Working on a 2000 ltf250f 4wd quadrunner. When I got it in has no recoil would not turn over by elec starter new starter, cleaned carb and new shindy kit put in. 150lbs compression valve lash ok. Petcock diaphragm is leaking fuel to vacuum line. Plugged both and running in prime position this thing starts and idles almost like new. Will take throttle in neutral no problem but driving it falls flat at 1/4 throttle new ngk plug shows to be lean have moved needle up and down with little change. It is a cv carb and has me at a loss

 

Plugging up the vacuum line is probably the cause.May be able to throttle up with no load,but under a load needs vacuum to operate the slide correctly.Sounds like you need to replace the petcock or rebuilt it if possible and hook all lines back up on this Mikuni cv carb.http://www.bikebandit.com/oem-parts/...7745#sch259343

 

Sounds like a vaccine leak or a compression leak on the lower end

 

It would have been running rich when the tap was leaking, so I wonder if someone has fitted a leaner jet. May be worth trying a new standard main jet.

 

More than likely the high speed jet is just stopped up..I ran into the same issue on a carb I upgraded to for my quadrunner..a can of carb and choak cleaner plus my trusty guitar string fixed it right up...

 

^^^^^^ I would also recommend replacing the fuel petcock/dia...they are inexpensive if purchased on ebay and such, and I'm talking an aftermarket type, not the OEM. I say this as it just makes it right, and eliminates that area of concern as running in the "prime" position is supposed to a temporary thing, just to ensure carb bowl is full of fuel after carb maintenance. I don't think plugging the fuel pump vacuum ( P/C ) line will have any effect on the carb operation. Did you give the diaphragm a good inspection for possible holes, tears? Shindy is a great kit, but did you compare the new jet sizes to the "old" jet sizes? Have you checked the airbox "air" intake for possible obstructions? And is there an air filter installed, and lid is on?

 

thanks guys guess i need to update this replaced fuel pump and helped it about half the problem did end up putting stock jets back in carb to get it to throttle up as long as you dont jab the throttle the owners werent able to sink any more cash into it but a few months later it is running fine and doing the job they need it to do thanks again