is cool... the tubes are vents for the hull and fuel system, I figured to adapt something into the bubble at the steering head area, using SJ venting stuff, as it is small and compact....
keep up the questions .. maybe something i havent worked out yet... i like the handle bar idea as those sweept back and up a bit will work well to adjust..or i may look for a shortened unit to use....
Last edited by w/rpm500; 07-05-2007 at 04:23 PM.
07-05-2007, 04:49 PM #5
I think before I spend any effort stuffing in a 701, or even working on a different hood, I need to figure out how difficult a pump swap would be. The 133mm mixed-flow pump is the Achille’s heel of 500cc Yamahas. Unfortunately, the 1-piece driveline housing/intake duct on the 133 pump is a really goofy design that really complicates matters.
I am trying to figure out how feasible it would be to simply mate a bigger pump to the existing WJ intake duct. The 133 pump's duct is actually only 114mm in diameter where it meets the pump housing, which I’m am guessing is significantly smaller than any better pump that’s out there, and there’s not enough material there to open up the bore much at all. I doubt that I could match the duct to a bigger pump, and having the flow path “neck up” and then widen again wouldn’t flow worth crap.
Is anybody with a spare 144mm pump lying around (or perhaps a 140mm Kaw pump?) willing to make a couple measurements for me?
Another option is the FX-1’s 122mm axial pump. Yea, FX-1 riders say it’s crap, but still much less crappy than a 133 hooked to a 701. Besides, if they’re that unpopular, perhaps I could pick up one cheap…
Furthermore, I am somewhat doubtful there is even enough vertical space between the driveshaft centerline and the WJ’s rideplate to fit a bigger pump in there.
At some point it would make more sense to simply glass in the center section of a SJ hull, pump, motor mounts and all. Of course long before that point in the process I always come the the conclusion, “Hell, I should skip all the work, sell the Jammer, buy a Blaster and just go riding.”
Here’s a really interesting thread on swapping a Kaw 140mm into the FX-1:
07-05-2007, 11:02 PM #6
I'm hopeing BULLRAIDER(jeff) will see this and comment .. he dropped a 701 in a WaveRunner and eventually was able to get 50+ out of it ... I'm not sure anymore what it was from that he ran for a pump ,but I'm thinking it wasnt the o/e..... there was mentioned a short time ago, of someone having run and commented as to try and install a the early WB/SJ pump...these being better with lots of grate styles to chose from...(I just dont remember the yami ski they recommended for )....
07-06-2007, 10:38 AM #7
133mm pump inlet dimensions
Okay, attached is a photo of the 133mm pump's inlet dimensions. Anybody want to measure the specs on some other pump models and see how far off they are? I am guessing the 122mm FX-1 pump is the only one that is going to be even close.
08-31-2007, 01:36 PM #8
[Note: I originally posted this over at PWCTooDumb, but I have given up on all the stupid nonsense over there for good. I thought it was appropriate to attach it to this thread.]
I finally put the Rend rideplate on my Jammer. It's a slotted, extended rideplate (about 60mm) with a D cut and removable skegs. A really nice piece, and very trick compared to the square cast block the came stock. Amazingly, I discovered when I replaced the old (stock) rideplate that somebody had washered the FRONT screws. Very odd. No wonder I had to stay up over the nose to keep it from porposing!
Took it to the lake on Saturday and spent about three hours on it. The new plate changes the character of the boat quite a bit, but I can't decide whether it's an improvement.
With the new rideplate, the jammer is much more stable on plane, with no hunting or vaugeness going straight. As I expected, it was much less prone to porposing, and I didn't have to have my weight so far forward. WOT was much eaiser to manage. That was the good part. Unfortuntely, I HAD be going close to full speed to get a smooth ride through a chop. At half throttle, the nose would just stop at every wave and the pump would cavitate like crazy. I also couldn't get any sort of launch off wakes.
Turning was much flatter, which I didn't like. Maybe I'll get used to it. The back end wouldn't whip around all at once, which made things much more predictable, but in a bad way. The slippery-sliding rear end was the only thing that made the jammer entertaining. It was like everything was happening in slow motion. If I was really hauling, I could still bring the rear end around, but I was having a lot less fun doing it.
Overall, I think the new plate probably could make the hull better, if not for the basic failures of the Wavejammer powertrain. I suddenly really wanted a really punchy 701 and a 144 pump.
I doubt I'd go back to the stock plate, but I might try it without the skegs and see how it works. It just reinforces my conclusion that there is too much wrong with the basic WaveJammer design for improving it to make sense.
09-01-2007, 10:29 AM #9
removing the skegs will let you slide that thing around abit again.. (try clipping off the rear of those pressed on skegs, before removing all of it (this may just give it further forward center point to spin out from,and give you better handling over the o/e)... there are some other aftermarket cast designs close to a stocker, with some built in channels for some stability... your washers in front would have lifted the nose out of the chop and would have forced you to lean forward gain handeling.... your pump angle,with the washers in, may have been right at it's sweet spot in its ability to prossess water...you could try a bigger pitch or tweak the one you have
Last edited by w/rpm500; 09-01-2007 at 10:43 AM. Reason: spelling
09-04-2007, 08:42 AM #10
I spent about three more hours on the jammer over the weekend, this time on some smoother water, and I got a much better feel for it. I learned to really commit to turns, really putting my weight to the inside even at slow speeds, and it would heel over quite nicely. It works because the hull no longer has that tendency to shift so dramatically and unexpectedly anymore. With the stock plate, the odd little ripple could toss me to the outside of a turn when I was least ready, so I was always focusing on what would keep me from getting dumped, not what worked for the turn. I did get dumped a couple of times, but at much higher speeds that I usually attempted stuff in the past.
I think I'm going to leave the ride plate as it is. The handling is so much improved, and so much more predictable, that I can't see removing the skegs. I got to the point where I could pretty easily bring the rear around in the length of the hull, but only after I had built up some pretty good speed going straight. The little "brap, brap" figure eights in a 10-foot section of the lake are out. But the problem isn't the hull or the ride plate. What it needs is more POWER! There were times that I had the throttle pinned and yet was just crawling through turns.
With more oomph, I think you could really carve a legitimate turn with this thing. (I kept wishing I had about 50% more throttle available to test that theory.) And yes, I know Pro-Tec made some sort of odd exhaust thingie for the 500...but FINDING one is the problem nowadays. Besides, it would probably cost 1/2 the price of a good used 650 motor...
…or a 760! And a 155mm pump, and--
Hmmm, I guess one mod DOES lead to another.
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