PJS Top End Kit

[NITEHAWK]

Dan Depardo,
I was just wandering your knowledge of this PJS top end cylinder kit for a 88 650sx kawi?? I have a contact for this complete kit with the t-3 cylinder porting! Reliability of this kit is what? What other mods need to be done? What pump mods and impeller selection should be done-used? Please help with any info thanks Kerry

[Dan DePardo]

Hi Kerry;
As you probably know, PJS built some very nice Kawasaki parts. The thing is, if we're talking about used parts, the condition of the items is a huge factor. Also, you need to keep in mind that the "old" PJS is out of business, so any replacement items specific to the kit, (gaskets, "O" rings, hardware, pistons, etc.) might be tough to find, even if the kit is relatively complete.

From a "reliablity" standpoint, racing oriented parts tend to require a much higher level of care and attention for best performance, and reasonable long-term life in a recreational boat.

I think the "T-3" PJS porting was the most aggressive level, so you might find that you'll need to replace pistons every season.

Aggressively ported cylinders, particularly the exhaust port (width, height, and overall shape), typically means that you're going to wear pistons and rings faster.

Depending upon your ignition timing, pump load, and how the top end is set-up, you might also find the need to run straight race gas to stay out of detonation.

Concerning your 650 pump set-up, I think the PJS 650 parts were developed just before the general introduction of progressive pitch SS impellers, so the PJS recommendations were probably something like a straight pitch 15 to 17 degree Skat blade and either a PJS nozzle or a bore job on the OEM reduction and turn nozzle.

However, we now have better pump impeller technology available. Tell me more about the parts you are considering buying, how your boat is set-up now, what sort of riding you do, and your engine tuning experience level.

Dan

[Bryan Glynn]

How 'bout it Dan?

[NITEHAWK]

Dan
The PJS top end kit is brand new just has been in storeage since PJS went out of business. He has all different cylinders avaliable with different porting T-3 T-2 etc.
As far as my ski now i have just rebuilt the motor last year from the ground up and had a mild port job done on the cylinder. All westcoast bolt on parts such as head ( 170 compression ) exhaust manifold,pipe,intake manifold and a 44mm carb. Running a 9-17 impeller best to date 45.3mph here in oklahoma city area. So is this good or what?
I just want the boat i always wanted to be able to give other stand ups a run for there money also some of the sit downs! I was a mechanic for some 13 years before i started to drive a truck for a living!!! So there you some more info look forward to here what you say thanks Dan

[Dan DePardo]

Hi;
45 MPH is respectable from a 650 powered 650SX, but a little slower than what I would expect with the mods you mention. Are you using a big loader style scoop grate? Do you know what flat water RPM you're pulling now? You might be RPM limited by your OEM '88 CDI. Stock 650SXs were 39-42 MPH boats.

Okay, here's my opinion about the PJS cylinder...if the seller has *complete* kits, (cylinder, pistons, head, parts kit and gaskets), you would have the best chance for success with the "recreational" T-1 cylinder.

I recommend that you get some help from a shop with a good reputation setting up mod two stroke PWC engines. You'll slag pistons left and right otherwise. Wrenching rather than riding isn't much fun.

I don't recall there being any "T-2" PJS stuff, but I know for a fact that you'll be squarely in race gas territory with the T-3 parts. I do not recommend attempting to run race oriented port timing and compression in a recreational boat.

You're going to need more airflow than a single 44 SBN can provide to see any major power increase over your current set-up. You might be able to get away with a properly jetted single 46 Mikuni, but a better choice would be either a set of OEM SXi 40 mm Mikunis on an aftermarket dual carb 650 intake, or a complete aftermarket dual carb package.

I also recommend swapping out your '88 CDI for a later model '93-95 650 X-2 CDI for a higher rev limit. You also might be able to find a WSM(?) aftermarket 650 CDI which has an adjustable rev limiter.

In all honesty, I think you would be better off looking for a complete stock "big pin" '96-01 750 SXi / ZXi engine which will bolt right into your hull, and cost you a whole lot less time, frustration, and $$$, rather than building up a 650 around one of those PJS cylinders. A piped 750 SXi in a 650SX hull should pull low 50's on flat water easy, all day, anytime you want to ride it. You won't be able to make that claim with a heavily modified 650.

