superjet bogging! any ideas why???

[hydrogoon136]

okay. i have a 94 square nose. its still mainly stock other than a riva red pipe and header. a waterbox, ride plate, and intake grate. my ski will run great for the first few minuts or untill i start to whip it around or stand it up or do a sub. once the engine gets under a heavy load it wants to bog really bad. and in a strait line it will run great up until about 3/4 throttle. then the bogging begins again.

i have put new plug wires and plugs on. rebuilt the carb im running bp 93 octane with castor 927 mixed at 50:1 i have adjusted the air/fuel screw out a little because the ski will smoke a little. i also tried putting some airfilter material above the screen on top of the carb. this made it bog from the very begining. and when i removed the airfilter material and opened the plug on the airbox it seemed to run much better. but still bad under a load. i was told that the riva red pipe is hard to get tuned in. and was told to put a ball valve in the water line going into the pipe and work on restricting the amount of water into the pipe. after messing with that all day it still does the same thing.

i am almost to my limit with this thing! its almost summer and while my buddies are out riding im at the dock trying to get my sj to run right. any suggestions on what the culprit could be?

 

[demolition_x]

does it sputter or just bog?

have you checked the fuel filter? it could be starving for gas if the filter is dirty. just take the filter off and blow air through it opposite of flow and it should clear it out.

 

[hydrogoon136]

which filter are you talking about?

 

[demolition_x]

number 3

 

[hydrogoon136]

the filter on my ski is not the stock one shown in the diagram. it actually looks like some autozone bs. although i can see a pretty good bit of trash in it. should i try and find a stock filter? and if this doesnt fix the problem do you have any other ideas?

 

[Fathom]

Go to Autozone or the likes and get a:
Puralator F20004
Deutch FF409
Fram G4169

Each is an OEM equivalent for about $2.

 

[hydrogoon136]

ill try that but it still doesnt explain why it runs fine at first and starts acting up when i really get into it and start standing it up and on its side... like its all it can do to pull itself out of the water...

 

[Mike W]

Check the filter/fuel tank for water contamination.

 

[demolition_x]

ill try that but it still doesnt explain why it runs fine at first and starts acting up when i really get into it and start standing it up and on its side... like its all it can do to pull itself out of the water...

well the filter gets full of fuel then when it uses it up then it bogs.

it may not be the issue but many forget about the fuel filter.

are you sure when you rebuilt the carb it was assembled correctly?

 

[hydrogoon136]

visually check? or is there a more technical method?

 

[hydrogoon136]

i rebuilt the carb because of this problem. and i am 100% that i put it back atlest the way it was. i used a mikuni kit for the 38 and the 44. the diagram for the 38 looked most like mine except for mine has a four bolt top where the 38 shows a three bolt top. i did have some rubber gaskets and a paper gasket left over but the kit said they are not used in the 38... either way same problem before and after the rebuild... could reeds be a factor? coming from racing motocross my whole life i know that a cracked reed will make my race bikes not even hardley run...

 

[hydrogoon136]

does it sputter or just bog?

have you checked the fuel filter? it could be starving for gas if the filter is dirty. just take the filter off and blow air through it opposite of flow and it should clear it out.

i guess sputter is a better way to describe what my ski is doing. its definately more of a sputter and then finally it will go right up untill 3/4 throttle then sputter sputter sputter... i just picked up a new fuel filter im going to kick my own butt if this is the fix! thanks demolition!

 

[SurfCrazed]

its probally your fuel filter or lines.. my sj would run perfect then out of nowhere cut off.. and on top end runs it would sputter.. new fuel lines and filter and she was back to life!

 

[SkiDaddy]

What do the plugs look like if you pull them right after it's been sputtering a bit?

 

[demolition_x]

i had similar issues with my fuel filter. i let my ski sit for a month or two then i rode it in the surf. ran great for 30 minutes then started to act up, would sputter and run out of gas and take forever to start. it was the fuel filter.

 

[hydrogoon136]

ok... so i bought some new filters at an autozone. they are close to OEM but they are paper filters. i swapped out the lawn mower style filters that the previous owner had installed when he put all new fuel lines on. i also threw some seafoam in the tank, as i was told it couldnt hurt. i will admitt that it is doing a little better but its still sputtering. the biggest difference is that it doesnt take as long to get it to wind all the way out again.

i mainly notice the problem when i sink the foot tray and ride around with the nose in the air. it does fine for a second or two then eventually starts sputtering and can hardley get itself back to plain.

could there be a problem with my fuel pick up? the new fuel lines installed two summers ago by the previous owner, are clear. and i can see bubbles in them. is this normal? also the fuel lines look like something from a hardware store and they look larger than stock.

my ski also white smokes a pretty good bit now is the smoke related to the sputtering?

this is getting to the point i wanna get my yz's back and keep moto'n :censored:

i really do appreciate all of you who take the time out of your day to help me with my problem! thanks!

 

[hydrogoon136]

What do the plugs look like if you pull them right after it's been sputtering a bit?

i havent checked but i will tomorrow and let you know.

 

[demolition_x]

ok lets back up. did you buy this ski then had the problems or was it running great from the beginning?

 

[Kaveman]

first things first...check the compression and do a leak down test. then check the electrical system. then check the fuel system. no matter what you tune or replace, if the engine is not in good mechanical condition this problem will not go away. if the head is stock the compression should be around 135psi at cranking speed, as low as 120 should still be ok. ensure that you do not have more than 10% difference between the two. on the leak down pressurize the engine to 8lbs and verify that no more than 1lb per 2 minutes leaks off, if so use a soapy mixture and spray the spark plugs at the head, the crank seals, the intake and exhaust gaskets,the cylinder head and base gaskets, the crankcase seam and the pulse line fitting and guage assembly to pinpoint the leak. also pull the water line from the head and listen for and air coming through the water jacket indicating a head gasket leak.

most likely the problem is not the reeds as the boat would take forever to plane out and would show little or no signs on top end.

does the boat perform any different according to the fuel level in the tank? for instance does it run better with a full tank?

make sure that the fuel lines are on the carbureter correctly. fuel will come in low and exit high(supply on lower nipple and return to upper nipple with pulse to the fitting in the middle on the outer most portion)

use a systematic approach and thoroughly perform each test, you WILL find the problem.

 

[SkiDaddy]

Kaveman is right, but from the white smoke I'd suggest a compression test first - you may have a leaky head gasket. Shoot us a picture of the plugs.

Also, completely drain & sop up ALL the gas, as it also sounds like water in the tank.