SuperJet, not making power

AquaToy

AquaToy

Jay-Are
Location
San Antonio, Texas
Ok, so i wasnt gettin any power at al out of my ski, took it to a friend who suggestted i rebuild the carbs....good thing, cause the filters were cloggged......did a water test ad same thing, just not making power.....checked compression......both sides equal at about 142lbs....so, any idea here.....Its a 2001 superjet, stock with rebuilt carbs. Now when i got this it used to be a race ski and i seem to have inhereted the bad part of the deal.....the not running right part. Summer is almost over and ive been down with out a ski for too long.....any suggestions here? Ive been told its my timing, or need a new top end, or it could be my CDI......any help here to eliminate the troubleshooting would be greatly appreciated my fellow riders.....thanks.

Jay-Are

:smashfreakB:
 
K

Kennay

Squarenose for the _____
Location
Myrtle Beach, SC
If you are down to 142lbs of compression with a stock head, I wouldn't worry about the actual motor itself.

Are you sure you are tuned correctly on the low and high speed adjustment screws? Are you back to stock jetting?
 
AquaToy

AquaToy

Jay-Are
Location
San Antonio, Texas
when i got the ski it had a Factory Dry Pipe ...some call it a type 4.....i took that off and went back to the stock pipe......what im wanting is to get the ski back to stock before i start any mods.....reliability is more important to me right now then power.. Now, when we installed the stock pipe we put in 130 jets......i dont know alot about carbs, or skis, but i was told that this/was the factory jetting. Funny, after my friend rebuilt the carbs, it will idle fine but i just cant keep the RPMs up at all.....takes forver to build up the rpms.....he said that since its not running good now its impossible to adjust the carbs,......... There is a JetSki repair shop here in town but he just doenst want to troubleshoot my problems.....he said if it was a top end job no problem he would do it quick, but to troubleshoot it he wouldnt be able to look at it for a month or so......this just sucks.....i want my ski to run!!!! Thanks for any advice!!
 
K

Kennay

Squarenose for the _____
Location
Myrtle Beach, SC
Dude, on a properly jetted engine, a few turns of the screws will make it unrideable. You should find a new friend or at least tell him to stop making up answers. I don't have a 701, but I will try to do some searching to see if I can come up with some stock jetting specs for you.

And the Type 4 is a sweet pipe if you set it up correctly.
 
K

Kennay

Squarenose for the _____
Location
Myrtle Beach, SC
In another post, Mike W says:

Stock jetting is:
70 Pilot ~1 turn out
130 Main ~1 1/2 turn out
1.5 n/s
95gm spring

I'd give that a whirl. Do you know which screws are the adjustment screws?
 
AquaToy

AquaToy

Jay-Are
Location
San Antonio, Texas
well, that could do me some help.....i only changed the 130 jets.....they were 145's............(main) As for the pilot, i guess i can check that.. As for the last two items.....not to sound totally ignorant, but im not sure what those are or what that means......As for which screws, i do know which ones to adust however, im not really sure which way does what, as far as lean, rich......man i know im rambling on here and making myself look stupid, im just really wanting to do whatever it takes to get it running......sucks that the only shop i have here wont work on it.....UUGGHHHH
 
K

Kennay

Squarenose for the _____
Location
Myrtle Beach, SC
It is better to admit you need help than than to act like you don't and totally screw it up. Lord knows I need help all the time...

This should familiarize you well with the adjustment screws, as well as other parts of the carb. If you would like, skim through this manual and it will help you understand exactly what is going on.

http://www.mikuni.com/pdf/sbn_manual.pdf

By twisting the adjustment screws in clockwise, it would be leaning it out, but twisting them counterclock wise, it would be richening.

Definately change the pilot as well to stock... I guarantee you the stock jet isn't in there anymore. Actually, I would also doubt the stock needle and seat, or the stock springs are in there anymore either. Anyway, this manual will help you out big time. Post back if you need some help, and don't worry about looking like a dummy... we all need help from time to time.
 
AquaToy

AquaToy

Jay-Are
Location
San Antonio, Texas
i know when i picked up the rebuild kits i also picked up new needles and seats.....but as for the pilot.....would that make a difference?

ok, so a new question would be how do u know if the motor is too rich or too lean.....????

Jay-Are
 
steve802cc

steve802cc

Team Ugly
Location
Sarnia Ontario Canada
A

aramis

Location
Rochester, NY
Might sound dumb, but did you replace the plugs and/or wires and try that first? If it runs OK on the trailer and makes no power in the water that's an easy thing to check. By the way, what plugs are in it? Should be B8HS or BR8HS.

If your SJ is the dual carb flavor, here's some more info for you:

from Factory Pipe instructions for Type 4 dry pipe on dual carb setup,
Main: 140
Pilot: 75
High speed screw: 1/2 turn open
Low speed screw: 1 turn open
Needle & seat: stock
pop-off spring: stock

that should give you an idea where you should have been w/ the Type 4 pipe. The good news is that if someone set it up "right" for the Type 4 (and assuming I grabbed the right Factory Pipe document), you shouldn't have to worry about the needle/seat and pop-off...

For a stock exhaust w/ dual carbs, here's the info out of the Yamaha manual:
Main: 130
Pilot: 70
High speed screw: 1 & 1/8 turns open (front carb), 1 & 1/2 turns +/- 1/4 turn (rear carb)
Low speed screw: 7/8 turn open +/- 1/4 turn (both carbs same)

So, if you just change the jets back to stock but didn't turn the screws you'll likely be really lean on the top. Hope that helps...
 
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