Bog when at a tailstand or on the side

[rollin5150]

The past few months I have been noticing that the ski will not hit while in a tail stand nor if it is laid over on the port side (carb side down). It just tends to load up and will not clear out. It did this last season, but then cleared up early on this season. I first thought that maybe I was putting too much water in my headpipe, but now I have two screws open. 1/8 on bottom and 1/8 on top. Also since the temp has dramatically increased, my tuning may be slightly off. I am suspecting either I need to rebuild the carbs or maybe water in the carbs and need to tune for the increased temperature. Anyone have any other input?

 

[Big Kahuna]

exhaust gases getting sucked into the pump tract. My SXR would do the same thing.

 

[rollin5150]

exhaust gases getting sucked into the pump tract. My SXR would do the same thing.

I could see that causing a form of cavitation but this is due to engine bogging.

 

[fastony]

could have a leak around your gas tank or vent that pours some fuel out when you nose stand it, but it probably is your needle valves in your carb are weak or worn and letting fuel leak through and making a rich condition when it's on it's side or standing up. Pull your breathers off and start it up and rev it slowly, you will probably see fuel leaking through the bomb site on your carb or carbs.

 

[Big Kahuna]

Mine bogged as well. It would cavitate, and then bogg (Load Up).

The Kawi's seem to like alot of fuel down low, but when you stall them, it cannot burn the fuel as quick.

Keep in mind, mine was set up for stock racing. You may could try changing popoff some and tweaking the jetting to lean it out some but still give it the fuel it needs.

 

[Dustin Mustangs]

I am having a very similar issue with a wb1 when trying to sidemount (leaning to left) with my new jetworks motor. Art told me to lean my low speed screws 1/8 turn and put in new plugs. Haven't had a chance to try it yet but the dude is typically spot on.

 

[rollin5150]

Thanks for all the input. I thought about the low speed being off, so I checked it by standing at an idle and then gunning it. The fuel metering seemed spot on with no hesitation anywhere. I suppose I could try going in 1/8 on the lows and see where that gets me. I will also definitely be rebuilding the carbs since they have not been touched other than rejeting since I bought the ski new.

 

[jetfest]

i changed me neddle and seat to a 2.0 and that helped a bit also on my wetpipe where it connects to the wetbox i had a poor connection after fixing that and the needle and seat it seems to be really good also a flow control valve going into the stinger will help

 

[kevbo]

The fuel mixture will get richer anytime the tank is above the carbs. Its most noticeable with low popoff pressure. Most skis that run clean at 15mph will begin to fourcycle in a tail stand. If the ski fourcycles at 15mph it may get a rich bog in a tailstand. Venting the tank could help or even cure the problem if its holding too much pressure.

 

[rollin5150]

Thanks. I am running a 2.0 NS and a pop off of 21 psi. Jetworks valve is on the stinger which is also set to open at 2200 RPM. That just might be the case for it feels like a rich bog.

 

[rollin5150]

This last weekend I tuned in the low screws again. The last time I tuned them, it was about 90 degrees F outside. This time it was about 114 degrees F. I ended up going 1/4 turn in and still did not feel a lean hesitation. The takeoff was a tad bit snappier and I am not bogging as bad during tail stands. I may turn them in a little bit more since I am 3/4 turns out. I like to run it a little richer with temps this hot outside.

 

[95FX1]

^^good idea

 

[X2Pilot]

Keep in mind that outside air temp will affect jetting. You said it cleared up earlier inthe season (cooler weather) but then the loading up became noticible in the last couple months (hotter weather). As the temps rise the ski will naturally run richer. If you are running 152.5s and it ran good earlier in the season I suggest dropping to a 150 for the summer months. I bet you will notice an improvement.

Mikuni tuning says go down one jet size for every 25° of temperature rise (main jet only)

 

[rollin5150]

Keep in mind that outside air temp will affect jetting. You said it cleared up earlier inthe season (cooler weather) but then the loading up became noticible in the last couple months (hotter weather). As the temps rise the ski will naturally run richer. If you are running 152.5s and it ran good earlier in the season I suggest dropping to a 150 for the summer months. I bet you will notice an improvement.

Mikuni tuning says go down one jet size for every 25° of temperature rise (main jet only)

Good info Jon. I was aware that the mixture setting would change with air temp. I must have missed the Mikuni recommendation in the manual. I did not think that it would cause them to drift that much. I also have to keep in mind that on a few lakes that I ride, the air temp just off the water changes. When you get close to the inlet of the lake (dam from the feed lake) the water temp drops considerably as well as the air temp off the water. If you are running right on the edge and you go WOT, you will smoke a motor. I been told a few guys have done that at Canyon Lake. Another good reason to leave it on the rich side.

 

[X2Pilot]

That info is not in the Mikuni Manual, it is contained in the Mikuni Pocket Tuner (Main Jet Tuning Calculator). This little device also gives you jet size adjustments for elevation too. Hope that info helps!