1020 x-4 question

[coldblaster]

Hey Bill,
I have finished my 1020 seadoo build in a carbon x-4 hull. I messaged you before and think it is an Odessey hull. The motor is a ported pump gas 1020 with a coffmans gsx pipe, Novi 48's and remapped Novi Mpem. The pump is a seadoo xpl pump with a adapter plate to the hull. It has a JD intake grate, sponsons and Baker manual trim tabs as well. I had it out on the weekend for one of its first water tests. Once it was warmed up I took it for a WOT run and it went from side to side uncontrolably and threw me off at upper 50's . I double checked the trim tabs and one was a bit lower than the other. Evened them out and it ran 62.4 mph at about 7400 rpm. The boat seemed very planted so I raised the trim up a bit did another run and it got unstable and almost thew me again. I know these boats are not the most stable, but is there something I am overlooking in the set-up? What angle should the tabs be at? They are currently on about the same angle as the hull, It is just built for a rec boat but I don't really like being thrown off of it.
Thanks Rob

[Mr. Bill]

Re: 1020 x-4 question

The extended trim plates on an X-4 hull are super sensitive to minor installation flaws and just cannot be installed without the help of a straight edge and an accurate angle finder. If you attempt to go faster than the hull was made to go, and you use any kind of aftermarket extended trim tabs ( or rideplate extension ) and it is not setup exactly the same on both sides of the transom, the hull will throw you like a rag doll.

I made my orginal fixed trim tab kits long before anyone else, beginning with my 1993 hulls and learned a few things most others never did learn about trim tabs, fixed or adjustable.

#1. The trim tabs cannot be less than level with the hull at high speeds much past 60 mph.
#2. Most trim tabs offered have too many square inches of trim tab protruding behind the hull
#3. I found that the angle of the trim tabs that protrude behind the back of the hull, need to be trimmed on an upward angle from level with the bottom of the hull, that varies a minor amount by the weight distribution of the complete hull and the contents under the seat, and the weight distribution of the person riding the hull. Placement of feet when attempting to go really fast and how far the rider leans forward to weight the handle bars. What I mean by that is that the rider should not be seated, but standing, with feet evenly placed towards the rear of the footwells, body leaning forward with equal weight on the handlebars. You will use this method to balance the hull not only side to side, but the attitude of the hull bottom as it glides over the water, nose not too high, not too low. The idea is to use only the hull from just ahead of the jetpump/scoopgrate's forward water intake tunnel. Directly forward of where the intake tunnel begins is a flat surface that evolves into the rounded keel that goes forward towards the bow. If you allow the hull to ride on the rounded keel at high speed, the hull will " bow hunt ", darting one way or the other, and not really within the riders control. Lever operated trim tabs are not the best way to control a fast hull at speed unless they have a way of adjusting each trim tab seperately, and they have a positive up stop to prevent them from going too high or raising at seperate degrees above the hull bottom level from one side of the transom to the other. They both must work exactly where you want them to be, on a slight angle above the plane of the hull bottom.

When I got tired of building trim tabs by hand, I went to R&D Racing and told them that I wanted fixed trim tabs that used the oem screws to attach them to the hull. I asked them to stay within the existing IJSBA rules that would not allow the tabs to protrude past the allowable amount as stated in the 1996 rules for runabout racing classes.

I mounted the R&D Trim Tabs and headed for the lake with a '96 limited class racing boat capable of speeds into the mid 60's. I rode it until I got used to the extended fixed trim tabs from R&D and returned to their shop with the set of tabs he had sent me, but I altered them by filing off the rounded mounting pads on an angle so that when remounted onto the hull, they had a 3 degree angle upwards where the tabs extended beyond the transom. I had tried one degree, two degrees, three and four degrees before shimming back to 3 degrees, where I found that to be the sweet spot for both me and my wife, who raced the boat.

I also found out during my earlier experiments with extended trim tabs, that having too much surface area extending beyond the hull was excessive and unnecessary, and it hampered the hull's ability to turn well in tight corner situations at high speeds like we were doing on the bouy race courses.

