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Y'all were right.....I give up.

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suke

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So after time and time again of trying to get my ski tuned, pointing in every direction looking for a "problem" and coming up empty. It's time to just go back to stock. I THOUGHT I found the culprit with finding the fuel separator gasket torn with about an inch gap in it. Figured that was sucking in air. Replaced that, went back to the carb settings the tuner gave me and headed out to see how she ran.

First out still a bit of a stumble at low speeds. Opened out the low speeds just a smidge and could tune that out to where from idle up to max RPM was really smooth and could distinctly feel/hear the raves open. At WOT she ran like a scalded dog and ran just flawless. I rode back to the beach and pulled the plugs. Nice and dark like I want.

So time for plug chops. Idle out past no wake, jam in the throttle and fly over to a little bay around the way. Go WOT for 5-10 seconds, pull the tether and coast to the beach. Pull the plugs and they're gray. I just can't tune it out regardless how much I open the high speeds. It gets to a point it just bogs like crazy and is unrideable.

It's beyond my knowledge/skill level to tune this ski using these aftermarket FAs. I'm sure a professional tuner could figure out just the right combo to get this thing tuned right. I need set it and forget it specs.

I feel pretty defeated and annoyed. I just want to be able to ride this thing without melting a piston. So back to stock I go.

I can't seem to find my stock carb parts. Looks like I need 142.5 mains and 70 pilots with 1.5 needle/seats. OEM seems to be best for mikuni parts, so where do I find them not in a kit? Also choke plates are gone, I'd imagine there won't be that much more air flow with the stock flame arrestors back on, no? Just fatten up the low speeds a smidge?

I tried to find some spark plug pics on the net, but the 2 stroke ones have disappeared. Was trying to show you what I was looking at.

Oh I'll also need new springs. What gram is stock....and where might I find those a la carte too.

I normally keep every little thing, but guess after the resto I figured all was well and threw out all my parts. To be sure I kept the handlebar pads I bought, so may have stored them somewhere.
 
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https://www.parkeryamaha.com/search...arts&log=false&manufacturer=1111&category=263

http://osdparts.com/index.php?main_...ption=1&keyword=complete+carb+rebuild+package

http://www.watercraftsuperstore.net/Sea-Doo-PWC-Mikuni-Parts.html

Settings:
http://www.seadoosource.com/carbreference.html

Needle and seat. 1.5 Set the needle lever flush to the top of the valve body.
Main jet: 142.5
Pilot jet: 70
Pop off : 27 to 39 psi Black spring 80 gram...I think. At least that is what I used to achieve correct pop off on my XP resto. Critical on the pop off is to get the carbs as close to one another as possible in the 33 to 36 range
Holding pressure 15 psi for at least 10 minutes. My carbs went 1/2 hour each.
Highs: 0
Lows: 1 turn out.
 
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Hey, at least now when I tell people to leave it stock, we can point to this thread. :)

Welcome back to light side. A ski that runs is faster than any modified ski that doesn't. :)
 
Suke,

Niche cycle parts had all the parts a la carte. Tonka has All the stuff too, I think he had the jets too.

Sent from my SGH-T889 using Tapatalk
 
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you can't discount the value of a experienced tuner. I had a heavily modified GP1300 that had issues right when I bought it and had 3 different guys (all that run shops) turn me down, they didn't want to touch it. After some searching I ended up towing the ski 2.5 hours north and the tuner had the problem solved before I was back in my driveway.

The more you mod, the more little adjustments need to be made, sometimes quite frequently. But minor mods like factory pipe/impeller/jets generally are set it & forget it type items.
 
Did you go to a 2.0 seat for the needle? I guess more air needs more fuel and the 1.5 seat might not allow enough flow for a safe WOT no matter what size HS jet you have it's still gonna be lean?

Or just go back to stock ride and be happy, that's best IMO.

I've not had any problems with aftermarket jets,, n/s or springs. I don't like the aftermarket diaphragms I've seen although they might work fine, they seem thicker than OEM and IMO the most challenging part to duplicate in the entire carb.

Or, buy a used set of carbs for the good OEM parts, [MENTION=41828]Minnetonka4me[/MENTION] has a set I'd bet?
 
Ive always got a wide array of jets, springs, needles and seats....but I am far from an experienced carb tuner. Ive got enough knowledge to be dangerous...lol

Ive got a buddy that knows mikuni like the back of his hand. People who THINK they know what they are doing get on his blasters and superjets and cannot comprehend how perfect his skis run. I have slowly picked up some from him but I really need to pay him a week long visit and pay him to bestow his knowledge.
 
