GROUP K 845cc SuperJet Freestyle Tech Info

[Polish jet pilot]

Me too. Not a lot of "scrilla" and GK are known to have relaiability in mind..what would really be nice is a review of this engine from a pro rider...

 

[x2skier]

I stuffed one into my friend's X2. To be fair, he is running the Kawasaki 650 pump with a cutback SXR impeller but other than that its setup 100% per Group K's specs. It also needs a bit of carb and head pipe tuning but is probably 95% tuned in. Nice even throttle repsonse with no cavitation or dead spots.

Overall, it pulls hard and has crazy top end but I was a little disappointed with the bottom end pull.........maybe my expectations were too high. In comparison, it probably pulls as hard as the Jetworks 62T/61X big bore in my SJ. Again, it is in an X2 and not running a Yamaha pump but ALL other components are new and per their recommendation.

 

[Polish jet pilot]

I think the 144mm pump makes a big difference. It hurts my balls more to get a shot from a Yami pump than from my frinds 650sx

 

[SN760]

The 144 mm pump WILL make a big difference, as well as using the correct prop. From what I have seen a lot of riders are overproping their skis.
With a little tuning and the right prop I think this motor will hit hard and be a good dependable ride.
Harry tends to build motors that not only run good but run a long time.

 

[2XLR8]

If the 845 X2 has a 650 pump chances are good it has at least an 80mm nozzle and with the stock 800 impeller that normally runs a 76mm nozzle it should be pretty darn good on the bottom end specially with such a big engine. It should have pulled like crazy on the bottom end. I don't see how a 144 pump would be so much better than the 140 mm 650 pump when many superstock 800sxr are running 140 and 142mm mag pumps. If the X2 has 44s then it should run impressively even in an X2 hull. The x2 hull has too much drag at top speed but out of the hole it should be quick.

 

[HLS30]

Any recent updates on this 845 cc yamaha powered X2, is it pulling any better now that it is fully broken in any pump changes ?

 

[Sharky]

Well i took a long look at the group k as my mate has just put one together and we will be rding it this week.
the boost port is just a few mm higher than the rest of the transfer ports and is the same porting or should i say very similar to my dan lamey ported 62t cylinder, the piston i have no idea where to get from as it is not like the seado piston as the pin height is higher than the 89mm weisco in my ada 10mm so i will have that to compate it to
It is runnning with some case porting , total loss and resonator and not a water box so we wil see what it goes like this weekend and post some results, at least with the resonator and total loss it soulnd like it will rip, also pump is 12/17 hooker with TBM

cheers

 

[skinnyman]

Just got my 845 broken in

My set up is straight up with what Harry said to run

Stk 44's from a b2
stk manifold
V force 2 owned
lpw ported cases
riva true/welded stk crank nib
great deal thanks Bonzi Bob
pro tec cdi
pro tec 1/2 girdle
stk FA
x-metal risers
845 kit
62t cylinder Thanks Again BB
stk head
TBM flywheel owned
Jss stator rebuild
b-pipe owned
13/16 prop owned
I have 4k in a complete motor out of pocket
The build was semi on time
Harry is easy to work with no bs on time of build
Sent the right jets/springs/NS with tuning specs spot on No rejetting Pefect
The ski hits as hard as my lamey stk stroke Non Pv motor/TL/full specs
That set up ran about 3k more than my 845

Bang for the buck In my case hell ya
I am very happy with this motor
Not sure what motor I would sell if I had to
I will have some of our crew ride both skis back to back and chime in
Going to ride surf this weekend cant wait

 

[jetski9010]

Just got my 845 broken in

My set up is straight up with what Harry said to run

Stk 44's from a b2
stk manifold
V force 2 owned
lpw ported cases
riva true/welded stk crank nib
great deal thanks Bonzi Bob
pro tec cdi
pro tec 1/2 girdle
stk FA
x-metal risers
845 kit
62t cylinder Thanks Again BB
stk head
TBM flywheel owned
Jss stator rebuild
b-pipe owned
13/16 prop owned
I have 4k in a complete motor out of pocket
The build was semi on time
Harry is easy to work with no bs on time of build
Sent the right jets/springs/NS with tuning specs spot on No rejetting Pefect
The ski hits as hard as my lamey stk stroke Non Pv motor/TL/full specs
That set up ran about 3k more than my 845

Bang for the buck In my case hell ya
I am very happy with this motor
Not sure what motor I would sell if I had to
I will have some of our crew ride both skis back to back and chime in
Going to ride surf this weekend cant wait

Thats good to hear

 

[Polish jet pilot]

That is the type of review we all love to hear. We wait for more. Thank you!

 

[SuperJETT]

One of these when this site makes enough money, I'll buy engine setups and do comparison reviews, like the Group K 845 vs Team Scream's big bore standard stroke, etc...

How much $$$ would I need? lol, I don't see that happening.

 

[the WaTeRhAwK]

One of these when this site makes enough money, I'll buy engine setups and do comparison reviews, like the Group K 845 vs Team Scream's big bore standard stroke, etc...

How much $$$ would I need? lol, I don't see that happening.

well, madmatt just had a good point when he mentioned "why doesn't M&M marine and companies like that advertise over here?" you could make some money off of them. advertising isn't cheap these days.

 

[ridethelip]

This site encourages people to build big bore, big money motors.In the surf riding the wave (actually following the wave) all that power is just not needed.It will cut down on your ride time as it guzzles fuel and is more prone to break downs.

 

[ridethelip]

I think the 144mm pump makes a big difference. It hurts my balls more to get a shot from a Yami pump than from my frinds 650sx

Where your from helps make sense out of what you said.Is that the crotch dyno?

 

[Foximus]

my 650 pump will hurt your nuts... Garunnnteeeed. =]

And if anything he has that backwards, the 650 pump puts out more pressure, the 144 more volume.

 

[kevbo]

I got to ride Skinnymans GK845, and I thought it ran good. It had good response with all stock parts. Best of all it was the easiest plug-n-play setup that Ive ever encountered.

 

[Shifty]

Good to hear some actual reports.

This makes me want to put my friends motor together this winter. It doesn't have a real port job though so I am a little scared I would not like it. If I did put it together I would be running 46mm BlackJacks, TL, and the Boyesen reed and manifold.

 

[jetski9010]

Anyone eles get one of these yet? I also was told from art that he will be making some 88mm and up big bore motor come dec or jan.

 

[aussiemat]

rode one in a rickter the other week and was very impressed at slight throttle it didn't feel unlike a nice limited setup (read predictable) but open it over 1/3 and it rips up through the rpm's. The owner of the boat has been getting much more air with this over his old 1000cc+ motor, might not be as powerful overall but alot more useable power.

Matty

 

[SUPERTUNE]

rode one in a rickter the other week and was very impressed at slight throttle it didn't feel unlike a nice limited setup (read predictable) but open it over 1/3 and it rips up through the rpm's. The owner of the boat has been getting much more air with this over his old 1000cc+ motor, might not be as powerful overall but alot more useable power.

Matty

What was wrong with the setup on that 1000cc?
Did he have the wrong impeller? Was he running a dry pipe that was improperly matched the the engine and pump setup? Was the engine overported for the compression ratio? Carbs not tuned right? Maybe the porting needed MSD-TL advanced timing?
There's ABSOLUTELY no comparison to a 1000cc engine to a stock Yamaha casting 5 port cylinder if it has been setup correctly!