787 carb adjustment

[PASTFAST03]

Hello i took my carbs apart and beofre i install them back i would like to know were i can adjust the low speed and high speed on the pto and mag to place it safe with out blowing a top end. Thanks

 

[LouDoo]

I can't give you specifics without knowing the model year. But the 787 HS is always all the way in, the LS is generally about one turn out but can vary, post the model year and I'll take a look in the morning.

Lou

 

[PASTFAST03]

1999 seadoo challenger 1800 twin 787
ok thank you i just blew my mag side and someone told me it was from running to lean. I was told i can make adjustments on the carbs to run slightly richer and have a little security from blowing another top end. Also i pump 87 octain in ny. Should i go up to 89 or 93?

 

[LouDoo]

The LS adjustment for a 99 Challenger is 1.5 turns out and the manual also states that a range of 1/4 turn either way is normal and that both carbs. should be adjusted the same.

You should be fine with 87 octane gas.

Lou

 

[PASTFAST03]

Ok is that running it a little rich In order for a little security not to blow the top end

What about the other high?

 

[LouDoo]

The high side is all the way in, just snug, not tight.

Lou

 

[PASTFAST03]

I wa reading somewere that someone installs a little inline filter before the pump to the carbs to avoid the pump clogging?

 

[LouDoo]

Yes, I use a Fram G2 inline filter, from Walmart. I think boats already use an inline filter, but you can replace them with this filter.

Lou

 

[PASTFAST03]

Yes I replaced my filters with the same fram g2 on the lines that cone Erin the gas tank now someone in another post said he put a same lawn mower filter right before the gas pump In addition

 

[LouDoo]

A lawn mower filter is way too small, as you probably already know these things use a lot of gas, the two inline filters that you already have are sufficient.

Lou

 

[Guest_User]

Ok is that running it a little rich In order for a little security not to blow the top end

What about the other high?

I hear ya on a little richer. I`m premixing and have the HS out 1/4 turn... so far so good... My lows are at 1.5 turns out...
98 challenger 1800...

just make sure there aren`t any other reasons why that cylinder is running lean...

 

[PASTFAST03]

I am. Going to take apart the pump as carbs today to change the grey fuel lines and clean out the filters in the carbs. Which is my guess the cause of the mag side piston.

What type of fuel line should I use I noticed it is very thin this one not so bulky can I use the clear tygon gas lines. They are a 1/4" correct?

 

[Guest_User]

I am. Going to take apart the pump as carbs today to change the grey fuel lines and clean out the filters in the carbs. Which is my guess the cause of the mag side piston.

What type of fuel line should I use I noticed it is very thin this one not so bulky can I use the clear tygon gas lines. They are a 1/4" correct?

Boats are more strict when it comes to fuel line. A1 and B1 USCG certs. That`s why they are so thick.
Yellow gas/oil tygon can be used at the carbs to pump, a good 1/4 automotive fuel line, heavy wall for the pulse line from case to pump, and 5/16 good hose from pump to tank... like EFI hose.

this is just a suggestion. as A1 and B1 hose should be used.. to satisfy any inspections and /or precautions...

 

[PASTFAST03]

Ok I am looking at the set up now all the hoses from the tank are black only a few grey lines on the carbs it self and a grey 5/16 looks like a breather to the motor

Ok I will pick up some blk fuel line from adavanced and attack this project also.

Thank you

 

[Guest_User]

Ok I am looking at the set up now all the hoses from the tank are black only a few grey lines on the carbs it self and a grey 5/16 looks like a breather to the motor

Ok I will pick up some blk fuel line from adavanced and attack this project also.

Thank you

are you referring the the hose that goes from the case to the fuel pump?

 

[PASTFAST03]

Yes that's grey gonna change that also

 

[Guest_User]

Yes that's grey gonna change that also

That is the pulse line. that is what makes the fuel pumps operate. you don`t want to use a to soft hose here...
I used the black 1/4 fuel line I found at Lowes that was pretty thick and a bit stiff, worked perfectly...

 

[PASTFAST03]

Has anyone put fuel shut off valves in this boat

 

[howie099]

I have used the Tygon lines for pulse lines with no issues. They are on Yamaha GP1200, Seadoo GTX, Polaris's, and Sportster 1800. I never had them collapse or cause issues. I beat that yamaha and I sure don't have a fuel issue. You can use the standard 1/4" black fuel lines also from Autopart store for the pulse lines.

It don't think the vaccum from the engine makes enough pressure to collas the Tygon lines. The grey tempo lines only seem to show up on the boats for the pulse lines. I did notice the fuel lines on jet boats are way thicker than the jetski's which must be for coast guard inpections. That fuel line isn't cheap but it looks like is lasts a long time. My lines are from 98' and look and feel like brand new.

I am not sure why they dumped the fuel selector valves on some of the boats. Must be the fuel pump and system design.

 

[PASTFAST03]

ok i attacked my carbs today and saw nothinng inside was fairly clean nothing clogged or debris inside.

now there ae some grey fuel lines on the carbs that look like 1/8" should i change them?

now the real question is how did i burn the mag side piston.

the only thing i changed on the boat when i purchased it was a solenoid for that motor cheap ebay brand new one but cant be the reason or the coluprite?

 

[howie099]

You could of had an airleak in the engine just from the age of it, the owner before you could caused damage to the engine.

 

[LouDoo]

Yes, I would replace the small fuel lines on the carburetor, use 1/8" tygon fuel line and cable ties for clamps.

It's hard to say why the mag. side piston failed, a lot of time it's a lean condition, but sometimes it's just a mechanical failure. Do you have a picture of the damage? Was it a hole in the piston, rings seized, how many hours on the engine?

Lou

 

[PASTFAST03]

Ok will try to do that today before installing the carbs back also did you a zip tie tool to get them very tight I dot have one and feel like I can never get them tight enough

 

[LouDoo]

Just hand tight, I think those were 3M cable ties.

Lou

 

[PASTFAST03]

Ok installed my carbs all the fuel lines and all now how do I get the fuel to flow up in the carbs I tired filling the inline filter and turning over the motor with the spark plug wires off