need to rejet

[mfmcculla]

I have a 95 waveraider 1100, I have added

boyeson pro power reeds
removed choke plate and assembly and installed primer
installed three ocean pro flame arrestors
installed 95 gram pop-off spring with stock n/s which my yamaha service manual says is 1.5 stock
I have maintained the stock jetting 75 lows and #1)107.5, #2)95, #3)107.5

I first was not getting any top end, I cured this by turning out my high speed screw one half a turn untill it didnt drop off at WOT. It is not at 2 turns out. now running 67 on the speedo, which is around what it was before, seems to be working fine. but!!

I am getting a bad hesitation or even dying after a highs speed deceleration (running top speed letting off, then accellerating quickly again) If I let the decelerate and then let the ski sit for a scond or two and then hit it again it runs fine.

At stock carb settings this problem started anywhere between 15 mph to 45 mph on the speedo, as I turned out the low screw in quarter turn increments this gap got smaller 1/4 turn more out dying and hesitation only 15-35, another 1/4 turn out 15-25, and so on.

I am now at 2 1/2 turn out on my lows and 2 turns out on my highs and I still have a little bit of hesitation in between 12-23 mph

I feel I need to rejet, maybe 85 on the lows and 115 on the highs? any suggestions.

Thanks,

[mfmcculla]

Re: need to rejet

Anybody?

[dtd696]

Re: need to rejet

Since no one else has replied to this I'm going to chime in here.

You definatley need to go larger than stock on the jets since you are now introducing a lot more air into the carbs.
What was your pop-off pressure before adding the 95g spring?
From what you are describing, it sounds, IMHO, like you have a couple of things "out-of-tune" I would say your pop-off pressure is still too high and your jets are too small for the added mods.

I am no expert, but just my $.02

Please post what you find out. Many here agree that there are too many that do not post their results when they get their stuff worked out. :emoticont

[mfmcculla]

Re: need to rejet

Thank You,

I was running stock pop off which is 115 gram springs and 1.5 n&s which ording to a chart I found on Jetskimechanic.com would be equal to 55 psi.

Aftter installing the 95 gram spring it would be 43 psi according to the chart.

Since posting this I have ordered a pop off guage and mini tach to start.

I also ordered a 2.3 n/s which will put it at 20 psi.

I also ordered #80's for my lows and 115's for my highs

I am hoping this combination will work for me. what do I start with for turns out now that I am not using stock jets anymore when I go to tune this?

[dtd696]

Re: need to rejet

Wait until you receive the pop-off guage to do the next steps. Regardless of what the chart says the springs alone can differ. When doing my carbs I had to clip the coils (1/2 coil at a time) to get all three within 1-2 psi. (Very important that they are within that range or you can get a lot of strange tuning problems)

I would go around 30-40 PSI on the pop-off. According to Mikuni, the 1.5 n/s supplies the max flow an SBN44 can provide. There are differing opinions on this.

With those jets I would start at...
Lows:
all 3 carbs 1 turn out

Highs:
#1: 1 1/4 turn
#2: 1 turn
#3: 1 1/4 turn

Sounds like the 2.3 n/s will lower the pop-off to 20 psi.
Like I said, I am no expert. Just putting myself in your position and thinking about what I would do. :emoticonc
BTW.. are you running premix or pump?

[Bill O'Neal2]

Re: need to rejet

The size of the opening in the seat DEFINATELY effects the pop off pressure.
For instance, a 95 gram spring with a 1.5 needle and seat pops off at around 43 psi, but that same 95 gram spring only needs 17 psi to open a 2.5 needle and seat.

[dtd696]

Re: need to rejet

I stand corrected. :emoticonn - Previous post edited :D

[mfmcculla]

Re: need to rejet

Thanks for the replies!

I am running premix.

I got the part about the turns to start out with for my lows and highs but what are you recommending with the needle and seat.

right now I have a 1.5 with a 95 gram spring giving me around 43 PSI, I will confirm with popoff guage. But the 2.3 I ordered with 95 gram spring will give me about 20....does this seem to low. If so should I go with the 2.3 and a larger spring which will only put me around 25, or should I go with the 1.5 and put a smaller spring on such as a 65 which will put me at 32?

thanks again?

[mfmcculla]

Re: need to rejet

also, why do you recommend running the middle carb less turns out on high?

I thought the aftermarket arrestor evened out the cylinders?

[dtd696]

Re: need to rejet

I can not take credit on those settings, I got them a while back when I was doing my brother's 1100. I do not remember who, but they did set the ski a little on the rich side then I adjusted from there doing low speed plug checks.
On all three of the triples (my 2-1200s, my brother's -1100) I found that the center carb always ran more rich than the mag and pto. (Many things affect carbs though, altitude, weather, mods, etc...) I wish I could give you a more technical answer, but I am just going off my personal experiences.
I believe the stock settings on that motor are...
Lows
1-1/8
Highs
7/8
As far as the pop-off. I always set mine higher than what I think is needed then clip springs from there. If you get too low the carb will dribble. Since the Mikuni tuning manual states that a 1.5 provides the max flow an SBN44 can provide, I would think that going to a 2.3 will allow you lower pop-off without going to too weak of a spring.

There are some great experts on this forum that may have a lot better answers than me. I wish some of them would chime in here to either confirm or reject some of this.

Please keep us updated on your findings.

[mfmcculla]

Re: need to rejet

I will try and see what I find out and when I get her going I will post.

I am just having a hard time correlating any logic to what the pop off should be.

I can see I need to rejet because I am so many turns out on the screws I have no more room for improvement.

[Bill O'Neal2]

Re: need to rejet

The center clyinder scavanges differently from the two end clyinders mainly because the way the single exhaust manifold runners are designed.

[mfmcculla]

heres the fix

I installed

80 lows - 2 turns out from bottom
115 highs - 1-1/2 from bottom
115 springs with 2.3 n/s (25 popoff)

the ski runs great!

[dtd696]

Re: need to rejet

Great to hear.:emoticonc Thanks for posting your results. I'm sure many will benefit from them.