Kawasaki 650sx 61.3 mph. Noob can't ride

[Big Kahuna]

Stock Kawasaki 650 engines are 76mm bore and 70mm stroke comes out to 635cc.
We built 2 or 3 of these engines.
We used a custom Falicon Crankshaft +2mm billet stroker 'T BONE' crank (72mm) and were bored 1mm over (77mm) this came out to 670cc.

First part of my post was regarding speeds for SXR Limiteds with minimal parts.

I think it is funny that so many people have narrow minds and because they did not see it they do not believe it........

I remember watching tour stop racing in Texas I believe back in the early 90's when sheldon and jacobs were getting 55mp on their 550's and the announcers were talking about them.

 

[2XLR8]

When Billy Pointer raced in the pro class with his 650 SX with a 750 mod engine I dont think it did 60 MPH. Look up Jeff Jacob's last time he raced I dont think it did 60 either, and that was a Hedlund tuned SuperStock There was a whole article by Personal Watercraft Illustrated right after the world finals on Jacobs Super Jet.

 

[Big Kahuna]

When Billy Pointer raced in the pro class with his 650 SX with a 750 mod engine I dont think it did 60 MPH. Look up Jeff Jacob's last time he raced I dont think it did 60 either, and that was a Hedlund tuned SuperStock There was a whole article by Personal Watercraft Illustrated right after the world finals on Jacobs Super Jet.

Your correct on Jacobs, they built and setup that ski to have much more bottom to mid power. Speed from "A" to "B" not overall speed. The year before his ski was much faster. 63mph+ and very uncontrollable powerband. (He could control it but it was violent).

Having a ski on a race course that can do 60mph actually does not mean squat. If you cannot get to the first turn up front you may be screwed. It is much easier to hold the lead than come from behind. Also, just because your ski may do 60 does not mean you can race that ski at those speeds due to water conditions. You got to have a well balanced setup where you can pull hard off the start and out of the corners.

Several years ago I took my Stock Class SXR and Yamacat's Limited SXR to one of the APBA National Tours stops (Lake Norman). Because I was not use to the power of her Limited, too much for me, I ended up racing my Stocker in Limited. There were times that I had faster lap times on it than the Limited.

 

[SNOWMAN]

61 mph? that would be the fastest vid on youtube on a stand up. there are 750's swapped with 951's not even coming close to that speed. that vid would be awesome.
post it

 

[Big Kahuna]

61 mph? that would be the fastest vid on youtube on a stand up. there are 750's swapped with 951's not even coming close to that speed. that vid would be awesome.
post it

Then they are not set up right. Open Class SXR's are seeing mid 60's easily. Even some full on limiteds are pushing upper 50's. I rode Brian Baldwins GP SXR 2 years ago, it was upper 50's and bone stock. I believe he said it was 57-58 all day. So if these 750's are not getting near 60 then they do not know how to set up their conversions.



Supertune has already answered the question about how strong the motor/ski is/was.

 

[SNOWMAN]

vid is proof. most people cant ride at 61 mph. like you said they are pro riders. looks and sounds like its strong. but its heavy. and bulky. i see it doing 50... if you are clocking it, you can film it.
shold be a cool vid is all. id like to see it...im not sayin its b.s....but dang a 650 that can smoke an open class sxr?
ill film it.

 

[Big Kahuna]

vid is proof. most people cant ride at 61 mph. like you said they are pro riders. looks and sounds like its strong. but its heavy. and bulky. i see it doing 50... if you are clocking it, you can film it.
shold be a cool vid is all. id like to see it...im not sayin its b.s....but dang a 650 that can smoke an open class sxr?
ill film it.

Who said a 650 could smoke an open class SXR?
Most Open Class SXR's that I have ridden were above 60.

Granted, I would not want to ride a 650 above 55!

 

[SNOWMAN]

nicely put together none the less.
sleeper ski. if i saw it id think it was slo. then id be in shock. hey OP, if you ever get to lakeland with it ill fim it or ride it or something.
lulz. yard sale!!!

 

[kevbo]

The old 650 hull can go fast and is the easiest to ride in a straight line. Im planning to install a Yami 1100 and 155 pump in one, just so I can blast around on cheap gas.

 

[kawapower@nl]

an old 650 sx ski of mine did 58 mph (93 kph) yes 58 on a 650 the engine was tuned al the way and only able to do 58 on total flat water conditions ... the hull off a 650 makes it f***king scary iff you go faster than about 52 mph

42 Keihin carbs, custom make exhaust, aftermarket electrics had the rev limiter at 7900 rpm i think ..... lots lots done

btw 650 engine needed to much service/overhaul, crank bearings etc etc didn't last long,

these days ride a SXR wetpipe and some small mods aprox 54 mph but much much more easy to ride and go fast and not as scary above 50 mph as the 650 was %^&*£

 

[Proptimus Prime]

an old 650 sx ski of mine did 58 mph (93 kph) yes 58 on a 650 the engine was tuned al the way and only able to do 58 on total flat water conditions ... the hull off a 650 makes it f***king scary iff you go faster than about 52 mph

42 Keihin carbs, custom make exhaust, aftermarket electrics had the rev limiter at 7900 rpm i think ..... lots lots done

btw 650 engine needed to much service/overhaul, crank bearings etc etc didn't last long,

these days ride a SXR wetpipe and some small mods aprox 54 mph but much much more easy to ride and go fast and not as scary above 50 mph as the 650 was %^&*£

My compression is at 210 on my 650sx, i just build a brand new motor this winter and i have no idea where to start on jetting it.i have dual mikuni 44's and i have no idea where to start on the jets. Where did you guys start? what octane were you using?