Hey, at least now when I tell people to leave it stock, we can point to this thread. :)

Welcome back to light side. A ski that runs is faster than any modified ski that doesn't. :)

Now THAT is a signature-worthy statement!

I've been 'into' high-performance Japanese sports cars for a long time, and one thing that always, ALWAYS happens is that the guys going for insane power levels end up broke, both mechanically and financially.
I stock or mildly modified engine is, 99% of the time, going to be better - driveability, reliability, etc - than one that is tweaked to the ragged edge.
 
https://www.parkeryamaha.com/search...arts&log=false&manufacturer=1111&category=263

http://osdparts.com/index.php?main_...ption=1&keyword=complete+carb+rebuild+package

http://www.watercraftsuperstore.net/Sea-Doo-PWC-Mikuni-Parts.html

Settings:
http://www.seadoosource.com/carbreference.html

Needle and seat. 1.5 Set the needle lever flush to the top of the valve body.
Main jet: 142.5
Pilot jet: 70
Pop off : 27 to 39 psi Black spring 80 gram...I think. At least that is what I used to achieve correct pop off on my XP resto. Critical on the pop off is to get the carbs as close to one another as possible in the 33 to 36 range
Holding pressure 15 psi for at least 10 minutes. My carbs went 1/2 hour each.
Highs: 0
Lows: 1 turn out.
Awesome! So 80 gram black is the stock spring? I found my parts and with the kits I originally bought i have every spring color available. Just don't have the jets.
Did you go to a 2.0 seat for the needle? I guess more air needs more fuel and the 1.5 seat might not allow enough flow for a safe WOT no matter what size HS jet you have it's still gonna be lean?

Or just go back to stock ride and be happy, that's best IMO.

I've not had any problems with aftermarket jets,, n/s or springs. I don't like the aftermarket diaphragms I've seen although they might work fine, they seem thicker than OEM and IMO the most challenging part to duplicate in the entire carb.

Or, buy a used set of carbs for the good OEM parts, [MENTION=41828]Minnetonka4me[/MENTION] has a set I'd bet?
Yeah I went to 2.0 needle and seat combo with 75 and 145 jets.Pop off was dead even at 24 or 22.....can't remember.
 
Ordered the n/s as well as the jets. Ordered from OSD, they're normally really fast at getting me parts. Now need to pull of the carbs and go through them again to make sure all is well. That and get up with [MENTION=72134]1983[/MENTION] to get ahold of a stock air box/FAs. :)


Ok so after this you guys think this is a set it and forget it setup? Is there any reason I could still run lean up top even being stock?
 
Haven't touched the carbs on my 96 since they were on the bench when I built them. Set them to the book, ski ran its ass off all week.

Sent from my SGH-T889 using Tapatalk
 
Just make sure the springs you have are correct. The standard mikuni kits do not have the 80 gram springs in them. But there may be a dark spring, that is not the one you need. Unless you are saying you have your old springs in the kit. I guess, just put in the ones you think are correct and check the pop off. If you hit about 30psi, then you are correct.
 
Awesome! So 80 gram black is the stock spring? I found my parts and with the kits I originally bought i have every spring color available. Just don't have the jets.

Yeah I went to 2.0 needle and seat combo with 75 and 145 jets.Pop off was dead even at 24 or 22.....can't remember.

Yeah well you're not alone, seems like. There are plenty of guys out there struggling to make factory stock run decently for some reason. I know I did, until I installed larger pilot jets but that's my story and mileage varies.

2.0 definitely should flow plenty fuel, you at least went the right way to get more.

The 2.0 seat + 80 gram spring should produce right at 21psi pop assuming the arm isn't goofed up too much. But then with the larger seat it's possible the needle is more susceptible to harmonic vibration if you believe in that kind of thing is possible, so low range might be inconsistently rich on occasion or something like that.

How about tossing the OEM flame arrestor back on, does it go stupid-piglet rich? Just an idea of something to try, no reply expected.

How about the main venturi, has someone modified the ring? I've seen where on some carbs guys will dremel off part of the venturi trying to get more flow.

It's fun to play with carb mods until it's time to go ride then it doesn't react as anticipated, been there done that many times myself and have mangled my fair share of carbs to the scrap pile but sometimes with success, it can be done but sheesh, I stopped trying too b/c it got old.