Later years brought us the real X-4 hulls, first as the prototype '95 XP hull from Sea Doo Racing in 1994. Besides being a lighter version of the 1994XP hull, the prototype '95 hull that I got in early 1994 had these two cut outs ( recesses at the rear of the hull bottom ) for fixed trim tabs. The cutouts were not drilled for screws, and they had no trim tabs on them when I got the hulls.
I had been making trim tabs for earlier model hulls that attached onto the outside of the transom vertically, with nearly a right angle at the bottom for the horizontal exented trim tab ( L shaped ). These were nice because I could use a linkage with a turnbuckel to change the angle horizontically with relation to the plane of the hull bottom.

For my mod class hulls, I had been using handlebar lever, cable operated adjustable trim tabs that Danny Gewecke had designed and Mel Miller made exclusively for Bullett Racing. Danny and I were close friends and competitors for years and we often exchanged thoughts about our racing boats. Eventually, Danny decided that he wanted to build CF hulls and hoods, and he gave me permission to use his design, produce them for profit, and sell them under the brand name Watercraft Magic. I sold 400 kits over the next few years for $400.00 each retail. Then the XPL came along and it did not really need adjustable trim tabs, although there were a couple of people making them as kits.

I can think of about 5 or 6 different outfits that jumped onto the adjustable trim for the X-4 hull bandwagon after seeing mine and Danny's boats out on tour in 1995.

IMO, as well as most of the pro class racers that used the X-4 hulls, no kit worked as well as Danny's designed adjustable trim tabs.
There was allways something the others missed out on when designing their kits. The main reason was they concentrated more on appearance than they did on function and overall weight of the kits. ( remember, we were building or buying $4000.00 plus carbon fiber racing hulls at the time, and weight was a major concern for me and Danny ).

After Danny's orginal design kits, a couple of us would modify the actual tabs to eliminate the rounded outside portion of the trim tab to reduce the sq inches of tab surface out there at the outer side portion of the trim tab. To achieve that was easy. Scribe a line from the back corner of the trim tab so that the longest part of the extension tab was next to the jetpump, and the outer side of the trim tab were it met the hull at the sides of the hull was as close to the hull hinge joint as it could be. Then just cut the line and presto, you have a long, narrow, triangular shaped tab that got wider the closer it got to the jetpump.
Now we had a tab that substaintually reduced the risk of causing the ill effects to the handling, but just as importantly, when angled slightly downward in a corner, drastically reduced the lift at the outside corner of the back of the hull. If you want a hull to corner well, you do not want lift. You want traction, you want a pump that stays connected to the water, sucking the hull down to avoid sliding out in the tight corners.

A properly setup adjustable trim tab never needs to move very much up or down, as a degree or three from the plane of the hull bottom, either up or down will drastically effect the attitude of the hull. More degrees upward will allow the hull to porpoise, and more degrees downward will cause excessive bow steer and the hull will dart left and right, what is reffered to as "hunting".

IMO, if you are not racing the hull, fixed trim tabs, on the correct angle for you and the weight distribution of the hull's contents, is a much better option than are adjustable trim tabs.

To stop the problem that you are having right now with you hulls handling, remove the adjustable trim tabs and install the oem trim tabs and then go ride the boat. You will see a vast improvement in the handling. Use the VTS nozzel to adjust attitude beyond what the capabilities would be if you bolted on aftermarket fixed trim tabs, like the 3 degree R&D trim Tab kit.

The beauty of a 3 degree kit, is it scrubs no speed off of the hull while only doing what is needed. What is needed is that when the bow rises and would start porposing, the leverage provided by the 3 degree tabs, will limit the amount that the bow CAN rise and reduce porposing.

The cardinal rule for a speedy hull is less DRAG in the water. Anything that protrudes below the plane of the hull is killing speed. That is where the amatuers and their aggressive aftermarket scoop grates end up spending $100's of dollars on speed parts to achieve a speed they might have been able to achieve for alot less money if they had not hung such an aggressive grate under their hull, or in this case, have trim tabs that are forcing the bow down too far at speed, while placing too much flat area of big wide trim tabs and such behind their hulls.

When you really get going on an X-4 hull, with speeds near 70 and beyond, you will not need alot of anything hanging in the water, on the contrary, you will want much less scoop on your scoop grate and you will be grinding the blade back further and further up out of the water inside the intake tunnel.

