Super Jet bog that comes and goes

[alberta guy]

I've been chasing problems on this ski all season. Its a 92 SN 6m6 bottom end with a 701 top end. I rebuilt the motor this spring Everything was purchased from jetmaniac along with a popoff spring and jet kit. I've got them all figured out except for one. It runs absolutely perfect and the plugs are a nice brown when I last checked. But from time to time when you let the revs drop down to around idle and gun it again the ski bogs down. If you work the throttle for a second or two it cleans itself back up and runs perfect again. It doesn't do it every time you drop the revs only sometimes. What would I have to check and or replace?

 

[OCD Solutions]

I have had this before and have seen it a few times since. Sounds like a tiny piece of trash in the pilot jet. Most common debris is the black paint chips flaking off the carb body while rebuilding.

Symptoms; If you manage to feather the throttle enough to get the revs up enough to get into the main pilot, it runs great but as soon as they dropped enough to draw thru the pilot, it falls on it's face. Every once in awhile it will run perfect so you know the jetting is spot on.

Set up a clean area on a bench with a white surface and go thru those carbs very thoroughly.

 

[JetManiac]

Have you tried leaning the low spd a little more?

 

[Vumad]

Did you check the pop-off with a gauge or just put the parts in? Did you buy Mikuni parts or SBT parts for the carb (rebuild kits that is)?

I'm not saying you have to rebuild your carbs, but I personally am not buying any more rebuild kits from SBT. You definitely need to test the carbs, not just assume the new parts made it work right.

 

[alberta guy]

When I met up with xjcrawler he checked it with a pop off gauge and everything was in the specs he had. The jets were from jetmaniac along with the pop off spring so I don't know who made them. badvinny mentioned putting in a water restrictor in the cooling line. Had the water line on the top of the head fall off on Friday but it still bogged. Turned the low speed down from two turns out to one turn out. There was no difference.

 

[Vumad]

Have you checked to see if you are leaking from your venturi? Your popoff might be too low at idle.

 

[Captain PegLeg]

Check the couplers for a exhaust leak

 

[alberta guy]

Thanks for the replies but at this point there is two weekends left in my riding season so this ski is going to collect dust and become a winter project or sold as is in the spring.

 

[IS0LD0UT]

I am chasing a similar problem. Here is how my day went.
Started in the water boggy of idle, will RIP when the REVs are up or if I chop enough.
I thought maybe I needed to lean out a little since it has gotten colder.

Turned in the low screws, maybe a bit better. Rode a bit. Turned in some more. It started ripping.

Sweet got it fixed. 30 mins later, the issue came back and I didn't change a thing. Boggy off idle. CRAP.

It comes and goes, so it is always hard to see if I fixed it.
Swapped coils, swapped stator, swapped batter, new plugs, new boots on plug wires, swapped CDI to new MSD. Checked pop-off, looked for crap in filters. Each time I think I have it licked it comes back.

How do I check for a small exhaust leak?
I know its not a major one because I have ridden with the hood off. Could a small crack in the chamber or in a hose cause that? How do I check other than visually?

Would a small air leak cause this?

Midshaft bearings?
Long shot, wouldn't I hear a screeching or some noise?

Any other ideas?

Thanks!

 

[Joker]

What pipe are you running?

 

[IS0LD0UT]

B-pipe

 

[Joker]

What are your screws set at? Too much water coming in will cause it to bog right off the throttle. Once the pipe/waterbox clears out it runs fine. Just something small to check that doesn't cost money.

 

[JetManiac]

I am chasing a similar problem. Here is how my day went.
Started in the water boggy of idle, will RIP when the REVs are up or if I chop enough.
I thought maybe I needed to lean out a little since it has gotten colder.

Turned in the low screws, maybe a bit better. Rode a bit. Turned in some more. It started ripping.

Sweet got it fixed. 30 mins later, the issue came back and I didn't change a thing. Boggy off idle. CRAP.

It comes and goes, so it is always hard to see if I fixed it.
Swapped coils, swapped stator, swapped batter, new plugs, new boots on plug wires, swapped CDI to new MSD. Checked pop-off, looked for crap in filters. Each time I think I have it licked it comes back.

How do I check for a small exhaust leak?
I know its not a major one because I have ridden with the hood off. Could a small crack in the chamber or in a hose cause that? How do I check other than visually?

Would a small air leak cause this?

Midshaft bearings?
Long shot, wouldn't I hear a screeching or some noise?

Any other ideas?

Thanks!

This is backwards. Colder, denser air needs more fuel not less. Richen in cold, leaner in warm weather.

 

[IS0LD0UT]

Tore the carbs down. OCD may get the prize. There was a piece of paint in the low speed jet. I wonder if moving the screw made the paint chip shift. Testing today hopefully back in business fully.

 

[IS0LD0UT]

OCD nailed it. Ran great all day!!!!

 

[alberta guy]

Tore the carbs down. OCD may get the prize. There was a piece of paint in the low speed jet. I wonder if moving the screw made the paint chip shift. Testing today hopefully back in business fully.

I've taken my carb apart and cleaned it out on more than one occasion. Used half a liter of brake clean the one time cleaning out everything. Is it possible there is still something in the carb that i may have missed??? Your problem is EXACTLY the same thing my ski is doing.

 

[IS0LD0UT]

I've taken my carb apart and cleaned it out on more than one occasion. Used half a liter of brake clean the one time cleaning out everything. Is it possible there is still something in the carb that i may have missed??? Your problem is EXACTLY the same thing my ski is doing.

Did you pull the screws? I swore I had checked the low jets before though didn't pull the screws the other times. Also with all that carb cleaner were you pulling all the rubber stuff? I just used an air compressor and wd 40, but mine were really clean.

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