Kawasaki 1100ZXi Modification List (Part 1)
Kawasaki 1100ZXi modification List, STAGE 1 modifications
This combination was compiled and tested using several different data aquistion medium and involved proffesional installation and tuning. Please use this as a rough guide only as every boat is different.
This is PART 1 (of 2) of the 1100ZXi modification list. I take no responsibility for your particular watercrafts results when performing these modifications, unless I did the work myself. Also, this is just one of about 4 different Stage 1 combinations we tried and liked. Performance is based on overall increases, not just top speed. Due to the large amount of data, you may want to print this post out and read. Please enjoy.
There are several good choices for carburation for the Stage 1 modified 1100ZXi. For Stage 1 modifications, I like the non CV (constant velocity) 38mm Keihin CDK2 carbs as found on '96 & '97 model 1100ZXis and/or prefer a set of Sudco 42mm Keihin CDK2s. Both choices are low cost but effective power adders for '98+ 1100ZXi Kawasaki watercraft. For the later model 1100ZXi watercraft ('98+), you will need to drill and press fit a new pulse line nipple into the cases when using the 38mm CDK2s or if you choose the 42mm Keihins, you will need to drill and tap two additional pulse line nipples into the cases. To accomplish this, you will need to remove the intake manifold and reed cages. To ensure that you do not get metal debris into the cases when drilling, I would spray WD-40 on a flexible sponge wedge and stick it into each intake port opening in the case. After drilling, carefully pull the wedges out which will pull most of the metal shavings out with it. Be sure to inspect each intake port for additional metal debris and remove as needed. A cotton swab sprayed with light oil works well for this kind of clean up as well.
As far as performance is concerned, the 42mm Keihins are the better choice between the two carburator types, but will cost about $700.00 ready to bolt on. As a comparison, you can usually find a set of good condition '96-'97 38mm Keihins in the $125.00 range.
For Stage 1 modifications, the following jetting will need to be used: for the 38mm carbs: A good starting point is 135-140 highs, 82-92 lows, 2.0 needle & seat, and stock spring. For the Keihin 42mm carbs: 110 highs, 98 lows, 2.0 N/S. POP should be around 20-22 psi. Start with the high speed screws 1.5 turns out and the lows 1/2 to 3/4 turns out. I suggest installing adjustment screws that have a paddle wheel for ease of turning the adjustment screws in or out as needed for tuning these carbs. Remove the chokes and add a primer kit. The OEM 38mm non CV carbs can use the stock intake manifold. However it would be beneficial to open up the intake runners slightly, especially where the reed cage meets the intake manifold. I would remove 2mm of material (all the way in) AND reshape the port (closest to the reed area) so that it is more round in appearence. I would also recommend checking the mating surfaces of the intake manifold to make sure the carbs line up correctly and that no "lip" is present. After all this is done, I would use a 60 grit sander band and take all the paint off the inside of the ports (intake manifold). Basically you want a rough satin finish, not a glass smooth polished finish. This keeps the air/fuel mixture "tumbling" and provides some additional power. If you choose to use the Sudco 42mm Keihins, I would highly suggest using an R&D manifold. The intake runners will need to be matched to the new carburator size. Since the R&D intake manifold already has larger inner diameter port size, it is not necessary to open up the rear area of the manifold, but is still beneficial if you want to do it. Other than that, You will want to add a rough satin finish to the manifold as well. Both these carburator choices will use the OEM rubberized carb gaskets. However, if you are using the 42mm Keihins, the gaskets will need to be matched to the bottom of the carburator and intake manifold. The 42mm Keihins come with no chokes. Each carburator has a nipple that can be used for a primer kit. If you want to continue to use your oil injection system, these brass nipples will work fine for that too. You will need to drill a small hole in the front carburator and add a dedicated brass nipple to use for a primer. If you have a late model ZXi and you are converting over to the older style 38s, you will also need an older style throttle cable. If you are using the 42mm Keihins, you will need to machine off your old throttle cable carrier (where the cable connects to the stock carbs) and attach it to your 42s. No new throttle cable will be needed.
