SX/SXi/SXi Pro 750sx runs like a lawmower for 10 minutes then runs great wtf??

[750rider]

Heres my issue, i picked up a 94 750sx bone stock fairly clean, and it had a god awful top end prop on it, no low end torque whatsoever, I take the air filter off to replace it with a prok filter, and in doing so the gasket between the manifold and carb slipped between the inlet and would only allow the throttle to move at about 1/4 throttle (rookie maneuver yes), after figuring this out 5 feet past the dock i bring back in to fix it

so I managed to get it back into place and she ran like a lawnmower very slow, only a consistent bogging, no matter how much throttle i gave her, not even fast enough to get on plane, about 5 mph, then after 10 minutes of that, it started to have abrupt RPM gains for about a second, which consistently increased in occurrence, till it started to run normally, this is was also in high altitude

then when i brought it back down to sea level, i installed a stock 800 prop, and took it out to the local marina and low and behold the same BS, ran like a lawnmower for 10 minutes, no matter how much throttle i gave her, but was able to get on plane and get her going at decent speed, but just a consistent drone of the motor, then the abrupt increase in revs started after i would give it 1/4 throttle for 10 seconds let off and then repeat and then the revs would increase in occurenece and eventually run good

i would appreciate any help at all...

 

[TontoM3]

are you jetted properly? put your screw out about 7/8 High and low. if it is stock exhaust and FA then it should be (I think) 70 low speed 120 high speed. thats for my Keihin dual carb set up at least. also make sure your head is torqued correctly, start with new plugs, check your plug wires etc. the list goes on.

usually it falls under three categories.
air
fuel
spark

start with one, then rule them out as you go.

good luck!

 

[Magyar68]

I recall the 94 had some wierd High and Low adjustment settings, in the Service manual, but 7/8 is a good start on each. Is the ProK filter new or used? and have you tried with the Stock flame arrester on it? did it run Ok before you put on the new Prop?

 

[750rider]

thanks for the response guys, me and a buddy were looking in at the motor just as perplexed as ever and he saw this little dial that said fuse on it. after turning it and pulling out the cord, i saw that the glass had a crack in it (im guessin just enough for the ski to start and run) after replacing the fuse with the handy spare that was provided (thanks for something kawi) the ol girl ran like a fuggin champ, took her out to the water the next day she ran just swell.