Super Jet Superjet randomly bogs then clears out...

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fst89lx

Location
Michigan
I have a 91 supejet 650, the only engine modification I have made is a coffman sizzler pipe. recently I was chasing a small low end / mid range "bog", AND ever now and then a severe bog which mostly occurred when I fell off but still happened at other random times. When the severe bog happenes, no matter what throttle position it acted like it had NO power, like it was on one cylinder, and it would turn into a smoke machine. If I babied it for a bit it would slowly clear out and be gone for a while.


I put in a brand new fuel filter, upped the pop-off pressure with a spring change, and went back to the lake. The low to midrange bog is gone, but the really bad bog still shows up. Any ideas on what can cause something like this?

I don't remember the exact jetting specs but I don't really think it matters as the problem is random. If it was a jetting problem, the bog would be persistent, not random.


Thanks guys!
 
rwilliamtaylor

rwilliamtaylor

Ride, Wrench, Repeat
Location
San diego
Random bogs are possibly water in the fuel. Check you water separator in your tank vent line to see if it's full. Once it fills it will let water into your tank.
 
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fst89lx

Location
Michigan
The two things that I have been thinking were a sticky needle or water ingestion.

last time I checked (before I leaned it out a bit to fix the low/mid bog) the plugs were VERY slightly rich, I didn't check them since sunday though which was the last time I rode.

I opened the drain to the water separator when I changed the fuel filter and pop off spring, nothing was in it btw.

I will check the filter in the carb before my next ride.

When I rode on sunday I took a lap around the lake, went slow, fast, and everything in between. NO problems. It wasn't until I started screwing around and falling off (getting water in the engine compartment) that the problem occurred. SO knowing that I am leaning more toward water ingestion. I run a pro k flame arrestor with a pre filter, but from what I have been reading it will still ingest more water than the stock airbox. Also my hood doesn't have those tubes that go down in the engine compartment, the water just falls out of the hood all over the motor/carb.

I am now looking for a stock airbox to replace my pro k, and I will put in another needle to eliminate that in the mean time. The needles are all the same right, its just the seat that is different?
 
rwilliamtaylor

rwilliamtaylor

Ride, Wrench, Repeat
Location
San diego
Your problem is the missing tubes that direct the water to your bilges. That's why the hood has the tubes. With an open filter FA you will ingest water.
 
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fst89lx

Location
Michigan
Yea, I figured that the hood needed the hoses. I need to see if I can find something to use for the tubes. Where can something for that purpose be bought?? I looked at the local hardware store but they didn't have anything I could use. I am going to do the Slutty hood mod that I read about on here once the winter comes but for now I need to find a way to rig it up :)

Also score602 I have done that, they were REALLY bad. Like the core of the wire @ the terminal in the boot was basically totally corroded away. Cut them back, crimped on new terminals, and put on new MSD boots. All good now.
 
davy87nj

davy87nj

Location
Santa Maria, CA
I searched home depot for the same thing, ended up buying these. http://www.blowsion.com/products/196-hood-baffle-air-intake-tube-and-flange-kit.aspx I probably could of made something, its almost like a peice of flexible electrical conduit and two plastic flanges. I was hopeing that the flange was going to slide in or over the existing hood intakes, but it doesnt. Just have to epoxy them in place I guess. I will be putting them on this week. I cant really sub my ski with out sucking up water with out these.
 
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fst89lx

Location
Michigan
I'm wondering if I cannot find any tubes, for the time being I may block off the hole that is nearest the carb. I would imagine that one breather would be enough for a stock 650 with a pipe right?
 
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fst89lx

Location
Michigan
RAGS, I will keep you in mind. I have to go to town tomorrow to run some errands so I'm going to look for a cheap solution @ home depot or something similar to get in there asap.
 
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