I think i blew my topend. help?

[motorida26]

Hey all.

I have a 2004 Honda Cr125,

Last weekend I was at the dunes with my friend and we were up at Patton's Valley screaming around the bowls up past the hill. I was around 4th gear pinned and all of the sudden my bike started bogging down, so I shifted to 3rd, still bogged down, 2nd, still bogged down, then first and my bike died at the BOTTOM of the bowls.

It sucked getting the thing back out, and all the way back to Ogelsbee(sp?).

Basically my bike WONT kickstart, but we did manage to get it pullstarted for a short time, until the bike bogged down the same as it did before.

I've had the bike for nearly 2 years now, and i havent replaced anything in the motor, not even the plug, which has never fouled.

My bike is now sitting in my trailer and the Kickstarter wont move at all, so im pretty sure my topend went out.

anyone have any other helpful items of knowledge?

[O.J. Simpson]

your kickstarter won't even kick over? might be something alittle more serious then just a top end. Could be crank or rod or both

[dualstroke]

Time to tear it apart.If you can't kick it you can't even do a compression test.Sounds like bottom end.You will have to take it apart and see what you can find.Keep us posted.Good luck.

[02yamahablaster]

sounds like it seized. Pull the topend off and find out.

[quadracer87]

agreed with the guy above my post

[ky 2stroker]

I had a 00 cr 125 a couple yrs back........same thing happened to me. I was rollin on across the field pretty good in 5th gear (mine was only a 5 speed tranny), and it started loosing power and bogging down. Im thinking the plug fouled out, but I pull the plug right then and there and ground it against the motor and crank it over and im getting a good strong spark. so I put the plug back in and start cranking on it. then I notice how its got no resistance at all when I kick it, like its got not compression.

so I had to push the bike all the way back to the house cause I was riding alone. pull the head off and find my problem.........the top piece of the piston on the exhaust side right above the ring, broke off, which caused me to lose compression. but I was very lucky that the piece of the piston exited right out the exhaust and didnt gaw up the cylinder walls. I thought it was pretty odd how it happened so I researched it online and found that it is a common problem thats caused from head gasket faliure, and sure enough, that was my problem. my cylinder head had a bad spot that was allowing the coolant to leak into the cylinder above the exhaust port. and since I rode it in tha condition for awhile without knowing it, it made the piston weak and caused it to break on top above the ring.

[motorida26]

thanks guys.

yeah. my buddy said the piston seized up. cause before when it first happened i could kick it, it just wouldnt start.

but when i tried at home its seized.

yeah. i need to get a job and get some money together and then ill start tearing it apart.

or just take it to a shop.

im not really knowledgable with dirtbikes just yet. So i doubt i could do it on my own. Im really good with directions though. so if i had those i could do it myself.

[FPMXer]

You can do a top end with a 10mm, 12mm, 14mm sockets. Remove all the parts and lay them on a clean surface in the order of removal. Buy a service manual or a Clymer manual and read over it a few times. My 11 year old son can do a top end. It sounds like your friend can help you do it.

Read through this page a few times and it will give you an idea of what needs to be done.

http://offwidth.co.uk/bike/crm_rebuild/index.html

[motorida26]

hey guys,

Just an update,

But my buddy said he'd help me do it. He's rebuilt 125's before back when he was on his own. Which was definitely close to the sickest cr125 i ever saw.

anyway.

I've almost got enough money to buy the parts, and im putting stuff on Ebay today to sell.

[motorida26]

Hey guys, finally got the head and cylinder off today.

I attached a pic of the piston.

sorry its a little blurry.

Theres definitely a piece missing from it.