1994 Yamaha WR700III need Help

[Autotech]

Ski wont run past about 1/2 throttle and just boggs down. Here is what I have done Cleaned Carb, Pulled fuel tank Cleaned out about two liters of Water in the process. Repalced fuel filters blown out all the lines and selector valve. check compression on cyl. about 105 PSI check fuel vent valves . Ski cranks and idles find it just want go and I have run out things to check. I am pretty sure its got to be in the fuel or ignition system. any suggestions would be greatly appreciated. Ski belongs to buddy of mine that has spent big bucks at a local dealer trying to get it running right with no luck. The only thing I have not done is the fuel pump on the side of the carb. going to try that this week end. Thanks for your help guys

Bobby

 

[Rob454]

Re: 1994 Yamaha WR700III need Help

First of all your compression is really low if its 105. if you meant to say 150 then its fine. is it a single carb or the dual carb model? check the pulse line coming from the engine case to either the external fuel pump or ot the carb.

Did you mess with any of the high low adjustments? Sounds liek the high speed screw is turned in all the way so youre only getting fuel from 0- 30% of the throttle lever then after that the high speed jet is supposed to open and overlap the low speed jet. i forgot what the settings shoudl be but I woudl start out at 1 1/2 turns out for the low speed screw and at 1 for the high speed. that shoudl give you a good baseline. then you need to run the ski and then check the plugs see if youre rich or lean and adjust accordingly. turning the screws out richens the fuel mix turning them in leans it. you DONT want to run lean on top youll smoke the motor. I rather you run rich and tune backwards than the other way. You coudl be getting too much fuel. When it bogs down and dies look at the plugs. Are they wet with fuel or dry ? if theire wet youre way too rich if theire dry then youre lean.
LMK
Rob

 

[Autotech]

Re: 1994 Yamaha WR700III need Help

Thanks rob454 The high speed jet is set at about 1 and 1/4, plugs look dark so it its running a little rich It does not die at all it just won't open all the way up runs up to about 1/2 throttle and you can play with the throttle lever and there is no more rpm or speed. I did not check the pulse line thats one more task ill take care of tomorrow. about 105 was the compression and i though that was a little low but did not have compression specs to make a comparision plus I was using a ragged looking gauge not sure how accurate it was I will carrymine this weekend and re-check again before I get in to deep.

 

[pinbodean]

Re: 1994 Yamaha WR700III need Help

Just cleaning the carb won't do it. You have to rebuild it. It's 13 years old and I'll bet some of the diaphragms are weak or leaking. This is a maintainence item and it's WAY overdue. Good luck.

Bodean

 

[Rob454]

Re: 1994 Yamaha WR700III need Help

Take the carb apart and look and see if the high speed jets are clogged up. the jets are located under the 1/2 moon shaped block of metal. the needle and seat spring arm sort of overlap it and the 1/2 moon block is held down by two phillips screws. BE CAREFUL taking those screws out. they are really really easy to strip. make sure you use a good screwdriver not something that has a worn out tip.
Personally I woudl go get a rebuild kit for the carb(s) they shoudl run abotu 30$ a pop and dotn take long to rebuuild. if you dont know how to do it you can send them to me with the rebuild kit and Ill put it together.
Its pretty easy though.
Rebuild the carb. the compressio rule of thumb for two stroke jet skis is abotu 150 for two cylinders and abotu 125 for 3 cylinders. give or take 5%.
Your buddy shoudl throw a set of rings on the ski and rehone it.
I wouldnt go back to that dealer. sounds liek they just like taking the guys money
Rob

 

[Autotech]

Re: 1994 Yamaha WR700III need Help

Found it . The filter in the fuel pump had trash in it. run fine now
thanks.