There is a reason that pro racers REDUCE their intake track diminsions. Fast boats, not stock boats, do not need huge intake tunnels slowing the hull down while overloading the pump with water it cannot process. If you try that with a really fast jetboat of any kind, you will experence what is known as "pump blowout" and the hull will get completely out of control. That is where the water is forced to come back out of the intake tract and other water to build up in that area under the hull, raising the back of the hull way up beyond where it sould be riding in the water, and the next thing you know is the hull is doing 360's at full speed. Can you say pain !

Bill O'Neal
WCM

[coldblaster]

Re: 1020 x-4 question

Thanks for all the help Bill. I knew you had done lots of research and testing with trim tabs, looks like I have to try some stock tabs, then R&D tabs.
Thanks Again
Rob

[Mr. Bill]

Re: 1020 x-4 question

Yes, If the handling problems disappear with the oem tabs, and you still have VTS, you may not want extended trim tabs at all.

If I remember correctly, I went almost 82 MPH on Miller's 1995 XP and he had oem trim tabs, stock rideplate without an extension.
His hull handled as good as anything 8 feet long that I ever rode at those speeds.

If your hull proposes with stock trim tabs, I also made some plastic trim tabs that, when mounted, look identical to the oem trim tabs, but have a very slight down angle to them to help keep the bow down at speed.
In 1995, Kawasaki still ruled the IJSBA as it was owned by them back then. When they saw that Sea Doo had oem trim tabs coming along for the 1995 model, a rule was inserted into the racing rulebook that banned us from modifying or shimming the oem trim tabs, or using any kind of extension at the trim tabs for the limited class racers.

At that time, I decided that I would make black plastic trim tabs that tech officials would never take a second glance at, but I had to keep it secret until 1996 when we got them to modify their rules to include extended tabs for limited class racers.
I think I had 40 sets made at that time. I still have some left over in my shop. My secret tabs do not extend beyond the hull, but they do have a down angle machined into them that goes unnoticed as they look just like the oem trim tabs. Without placing an angle finder onto them, no tech offical would ever notice a difference.

No, racers do not cheat. Good racers do bend the rules here and there if they are any good at what they are doing...........

Boy, do I have some stories that never got told !

Bill O'Neal
WCM

[coldblaster]

Re: 1020 x-4 question

What Motor did you have in it to reach 82 mph? Thats fast, I would not want to be thrown off at that speed. I came off my GPR at high 70's and bruised a couple ribs, decided then to never ride without gloves again.
Your old stories are great Bill, back then I would use what ever part I was told the pro teams were using. Before the times of the internet, or GPS systems. You had to have someone standing on a dock to try to radar your speed, make a couple of adjustments and wait till the race weekend to see it anything helped or not.
Thanks Rob

[The Wayniac]

Re: 1020 x-4 question

Personally, I'd ditch that JD. They always sucked major speed off my skis top end and are def *not* the grate for any kind of high speed anything. For closed course they will keep you hooked up though, but turn to turn you're not hitting 70.

[Mr. Bill]

Re: 1020 x-4 question

Personally, I'd ditch that JD. They always sucked major speed off my skis top end and are def *not* the grate for any kind of high speed anything. For closed course they will keep you hooked up though, but turn to turn you're not hitting 70.

Miller had a JD grate on his 82 mph X-4, but it took some creative grinding on it to get the drag out of it.
JD makes a deep grate, a medium grate and an Avenger grate. I cannot recall what the part numbers were for the deep and the medium grates, but I think it was 16 and 23 or something like that.

I could not find a use for the deep grates, but the medium grates work well for closed course, and with grinding and reshaping of the scoop paddle and the center bar, Mel was able make it work well at high speeds, but it took a few trips to the lake with grinding sessions back at the garage inbetween the trips, to get it just right.

In fact, if memory serves me, he showed me where he ground it and built some of the paddle up with aluminum welding to reshape it to make the paddle shape like a wing on an airplane with a larger radius, rounded leading edge, and at the back of the paddle, he did some buildup and grinding to send the water into the top of the impellor blades as he did not like the way the paddle was shaped. Then he rounded off the leading edges of the center bar above and below the paddle. He even put a slight radius on trailing edges too to prevent turbulence.

