Have a couple of the fuji 500's here. Same issues over 35* or so. THey don't like the warm weather. I generally run 2 steps lower than stock most of the time in them. Yours is 350 stock for -20 to +10. +10 to +40 says 330 and more than 40 is 310's. I would run the 330's or 320's all the time unless it is help wide open for a long time below 0. Guessing it is probably more of a backup sled for you anyway and ridden mostly in warmer temps, above 0.

 

Correct. It's mainly a backup for me and a sled for my stepson. Sounds like the the 330's will be a good compromise. It's highly unlikely that the sled would be out for any major speed runs with him on it.

I'll grab the 330's on Saturday and slap them in and hope for the best.

 

My 97 Indy is doing the same thing. Would dropping the needle a step or two make enough difference or should I plan on getting a couple of jets?

 

I smoked my '91 500 a couple years ago by dropping the main jet down one size AND lowering the needle one notch.(raising the clip position). The tech who did the rebuild said I probably would have gotten away with just jetting down one size but I would be warry of leaning out the midrange - just start with the jet and see if any improvement.

 

Not familiar with the indy 500 sleds after 93 but we never had any of those warm weather issues mentioned on the older sleds with 38 mm round slides. They ran pretty crisp with stock jetting or a size or two leaner on the mains only depending on temps. Start leaning the needles a clip and you will burn it down. With todays ethanol fuels i'd be wary making jetting changes.

 

The mains will do nothing for you low and mid range. Sure it will lean down some when you go full throttle but will still run like crap everywhere else. When it gets those temps I just lower the needle a clip position. clears up the low and mid alot. gets cold I put it back the way it was. No big deal but always do a plug check after any changes to your fueling

 

I have the same problem...forgive my ignorance...but how does one "lower the needle a clip position"?

At what temp do you do so?

Thanks in advance for the help!

 

Your pilot jets handle idle and a little rpm above then the needle comes into play. The mains don't take effect until half throttle. At idle its all pilot jets. You may have plugged air jets also. Spray some Carb cleaner or take an air hose and blow out the front of the carb Try playing with your adj screws on the side of the carb. If u have to turn it out more than two turns then your pilots are to big for sure. When u turn the screws out it leans out the motor as it lets more air in. When you turn them in it richens the motor as it blocks air intake that's were I would start

 

To adj the needle on a round slide mukuni. Turn off the top of the carb. There will be a slide that comes out of the carb attached to a cable with a spring in the middle. The needle is there. Take your hand and compress the spring and gently pull the needle out from the center of the round slide. Take a long needle nose pliers to grab the top of it and pull it out A clip will hold the needle from sliding down. Just move the clip up or down depending on a richer of leaner position required. Never go more than one setting at a time as it does make a difference.

 

Hello All,

Not to offend anyone but this is what I did to my '96 500 SKS which made a large difference:

1) Put in a dark blue spring in the primary with stock weights. This raised the engagement rpm slightly. This seemed to put the engagement in the early portion of the 500's power band which allowed the sled to take off, not bog.

2) Lowered the needles 1 -2 positions (can't remember). Made the mids crisper. One must look at plugs/wash and feel how the sled is running to ensure it is not too lean as another poster cautioned. Move 1 step at a time.

I also put a different helix in to help backshifting but this won't change the engagement part of the scenario.

Also - make sure the belt is not worn, side clearance at primary clutch is ~ 0.020", belt tension is correct, motor mounts are good and case stop is tight to crankcase.

Good Luck!

Steve :thumbsup:

 

well...you guys have got me nervous...

When the bog happens, it is always on the low side of the throttle. If I get past 1/2 way, it starts to run better...this tells me the jets are right, but the needle is off maybe 1 click?

 

What does it idle at?...does it happen after u drop the rpms down then try to go again right away, or after it sits and idles?..turn out screws 1/4turn and idle it around 2000 so it doesn't load up..
Could be ur floats r bad, and sled can only burn the xtra fuel in colder climates?
Take out crank plugs and jack up back end.. If fuel is comin out, ur floats r leaking..


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