Once you get that 650SX hull up into the high 40 MPH range it's going to get squirrelly, and you'll need some handling Band-Aids. I recommend a set of the Beach House "Rail Wedge" sponsons, and lengthening your stock ride plate. Take your 'plate to a good welder and have him add 3" to the center flat portion, be sure to machine the planing surface flat, and radius all sharp edges and corners afterwards.

A 9-17 is a good impeller, but if you find that you're cavitating under hard acceleration after adding a big dose of power, consider a Skat 10-18 or send the 9-17 off to Impros (http://www.impros.com) and have Dave give it a tweak. Dave might also have some suggestions concerning a good blade for your set-up.

Good Luck!

Dan

[ April 08, 2002, 06:46 PM: Message edited by: Dan DePardo ]

[NITEHAWK]

Dan
Thks again for your reply! The 650sx turned 7050rpm at that 45.3mph with one of Dales cdi boxes. Has a Rend open style grate on it for that test also but switching back to my top loader for better pump hook up. So where is my problem for this boat to be so slow with mods?
As far as PJS kit i was told by good sources that this cylinder was direct bolt up just had to remove my studs on the cases and place longer ones the block off reed area on the 650 case with blocks that PJS made for this specfic kit. Cylinder has reed openings with the use of 750 reed cages there own head and a dual carb intake with dual 42mm kehin carbs set up for this kit. Was told my 650 exhaust would bolt up for use. No mention of any maching to cases or no other problems!! Are you out in the dark on this one or am i not getting right info from my sources?? Who by the way are in direct contact with the people who use to work for PJS. So there you are so please let me know!

[Dan DePardo]

Hi;
Don't get me wrong, 45 MPH is pretty good for a 650SX, however I do think that the ski could be a couple of MPH faster with the 650. Even with very mild "clean-up" cylinder porting, I'd expect to see more like 7200-7300 loaded RPM out of your set-up.

My guess is that the Westcoast pipe, and possibly your carb tuning are the most likely reasons you're only seeing 7050 RPM. The best 650 pipes are the Factory Pipe Limited pipe, and the Coffman's pipe, in that order.

It sounds like your source does have a 650 specific PJS kit, it's just that I personally have not seen one. I have only seen the 750 and 550 PJS cylinder kits, but after looking around a little, I did find references to the PJS 650 cylinder.

I can only offer you my opinion, and that is if you're getting all the parts "way cheap", you're looking for a tuning challenge, and you don't mind sticking a piston or two in the process of getting things right, the PJS cylinder kit should wake up your 650 in a big way.

Just keep in mind that while the 650 is a good engine, the crank assembly really isn't up to the task of reliably handling big HP increases.

I think you'd be much better off in terms of power, reliability, and cost, with a late model big pin 750.

Good Luck!

Dan

[NITEHAWK]

Dan
Another source told me that my stock water box was holding me back alot. Said go with like a TDR box might give me another 150rpms also ditch the 9-17 and go with a solas 16-19 because the 9-17 might be cavitating on the low and top end plus he thinks the solas is a better prop. Plus said to advance stator 6 to 8 degrees over stock timing but i read not to do this by David Simon unless you run race fuel because engine will produce to much heat with more than stock timing.
I dont know now what to do except to focuse on what i have now since i have rebuilt it last year and have some money in it but i just need to figure out what to do to get this boat running where it should. So whats your opinion on this?

[Dan DePardo]

Hi;
Keep your stock waterbox. A TDR waterbox will make your boat annoyingly loud, and it's just not worth it for a recreational Ski. I've pulled 7300+ loaded RPM with a mildly modified single carb 650, running through the stock waterbox, spinning a Skat 9-17.

If you were cavitating at low speeds, you would hear it, and since you're only pulling 7050 RPM now, I doubt you have a high speed cavitation problem. As far as a Solas 16-19 being a "better" impeller than a 9-17 Skat, "opinions vary". In my opinion you have the best available off the shelf impeller for the 650 pump. If you want a better blade, you'll need a professionally set-up impeller, not an out of the box Solas. Contact Dave at Impros as I previously suggested.

If it were my boat, I'd "Ebay" that Westcoast pipe and install a Factory Pipe 650 Limited pipe

Dan

[ April 08, 2002, 06:53 PM: Message edited by: Dan DePardo ]