Carb Jet adjustment knobs

[Rosie2514]

Just wondering if there is any kind of product out there that can make carb tuning any easier. Like do they make anything that might go on top of the high jet/low jet screws that could make them easier to tune by hand such as wing style adjusters so you could fine tune with your hand?

 

[suke]

They make T style adjusters like the low speeds for the high speeds. I wish I had those for my ski. Especially right now when I'm constantly tuning.

 

[Sportster-2001-951C-Stock]

You can even get an electric setup to allow adjustments on the fly, cart racers have them. I can't imagine, haven't touched my carbs in three years now....

 

[suke]

You can even get an electric setup to allow adjustments on the fly, cart racers have them. I can't imagine, haven't touched my carbs in three years now....

I'm also kind of a tinker-er. I constantly adjust my yammis carbs just a touch here or there to get the perfect plug color I'm looking for. Even though it runs great!

 

[Dr Honda]

Actually.........


If the carbs are clean, and there isn't an issue with the engine... a seadoo will run great at the factory specs. So honestly... you shouldn't need to "Tune" via the needles. AND... if you are constantly tuning... then I would look for the reason.

 

[suke]

Actually.........


If the carbs are clean, and there isn't an issue with the engine... a seadoo will run great at the factory specs. So honestly... you shouldn't need to "Tune" via the needles. AND... if you are constantly tuning... then I would look for the reason.

All else stock....you'd be correct. I'm being a little obstinate by not buying stock parts and going back to stock. So it's sort of my fault. I can't stand letting mechanical things beat me so I'm going to get this thing tuned right if it kills me. LOL! With that being said....I do believe there is a "problem" somewhere. Just yet haven't found where. I'm not convinced it's 100% a tuning problem, but I digress.

 

[Dr Honda]

OK... so... lets take a step back.

1) What are the "Mods"?
2) how old is the engine?
3) What's the compression?


And most importantly....

4) What is the ski doing that requires the adjustment?

 

[Rosie2514]

Nice to see you back Honda.
1.Head,jetkit,prok's
2.under 1 hour complete rebuild
3. Even 170

Mine runs fine everywhere all day long. IF i shut my ski down and wait for 30 mins or so. It will restart easy and idle but won't take off without feathering the throttle or else it will die. After a couple of seconds of feathering , all is back to normal and i can bring it back down to idle like normal and have normal throttle response.
Im not actually sure what my lows are set at right now to be honest.
This was my first tank of fuel on the motor at 32-1, premix.

 

[Dr Honda]

It's nice to be back. I needed some time away after closing my shop, to get my head on straight.



OK.....


So... once restarted, "Feathered" and cleared out.... It's 100% fine until you shut it down again????


If yes....


The it's easy.

1) There are too many fumes in the bilge.

TEST: Try pulling the seat off for a minute or two, and use a fan of some kind to blow in fresh air before taking it for a run.

Solution: Mount a bilge fan, and/or find the source of the fumes. (most likely the aftermarket air filters. I bet they are wet with fuel after a run)


2) The high speed check valve is leaking.

Test: unfortunately... there really isn't one. But, it will show it's head again after a long idle.

Solution: Take the carbs apart, and check them.

3) You don't really want to hear this one.... But Proks don't like 720/800 Seadoo's. every time I hear about tuning issues... that's the filter in place.

Test: Put the stock box back on.

Solution: live with the small warm-up/re-start issue if it's running ok elsewhere.





Basically... on that re-start... you are simply running out of fuel (or out of fresh air) when you open the throttle. (in transition) SO... if there isn't a mechanical issue (like the high speed check valve) or a bilge fume issue... Then I would go up one more size on the pilot jet, and then close the low needle about 1/8th of a turn, to trim the fuel back at idle.



One last question to you.... since things are mod'ed... do you have accelerator pumps on your carbs? (a 96 XP normally shouldn't)

 

[Rosie2514]

It's nice to be back. I needed some time away after closing my shop, to get my head on straight.



OK.....


So... once restarted, "Feathered" and cleared out.... It's 100% fine until you shut it down again????
I can shut it down, and restart within a few minutes and it acts fine. No bog, no starving for fuel..Nothing..Perfect

If yes....


The it's easy.

1) There are too many fumes in the bilge.

TEST: Try pulling the seat off for a minute or two, and use a fan of some kind to blow in fresh air before taking it for a run.
Never thought of that, will try to pull the seat next time
Solution: Mount a bilge fan, and/or find the source of the fumes. (most likely the aftermarket air filters. I bet they are wet with fuel after a run)


2) The high speed check valve is leaking.

Test: unfortunately... there really isn't one. But, it will show it's head again after a long idle.
If riding normally I can idle for a good 300yds and gun it and take off normally
Solution: Take the carbs apart, and check them.

3) You don't really want to hear this one.... But Proks don't like 720/800 Seadoo's. every time I hear about tuning issues... that's the filter in place.

Test: Put the stock box back on.
Dont really want to , but might have to try!
Solution: live with the small warm-up/re-start issue if it's running ok elsewhere.