To redirect the water to the upper half of the jetpump, I think I remember that he cut the paddle loose from the centerbar, then tilted it upward and reattached it to the centerbar, then he ground the leading edge back about 1/2 to 3/4 inch to bring it up into the intake tract and away from the plane of the hull bottom so it could not create drag.

These small things like his JD grate reworking, reshaping the venturi nozzel and matching the nozzel to the 148mm pump diameter, machining out the aluminum rideshoe and the mounting ring on the pump support plate to match the 148mm jetpump opening size, gained us about 4 mph.

BTW, his '95 XP hull was never trued at all, and no work was done to the strakes under the hull either. He just made sure the oem rideplate was reset perfectly into the hull to eliminate any possible drag that the rideplate may have caused. To the best of my knowledge, the only hull modification was adding BHE sponsons and not setting them too low so that they would not create drag when running straight line runs.

I remember seeing a picture that someone shot of me riding it at full speed. The camera was shooting the XP as it passed him sitting out on the water on his pwc. From what I could tell, those sponsons were nowhere near touching the water at high speed because the hull was riding as high as possible with the least amount of hull bottom touching the water. That was what I was talking about when I said the hull needs to ride on that flat spot right in front of where the scoop grate front mounting bolts are located. From that point rearward none of the angled portion of the hull should be in contact with the water. You are riding on the flat spot intake opening and the flat part of the rideplate. That is also why I was talking about standing and balancing the hull to keep it level and not allow it to lay over to the left or right, and placing the feet to the rear as far as you can, and leaning forward with the head and chest with the arms and hands on the grips. Any buttons that you may need to push at speed, must be within the reach of a thumb or a finger. We had a button to activate the nitrous system solenoids and electric fuel pump to feed the extra fuel nozzels into the engine, with a micro switch on the throttle linkage at the carbureators to activate nitrous and to turn on the auxiliary electric fuel pump only after 7500 rpm ( that rpm was adjustable ), but the micro switch was deactivated when the rpm dropped below where we had set the rpm at 7500 to activate the micro switch so it could turn on the system during accelleration, and turn it back off upon deaccelleration. That micro switch was dead unless you had your thumb on the handlebar button.

There was another button within finger reach so I could toggle through the LED screen that was mounted in the center of the oem handlebar padding. The LED screen provided us with EGT readings for both clyinders at the same time, engine temp, rpm, and as you toggled, the seperate readings that toggling provided moved the readings from the small lettering and numbers onto the main part of the screen in larger script. We also had bright LED red lights for high EGT, overreving rpm, high clyinder temps all right there on the screen and they were automatic when any of those pre-set parameters were surpassed.
You do not want to let go of a grip for any reason other than bailing off the boat when you are travelling at high speed.

Race Pak made the unit that Mel bought for motorcycle racing and auto racing applications and he could program the parameters for all of the functions, plus some we did not need.

The screen size was huge for a pwc, at about 2 1/2 tall and about 4 inches across. Danny at Bullet made a real nice carbon fiber bucket and bezel to put into the oem handle bar pad, and the Race Pak digital readout screen fit perfectly into it. You would swear it was an oem option if you did not know better. It looked like the navigation screens that are factory dash mounted into most cars and trucks these days.

Bill O'Neal
WCM

[Mr. Bill]

Re: 1020 x-4 question

What Motor did you have in it to reach 82 mph? Thats fast, I would not want to be thrown off at that speed. I came off my GPR at high 70's and bruised a couple ribs, decided then to never ride without gloves again.
Your old stories are great Bill, back then I would use what ever part I was told the pro teams were using. Before the times of the internet, or GPS systems. You had to have someone standing on a dock to try to radar your speed, make a couple of adjustments and wait till the race weekend to see it anything helped or not.
Thanks Rob

Believe it or not, but I used to hit the lake before anyone else could muck up the glassy waters. There was a straightaway on the far side of the reseviour that I could head straight at the beach where the pwc's and ski boats were parked later in the mornings if any showed up. Beyond the beach about 100 feet from the waters edge, was a concrete retaining wall. I would go full speed with one hand controlling the throttle lever and the other resting on the left grip while holding the pistol handle of my Stalker Pro radar gun. That wall provided me with very accurate radar readings because it does not matter what is moving, the vessel or the wall, the radar reading is the same either way.
By doing this, the guy that normally would be there holding the radar gun was back at the shop making me money.

