Super Jet 62t/62t + Reeds + B-Pipe --- Need help jetting/tuning dual SBN 38's

[MrBlack]

Ok so I've got a tuning/jetting nightmare on my hands.

I put a 62t/62t into my square nose from a 95 Wave Raider. Running dual 38mm carbs, added some boyesen reeds, brand new factory B Pipe, & I milled the stock head down (186psi in each cyl.)

From the factory site I've got the carb jetting stock -- 130 rear / 120 front for the mains and 67.5 for the pilots. I had tried running stock 95gr spring with 1.5NS but it wouldn't even rev up. Both the black (80gr) and shiny silver (65gr) springs work much better. I can run the ski and I tuned the low screw on the trailer but it doesn't rip unless I get it up to speed and hop it out of the water. Once I hop it it takes off like a banshee. I'm pretty sure pop off is good but I really need help tuning the middle & bottom end.


Q1 - When you add reeds do you have to increase or decrease the jetting? Same goes for bumping up the compression (from 155 to 185psi) - do I need to adjust jetting for that as well?


Q2 - People with dual 38's ---- When reading the Wave Raider manual it specifically says to run the rear carb with the 130 main jet (with 1 &1/8th turns out on the high screw) and the front carb with the 120 main jet (with 5/8 turns out on the high screw) --- Is this critical? If I start messing with jet sizes do i need to keep that the same? (i.e.: if I go up to 135 on the rear should I go up to 125 on the front? Or should I match the rear 135:135? Also if I adjust the rear high screw 2 more turns out should I adjust the front high screw 2 more turns out or should I match it 1:1?)


Q3 - Is there a total # that my jet sizes should add up to? If I bump up my low, say to 75, do I need to adjust my high as well or is this going to give me too much fuel on my top end?



I've pulled my carbs at least 10 times now and its getting old. I really need an idea of what to do jet wise (up or down). Also I don't really want to dump a lot more cash blindly on jets that I don't need. People with similar setups could you please give me some advice? Thanks.

 

[STi410]

I have just about the same setup, but I haven't started tuning it yet. Just waiting on a pro-tec pipe to arrive. Hopefully someone with a running ski can help us out.

I know yamaha changed the jetting on the rear carb because of issues with the rear cylinder burning up. This could have been caused by leaner mixtures in the rear cylinder from the poorly designed exhaust manifold, or cooling issues with the single water outlet on the head. My guess, and thats all it is, is that if your running a factory pipe, the exhaust flow will be more balanced between cylinders. Couple that with a head with dual cooling, and you could probably get away with running both carbs with the same settings.

 

[hondamxracer]

I'm running a 62T/62T in my RN with the following mods:
* delta force 2 reeds
* lightened flywheel
* Epic ignition
* B-pipe, mod chamber
* Dual cooling

For my dual 38s, I am running:
* main: 135
* pilot: 75
* NS: 1.5
* pop off: 43
* HS: 1.25 turns out
* LS: 7/8 - 1 turn out
* OEM FAs: 1 screen

For the first 10 hours I had on the motor, I ran two screens on each FA which resulted in a bit of hesitation if I cruised at the same speed then blipped the throttle. Since changing to just one per FA, I have no hesitation.

Hope this helps.

 

[Vumad]

I have a limited sj with a stock motor, so very similar except I have a 61x/62t motor which is stock. Port timing on the 62t cylinder could change your jetting a tad from mine.

Stock airbox
Stock motor
Dual stage carbon reeds
B-pipe limited
Stock water box
180 psi
Msd enhancer
Lightened flywheel

I'm running 135/75 with a pop of 53 (stock pop, 1.5/115). I have a lean hesitation at 1/4 so i am going to try a 95 spring which would give a pop a out 42. I also have a leaning issue on the front cylinder at wot so I may go to dual fuel pumps. Other than that I have very good response everywhere.

I would say your biggest problem is your jetting is fubared. I don't know why you'd be running mains 4 jets apart. Maybe one jet apart but not 4. I don't know where you got that 120 130 spec but that can't be right. Try 130/70 in both and see what happens. That's richer than you are right now so it can't hurt.

Get some better jetting specs and read the mikuni manual a few times.

 

[jetx]

im running the same setup as you exceot with a blaser mod chamber in a sj and im running stock sj jetting. you need to even out the jetting and increase your popoff

70 pilot
130 main
1.5 ns with 115g spring

the t cylinder seems to get away with stock jetting as the stock waveraider has a larger expansion chamber than a sj. you could actually probably keep your 67,5 pilots and see how thy run, my 70 pilot seems a tad rich but it still responses well so haven't bothered to change it yet but I would like to drop it down to see if it changes much.

 

[MrBlack]

Thanks for the replies. I'm sorry I forgot to mention that I am running dual cooling as well (2 into the exhaust manifold & 2 out of the head) From what I've read on other forums, I think that YAMAHA set up the carbs like this in the wave raider because of overheating the the rear cylinder (heavier ski, more load, etc). I think with my dual cooling & lighter ski that I'm just going to set both carbs the same. (It seems to be working for other people)

Factory specs for the Wave Raider : http://www.mediafire.com/view/xytwm2dmwxm/WAVERAIDER_MANUAL.pdf --- see pages 19 & 20 for carbs specs. It threw me for a loop the first time because I thought someone messed up the jetting.


jetx - i was just up in your neck of the woods (Killbear park) last weekend.


I appreciate the feedback with the similar setups. I'm going to try going with 130 mains & 67.5 pilots for now and see how it runs.
If its better but not perfect I'll order up some 135 Mains & 75 Pilots and see how that runs.
I'll post back with the results once I've had some time to test it out.

 

[MrBlack]

SOLVED!

I rejetted the carb with these settings:
75 pilots
135 Mains
1.5 N/S w/65gr silver spring
1 Screen on each Flame Arrestor (down from 2).

And it rocks!

From what I've gathered the popoff is going to change from person to person because of altitude/air pressure. I originally tried "stock" settings with the 95gr silver spring and the second you touched the throttle it would die, there was no chance I could run that or even the 115gr spring. The black spring was better but I think I'm getting the best performance now that I'm running it with 1 screen & the 65gr. spring.

Thanks to everyone for the valuable info!