going from 44 to 46, should i need new jets?

[romack991]

currently I'm running a stock 44 on a 61x. cylinder ported, cases are stock. b-pipe, lightened fly, boyseen reeds.

right now I'm at 2.5 turns on my low and 1.5 turns on my high. Can't remember exactly what jets i have in there.

Going to an aftermarket 46, do you think I'll need to change up my jets or just be able to tune it with the screws. Only reason why I ask, I'm thinking of switching out the carb and don't have extra jets on hand, so if it probably will need it, I'll order some before the switch.

 

[#ZERO]

Yes..... what's in the carb now?

Pilot Jet Size?
Main Jet Size?
Needle & Seat Size?
Spring Gram Color?

 

[Matt_E]

Yeah, you'll probably need to change those jets.

Air velocity will go down, I am guessing your jet sizes will go up. May need to lower popoff as well.

 

[romack991]

currently
150 main
125 pilot
stock N&S
95 gram spring
and like i mentioned, I'm @ 2 1/2 turns on the low, 1 1/2 on the high

 

[#ZERO]

Increase your needle & seat up to a 2.0 because you're at the max flow of that 1.5 N&S with the 150 main jet.

 

[demolition_x]

i have a wet jet 46

150 main
120 pilot, might need a 122.5 but i didn't have one
2.0 n/s

and i think 1 turn top and 1.5 bottom.

 

[romack991]

the 46 currently has

180 main
120 pilot
2.0 NS
dark gray spring


demo, whats your engine and any porting?

 

[demolition_x]

61x, mod pipe, ada head, mild porting.

that is what LPW told me to start off with. have not ran it yet.

 

[#ZERO]

I would recommend this as a starting point and tune from there.

155 or 160 main jet
122.5 or 125 pilot jet
2.0 needle & seat
95 gram-dull silver spring
Idle screw 2.5 turns
High speed screw 1 turn

 

[douglee25]

I just got finished tuning my 46mm on my 61x this weekend. I started with:

2.0 N+S
145 high - 1/4 to 1/2 turn
130 low - 1/2 - 1 turn
95 gram spring

I started with the low screw and obtained the highest idle. That came at about a turn out or so. The engine seemed to respond quickly when the thottle was snapped, but it would not rev up fully. While the ski was up against a dock, I revved it full throttle and turned the high screw in. I'm at about 1/4 - 1/2 out on the high. The ski is runs crisper than it ever has. Since the ski was bogging with the high screw out at 1 turn (ended up at 1/2 turn out), I'm thinking my jetting is about spot on (not lean anyway).

Doug

 

[kurtwolff]

Hey Doug - What is your motor setup?

 

[douglee25]

Hey Doug - What is your motor setup?

Currently I'm running:

61x cases
61x ported by Tim Judge
46mm wetjet carb
Wetjet intake
ADA head 31cc's
B-pipe bored to 47mm
Lightened flywheel

I must say the ski honestly has run the best it ever has. The power delivery is so much smoother and predictable. I'm not sure if I just got the tune down on this one, or I just selected a good match parts wise. But honestly I am pumped to ride this year! :woot: :woot: Last year I ran:

61x cases
61x ported by Tim Judge
Riva Red pipe
44 mm
Protec Head
Bored stock intake

The power delivery last year seemed more on/off and abrupt. I don't know if my jetting was just off or what. I'd be curious to throw the pipe back on someone else's ski and rejet. I think I got a better feel after reading the Mikuni manual and reading MattE's post all the time about only adjusting the low screw for the highest idle. :sneaky: :cool2: :biggrin:

Doug

 

[Matt_E]

:biggthumpup:

 

[douglee25]

You were right though! It works so much better!

Doug