Bike will not run if the choke isnt on. in other words it starts then as soon as you push the choke in it stalls please help! I just bought a yz250 4stroke. It's extremely hard to kick over, so it has a pressure release lever on the handle bar. Is there some "proper" way to kick it over, or do I just kick it while holding the "pressure release lever" once, and then kick it regularly to get it started?? is there a proper method to kick starting a 4-stroke? my bike has a pressure release... I've heard you kick it over while holding in the pressure release until you reach the engines TDC then give it a kick without any throttle. Also, how do you know when you reach TDC?
Yes, there is a proper way to start the engine. Four controls are on your bike to assist in starting.
Don't kick, instead, push the kick lever downward. You will feel the back pressure as the piston is going upward on the compression stroke to the point the pressure is great enough that the kick lever "locks up". You are very close to TDC. NOW, pull in the de-compression lever. Push the kick lever a little bit more to get the piston past TDC. Give the throttle a 1/4 turn then let it snap closed. A diaphragm in the carb gives a shot of gas when this is done. DO NOT do this multiple times because you will flood the engine. Leave the throttle closed when kicking. Release the de-compression lever and give a strong kick through the full sweep of the kickstart lever. Quickly get your foot off the kick lever at the end of the kick to avoid any chance of "kickback" from the kick lever. This happens in the case of a misfire, aka > backfire. It can be very painful, and can even break a leg. I am serious about that. Repeat the process (but without the throttle priming), until the bike starts. A good battery, a clean spark plug, a clean carb and clean air filter will also aid in starting.
As to the inability to keep the bike running, Clean the fuel system.
ALWAYS have a fire extinguisher on hand when working on carburetors. Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ). Be sure the gas cap vent hose is clear and the fuel petcock vent hose is clear. Check to see the fuel flows freely through the petcock.
Drain the carburetor. There should be a large screw on the bottom of the carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. Install a new stock NGK spark plug and try to start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine. At the back top left side of the carb is the TPS, Throttle Position Sensor. Do not remove the TPS from the carb. Rather, disconnect the TPS wire lead from the wiring harness.
Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the air screw on the outside back throat of the carb and spray into the screw hole as well.
< < READ CLOSELY > >
IMPORTANT > re-install but do not tighten the air screw down. Only screw it inward until it LIGHTLY seats. Now turn the air screw one and one half turns outward. Pay special attention to the pilot jet, aka > idle jet. It is located at the front edge of the carb. Turn the adjuster outward 1/2 turn. Put the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. This process should get you back on the road. I suggest you install an in-line fuel filter between the petcock and carb.
Go to the site below where you can see a parts diagram for your specific bike. You will select the actual brand, year, model, etc., once you go to the site. Part numbers and prices are also shown. You can order parts from this site. In the event no price is shown on a particular part, the part is not in stock.
www.babbittsonline.com/pages/parts/viewbybrandand/parts.aspx
This all sounds complicated, but right now it is a learning process for you. Pretty soon your friends will be asking YOU for advice.
Please top rate this solution. Thanks!
I Someone else must have answered your question on the unknown knob. I can't find the posting. When someone gives a solution, the posting gets dropped from the listings. The screw adjusts the idle speed.
FixYa is constantly changing their website. I just posted a comment for you that ( I think ) went to the guy that offered a second solution to your kick start problem. I don't have access to a 2004 service manual but you can download a 2003 manual at the site below. Best part is the download is free and there is no "sign up" or "email required" stuff that other sites have. The 2003 repair manual is 95% the same as the 2004 manual. This should help you greatly.
http://www.carlsalter.com/motorcycle-man... Most of the manuals are in English but some are not. There is no way to be sure without doing the download. You can always delete it if the one you pick is in a foreign language.
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Hi there you can down load the full service manual from this site
http://safemanuals.com/annexe_SERVICE%20MANUAL_YAMAHA_YZF%20250-_E.htm
this should answer all your questions
but here is what it says
The carburetor on this machine has a
built-in accelerator pump. Therefore,
when starting the engine, do not operate
the throttle or the spark plug will foul.
Unlike a two-stroke engine, this engine
cannot be kick started when the throttle is
open because the kick starter may kick
back. Also, if the throttle is open the air/
fuel mixture may be too lean for the
engine to start.
Before starting the machine, perform the
checks in the pre-operation check list.
STARTING A COLD ENGINE
1. Inspect the coolant level.
2. Turn the fuel **** to “ON”.
3. Shift the transmission into neutral.
4. Fully open the cold starter knob 1.
5. Kick the kickstarter crank.
WARNING
Do not open the throttle while kicking the
kickstarter crank. Otherwise, the kickstarter
may kick back.
hope you found this useful regards JR
That lever is a compression release and pulling it will make kick stating an excersie routine. Kick start without the pulling the lever. See how that works. good luck.
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I have another question... I'm used to 2-stroke bikes, I recently bought the 4-stroke yz250. the guy who sold it to me didn't go through a full rundown on all the differences so I'm trying to find out as much as I can before using it too much... There is one knob that I have no idea what it does (I don't even know what to call it). So there's the cold and hot start knobs, and then there's this other knob that you can turn. It's located towards the bottom of the carburetor --
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and below the cold and hot start chokes. Anyone know what it's called, what it does, or how I should/shouldn't use it. Any input is helpful...
and thanks, your comments so far have been very helpful....
I just posted a question about an "unknown knob" on my 4stroke carburetor, here's a link to a picture in case you had no idea what I was asking about.
http://www.atlanticmx.com/archives/DSC01...
It's the knob on the bottom left
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