Nozzle size

[nickwad]

What Nozzle size is most used on SJ for freestyle?, stock pump stubbie cone Solas 13/17 .engine mods are porting, ADA head 195 psi, light flywheel, B mod pipe, modified stock carbs.

I had a nozzle made oversize 87mm the ski has very good punch but I think it maybe too big, I tried a std cone with it but it just lost a bit of punch low down


IMG_1047.jpgn.

 

[Polish jet pilot]

How can a punch be too big?

Anybody know what are approximate venturi sizes for best hit on stock, and ported motors with bolt ons?

 

[ksarge91]

Alot of people take them out to 85. That's what my cat's nozzle's at. My stock nozzle was at 86.5

 

[nickwad]

Polish jet pilot, I did not mean the punch was too big ...I meant I thought the nozzle may be too big to load the engine to the best degree!

Ksarge91, Confused , What is your ' cat ?' Did you really mean your standard nozzle was 86.5 ?

Thanks for the repiies

PS some days I wonder WTF I am doing in Thailand , But then I see many pictures of skis on the forum with snow in the background !!
I am very lucky I can ski every day of the year, Although I wish There were more Brap buddies to go with!

 

[SuperJETT]

Around 85mm for the reduction nozzle and at least 2mm bigger for the steering.

It depends on a lot of variables though.

 

[ksarge91]

Ksarge91, Confused , What is your ' cat ?' Did you really mean your standard nozzle was 86.5 ?

My C.A.T.S (cheap arse trim system) uses a raider reduction nozzle. I only took it out to 85 and with a solas 13/17 and I'm happy with it. My stock reduction nozzle was at 86.5mm

 

[#ZERO]

The 6R7, 6R8 and 61X nozzles can be taper bored out a bit larger from the stock size at 82.3mm all the way up to around 86.8mm depending on the overall set up and tail cone used. They use a steeper reduction angle of 25.5-dergees with the nozzle angle ranging from 1.0 to 2.2-degrees and are more suited for bottom-end performance.

The 62T, 65R and 65V nozzles with & without tilt trim use a shallower reduction angle of 21-degrees with the nozzle angle at 3.5-degrees and are more suited for mid range and top end performance. They cannot be bored out as much because of the short distance at the actual nozzle area and it will make the pump load decrease significantly if opened up too large.

Also you could have used the 6R8 nozzle without the pressure hose attachment fitting, because the outside diameter is a bit larger and it can be taper bored very close to 87mm. However, with your nozzle straight bored through at 87mm, it's probably still too big for your application, as most people are using between 85mm to 86.5mm taper bored with your type of setup.

 

[nickwad]

Thankyou # Zero,

I take it when taper boring a nozzle the diameter measurement is taken at the very end of the nozzle?

Ksarge 91 , Thankyou for your reply I never would have guessed what CATS stood for Lol.

 

[#ZERO]

Yes... the inside diameter measurement should be taken at the very tip of the nozzle.

Also if you ever measure a steering nozzle, check the height and width because some are slightly oval shaped on purpose.

 

[kevbo]

Replaced an old protec nozzle straight bored to 85mm with an 800 nozzle bored to 85mm and felt the same.

 

[#ZERO]

Replaced an old protec nozzle straight bored to 85mm with an 800 nozzle bored to 85mm and felt the same.

Going from a bowl shape pro-tec to a shallower reduction angle 65V nozzle both straight bored the same size probably won't make a lot of difference.

You should try using 61X or 6R8 nozzle with a steeper reduction angle, taper bored to 85mm and see it feels them same.

 

[nickwad]

Thanks Zero, You sure know your nozzles !

 

[masterblaster]

interesting,how much better does the taper bore to 85 or 86 do than the straight bore? I picked up alot of low end snap by straight boring mine to 85.5 on a mild stroker. might try a short cone next

 

[kevbo]

Going from a bowl shape pro-tec to a shallower reduction angle 65V nozzle both straight bored the same size probably won't make a lot of difference.

You should try using 61X or 6R8 nozzle with a steeper reduction angle, taper bored to 85mm and see it feels them same.

It was an OLD 61X style Protec. It should be and probably is more restrictive than the bowl shape for a given size. In this case, with a short cone it felt the same so it wasnt tached. This engine has a high port cyl so it had no problem with a few more rpm.

 

[#ZERO]

interesting,how much better does the taper bore to 85 or 86 do than the straight bore?

With the bore tapered at 2.2-degrees the standard 61x nozzle diameter will be 4mm larger at the entry point than the straight through bore.

 

[chriselmore_1]

what about the plastic nozzles. can they be bored?

 

[JetManiac]

what about the plastic nozzles. can they be bored?

IMO, they (plastic nozzles) have no place on a freeride ski bored or not, replace it with a metal one and then bore it.

 

[#ZERO]

Yep... the plastic nozzles will break.

 

[Foximus]

How about SXR stuff? Wheres a good bore point there? I'm using an x2 nozzle, and from what I understand they are the biggest kawi nozzle made... (at least on that pump...?)

 

[Waternut]

How about SXR stuff? Wheres a good bore point there? I'm using an x2 nozzle, and from what I understand they are the biggest kawi nozzle made... (at least on that pump...?)

I ran 82mm on my metal 750 nozzle and it was great improvement. When I got the X2 nozzle with the guide veins, it was at 83mm and I couldn't tell a lick of difference between the two.