Couple of probs on YZ250F

[whenfoxforks-ruled]

I would not EVER recommend cutting wires. What is the temperature in Israel? From the main jet change I am guessing its 120 degrees Fahrenheit. If you are in winter like I am, you should be putting a bigger main jet. A 180 and dropping to a 168 is incredible. Stock jetting should be good for a starting point. Check the ap, take the subframe with the air box off. You can see the back of the carb. Twist the throttle and see if you can see the ap squirt from a closed throttle position. It should squirt as soon as the slide goes by. If your carb has issues it will cause a bog all the time. If you are way lean you will get a bog all the time. I would get a second opinion if you have another mechanic in the area. If your bikes clutch is slipping it will feel like you hit neutral, and 5th gear is where it shows first.

 

[oldguy]

Actually Eric Gorr cut the wire on all of our YZFs the first time he worked on each. I replaced the unit in the engine that the wire ran to with a site window so I could verify oil level with a quick glance so I guess cutting the wire is a safe move.
RPM to set the jetting it is also important to work with air temperature as well as elevation. Do you have the Yamaha manual for a referance on jetting? From what I remember there is a chart in it that gives recomendations at temperatures and elevations. If you do not have a manual I can hunt mine down from the 2004 I have and scan and post it. Unfortunately the earliest I will be home to do it is sometime Sunday (early Monday for you)

 

[R.P.M]

Actually Eric Gorr cut the wire on all of our YZFs the first time he worked on each. I replaced the unit in the engine that the wire ran to with a site window so I could verify oil level with a quick glance so I guess cutting the wire is a safe move.
RPM to set the jetting it is also important to work with air temperature as well as elevation. Do you have the Yamaha manual for a referance on jetting? From what I remember there is a chart in it that gives recomendations at temperatures and elevations. If you do not have a manual I can hunt mine down from the 2004 I have and scan and post it. Unfortunately the earliest I will be home to do it is sometime Sunday (early Monday for you)

Thanks, but i already did the safe way and just disconencted it. it didn't solve the problem.
i replaced the cdi with other bike and the guy who take care of it said it over. im not sure about it.
but he claims that what i feel now is happning becuase i need to change transsmision gears. 5th and 3th.
and ofcourse do a little bit of jetting cuz 168 is small.
so i guess i need to open the engine. so i will also do some valuve checking and timeing chain with the gears.
any other things i should check ?
and what should be the price for fixing 3th and 5th gears and timeing chain + cdi ?
Thanks

 

[Ol'89r]

but he claims that what i feel now is happning becuase i need to change transsmision gears. 5th and 3th.

and what should be the price for fixing 3th and 5th gears and timeing chain + cdi ?
Thanks

Ok, now we are starting to get somewhere. :cool:

What you describe as missing may be your gearbox jumping in and out of gear. If this is the case, the bike should run smooth in all of the other gears. If the bike accelerates smoothly in the other gears, that would eliminate a miss in the engine. (Ignition, carburation, etc.)

If it only does it in 3rd and 5th gears you most likely have worn shift dogs or bent shift forks or both. Most likely both. When the shift dogs (the little engaging dogs on the sides of your gears) wear on the edges, it rounds them off and produces a taper on the dogs and the mating gears. Under power, the taper forces the gears apart and eventually bends the shift forks. If you continue to ride the bike it will only get worse and could damage the rest of your engine. The engine oil and gearbox oil is the same oil. So, any bits and pieces in the gearbox can get into the engine and cause more damage.

I have no idea what it would cost to have this done in Israel. Not sure what they charge for labor there. You can check on the parts prices online at one of the Yamaha dealer sites.

While the engine is apart, you will also want to check and possibly replace the piston and check the valves. New rings and gaskets are a must. Your mechanic should be able to measure the wear on these items and determine if they need replacement or not.

 

[R.P.M]

ok, thanks. just hope it will end with thies and not other things.
i guess only the parts will cost me around 500$-600$
thanks! i wont touch the bike until i fix it.

 

[R.P.M]

well the guy opend the engine and i need to change some of the gear parts.
so i already got CDI and got some parts for the gear. i guess that in a week i will get my bike back home agian then i will know if it's need some jetting too.
anyway thanks for all the info and advises.
im not sure if it's allowd but i just wanna mention that i bought the OEM parts from Shop called Generationmx and the price and service was really good (just my own advise for you).
I also gonna get rid of my gearing setup (13-45 and 110 Wheel).
for a stock one.
Thanks!

 

[whenfoxforks-ruled]

Good luck and let us know how it turns out!

 

[R.P.M]

well, the problem with the slipping gear mainly on 5th gear has passed away but it still
CcccuttttTTTiiIInnG!
i guess i should check better the AP/Carb.

 

[R.P.M]

Well after a little (very little) working on the carb, the prob solved!
the needle were to high and ichanged the pilot jet.
:)
thanks agian for all the advises!