Mel built a bored and stroked to 1185 cc motor out of a 787 case and a special VE mono clyinder casting that was like the 970 cc motors had, only this one was taller. Then he spent countless hours designing his own sleeves, welding, reshaping all of the standard VE ports in the aluminum casting, and then the final porting job. There was quite a bit of flowbench work that went into that clyinder. In the meantime, he made a CAD program for the Miller Sleeves and for a twin sparkplug head.

Then he flycut out the case for a 12mm stroker crank and ported the cases and added a watercooler cover to bolt on under the case to help keep the cases cooler, he also did a CAD program for the case cooler after making one on the mill and having me test it on one of my motors out at the lake. He also added 12mm threaded holes for ARP clyinder bolts as the holes were enlarged in the VE casting for 12mm bolts.

Then he designed and made a CAD program for the one piece intake manifold/rotary valve cover for 46mm Mikuni's.

He had a special thick copper base gasket made to fit his clyinder and case port patterns and to have 12mm bolt holes built into it.

He got a set of CR500 oversized pistons and a set of CR500 rods. He then stress relieved the rods with a fine carbide grinding tool and sanding roll in the porting tool after machining the thrust surfaces to fit onto a 787 crank and still have side to side clearances. Next the rods were heat treated, and shot peened. He did some gas porting on the pistons and a bit of cleanup work to stress relieve them, and set the ring gap a bit wider than normal for ring expansion.

After that part was all done or being made, he assembled and finish ported the clyinders and sleeves, then bored the sleeves and did a four stone hone job, including the break-in honing.
In the meantime he had Novi build him up a set of carbs to his own specs and diffuser design. He had MSD build a special ignition to run the four coils, with adjustable rpm activated switch control wires and all of their other optional timing, retard control, rev limiter, ect.
NOS built him a N02 kit and Bullett built the carbon fiber mounts for two small N02 bottles for up next to the gas tank so it would all look very professional along with the oem carbon fiber bezel for the Race-Pak to fit into. Jettrim made a seat cover, because at 6'5", Miller's butt sat right on that '95XP humped up seat and when he lifted, the butt would move forward off of the hump and his knees would jamb up the handlebars and he couldn't turn the boat. X-4's are made for guys my size, not for Wilt Chamberlian types. They also threw in matching mats.

From day one, back when it was a 970 doing 69 mph on gasoline only, it needed a larger jetpump. Skat had been making some Kawasaki pumps with 6 stainless steel vanes. They were all at or near 140 mm.
One day when Miller drove out to the Skat Trak factory, he noticed a pump laying on the shelf that was a Skat Trak Sea Doo pump housing. It had 6 vanes in it and was larger than other SD pumps. Ken said it was a 148mm housing and that a few years earlier, he had made it for his GT that had the Evenrude 6 clyinder motor in it. But he said it was a "waste of time" and he had shelved it with other cast parts in his office for showing casting customers what they could build in their foundry and machine shop.
Miller asked if he could "borrow it" and Ken said if he could figure out how to make it work, he was welcome to it. Bingo, we have a winner ! The D pump was born shortly afterwards, followed by the 8 vane, 10 vane, 12 vane, 14 vane and even an 18 vane D pump. We tried them all and for our use, it was the 8 vane that worked best for speed and the 12 vane for hookup out of all of them, but then we were only going high 60's low 70's. That is where the scoopgrate and rideshoe pump support plate and the nozzel work came in, all the while Skat was making him one impellor after another. Eventually the 970 gasoline fueled project maxed out at about 74 mph.

Time to build and install the N02, new ignition, twin plug head with an array of domes sizes and shapes, and an auxiliary fuel suppy system, with a bigger twin two stroke motor.

After sorting out the bugs, like installing full length 14mm studs to hold the head and clyinder from lifting off of the cases during a full blast N02 speed run, the rest is history. In November of '96, he had it down pat. We could go to the lake with confidence that the boat would top 75 mph on gasoline only, and accellerate to 82 on the bottle, and still be in one piece, not needing new pistons, for the next trip to the lake.

