Carb Tuning Skinny Plz...

Yamah0

XFT
Location
Dubai
Thanx for the replys... Superjett that was a good informative reply.. im going to mess with it a bit more tomorrow. From the sound of it i think im running a bit lean, so im gonna try opening the low up a bit and see what happens.
 

Yamah0

XFT
Location
Dubai
Ok just got off the phone with Ed Brazina Full Spectrum... he told me this 130 high jet is my problem... im supposed to have a high jet between 150 - 160. So im gonna do that tomorrow and see.

Keepin my fingers crossed:biggrin:
 

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
Zane, I just did a similar motor as yours. I used a single 48 Full Spec
here is the jetting I ended up with

Main 155 H adj 5/8
Pilot 127.5 L adj 1 adj
2.3 n/s 115 grm spring

when I did this I consulted Ed. He stated, with the singles, the low jetting is a little funny & it could fall anywhere between 125 - 140
If you happen to read this before you tune today, please try this as a base line.

ski ya, Paul
 

Yamah0

XFT
Location
Dubai
Hey thanx Paul... I didnt have a 155 or 160 so i put in a 150 H and the ski felt better.. so it definetly needs the 155 or bigger.
The Low right now is 137.5 which is what Ed recommended.
Im gonna put in some bigger high jets and see what happens.

Now should the jetting be a lil different between the 48 and 49?

Thanx for all the help guys:biggthumpup:
 

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
Yes, The 49 will require slightly more fuel, 157.5 or 160
bottom should be about the same
 
We are all waiting to hear the news of how well its running. It sounds like you are getting close,, Do keep us posted. Do you have other super jets to compare it to?
 

Yamah0

XFT
Location
Dubai
Jr. Magoo's said:
Yes, The 49 will require slightly more fuel, 157.5 or 160
bottom should be about the same

Bottom should be about the same as i have on right now 137.5 or do u mean the same as ur setup 127.5?

Also... what would the difference be between the 2.3NS, 115g and the
2.0NS, 95g?
Like what does it change in the runing charastaristics of the motor?

Thanx Paul.


2XLR8 said:
We are all waiting to hear the news of how well its running. It sounds like you are getting close,, Do keep us posted. Do you have other super jets to compare it to?[\quote]

Ill keep u posted till it hopefully runs like it should.
As for other superjets to compare... i have 2 of my buddies with OEM 760 cylinder one is running a single 48 Novi and the other is running duals.. and both these skis rip reeeeeal nice compared to mine.... but i ant be comparing now since my carburation is off... im keeping my fingers crossed.:wink:

Thanx
Zane...
 

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
Zane, the differance with the N/S will be very minimal in your application. you might want to try it once you get everything as best as you can with the regular jetting. just to use as a final tune.
the 137.5 is the pilot jet that I feel will be best for you, mainly because if the climate you are in. I have been working with another indidual who is in an arid climate as you. he is experiancing similar tuning issues as you are. all his settings seem to be several points higher than what would normaly be required. keep us posted as your progress continues

ski ya, Paul
 

Yamah0

XFT
Location
Dubai
Ok... i got around putting a 160 main jet but left everything else the same.. i dunno im sorta confused. I think that initial delay got minimised a bit but the ski feels sluggish and heavy at times..

How do i know if the 160 is too big and i may need a 155 or 155.7? Same for the low jet!

I had the top screw anywhere between 5/8th to 1/2 out and bottom screw anywhere between 1 and 1.25 out.

I know its really hard trying to tackle carb tuning on a forum or over the phone.. but what can i do :dunno:
:banghead:

Thanx
Zane...
 
Last edited:
I don't think being off by a few points in the main jet can make the response around the turns be that bad. I would try adjusting the high mixture screw both in and out and take note of where it seems to work better coming out of turns. This will tell you if you need to lean or richen the mixture. It is possible that you may be feeling the high speed mixture and you are trying to compensate with the low speed circuitry. What I can't understand is with that pitch impeller -that large of a nozzle AND that cone, it can't be in transition from low to high for more than a fraction of a second.You should go right past any hesitation or blubbering. Maybe its something else
 
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