Question about 2003 Yamaha YZ 125

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When i kick it over, it runs but howls like a dying cat, then stalls out easy, pulled the head and the cylinder walls look good, arent scraped?

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  • Ben Thompson May 11, 2010

    Have you done any clutch work or any engine work to the bike recently?

  • Ben Thompson May 11, 2010

    Will it rev up, and does it stall when you put it in gear?


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  • 5 Answers

Probably bad crank or rod bearings

Posted on Jan 10, 2009

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Water comes out of spark plug hole when turned over have changed gaskets but still lots of water

do a coolant pressure test , if water comes out you'll have to do gasket again make sure head is not cracked and gasket is on the right way, good luck.

Sep 09, 2016 | Motorcycles

1 Answer

Kx250 98model low pressure on kickstart

complete cylinder compression test. should be approx 120 psi
if low you will have to replace piston rings.

was bike running good before?

Mar 06, 2012 | kawasaki KX 250 Motorcycles

1 Answer

Running fine until today motor just started cutting out popping and eventually just died no battery have joe hunt magneto and its a kicker need input on what might have happened. the motor is a 1960fl...

Well, you need three things for any engine to run. You need compression, ignition, and fuel. You should be able to tell if you have compression by kicking the engine over. Does it feel like it used to or is it way too easy to kick now? If you're in doubt, run a compression test on it. You should have somewhere around 100 psi on each cylinder.

Next, pull the spark plugs out of the heads, plug them back into their wires and lay them on the heads so that they get a good ground. Kick the engine over and watch the plugs for spark. If you have spark, you are probably fine in that area. No spark, check that magneto. I'm fairly sure that the magneto has a set of points in it. I'm not familiar with a Joe Hunt mag but I know the original Harley mag.

Now, for fuel. Pull the fuel line loose from the carb and turn the fuel petcock on. Do you have a good fuel flow? Now, you didn't tell me what kind of carb you have but if you have fuel going to the carb, you may have to drop the float bowl and check the jets for obstructions. But, just use a squirt can and squirt some fuel into the throat of the carb and see if the engine will fire. If so, then you know it's a fuel problem.

good luck

Apr 23, 2011 | Harley Davidson FLHR - FLHRI Road King...

1 Answer

How to start yamaha yz 400f?

pull the choke out, make sure fuel is on, DO NOT turn the throttle before starting. now you have to make sure the cylinder is at the top of the stroke, give the bike a couple short, easy kicks your not trying to kick it over yet, you are just trying to get the piston to the top of the cylinder, as your givivng it the short easy kicks, you will notice that the kick is getting shorter and harded......until you are at the top of the it is ready to kick over, hold the hot start lever in about half way to release some compressionand give it a hard strong kick, if it doesnt start on that kick, make sure you are at the top of the cylinder again and when you are, give it another strong hard kick all the way to the bottom, when it starts immediatly release the decompression lever or you could do damage to the valves. relaese the choke, you dont want to leave the choke on too long because it is a very rich gas mixture and will eat the oil off the cylinder walls after a while. and DO NOT high rev the bike until it is warm, because you need to make sure that oil has gotten to the top end. it isnt a 2 stroke, ya cant make her screem right away.

Apr 21, 2011 | Yamaha WR 450 F Motorcycles

1 Answer

My 1999 Harley FXD makes a scraping noise and seems to loose compression and stalls at idle only. Noise seems to be coming from the top of the front cylinder. Runs fine under load. I removed rocker cover...

The "scraping noise" is the crankcase vent venting the pressure out of your engine as it runs. In 1994, Harley moved the crankcase vent to the heads with is why most mechanics referred to bikes of this year model and later as "head breathers". The two large bolts that hold your air filter onto the engine's heads are hollow and that's what the vented air comes through. If you've replaced your stock air filter with a SE or aftermarket unit, you may be able to hear the vented air better due to the reduced restriction of the air filter.

Now, excessive crankcase pressure will increase the noise that you're hearing. This is caused by ring blowby is the rings are worn. My suggestion would be to have a compression or better yet, a leak down test done on the engine to determine the condition of the rigns. It may be time to replace the rings.

As for the stalling, I doubt that it's loosing compression. It's probably the idle speed is adjusted too low or the carb needs going through and a bit of tuning done to it.

If it''s fuel injectied, you'll need to take it to a shop that can reset the idle speed and such as it's all done electronically.

Good Luck

Oct 15, 2010 | Harley Davidson FXD Dyna Super Glide...

1 Answer

Bike was running perfect then it bogged down. now it wont start and is making a really loud squeeking noise when i try to kick start it. iam begining to think it could be the piston and/or rings but not...

Sounds serious, but good that you have compression. Can you remove the head? If yes, you can get a look at the cylinder walls.
Hard to diagnose without disassembly.

Aug 23, 2010 | kawasaki KX 125 Motorcycles

2 Answers

How do you tell if honda motor froze up

can you move the kick starter? if no kick starter, then take the spark plug out and put it in first gear and see if it rolls, lol if its locked up you might just free it back up and run again,

Jul 03, 2010 | 2003 Honda CRF 150 F

2 Answers

Just put new piston and rings in my 1993 liquied cooled polaris 350cc ATV and after starting, right away it starts to bubble back in to my overflow bottle. With in 3 min. it starts to overflow. checked to...

you may have a cracked cyl. head or warped head...a crack in the cyl. is rare but does happen.....have a quality engine or machine shop inspect them for you..

Apr 10, 2010 | 2003 ATK 260

2 Answers

VERY hard starting takes way to many kicks usually play out befo

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. 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. 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 a 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.

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Jun 11, 2009 | 2003 Yamaha YZ 250 F

1 Answer

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!

Mar 23, 2009 | 2003 Yamaha YZ 125

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