I would use a set of V-Force Delta 2 reed cages with their updated carbon fiber reeds. You will want to use the Kawasaki "thin" reed gaskets (Kawasaki makes thin ones and thicker ones) and the three supplied with the new reed cages. The thin ones are more expensive, but the thick ones will not work well (especially with the R&D manifold). The V-Force reed cages are thicker than the OEM ones and the R&D intake manifold is also slightly thicker. If you use the thicker gaskets, there may not be enough stud length left on the intake studs to get the 10mm chrome nuts securely on and tightened down without problems. You will use one thin reed gasket on each side of the reed valve. Install the first thin intake gasket over the studs and push the gasket down to the mating surface. Carefully install the V-Force reed valves next. The rear V-Force valve will need to be installed with the 'V-Force" insignia downward so that the valve will clear that section of the cases where the engine number is stamped. Next, install another thin reed gasket onto the studs and carefully push so that it is mated to the reed valve. Now you will install the intake manifold. Be very careful to esure you push the manifold onto the studs evenly as it is a VERY tight fit. Failure to carefully install the manifold could bend some of your intake studs. Once the manifold is securily on, install all 18 chrome 10mm nuts by hand. Using a shorty socket wrench with 10mm socket and small extension tighten down the nuts enough to be nice and snug working your way outward. The top 6 nuts will need to be tightened using a 10mm open end wrench. Keep tightening each nut in incrementally until they are all "good-n-tight" (good german specs..heh). DO NOT OVER TIGHTEN. The stock intake manifold is installed the same way.
Once the manifold is installed, take the modified carb gaskets and put a super thin film of Ultra Blue silicone on them (to keep them in place when attempting to install the carbs. Install the gaskets onto the top of the manifold. let sit for 20-30 minutes. Install the carburators using small bore Tau Ceti adaptors (38mm carbs) or big bore keihin adaptors (42mm carbs). There are two choices for flame arresters for this application. For a slight advantage in upper rpm gains, The Tau Ceti 3" cones work best in our testing. For overall performance gains, the Prok F/As provide the best powerband attributes (better throttle response, better acceleration). The difference in peak rpm between both brands is less than 50 rpm, but it is repeatable in back to back testing, so there are some differences.
Stage 1 modifications include a top end freshening up. I would recommend using 1.5mm (81.5mm) overbore Wiseco XP-S pistons (commonly called "seizcos" by some shade tree mechanics). DO NOT FOLLOW Wisecos piston to bore clearence specifications. I would recommend no LESS than .006 and no more than .0065 piston to wall clearence for Stage 1. .005 might be fine for use as stock replacement, but not in modified watercraft. When honing the cylinder, use a 60 degree cross-hatch pattern on the bore. This will increase the amount of time it takes to seat a set of rings (during break-in), but is useful for increased compression and longer service life. This would be a good time to check port chamfers and chamfer if necessary. No other cylinder or engine modifications are necessary for Stage 1.
There are two popular ways to increase compression on a two stroke PWC. You can either mill and reshape the combustion chamber of the stock head (cheaper) or use an aftermarket head. After many years of testing and gathering data, I prefer to use an aftermarket head. There is no benefit or need to get into the reasons why in this post. For recreational riding, I use a Pro Design head with interchangeable domes. The Pro Design 1100 head is a 5 piece design. It has a head shell (frame), domes with a locking feature to prevent spininning the domes when R&Ring spark plugs, a top plate and o-rings. I would suggest 31cc domes which are pump gas compatible. This moves corrected compression from 5.8:1 to 7.2:1 and increases performance across the powerband. The top plate has one water outlet and you will use the stock 1/2 inch fitting from your OEM head. You will also want to add two additional cooling lines coming out of the head above the front and rear cylinder in the same location as the stock one. Drill and tap for 1/4" thread. For Stage 1 modification, you will use 1/4" ID straight up barbed brass fittings front and rear. However, when you install the head, turn the top plate so that the water outlets are closer to the intake side of the motor (v.s. the exhaust side as the OEM outlet is). This effectively forces the water over the combustion chambers and will draw more heat away, as well as equalize any hot pockets within the cooling chamber. You will need to run PREMIUM unleaded fuel with added compression.
