Hard to start when cold, low compression in kick starter
I own a 2005 YZF 250, when it is cold it takes me forever to start, and there is very low compression in the kick starter I've clean the air filter change the oil and the spark plug regally (all the basics) and haven't got a clue what it is. Cheers
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My guess would be that you have dried out seals/gaskets taking away from the overall compression. This will either get better with use as everything lubes up or you will have to replace all that are leaking.
If the bike has been in storage for any length of time, more than a year or so, the carburetor is plugged up and needs to disassembled and cleaned. If that's not the case do a compression check. You need to see at least 140 psi of compression for it to start reliably. If the compression is low, adjust the valve tappet clearances (tight valves will cause low compression).
Other than that, make sure the choke is functioning properly and that there are no air leaks between the carburetor and the engine.
Low compression can cause this. Insufficient valve tappet clearance is the most common cause of low compression on this engine. So, check the compression and, if it is lower that about 130 psi, have the valves adjusted.
Also make sure the kick starter actuated compression release isn't sticking after the kick starter is operated.
Another thing that can cause it to be difficult to start is a plugged up carburetor. If the bike has ever sat for more than about a year, then the carburetor needs to be disassembled and cleaned out.
There is a proper way to start an engine. Most bikes have four controls to assist in starting.
The choke, used when the engine is cold. Pull the red knob for choke.
The " Hot Start " Lever, used when the engine is hot. Pull the lever to lean the fuel mix when the engine has been running.
The de-compression lever, always used.
The throttle, used to prime the cylinder.
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. Now release the de-compression lever. 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. A flooded engine will often backfire. Now give a strong kick through the full sweep of the kick start 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. Go ahead and give it another primer shot after the 5th kick attempt. A good battery, a clean spark plug, a clean carb and clean air filter will also aid in starting.