gz 250 wont rev up

[jonathan180iq]

:blush:

corrected

[22matt22]

ok the diafram is fine nothing looks rong with it the slide looks good its not sticky i have dipped the carb 5 diffrent times ok here is what it is doing. ok u start the bike its idels up a lil then when its warm it idels normel put it in first u take off an u only have a lil more than half thotel go throw first, second hit therd. now the bike is going 30 mph it want go any faster than that u can put the bike in 4 5 still 30 mph. its like it loses power if u pull more thotel if u put the bike in nutrel it idels high an it dont go back down. ok if u take the air filter off put ur hand over the port an slap it repetedly an pull the thotel all the way back it will tac out

[22matt22]

o an i drand the gas when i got it an put 93 in it thats all i have ran in it

[jonathan180iq]

You have a vacuum leak somewhere. Almost guarantee it.

Check the connections at the carb boots. (These are the things that connection the carb to the aribox, on the pilot's side, and the engine, on the engine side.)

Also, check your the connections where all of your little vacuum hoses connection. There are two on top, I believe, between the carb and the gas tank. There is also a fatter "S" shaped hose between the crankcase and the air box. At the bottom of the air box, there is a long drain tube that should have a plug at the bottom.

Does the bike also "buck" and "chug" when you try to accelerate?

[b1pig]

i have this issue every time Lori lets her GZ sit up. (which is annually)

first, you need to understand that the carb has several ports which fuel flows through. if you look inside the throat of the car, you will see 4 tiny little holes right around the spot where the throttle valve closes against the bottom of the carb throat. ALL of them must be clean.

each time i have to break down Lori's carburetor, i have had to remove ALL of the jets from inside the float bowl. I spray gumout carb cleaner in there using the little tube until all of the holes are flowing free. clean the jets out too. do NOT get any carb cleaner on the diaphram! (some carb cleaners will ruin them)

remove the cover from the accelerator pump. (or what looks like an acc. pump) be very carefull not to tear the valve... and remember that the cover has a large spring under it... **** will go flying!!!
remove the tiny jet from there. clean it and that port. poke tiny spray tube into "ball bearing" in middle of valve and spray till cleaner is coming out of bowl of carb clearly. remove tiny jet from the INLET side throat of carb. clean jet and port. same for pilot jet. (reset to original setting. make sure before removing, you screw it in and make note of how many turns out it was)

replace all the jets after they've been cleaned THOROUGHLY. once its back together, it will take some time getting stuff situated. my wife's bike was idling GREAT, however the engine would sputter when i revved it. i rode it to the store for fresh gas. had no power over about 1/2 throttle. i did what i've done in the past. i ran it in first gear... throttled it up and then closed the throttle quickly. what this does it raise the vacuum in the intake. i did this several times. it helps to pull fuel through the carb. also seems to pull remaining loose junk out. did that in the driveway 4 or 5 times. bike runs like a champ now.

long way to spell it out... but hope that works for you.

[alantf]

From what you've written it seems like an awful lot of carb stripdowns. Don't you add carb cleaner to the fuel, every 3 or 4 fillups? I use a fuel additive (can't get carb cleaner, over here) and in 22,000 km in 6 years, I've never had to strip the carb.

[deigored76]

My girl friend has a 99 gz250 and it wouldn't go over 40MPH. cleaned the carb, still same problem. I then notice that the Valve, Piston wasn't moving when the throttle was opened up. I found that the diaphragm (13507-19E00) was damaged. replaced it and now the bike runs great. when replacing the diaphragm.

good luck
rick