The 1100ZXi exhaust system is adequate for stock power levels and actually works quite well. However, once you modify your ZXi, you will want to address the exhaust system question. There are a couple of aftermarket (single pipe) exhaust systems on the market. I have tested them each of them. Yes they improve power. Unfortunately the question is not how much power increase is available but rather, where the power improvement is coming from. In my testing 80-85% of the power gain came from a $25.00 timing advance plate (6 degree advance). The other gains were mostly the result of careful manipulation of water being injected into the pipe. In my opinion, not worth the $900-$1100 asking price. You can add the same water "manipulation" features of the aftermarket systems to the stock system. I have what I call the Dominator 2 (D2) exhaust modifcation for the 1100 Kawasaki applications, which does not use a timing advance plate, but rather, makes power from the exhaust system and not advancing the timing as part as the "exhaust" question. It is a well known fact that the exhaust manifold on the 3 into 1 single pipe exhaust as used on three cylinder personal watercraft, is by far the biggest bottleneck as far as performance and horsepower is concerned. Due to design features built into the manifold, it is not only very restrictive, but also inhibits "multi-port plugging" (a quasi-pseudo exhaust scavenging which occurs on 3 into 1 systems). Since there are three exhaust ports opening or closing at any given time in the cycle, there is no such thing as a "tuned" pipe 3 into 1 system because one port may be opening, one port may be closed and another may be opening or closing, all at the SAME time. Basically the "sonic sound wave" never makes it back to the exhaust port and is wasted. So, think of your big 3 into 1 exhaust system as just a big "muffler".
How do I modify the stock system to improve power you may ask? I extensively modify the exhaust manifold so that there is less distance needed (between each exhaust port) to be travelled to "plug" each cylinder.This is done by reducing the "deflectors" within the manifold. I open up the manifold port runners 2mm and the manifold "collector" up to 3mm and match the headpipe to the top of the manifold. I then install a 150 Keihin main jet to the main chamber jacket, which is under the 1/4" "L" bend brass fitting (the hole just needs to be tapped), and I by-pass some water which comes from the stator cover to the pipe fitting. To improve holeshot & mid range acceleration and to facilitate more overall flow, I enlarge the "stinger" section of the pipe from 54mm to 57mm. I then add a dedicated 3/8ths water line to the stinger (reducing size down to 1/4" line where it connects to a 1/4" brass fitting) and tap in a Keihin 200 main jet. I use a 3/8ths Jetworks valve set to open at 5000 rpm. The overall effect is that for roughly $400.00, you can pick up as much as 15-18 peak horsepower (and about 200-225 rpm) while increasing torque from off idle to peak rpm. Our race pipe is loosely based on the D2, but is designed with acceleration in mind. Performance bewteen the aftermarket pipes and the modified OEM one is very similiar, except that the increase in power is from the EXHAUST and not an increase in timing advance.
The OEM 1100 waterbox is more than adequate for stock level performance, but as you increase power can be modified to flow better and manage water better at any given rpm range. The easiest way to get a slight increase in performance and to reduce back pressure would be to take a 1" holesaw and cut a hole in the rear baffle. As far as my full waterbox modification that we sell here at PE, we actually cut the box in half, make additional changes to the flow through tubes, baffle and exiting tube for a 75-100 rpm gain. But the 1" hole in the rear baffle will offer an increase in performance you can feel and it is free. Just don't cut a hole in the exit tube while cutting the hole in the baffle (easy to do if you are not careful, because there is very little room between the baffle and the exit tube).
I am not a big fan of ignition advance on recreational pump gas applications (unless other modifications are performed). However, jumping the temperature sensor will give you a mild 3 degree timing advance up to 5000 rpm (above that the advance curve is stock). The temperature sensor is there to advance the timing on days over 95 degrees to help eliminate power fade on those hot days. You can safely jump the temp sensor so that you get this advance all the time. To do this modification, locate the temperature sensor cylinder above the battery. Cut the two wires and crimp them together using a male and female connectors. It is that easy. As far as spark plugs are concerned, I would stick with NGK-BR9ES plugs for Stage 1 level power. No indexing is needed at this stage, but can be done if desired.
The stock 148mm 1100 Kawasaki pump is similar to the 140mm 750/900 design but has some inherent design flaws. If you have a '97 or up 1100ZXi you can proceed with these modifications. However, if you have a '96 1100ZXi, I strongly urge you to update your pump bracket shoe to '97+ specification. This shoe will vent the pump and prevent the pump blow-out that occured on many '96 model 1100ZXi watercraft. FAILURE to update this bracket shoe could cause INJURY or DEATH at speeds above 60 mph.
For best top end in smooth water I suggest an Impros "Power-tuned" Nujet 5.0 impeller. This is the fastest impeller available at Stage 1 power levels. However, do expect some ventilation (ie: caviatation) initially at low speed take-off. The best all-round impeller for the 1100ZXi is an Impros balanced and tuned Solas Concord 10/24 (read 13/20 on box). This will give you an increase in acceleration (with little or no slip on bottom), better mid range and an increase in top peak speeds. If acceleration is your main focus, a Skat-Trak Swirl 13/19 or 13/20 will make your 1100ZXi rip out of the hole and out accelerate the other two choices by a fairly wide margin. There is a mild trade off. Expect to see a 1-2 mph loss in peak speeds with Stage 1 and the Skat-Trak Swirl type impellers.
