96 787 GTX rough idle at low rpm

[Psicurella09]

New to this forum and new to the Sea Doo world any help/advice is appreciated in advance. Bought a 96 787gtx ran great at high rpm and wot but when slowing down the ski fell on it's face and died. Very hard to start after and when it did start it was difficult to give it any throttle it just keeps dying.

 

[mikidymac]

This is typically a fuel issue so I would check to see if you have gray fuel lines and if so replace them.
You should also replace the fuel selector and at a minimum clean and replace the o-ring on the fuel seperator. I would also rebuild the carbs with only Genuine Mikuni parts as there are 3 little fuel holes that can plug and cause exactly your symptoms.

 

[Psicurella09]

This is typically a fuel issue so I would check to see if you have gray fuel lines and if so replace them.
You should also replace the fuel selector and at a minimum clean and replace the o-ring on the fuel seperator. I would also rebuild the carbs with only Genuine Mikuni parts as there are 3 little fuel holes that can plug and cause exactly your symptoms.

Ok, thanks Miki the previous owner did let is know the fuel lines were replaced with clear approved fuel lines and the fuel selector was also replaced as far as the separator I'm not sure about. In regards to the he little holes are those in reference to the Jets inside the carb?

 

[mikidymac]

No, there are bypass holes for the low speed circuit. You can see them in my Carb Rebuild thread in my signature below.

 

[Psicurella09]

No, there are bypass holes for the low speed circuit. You can see them in my Carb Rebuild thread in my signature below.

Ok will the rebuild kit cure the clogged bypass holes if they are clogged? And I cannot find that thread your referring to

 

[mikidymac]

You will clean out the holes with cleaner and air.

See the laist just below this sentence in blue? It's the 3rd one down that says Carb Rebuild How-To. Just click on it.

 

[Psicurella09]

No, there are bypass holes for the low speed circuit. You can see them in my Carb Rebuild thread in my signature below.

Is there a picture anywhere I can see of these two carbs to tell where the low speed adj and high speed adj screws are or tell me where

 

[mikidymac]

They are on the side of the carbs. the high is about 3/4 of the way up on one side and the low is 1/4 of the way up on the opposite. What you are describing is not from an adjustments screw. You have to take these apart and service them correctly.

 

[Psicurella09]

They are on the side of the carbs. the high is about 3/4 of the way up on one side and the low is 1/4 of the way up on the opposite. What you are describing is not from an adjustments screw. You have to take these apart and service them correctly.

I understand, I am just wanting to know for reference in the future, where would you suggest a place to purchase genuine oem Mikuni carb rebuild kits?

 

[mikidymac]

OSD seadoo.

 

[Psicurella09]

This is for Miki, I was able to get the carbs off the ski today, and also I was never able to locate your thread about the carb rebuild I'm kinda new to this forum stuff. My question now is where are these bypass holes in the low speed circuit I have attached a pic of my carbs if you can somehow direct me. I am purchasing oem rebuild kit but also want to clean out these holes as well

 

[mikidymac]

just click this link.... Carbs

 

[Psicurella09]

just click this link.... Carbs

Thanks for that Miki you are a big help for me n my son first text ski owners but longtime 2 stroke owners of motocross bikes whole different world in the pwc

 

[Psicurella09]

Anyone know what the factory settings are for low and high speed adjustments

 

[mikidymac]

LOW- 1 HIGH- (MAG-0 PTO-1/2)

 

[Psicurella09]

Not sure I'm following you on that Miki, sorry

 

[mikidymac]

Both low speed screws get 1 full turn out from seated. The Front or (MAG) carb gets the High screw closed and the rear or (PTO) carb gets it set at 1/2 turn out from seated.

 

[Psicurella09]

Now we're cooking with ...lol another question in regards to the premix oil in the reservoir is it not a good idea to mix them with different brands

 

[mikidymac]

Absolutely not, they can gel and starve the engine. You need to make sure it is only API-TC full synthetic. If changing brands you need to drain the tank, flush the rotary cavity and change the filter then bleed the lines.

 

[Psicurella09]

That's just it I don't know what the previous owner used. Are there any threads out there that show how to perform that?

 

[mikidymac]

This is per Dr. Honda,
"
No real instructions on it, since it isn't a normal "maintenance" thing. But it's good that you are the original owner. I will run down the list for you........


1) Drain out what you can from the tank. I would simply disconnect the hose going to the engine under the carbs. Yes... this will make a mess, so, get a shallow bucket to catch what you can, and a bunch of old towels ready.

2) Disconnect the hose at the oil injection pump. (Let it drain) At this point, you cut the in-line filter loose too. I'll assume it hasn't ever been changed.

3) There are 2 small hoses going from the oil pump to the intake of the engine. I'll assume these are 20 year old hoses, and are getting crusty. I would replace them with new tygon hoses. I'm guessing if you squeeze, and/or twist them... they will split, rip, or squish. Regardless, the original hoses will eventually fail. (time just kills them) They are held on with clamp bands... but I just replace them with small, high quality zip ties. If you have wire tie pliers, and wire... do a double wrap and a bent twist. These are low pressure so you really don't have to worry about them falling off.

3b) This is a good time to replace the rubber grommets in the oil tank if they are leaking. Also... if the tank seems dirty... a little gasoline can be sloshed around to clean it out.

4) Put in the new filter, and put the hoses back on the engine, and pump.

5) pour some oil into the tank.

6) Remove the bleed screw from the oil pump, and let the oil flow to the pump, and feed the pump hose. The 2 hoses going to the center of the engine will fill on their. When replacing the screw, make sure you have the little fiber washer on it, and DO NOT over tighten it. It's small, and you could break it. Just make it snug.

7) Pop the cover off the air box, and remove the mesh inside. (good time to clean it with a degreaser like super clean) Pour about an once of oil into each carb.

8) WITH A HELPER........ hold the pump arm to "Full", and have your helper start the engine. LEAVE IT AT IDLE !! watch the 2 small hoses, and you will see the oil pump up to the engine in 5 to 10 seconds. Once filled... turn off the engine. The oil you poured in will keep it safe.

9) Check for leaks. If it's good... top off the tank, and rest assured that the oil system is now fully serviced and will keep your engine safe. "

 

[Psicurella09]

Should pressure be equal when checking pop off?

 

[Psicurella09]

I have 38 psi on 1 card and 33 on the other during pop off Is that going to be something I should worry about?