SX/SXi/SXi Pro HELP... me figure what's wrong with my 650sx

[OTT]

I have a fuel problem (I think) I cant figure out. my ski is a 89 650sx (28mm with external pump) with a westcoast head and coffmans exhaust. The ski will only start when it has been primed then it will run for a couple seconds somewhat normally then the idle will get really high like its going lean then stumble and die. If I rev it up a bit and get it on the high jet it runs fine. In fact, It runs great at full throttle but will go lean and die every time it drops to idle or low rpms. The position of the low needle seems to make no difference what so ever. The carb has just been rebuilt. Please HELP ME, I need to sell this thing to put money in my new SJ!


Steve

 

[junkyardj]

did this happen before or after you cleaned the carbs? i have a couple of those carbs and pumps kickin around if it turns out to be that..

 

[OTT]

Before I rebuilt it the idle was perfect and the high was jacked up now is the opposite.

 

[Waternut]

I had the same thing on my 750. Turned out to be both the fuel pump and the carb. I don't know what it was but it acted like an engine with an air leak. Got a good used carb, transferred the jets to it and it ran like a champ.

 

[six5hooSX]

mine did about the same thing it was a rip in the fuel pump diaphragm

 

[OTT]

My fuel pump looks great... I'll try to clean the carb again and replace the gasket and go from there. Thanks guys!

 

[OTT]

Replaced the gasket and clean the carb, no change. Ideas? Please!!!!

 

[OTT]

So to give another discription or whats happening: The jet ski will start only when primed. Idles for a couple of seconds until the idle increases in rpms then it dies. It wont rev unless you prime it 3 times and rev right or the start. I'm think the low jet isn't working but dont understand why....

 

[OTT]

I found a vacuum leak between the carb body and the throttle shaft. I'm going to try to fix it tomorrow, hopefully this is the problem.

 

[OTT]

So it still isn't running right. I took it out today and it wont idle or run at partial throttle, only 3/4 or higher and you have to prime it to get it there. Any ideas??? Again the carb was just rebuilt and the fuel pump looks good. Its like it only gets fuel when there is a large amount of vacuum like under full throttle. help... I need to get this thing on craigslist soon.

 

[OTT]

anyone? To give a picture of how the ski is set up: westcoast head, stock carb with 55 low and 125 high, full coffmans exhaust. don't know the compression on the head

 

[550surf]

hey dude, figure out your problem? i have similar issues

 

[JEMJET]

Did you check your reeds? Sounds like you have a broken reed.