Question about 2003 Yamaha YZ 125

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Dirtbike kick star

My kick start locks up then when u kick it harder then usual it releases then after a minute or so of kicking it locks up again, and it also has no compression

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  • Laurie Wookey Mar 20, 2014

    OOPS! premiture click...You have, i think, two seprtate issues here. Given you use the bike accross country, the kick start mechanism is either gummed up with debris or the shaft has been bent at some time during your activities resulting in a binding spot in its' travel, loosening up later when you ride over more bumps. Re the lack of compression, you'll best test it with a compression gauge and if below spec., you have a job to do, just as much fun as riding!!



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This happened with my sons pw50 where the piston ring had snapped and when it locked it was stuck bewteen the piston & bore

i would seek a shop or mechaninc to look at the top end and isnpect the piston & rings for wear or damage

dont keep kicking as this could result in further damage

Posted on Mar 20, 2014


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Posted on Jan 02, 2017

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SOURCE: my 426 is kicking over without the compreshion release lever

I had the same problem on my 01 WR426 just recently after having it transported from Sydney to Perth. Valve clearances were within spec. I removed the head and poured a solvent down the intake and exhaust ports as detailed in the repair manual and found two valves on the intake side and one valve on the exhaust side leaking. After removing the valves I found small carbon deposits on the seats causing the leakage. I relapped them with the fine paste, reinstalled and found they held on both sides. At the same time I checked the rings in accordance with the repair manual and found them outside the standard spec but within tolerance and therefore replaced the rings as a set also (the piston and cylinder were still in spec and original hone marks were still evident on the bore). After replacing the head and the cylinder and installing the spark plug I kicked it over and had the compression back again (I can put my entire bodyweight on the starter and it will not budge at TDC). Hope this helps.

Posted on Jan 13, 2009

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SOURCE: while riding my yz 125 it just died and won,t kick up again

  • If a hole in the piston then install new piston and rings. Next, clean the carbon off the head and install a new head gasket.
  • If cylinder wall is scared the piston has seized up. Pull the cylinder off and take it to the dealer. Have them bore the cylinder and return it along with a new oversize piston and rings.
  • While at the parts counter, get a new stock spark plug and a supply of Yamalube Two Stroke Motor Oil. You need to add 4 ounces per gallon when filling up. This will be a 32/1 gas to oil ratio. NEVER ride the bike without at least the needed 32/1 mix.
Please rate the solution as a "FixYa" if able. Thanks!

Posted on Mar 23, 2009

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SOURCE: Loss of compression with dtr 125, kick start

change the rings anyway then you know if its them,cheap and easy to replace

Posted on May 14, 2009

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SOURCE: yz 250 4-stroke 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 rel

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.

Posted on May 29, 2009

  • 3567 Answers

SOURCE: 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

Yes, there is a proper way to start the engine. Four controls are on your bike 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. 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.
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.

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!

Posted on May 30, 2009

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Its getting dam near impossible to kick start, it will start after 30 or so kicks, any ideas?

Could be low compression due to head gasket leak, worn piston rings. Or bad spark due to dirty plug, wrong gap, plug breaking down, lead or cap breaking down, ignition fault. Choked air filter, fuel filter.
Try these in easiest order I.E. remove air filter and see if it starts easier, do a compression test, cahnge plug, lead cap. Check the fuel filter.
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