Freestyle Falling flat on its face

UKUnicorn · May 29, 2020

Hey everyone,
So I've been having some issues with my ski,

(Heres the spec list to hopefully help you get an idea of my set up:
- 2014 Polar composites Trixstar freestyle jetski
- 61x 701 150/150 comp
- Msd enhancer
- Coffman sizzler
- TRD waterbox
- Carbon reeds
- 46mm true cad design red top annular discharge carb
- 135 pilot 130 main 2.0 n/s 25-27 popoff
- ProK air Filter
- Rhaas engine mounts
- Skat Trak 14-18
- New kart tank
- X metal trim
- Flow control valve
- JRE Pump Cone)

My problem is that everytime i make a set wake and grab wide open throttle it bogs down then hits (if you continue to hold the throttle wide open) a few seconds after (almost like turbo lag in a car). This happens weither I burp the throttle prior or just ride normally and open it wide.

So far I've tried:
- changing plugs (just to see if it made a difference
- burping the throttle vs just riding normally prior to wide open
- making sure i have sealed all gas lines correctly (someone mentioned kart tanks don't seal great so figured id try it)

Fully open to any tips,advice or questions
Ive also been told a 46 is pretty big for the setup i have i just want to leave changing to a 44mm to the last option if possible.

Also i run my fuel mix at 50:1 and I am 482m above sea level, any help would be great many thanks guys.

Storbeck · May 29, 2020

What you're describing is a classic symptom of a pilot jet that is too lean. I'm not saying that's your problem, but a lean pilot jet can cause exactly what you are describing.

I hate to be disagreeable but I wouldn't expect a single aftermarket carb on a 61x to have any relation to the jetting of a twin carb dasa 850.

Storbeck · May 29, 2020

I'm also surprised you're using such a small main jet, seems like single 46's on motors in the 701 ish neighborhood are usually more in the 150-170 range, but I have no idea at all how a red top would be relative to a "regular" sbn 46.

Carrera911 · May 29, 2020

As stated before, that jetting seems off but I'm not sure how much different an AM carb is than a regular 46. I have a very similar setup at 1200' elevation (yes I use moon units)

. Jetting isn't yet perfect yet, but I'm at 130p, 150m, 2.0 NS 19 psi pop off. Try your low speed screw to see how that helps your bottom end. Play with it in 1/4 - 1/2 turn increments and try some idle to wot blips to check the response. I tried a 135 pilot jet in mine, it was way rich, got loaded up and bogged off idle. Chances are you'll need 3/4 turn out or less with a pilot that big.

As also stated, your prop seems too steep. Mine came with a skat 12/17, which felt just a bit steeper than the hooker 9/15 I have now.

UKUnicorn · May 29, 2020

Hey guys thanks for all your replys so I'm going to play around with the air/fuel screws tomorrow and see if i can work it out and i think i have a friend with a 9/15 hooker that i might be able to buy off him which ill install too.

UKUnicorn · Jul 17, 2020

I have the 9/15 Hooker in also found out blew a headgasket -.- which is also now fixed.

So now running
127 pilot and a 130 main 2.0ns 25-27 popoff 2 7/8 turn out on the high and i cant remember what i had the low at but not very much, and did the nose to a sock in water test and ran mint, get in the ski and try it and she would occasionally hit but still do the same thing so i just got a 145 and a 151.3 main jet which im gonna try and fiddle with and hopefully get it dialled hopefully, thanks for the tips everyone and one else feel free to chime in.

clouse22 · Jul 17, 2020

9/15 hooker should be spot on for that setup.

2-7/8 seems really far open to me. Id jet up to a 135 or 140 main

UKUnicorn · Jul 18, 2020

clouse22 said:
9/15 hooker should be spot on for that setup.

2-7/8 seems really far open to me. Id jet up to a 135 or 140 main

Ive gone up to a 151.3 main and 125 pilot (slightly reduced it as i was told to)

iQRTurbo · Jul 18, 2020

Do you have a choke or primer on the ski? Sounds like your lean bogging when you whack the throttle. Try kneeling in the tray and whacking the throttle while you punch the primer or cycle the choke quickly. If it picks up on the bottom end that’s a down and dirty way to determine if you’re lean.

UKUnicorn · Jul 18, 2020

iQRTurbo said:
Do you have a choke or primer on the ski? Sounds like your lean bogging when you whack the throttle. Try kneeling in the tray and whacking the throttle while you punch the primer or cycle the choke quickly. If it picks up on the bottom end that’s a down and dirty way to determine if you’re lean.

Thats a oretty clever way that I never thought of unfortunately I dont have a choke or primer on my ski, Im going to the test lake today to see how i do with my new jetting ill keep you all posted

UKUnicorn · Jul 21, 2020

So after two days of testing, Ive come to the conclusion that my popoff spring may be too agressive as its still running lean, so i decided to put a sock over the filter and it hits everytime, so getting way to much air off the intial wack which reading mikunis tuning guide they say this may be a result of a big popoff spring, so ive ordered all the sizes and will test this theory i have.

UKUnicorn · Aug 4, 2020

So havent changed my popoff spring yet but new setup is

151.3 main 130 pilot 2.0ns and 95gram spring,

Testing tomorrow will keep you all updated

Freestyle Falling flat on its face

BDB Kustomz