Unless you race or run primarily out in ocean surf, you should just cut the center bar out of the OEM intake grate. If you ride in rough water, the best intake grate in my opinion, is the Worx. It has the least amount of smooth water drag (about .5 mph) and really keeps you glued to the water in chop.
The handling of your 1100ZXi leaves little to be desired as far as a stock personal watercraft is concerned. The rear end slides out too easily due to the "soft" sponsans and the hull has a tendency to porpoise. I would highly recommend finding a set of used Twist sponsans or purchasing a new set of Worx sponsans. The Twist sponsans are less race "oriented" and provide the least amount of speed loss in smooth water radar runs. The Worx sponsans are a little more aggressive and will scrub about 1-2 mph off your peak speeds, but are great for rough water riding and for closed course racing. And, unlike some *other* designs out there, the Worx sponsans for the ZXi are hydrodynamically correct. The Beach House sponsans for the ZXi hull are too aggressive for recreational riding and have a tendency to cause bow hunt (chine walk) at low speeds and tend to over steer around buoys. Unless you plan on racing, the first two choices are best in my opinion. Not only will a good set of sponsans turn the ZXi into a great turning boat, but it also will get rid of about 80-90% of your porpoising problems.
If you have a '96 model 1100ZXi, keep your stock ride plate. Contrary to popular belief, ride plates on the ZXi hull do very little to combat porpoising. If you find one that does, it is probably slowing you down 2-3 mph. I have yet to see a commercially produced ride plate INCREASE peak top speeds on a radar gun in glass smooth water on the ZXi hull and I have tested 10-12 different types including a few prototypes. If you run primarily in surf or choppy conditions, a Shredmaster or R&D might be beneficial as far as stability and control (on '96 models). Later models ('97+) already have an extended ride plate that resembles an R&D plate very closely. Again, unless you ride primarily in surf, it would be best to cut the extension off the stock ride plate so that it is flush with the rear of the hull. This will add around 1 mph in smooth water peak speeds. Some might question cutting off the extension for fear it would cause additional porpoising and that might be true if we were not adding an extended turn-nozzle to the list.
An extended turn-nozzle has some great benefits in many different areas of 1100ZXi operation. By extending the turn-nozzle, you effectively change the "throw" of the thrust as it exits the nozzle area, thereby using more thrust for propulsion, than wasting it out to the sides. Ever notice how WIDE the thrust pattern is as it exits the nozzle at WOT? (EDIT: please use caution looking behind you at wide open throttle!). By lengthening the nozzle, it "tightens" the throw of the thrust. This can increase top speed by about .5-.8 mph on the Stalker radar gun. Extending the nozzle also changes the deflection properties as you turn the handlebars. By lengthening the nozzle, there is more surface area for the thrust to deflect off of. This effectively tightens up the "slop" in the steering and provides better feel and added control. A longer turn-nozzle also has a "fulcrum" arm effect. This is due to the exit point of the thrust being moved further back. This also makes your trim system work even better, with more noticeable change (up or down) when operating the electric trim system as found on the ZXi. You no longer need to put your trim all the way down to come out of the hole effectively and you no longer need to have your trim set all the way up in smooth water to get the best speeds out of the hull. An extended turn-nozzle will also add straight line stability in all water conditions, reduce porpoising and increase overall performance.
8. STAGE 1 OVERVIEW
42mm Sudco Keihin CDK2s $695.00
R&D 1100 intake manifold $153.00
Prok flame arresters $120.00
Tau Ceti carb adaptors $45.00
Primer kit for carbs $16.95
Delta 2 V-Force reeds & cages $348.00
Reed gaskets $27.00
Pro Design head w/31cc domes $379.00
Cooling upgrade kit $45.00
Wiseco XP-S piston kit (81.5mm) $378.00
Performance hone $30.00
D2 exhaust modification $399.00
Waterbox modification Free
Temperature sensor jump Free
Impros "Power-tuned" Nujet 5.0 $190.00
Impros "Power-tuned" Solas Concord 10/24.5 $219.00
Skat-Trak "Swirl" 13/19 or 13/20 $211.00
Cutting center bar out of itake grate Free
Worx sponsans $189.95
Ride plate modification Free
Extended nozzle $60.00
Power-adder only $2547.00
Stalker radar gun w/ATS acceleration software:
Stock top speed: 57.12 mph*
0-50 mph acceleration run: 6.42 seconds*
0-57.1 mph acceleration run: 14.29 seconds*
Stage 1 modified top speed: 64.79 mph
0-50 mph acceleration run: 3.44 seconds**
0-60 mph acceleration run: 4.79 seconds**
0-64.7 mph acceleration run 12.45 seconds**
*1996 model year 1100ZXi (57-58 mph average). Later model ZXis perform even better.