At least a dozen or more different riders and radar gun holders, all working or racing in the pwc racing world, were able to see speeds over 75 mph and as high as 80 mph. I had the experence on that boat to be able to squeeze the extra 2 mph out of it that nobody else seemed to be able to get. Mel weighed 235 or more depending upon if you asked him in the morning or the afternoon or if a pig had flown over the moon the night before and he had no chance of going as fast as me. Truth be told, I bet he was 250 or more on his lightest days back then. I think he thought he was still in 8th grade or something when he used to say 235.

Nobody believed me when I first posted that on the old pwc newsgroup, RSJS. Back in '96, not even the fastest Tim Judge Yamaha's or the Darren Hedlund Polaris's were coming close to those speeds, and the average racers were topping out in the high 60's and thinking they were doing mid 70's. I radared enough of those mid 70's Yamaha's to know they were not hitting 70 mph. We all shared the same test site on the same days. Everybody knew what everyone else had with very few surprizes. That is why Mel decided that anyone he thought could handle the speeds was more than welcome to go ride the boat unless we were in the middle of doing something to it to make it better.

This was not one of those deals where you go buy the parts, bolt them on and even come close to what we were doing. I have not even talked about the accelleration curve of that boat ! That was really the most impressive part of the whole project. It went from zero to hero faster than most people could hang onto it without the N02, but with it, it was absolutely mandatory that he add that rpm activated switch that disabled the solenoids and fuel pump before achieving the minimum rpm of 7500.

Miller made the mistakes of hitting his N02 button a couple of times that he should not have at the speed he was doing. Once coming out of a hard left hand turn at about 40 mph. The hull came completely out of the water and threw him 50 yards away from the hull. Another time, he tried the button leaving the beach from an idle. The hull stood straight up, bow to the sun, and he had to bail before it came over backwards and hit him.
I have no idea what he was thinking, that hull would almost do that on straight gasoline. With that engine and pump in an X-4, it was all about squeezing the throttle slowly when accellerating.

Bill O'Neal
WCM

[800X-4rider]

Re: 1020 x-4 question

Wow! This was the greatest post ever EVER!

Bill, please write a book. Your stories are awesome.

[profiesy]

Re: 1020 x-4 question

Wow! This was the greatest post ever EVER!

Bill, please write a book. Your stories are awesome.

I would buy that book

[redheat1]

Re: 1020 x-4 question

After Danny's orginal design kits, a couple of us would modify the actual tabs to eliminate the rounded outside portion of the trim tab to reduce the sq inches of tab surface out there at the outer side portion of the trim tab. To achieve that was easy. Scribe a line from the back corner of the trim tab so that the longest part of the extension tab was next to the jetpump, and the outer side of the trim tab were it met the hull at the sides of the hull was as close to the hull hinge joint as it could be. Then just cut the line and presto, you have a long, narrow, triangular shaped tab that got wider the closer it got to the jetpump.
Now we had a tab that substaintually reduced the risk of causing the ill effects to the handling, but just as importantly, when angled slightly downward in a corner, drastically reduced the lift at the outside corner of the back of the hull. If you want a hull to corner well, you do not want lift. You want traction, you want a pump that stays connected to the water, sucking the hull down to avoid sliding out in the tight corners.

A properly setup adjustable trim tab never needs to move very much up or down, as a degree or three from the plane of the hull bottom, either up or down will drastically effect the attitude of the hull. More degrees upward will allow the hull to porpoise, and more degrees downward will cause excessive bow steer and the hull will dart left and right, what is reffered to as "hunting".



Bill O'Neal
WCM

I love reading about your modification of your pwc, There are no pictures of these trim modifications???

[Mr. Bill]

Re: 1020 x-4 question

Not unless you find some from an old race XP that still has a set on it.

[chrismcallister]

Re: 1020 x-4 question

I love reading about your modification of your pwc, There are no pictures of these trim modifications???

Ours came cut when we first got our Team West Coast Race Boats...

[Matt Braley]

Re: 1020 x-4 question

I love those Westcoast race boats. I have many carbon fiber hulls but none that show the weave on the outside like that.

Westcoast made their own adjustable trim tab kits though. Your skis probably have those. They usually have a pretty "splash" anno job on them.

[Merlin4204]

Re: 1020 x-4 question

I want one


Sent from my iPhone using Tapatalk