Basically... on that re-start... you are simply running out of fuel (or out of fresh air) when you open the throttle. (in transition) SO... if there isn't a mechanical issue (like the high speed check valve) Then I would go up one more size on the pilot jet, and then close the low needle about 1/8th of a turn, to trim the fuel back at idle.

Not sure of the jet sizes that came with the kit.
I was thinking i may be flooding it at idle with the lows since i never checked them.
Thing turning them back 1/8 turn could help?

One last question to you.... since things are mod'ed... do you have accelerator pumps on your carbs? (a 96 XP normally shouldn't)

No acc. pumps

 

[Dr Honda]

If it was flooding a little... then when you would open it quick... then it would cough, and chug... and then clear out. If it goes thin, and dies... it's running out of fuel, or enough air to support the burn.


Oh... since you mod'ed the ski... did you take the rear breather tube out? Without it... it won't push the heavy fuel fumes out properly. The air flow comes in the side grates by your legs... threw the seat... then down that rear tube. Then... the fuel fumes will move forward, and out the small vents under the front hood.

 

[Rosie2514]

Sure did take the tube out for the first ride! Took it off so i could visually keep an eye on everything.
I put it back in after I got back home and have not rode it since.

 

[Dr Honda]

FYI... My Polaris does the same thing. I just feather it... and don't worry since it runs fine after.


When you get a "Transition" or re-start issue that clears up... it's dang near impossible to tune it out. The reason is... you tune for running, and if you tune out the start up issue... then you will probably mess up the running after.


If it turns out to be a fume thing... then mounting a small fan, in the rear tube (blowing down) will take care of it. Just turn it on for a minute before the re-start. (add a small switch to the dash)

 

[Rosie2514]

Thanks for the info doc. Does make sense of how it would clear up once it starts idling because the air is moving again. And your right, it runs like a spotted ape off the line, so i was worried about changing the tune too much.

 

[eddie708]

Thanks for the info doc, I'm also having the same issue except with a stock Airbox. I have never thought of the fumes. I keep driving myself nuts trying to tune it out when it could be something very simple. I knew I should have left it alone I have over 70hrs on the rebuild with it doing this

 

[eddie708]

Where are the high speed check valves located

 

[Sportster-2001-951C-Stock]

Where are the high speed check valves located

There's one on each carb on bottom side of the kidney-shaped metering plate in the fuel chamber, that piece of mylar film covering the HS feed hole. The piece of film needs to be lying flat over the hole to keep air from back-streaming into the fuel chamber from the large venturi bomb-sight doo-hicky(and messing up, esp low speed, fuel metering as result).

 

[Lake Sailor]

"large venturi bomb-sight doo-hicky", Sportster, don't get all technical on us

 

[Sportster-2001-951C-Stock]

I'm also kind of a tinker-er. I constantly adjust my yammis carbs just a touch here or there to get the perfect plug color I'm looking for. Even though it runs great!

I think they call them remote mixture adjusters. And I've seen a cable type that mounts on a remote bracket to extend the needle out.

Do you also monitor piston wash? I'll admit not looking closely in a long time. I can definitely appreciate the desire to tweek, it's nice to have a good tune.

Our new oxygenated fuel blends are intended for FI so aren't as stable at atmospheric pressure as the old fuels and BTU content is lower too, IMO, so I probably compensate for that by going with fat side of happy I think works pretty good for me.

IOW, I'd rather hear some occasional 4-stroke gurgling than put up with a lean hesitation as long as my heat-soaked restart doesn't suffer.

Further supporting the clear out bilge air using a fan theory esp for heat-soak restart, our new fuel blends are more volatile with higher vapor pressure and evaporate more quickly into atmosphere, so arguably you could expect bilge air contamination that way too. Can't say I notice it much in my boat but maybe in a ski....

For me the hall-mark of concentration has always been the heat-soaked restart, second to eliminating lean pops and hesitation.

 

[Sportster-2001-951C-Stock]

"large venturi bomb-sight doo-hicky", Sportster, don't get all technical on us

LOL, but it sounded good!

 

[suke]

I think they call them remote mixture adjusters. And I've seen a cable type that mounts on a remote bracket to extend the needle out.

Do you also monitor piston wash? I'll admit not looking closely in a long time. I can definitely appreciate the desire to tweek, it's nice to have a good tune.

Our new oxygenated fuel blends are intended for FI so aren't as stable at atmospheric pressure as the old fuels and BTU content is lower too, IMO, so I probably compensate for that by going with fat side of happy I think works pretty good for me.

IOW, I'd rather hear some occasional 4-stroke gurgling than put up with a lean hesitation as long as my heat-soaked restart doesn't suffer.

Further supporting the clear out bilge air using a fan theory esp for heat-soak restart, our new fuel blends are more volatile with higher vapor pressure and evaporate more quickly into atmosphere, so arguably you could expect bilge air contamination that way too. Can't say I notice it much in my boat but maybe in a ski....

For me the hall-mark of concentration has always been the heat-soaked restart, second to eliminating lean pops and hesitation.

I keep all mine on the fat side too.