** Using a Solas Concord 10/24 (13/20)
While most people ultimately will scroll down almost immediately to find out "How fast will it go?", this Stage 1 modification list for the 1100ZXi concentrates on overall performance, not just peak top speed numbers. This combination does everything well (accelerates like a banshie, has excellent top speed numbers, better handling, increased stability in all water conditions etc.) , but as always, there are trade-offs to ultimate top speed numbers (or any other catagory for that matter). Obviously, the 42mm Keihins are faster than the 38s, so I used them. The trade off here is a reduction of up to around 10% fuel economy. There is also no doubt I could get more top end out of the 1100ZXi in this configuration if I deleted the sponsans and used the Nujet 5.0 as the test impeller, which I did not do.
There is no *stock* personal watercraft to date that can beat an 1100ZXi with the prescribed Stage 1 combination in a drag race in smooth water (at least not for 6-8 miles or more sic) and the top speed is competitive with modern day musclecraft technology for A LOT less money than going out and buying a new boat. The end result of this combination as far as hard numbers go is a 7 mph speed increase and a 4 second reduction in 0-50 mph acceleration (with no cylinder porting or any other internal modifications other than the piston swap/top end rebuild) . The Stage 1 modified 1100ZXi will also top out nearly two seconds quicker at that 7 mph increase in top speed over the stock '96 ZXi. The Stage 2 next week will cover more radical modifications, which will push the 1100ZXi up to the 70 mph mark. Crazy you say? Hang tight (not literally...heh)! Please submit feeback concerning this post to my PRIVATE MESSAGE area. Thanks.
PWCToday.com Is My Home Away From Home
wow.. put a little bit of thought into that eh?
Not at all. Just scanned about 40 pages of data and cut and pasted the results and then made it "readable"...heh.
Originally Posted by Rob
Drop me an e-mail. Need to ask you a question....
Re: Kawasaki 1100ZXi Modification List (Part 1)
How much know how is needed to replace this aand how much is a pump shoe?
Originally Posted by ZXiMan
Re: Kawasaki 1100ZXi Modification List (Part 1)
Originally Posted by ZXiMan
You will need to purchase these components from Kawasaki. I'm not sure about the price. This modification is very time consuming and can be difficult. I'd hire someone that has done this kind of work before to handle this job.
hey james i was wondering??? i want to buy your pipe later on this summer,i may would buy it now if you had one ready to go in stock,without me having to send mine in for a core,(1998 1100zxi),but i bought a set of '96 model zxi carbs and was wondering?do i need to change the jets and needle to your specs now or when i add the pipe? meaning can i ride it with the carbs like as is now? they have 78 lows and i think it was 120 highs not sure on that one? it has what looks like a 1.6 or 1.8 needle in it now....
hey james i am wondering some things about your zxi mod list.....
i bought a set of carbs off a 96 zxi that has 78 lows and looks like 120 or so high jets and a 1.6 or 1.8 needle and seat(cant tell) according to your mods i need to add 82-92 lows and 135-145 highs with 2.0 needle and seat my question is do i need to add these now as my ski is still stock or after adding your detonator pipe,meaning can i ride it with the carbs as is now? i would like to get your pipe and would get it sooner maybe if you had a ready to install one without me sending in mine for modification and having to wait now that i have waited so long!!! stupid me.... thanks in advance man
any of you ever take a picture of this process?
I know this is an old thred and an even older boat...but I am interested in performing these mods soon...so any help would be appreciated!
Re: Kawasaki 1100ZXi Modification List (Part 1)
Originally Posted by ZXiMan
Am I just splitting the plumbing from the 1/2 chamber/flush fitting and using a combination of fittings to make three connections to the manifold?
Or, was this taking from the stage two mod where you opened the pump boss and tapped a fitting?
PS. If anyone else has a comment...please reply... I am not sure James is visiting that often...
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