SX/SXi/SXi Pro 1993 Kawasaki 750 sx Fuel Problems? Please Help!

[abenjes1]

I have a 93 kawa 750 sx, with a decent amount of aftermarket parts on it. I bought it already modded. When I originally purchased the ski, I dropped it in the water last summer and for some reason it would not go faster than 5 mph. Out of the water hooked up the hose it sounded great. I took it to a mechanic over the winter who informed me the carb hoses were hooked up wrong and the reed's were installed wrong. He fixed it for me and I put it in the water for the first time this yr.

Day 1: riding great, fantastic throttle response, no complaints at all!
Day 2: riding great at first. Throttle response then started to lag. I would pull full throttle and it would take a second or 2 for the engine to completely take off.
Day 3: started out doing the exact same thing it did at the end of day 2 but then completely cut back to not going over 5 mph at full throttle.

I assume it has to do with the carb yet again. I have a mikuni carb on it and have downloaded the PDF manual for it. I started to read through the manual and thought about doing some minor adjustments on the high and low speed adjusters. I did notice the high speed adjuster is turned out 3 full 360 degree rotations from closed. How many rotations should they be turned out from closed?

Any help would be greatly appreciated!

 

[sxipro02]

No more than 2 turns usually, If you need to go out further its time to re jet bigger.

 

[tor*p*do]

sounds very lean. what jets are in the carb?
probably needs to be jetted up
before the motor seizes

 

[abenjes1]

So no more than 2 turns on the high speed adjuster? It idles fine in and out of the water. It even revs up fine out of the water. I still a complete noob at this carb/engine stuff. I am not sure what you mean by re jet bigger or jetted up. I am not sure jets are in the carb. I would just hate to take it back to the guy who worked on it before just to have him spend an hour on it for some simple problem and charge me $300+ again. I dont really have anyone near me that can work on these things....

 

[sxipro02]

Also could be the plug wires, It didnt hit me untill I read it again. Three turn out is too much but if it ran then thats not your issue right now.
1st pull the wires out of the spark plug boots and cut them back until you get good clean wire inside them, kawi wires have a issue with corroding at the boots. see if that helps.
2nd the jets are in the carbs and will need to be replaced with larger ones soon, three turns means your carb isnt supplying enough fuel. running lean is no good and will result in a motor seizure/rebuild.

Check the wires out though, I'v had this happen to me before and had to cut almost 1 1/2" of wire until I found good, non rusty metal. The boost simply twist back onto the wire (there is a screw in the boot that digs into the core of the wire) then add a zip tie to keep out the moisture.

 

[abenjes1]

Ill check the plug wires, I may just order new ones and replace the old ones all together. I just remembered reading on the Mikuni PDF that 3 turns out is the stock setting on the high flow knob from the factory. Mine was roughly at 2.5 and i turned it to 3. I only have a single carb on my 750, not a dual setup. Ill check the plugs though and pray that's the problem because if i need new parts on my carb, ill probably end up having it take it to this guys shop. Thank you for all the advice!

 

[abenjes1]

One other thing. How many turns out should the low speed adjuster be turned out from closed?

 

[tor*p*do]

search for the Mikuni manual and read it.
then read it again.
you have much to learn and random questions aint gonna cut it IMHO

 

[Pnutt]

it could also be the pump diapham on your carbs being old and not making a good seal. If you watch some carb rebuilding videos on youtube you should be able to pull apart your carbs and clean them and rebuild them for around 30$. look at the manual it has tuning procedures for your carbs in it that will tell you how to tune the carb's needles and there will be a diagram in it that shows where the 2 jets are in the carb. when you rebuild it look at the number stamped on the jets and compair them to stock sizes that any dealership will tell you for free. i would rebuild befor rejetting it might not need it. if it runs 3 turns out go one size biger on the jets and re test they are pritty cheap so you just repeat the tuning process with bigger jets and then if you need biger start over.

 

[Pnutt]

oh and dont forget to tune it in the water... the engine is under a load when in the water because the pump is pumping water witch gives it some resistance that you dont get out of the water with a hose hooked up. we just hook a rope to the truck and to the back of the ski in knee high water with the hood off and tune it . if you have 2 carbs you can get a carb tuning tool for 19$ so you dont have to pull your carbs off to get to the needle adjusters.

 

[sxrchris]

Old thread! Mine does this also from time to time. Water in the fuel!