YZ125 Died

[dirtbikerida63]

I was riding my 2003 yz 125 around my yard earlier. It was running fine! I just bought it from a guy the other day and it was running fine then too. Then i went to go ride some trails today and on the way to the trails, my bike died in the middle of the street. I was so embarrased by all the cars going by. I looked at the plug, its fine and sparking. What else could be wrong? in one of my other threads, someone said my bike was running to rich and thats why i was having trouble starting it. Could there be to much gas going to the engine and flooding it. Also, before this happened and now, when i kicked it, it didnt even sound like it wanted to turn over. When i gave it a little bit of gas i could hear it try to kick over. what does this mean?

 

[kx125412]

Top end couldve went and now it doesn't have enough compression to start. Do a compression test on it and see what you come up with.

 

[dirtbikerida63]

what should the normal compression on it be?

 

[kx125412]

Between like 120-160psi for a 125.

 

[ohmthis]

120 psi is barely enough to start and run. My 125 has 185psi with a new top end. when it gets to around 140-145 psi it's about ready for a new one. When compression is good it'll start first kick. When it starts getting low.....3rd,4th,or5th! I'll bet that it was heading south when you bought it. Since you said you were having a hard time starting it. Did you run a compression check on it before you bought it?

 

[dirtbikerida63]

no, i have never owned a two stroke before so i didnt know i should do that. How much does a new top end cost?

 

[Coop]

I would do a compression tester to be sure first. But if it just needs rings those are around $20 plus gaskets (head and base). If it needs a piston also I just checked DennisKirk and they run between $85-$140 depending on the brand for your bike.

 

[mox69]

Before you go tearing your motor apart, please check all of the smaller things first.

Put a new plug in, they are only a couple bucks and you will eliminate that part 100%. Take the carb off and clean it out. Put some fresh gas in there, and make sure the petcock is in the ON position :)


It is "possible" you need an engine rebuild, but consider that a final option after all of the simpler things have been looked at.

 

[dirtbikerida63]

i think the bike have sucked some dirt into the carb. I took the air filter out, and it literally crumbled in hand. So i am thinking thats all it is. Luckily the guy knows the owner of a local motorcycle shop and has aranged plans with them for me to drop the bike off.