 

[motoman96]

Who built the engine? A reputable builder should be able to get you really close. Otherwise, it's trial and error for jetting and poppoff settings. 210psi is race gas tho, unless your running a huge squish.

 

[fastgtfairlane]

its totally possible if its a true race ski.. the guys that dont believe it because their stock engine with a pipe sxr wont do it dont understand.. there is nothing stock about the internals of a true race engine..EVERYTHING is precision tuned, balanced, blueprinted and tweaked to the max.. these engines are not nearly as reliable and have a lifespan that is about half of their stock engine sxr.. these engines are designed to turn 9k plus rpms as well where as their stock engine sxr will turn 7000ish rpms.. I just got a pjs 550 engine which is a far cry from a stock 550 reed engine interally.. back in the 90s pjs was getting 90+ hp in their 550 pro mod race skis..

 

[Proptimus Prime]

Who built the engine? A reputable builder should be able to get you really close. Otherwise, it's trial and error for jetting and poppoff settings. 210psi is race gas tho, unless your running a huge squish.

I built the motor this winter, the head came off of a 650sx top end that was 1.5 MM over bore and the compression was 165 in each hole, i bought a pair of HPR ported cylinders this winter and had the local machinist put new sleeves in them and he returned them to stock bore. I didn't think about the compression rising as i returned to stock bore.
i'm about to have the machinist cut out some of the domes because I can't find any thicker gaskets online anywhere. only the thin paper ones.

 

[runninAmuck]

did we ever get pictures of this thing. i had an 88 650sx with motor work. ran it against my dads kawasaki stx-f 15 and he said it was about 50. motor went shortly after that ride

 

[jetpilot36]

60mph is believable for a 650sx. its unusual,but very possible. especially if it was built by chucky.my brother had a superstock that did well over 50.and got there very quick too.we only rode it about 3 times till he accidentally put 93 octane in it and southern fried the engine.but i do want to see the video!

 

[Vumad]

I'm pretty sure my GPS is good but I'm curious too and not claiming I have the fastest ski know to man. Anyone with a GPS willing to meet me at 10 cent toll by Tera Verda this weekend and help me out? I'll let you ride the ski with my and your GPS and video it. I honestly thought the GPS was wrong but got two runs with similar numbers. Also I have run many skis before and never gone so fast on a stand-up. It's wierd but if you see the ski you will see nothing but the best of everything. It is a honest Ex-sponsored ski with one race on the motor...

I assume you are talking about Tierra Verde by Ft. Desoto in FL. I PM'ed you. We can just ride. I can try to help you GPS it but I can't promise to hold onto a 650sx that fast. In anycase, we can ride some surf or drop my bouy's if it's flat.

My old 650sx did about 45mph. It was ok on glass. It was stock except a carb, prop, intake, ride plate. I found the most control on that ski at high speeds to have my left foot all the way forward, my back all the way back, both side surf stance, pulling on the bars haning off the back crouched. That was a long time ago. I found the ski did not like to plane flat on the bottom. It rode best slightly crooked. It didn't handle well straight up and down. Much better at a slight angle to either side.

I would say it is a combination of you and the ski. The hull was not designed for those speeds. I've always heard they get loose over 45. However, if you can get it to 60mph kneeling, the problem is you. Any time I feel like the ski can't do something, I remind myself that if the ski can do it with me kneeling, it can do it with me standing.

 

[Vumad]

its totally possible if its a true race ski.. the guys that dont believe it because their stock engine with a pipe sxr wont do it dont understand..

My X2 with a 750 motor bored 0.75 (for repair), with stock electronics, 650 pipe with stock 38 carbs poorly tuned dumping gas out the westcoast 650 exhuast as it ran with a prop, intake and ride plate barely lost to a SXR. Stock SXR is nice, but it's not something that I would use to compare a true race ski.

My stock 650 with a 44mm carb was pushing 45 (probably closer to 40-42).

Anyway, noticed after my 1st post someone bumped this old post into the new posts links. This thread was started in 2008. Don't expect much from the OP.

 

[kevbo]

My X2 with a 750 motor bored 0.75 (for repair), with stock electronics, 650 pipe with stock 38 carbs poorly tuned dumping gas out the westcoast 650 exhuast as it ran with a prop, intake and ride plate barely lost to a SXR. Stock SXR is nice, but it's not something that I would use to compare a true race ski.

My stock 650 with a 44mm carb was pushing 45 (probably closer to 40-42).

Anyway, noticed after my 1st post someone bumped this old post into the new posts links. This thread was started in 2008. Don't expect much from the OP.

He probably toasted a piston with pump gas on the very next ride. I can picture the ski laying on the ground in someones backyard with the disassembled engine sitting in its hull that is half full of water. The typical death of modified skis.