End my Impeller debate.

[Foximus]

Ill start off by saying Ive searched. And still come to no conclusions. I've had my square nose less than a week, and Im coming from modding 550s where straight pitched impellers are the only way to go.

So let me tell you first about my ski
'90 SJet
62t/61x
Dual 38s
Triton Eng. head
Riva red pipe - planning on swapping to a limited B when I can find one.
I believe the thing has reeds and porting done, but I am not sure what brand or to what extent. This motor was built buy a guy who used to build for Riva, who now works around the Orlando area, his name is Peter, not sure of last name.

I have a Skat in there now, and Im unsure of the pitch, I will be removing the pump housing tomorrow to find out for sure but I have a feeling its a 14-19*.


Ive read so many accounts of different things.

I know I want a concord or swirl for sure, and most definately with a cut back of 3-5mm... (how much though im not sure? In 440 pumps you can only setback so much before you lose efficiency) However after that Im at a loss.

Impros says their 13/15 concord cutback is the absolute best, and Ive read that one guy thought that a 13/17 was to low of a pitch and wasnt fun to ride lakes anymore, another guy said a 13/16 was to high of a pitch and lost bottom end (compaired to a stock impeller... that seemed BS) and still more Ive heard that a 9/17* will absolutely rip,this seems like to wide of a spread and that would end up being an inefficient impeller with bad water slap.


I ride lakes, plan to ride ocean. Love that bottom end pop, enjoy brappin around, but naturally I dont want to ruin a nice topend. If I could keep about a 45mph topend that would be nice. Not sure if thats achievable with a impeller pitched to get a killer bottom.

So you tell me! lets be conclusive about it this time. Thanks in advance

 

[Foximus]

on a side note, the 38s I have have a huge block obstruction casted in right above the main jet. I was planning on boring this section straight to get better flow. Dont have the cash layin around for dual 44s now so dont even bother sayin it, heh. Is boring out (or at least removing this restriction point) 38s worth it?

 

[Mike W]

I have a Scat 12/17 and like it. Nice bottom end and pretty good top end as well.

I have seen people bore out their 38's but dont know anything about it. For the money you would spend doing that mod you could get a pair of OEM 44's. That would be the way to go.

 

[Big Kahuna]

on a side note, the 38s I have have a huge block obstruction casted in right above the main jet. I was planning on boring this section straight to get better flow. Dont have the cash layin around for dual 44s now so dont even bother sayin it, heh. Is boring out (or at least removing this restriction point) 38s worth it?

Do not remove that, that section is there for a purpose, if you do bore it out, you will mess up the flow characteristics of the carbs.

 

[vomitspot]

fox glad you made it to the x
here is where you will get the best standup info!

 

[Foximus]

well, I noticed that on the Today, when I went into the yamaha section, they seemed confused by when I said I had a stand up.


They all said they all had stood up too.

no no, I say, not stood up, Stand up.


Right, thats what we do, we stand up.


really they were just confused when I told them it cant have a seat and side mirrors if its a standup.... They were really perplexed by this.


So I figured Id oughta just come here.

 

[Foximus]

Do not remove that, that section is there for a purpose, if you do bore it out, you will mess up the flow characteristics of the carbs.

and what about the more than numerous 38s ive seen on kawis that dont have that huge block there?

I can understand restriction to create high velocity but that thing is ridiculous. Ive seen 28's that are more free flowing.

 

[WFO Speedracer]

post a pic of what you are referring to on the carbs,

 

[Big Kahuna]

and what about the more than numerous 38s ive seen on kawis that dont have that huge block there?

I can understand restriction to create high velocity but that thing is ridiculous. Ive seen 28's that are more free flowing.

what 38's on Kawi's, they never came with 38's.

The OEM yamaha 38's are actually very good carbs.

 

[Frosty]

hell yeah... i'm still running my OEM 38's on my ported 701 with a B-pipe and ADA head - 185psi. it rips pretty damn good.

get a pic of the throat of the 38's - not sure what obstruction you mean - mine have nothing in them.

I have a set of 44's on my other motor and i am still trying to dial them in. for the price, i think i may change that motor back to 38's and sell off the 44's (or hold on to them for when i go BB).

also, i am running a Solas 13/16 w/3mm cut back... nice bottom end, although i hear the newer Skat has a better bite at low speed.

 

[WAB]

I ground all that casting out of my 38's. I can get a pic over the weekend and post it on mon. It was tricky to tune in after that at first, I don't recall what I ended up jetting it to....

You can get an OEM flame arrester for pretty cheap and ditch the Ocean Pros. The OEM one does a GREAT job of keeping water out.

 

[Foximus]

I thought the OEM tube was only for single carb...?

WAB, please post pictures. Heres the best shot I could get of that block. Not the best angle though

Edit.

Went onto jetski solutions site, they reccommend removing the bore obstruction and they do it for $50 each. I called but they did not answer. Ill call again and ask how it directly effects the carb performance and what jet changes need to be made. If $50 each includes a rejet Ill probably have mine sent in, otherwise Ill just bore it myself. first pic is from their website. Second picture is my carb.

 

[Foximus]

damn. Enough about carbs, off topic.

WHat about impeller? 13/17 with a 3mm cut back? Should I just get my skat repitched and cut, or should I go for a concord/swirl?

 

[Waste Land]

Get a Skat Trak Swirl.....I have a concord...good props. but Swirls are better I'm unsure of pitch.

DO NOT let Jet Ski Solutions touch your carbs. He does wonderful electric work, just keep your carbs away.

 

[Foximus]

lol... k. good on the skat then.


Ill be doing the carbs myself.

 

[Waste Land]

lol... k. good on the skat then.


Ill be doing the carbs myself.

Let me rephrase that....take your carb modding issues with a motor/carb builder:wink1: They'll know what to do

 

[Big Kahuna]

lol... k. good on the skat then.


Ill be doing the carbs myself.

The JSS Carb mod seams to only work when running a dry pipe, with a wet pipe it does not work, FreestyleGeek, SJ13, Parrdaddy and others tried these carbs modded by JSS and they could never get them tuned........

You can do the mod, but be prepaired for some tuning problems, it is not worth it..


The skat freeride swirl is a great prop, the hit right off the bottom is instantanious, you cannot go wrong with either prop (skat Freeride or the Solas Concorde), I could run either and have, I choose the Skat.

 

[WFO Speedracer]

Seriously if you want a set of carbs that are hard to tune,finicky and downright ornery I will trade you a set of Keihins for those mikunis,heck I won't even chagre you anything.:439:

 

[Foximus]

what pitch though?!?

 

[Big Kahuna]

13-15/16 or 12 -16 Best thing is to check with Impros. It all depends on which prop and what power you have.