2-Stroke carb mods are much trickier to get right I think, b/c being too lean can bite hard and fast. The engineers earned their paychecks.
 

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Per the Mikuni SBN manual, the 1.5 needle/seat combo will flow the max fuel a SBN can take. But you can use larger ones to set pop-off differently (as in sportster's chart) (from the manual) . DL the manual if you don't have it. http://www.mikuni.com/pdf/sbn_manual.pdf It has a ton of good information on the theory of all of this odd carb.
 
Soccerdad, yes the Mikuni manual does suggest the 1.5 seat is adequate for all applications but even their info is not gospel.

As far as the 1.5 seat orifice goes, a 951 engine with SBN46i will run lean on the top end if it has a 1.5 seat installed by mistake, as opposed to the factory spec'd 2.0 seat. Just b/c Seadoo doesn't provide a pop spec for the 2001 SBN46i doesn't provide license to fantasize an arbitrary range of 19-23psi, either. The 95 gram spring on a 2.0 seat does pop at 25psi when set up correctly. The 80 gram spring on a 2.0 seat pops at 21psi, that combo works fine in my 951 as well.

Not sure what combo the OP really needs and that's up to him but the factory setup is a great place to start as long as incorrect info found on the internets isn't accepted as gospel.

These guys tried, and I give 'em a thumb's up for that. It's up to us to interpret and perhaps experimenting a bit, for our particular application, is okay IMO. If it's still too lean and the engine is in good shape, no leaks, bla,bla, then make an adjustment, it' should make an immediate difference.

Not rocket science, there's usually a reasonable explanation of some sort but lean is lean and we know what happens, been there done that enough times to know the result.
 
Yeah well you're not alone, seems like. There are plenty of guys out there struggling to make factory stock run decently for some reason. I know I did, until I installed larger pilot jets but that's my story and mileage varies.

2.0 definitely should flow plenty fuel, you at least went the right way to get more.

The 2.0 seat + 80 gram spring should produce right at 21psi pop assuming the arm isn't goofed up too much. But then with the larger seat it's possible the needle is more susceptible to harmonic vibration if you believe in that kind of thing is possible, so low range might be inconsistently rich on occasion or something like that.

How about tossing the OEM flame arrestor back on, does it go stupid-piglet rich? Just an idea of something to try, no reply expected.

How about the main venturi, has someone modified the ring? I've seen where on some carbs guys will dremel off part of the venturi trying to get more flow.

It's fun to play with carb mods until it's time to go ride then it doesn't react as anticipated, been there done that many times myself and have mangled my fair share of carbs to the scrap pile but sometimes with success, it can be done but sheesh, I stopped trying too b/c it got old.

2-Stroke carb mods are much trickier to get right I think, b/c being too lean can bite hard and fast. The engineers earned their paychecks.

If I had the stock airbox I would. I bought my ski with the aftermarket FAs.
 
Just make sure the springs you have are correct. The standard mikuni kits do not have the 80 gram springs in them. But there may be a dark spring, that is not the one you need. Unless you are saying you have your old springs in the kit. I guess, just put in the ones you think are correct and check the pop off. If you hit about 30psi, then you are correct.

I don't have the springs I pulled out, but they're definitely black.....I'll take a pic of what I have.
 
20150705_135729.jpg

This is what I have. Appears I do have the stock ones they're on the left. They're not quite "black". I supposedly have the 95 gram shiny silver in there, but the ones I have look pretty shiny to me.....
 
IMG_20150705_152006.jpg
Just pulled the carbs right quick. I at least had the right springs in there according to the specs I was given. The carbs were just flooded with fuel. Just blows my mind with that much fuel flowing that it's lean on the high end.
 
IMG_20150705_163607.jpg
So this is all of them for ease of use. So are those the "black" I should be using? I'm pretty certain those were what I pulled out.
 
Not to sound weird but smell them. If they smell like gas, and the others don't.......

Sent from my SGH-T889 using Tapatalk
 
Not to sound weird but smell them. If they smell like gas, and the others don't.......

Sent from my SGH-T889 using Tapatalk

Not weird that waswas the first thing I did. They've all been sitting in the same bag for 2 years they all smell the same. Only ones that smell like gas are the ones I just took out.
 
If this doesn't sort it I'm gonna sell it and save up for an R12x or grab a speedster with the dual 717s. Cause it's apparent a 787 isn't for me.
 
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