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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Probably bad crank or rod bearings

Posted on Jan 10, 2009


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Check the torque on the head bolts. I can't tell you what it is, been a long time. If they are good, run it till it dies. Then check for spark at the plugs or coil/s. No spark replace the coil/s. My guess would be coils. But I have seen the head loosen up.

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What is the engine code for this Civic? Open the hood, It will be on the engine block proper, to the left of the exhaust manifold, on a small flat tab just below the cylinder head where the transmission and engine bolt together. I need that before anything else...

To put it simply, if this is a D15B7 or a D16Z6 (the two most common D-Blocks in the United States from the OBD1 era), then everyone who's talking about EGR valve operation should be ignored. Because 95% of ALL global OBD1 Honda D-blocks don't have EGR valves, or ports, or even the thought of an exhaust gas re-circulation system. 1994 is too early for EGR Honda's, and most of the up-to model year 2000 Honda D-Blocks were simple exhaust port drill holes with no valves, such as on the D16Y8 and Y7's.

Are there any modifications? Hot rod parts? If so, what. Exactly what, not "a one of these, a one of those", I need to know exactly what. Are you running a stock ECM chip? If not, what fuel MAP and who wrote it? Are you even sure the ECM is original? If it's ever been owned by a kid, the odds are slim that it's running an OEM fuel and timing MAP today. How any miles on the engine? Does it burn oil? What is the overall maintenance condition of the engine? Most recent valve adjustment? And recent major work, such as head gasket, etc?
My best guess is that you're dealing with a missing CAT (knocked out), a clogged or ineffective CAT, or simply a worn out and wiped out major rotating component in the engine (valve seals, rings, pistons, etc). If you had a complaint of a running condition, such as idle surge, stalling, no power, check engine light, etc, then you've got another issue. Fix that first and move on from there. But if all you've got is a failed emissions test with no other symptoms, you've got a bad/missing CAT, or a bad engine. Period.

The early to mid 90's Honda's are flat out the best engines designed and built by man in my opinion. The D16Z6 is one of the marvels to modern engineering. These things ran so good, for so long, everyone who owned one either forgot to take care of it, or drove it till it died. Or, raced it till it died. And now these poor D-Blocks are showing up like rats to the piper at my shop asking if "The Guru of D Series" can breathe any new life into a 250,000 to 350,000 lower ends. I had a D15B7 show it's head last week with 325,000 on it. It was actually the old engine I pulled from one of my del Sol race cars in 1997 with 150,000 on it then (in favor of a B18C) and installed it in this customer's car. Here it is, 325,000 on her today, still kicking. Original head gasket and valve seals, blowing smoke like a diesel past the valve seals and guides, yet still pulling like a freight train still getting rubber when you grab third. But there's NO WAY that 'ol 325,000 mile bird could pass emissions, than god we're in Michigan She's just too old, and too worn out.

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1 Answer

Engine howls

First you should try to get codes out of the OBD port with a quality scanner. When was the car last running great and not overheating? What changed first and when? Have you done a cylinder leak test? You could have a blown headgasket.

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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

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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,

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That cap was most likley broken upon pulling off. You need new wires.

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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!

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