TROUBLE!!! PLEASE READ

[yamracer58]

I went riding today and my bike was running fine. then i went to my friends house it started to run bad. From closed to about 3/4 throttle it sounded like a four stroke. so i messed with the air screw and nothing changed. I could only roll start it, it would not start by the kicker. So i tryed a new plug and still had to roll start it.

I also noticed that when it is in gear that i can roll it forward with only little strength. could this be ready for a new pistion ring.
The plug is Black, not wet, but dry.
Do you guys know what is worng?
thanks

And my friend said it smokes alot

[desertfreak]

you might of blew the enigin

[yamracer58]

if i blew the engin it wouldnt start

[Woody_393]

Kind of sounds like the piston skirt has cracked. Doesn't it do that when it's starting it's decent to the trash bin???

[yamracer58]

but the piston in fairly new

[Woody_393]

Still could be the case.

If it ran fine before and now all the sudden it doesn't, your jetting should still be fine. I would start by taking the carb off and making sure all the jets are still in, and not clogged. If it still runs like crap, something is wrong in the engine. I wouldn't mess with the jetting as I doubt that's the problem.

[YZGreg]

To me it sounds like low compression most likely caused by worn ring(s). I would take the jug off and check it out.

Hmm, seems weird that the fella that said the engine might be junked is a thumper rider, maybe he want's you to join the fart club???

[Antebios]

How new are your rings?

[Woody_393]

Originally posted by YZGreg
Hmm, seems weird that the fella that said the engine might be junked is a thumper rider, maybe he want's you to join the fart club???

LMAO.. Oh brother. Give me a freaking break. I said nothing of the sort. I said it sounded like the engine needs some work (read rings, piston etc). I would have thought you would throw out the old piston, but maybe you keep yours ???

As for him joining the "Fart Club" I don't want that either. You guys are free to ride whatever you want.

[RMZracer212]

My 125 sounded like that when I lost the bottum end berring. But mine would still start up with the kick starter.

[YZGreg]

Originally posted by Woody_CRF
LMAO.. Oh brother. Give me a freaking break. I said nothing of the sort. I said it sounded like the engine needs some work (read rings, piston etc). I would have thought you would throw out the old piston, but maybe you keep yours ???

As for him joining the "Fart Club" I don't want that either. You guys are free to ride whatever you want.

HAHA I was just joking, thumpers are cool just sound like they're farting or something.

[twoofeach]

That happened to my weedeater a few months ago. I realize it's not a bike but the same concept. Low compression, hard to start, ran like crap, sounded like a thumper. I opened it up and the main bearing was wrecked, the rings were fragmented and the skirt was cracked. That must of been one hell of a weed. Anyway, it's not rocket science. Open up that bad boy and give it an inspection. My guess is that it whatever is wrong, will be quite visable by the naked eye. Otherwise, all of us are just giving you an idea of what "might" be wrong.

[Dell30rb]

yep... if compression just goes all of a sudden something very bad has happened inside your motor....

[taekid]

I had the exact same thing happen to me, on mine it was a combo of the power valve seal and believe it or not my muffler was clogged! Something simple and stupid you might want to check just in case.

[Oring]

Mine just blew a piston the same way !
It ran great but was a little too lean, If you ride a 2stroke you have to remember that the cooling for the piston comes from the fuel going in.
A good machinist told me some info on this very subject!
If you are riding around and not on the pipe you run the risk of cooking it. A new piston can get cooked real quick! Can blow in 5 minutes
I coudn't start mine but roll started it. It ran great then once stopped, it would not kick start. A quick check is to remove the pipe and look at the piston thru the pipe hole! If they are gonna cook the damage is usually there! All I could feel was the ring (Dang) No piston skirt on top of it!
Next piston go down on the clips of your needle or go up a main jet size.
Woody was spot on!
The good news is this can easily be fixed with a new piston, rings and jetting change. Also go abit harder, low gears if its too quick for ya! Keep it revving, Keeps them cooler!
Idling around on a Lean motor equals blown motor!
One trick is to wear earplugs so the revving of the motor doesn't bother you so much
Take the head off and check the piston.
You will have to look in the barrel but get used too that! check the inside.
The other fix for this is to get a thumper! They like to idle around :P
Its good to know how things work!
Live a little, Learn alot!

[pragmatic393]

Originally posted by Oring
If you are riding around and not on the pipe you run the risk of cooking it.

Also go abit harder, low gears if its too quick for ya! Keep it revving, Keeps them cooler!
Idling around on a Lean motor equals blown motor!

Interesting, I would have guessed the opposite??

[Woody_393]

it's true to my knowledge. A slower running engine circulates less fluid, and generally speaking gets hotter. Not to mention the lack of cooling air running through the rads and around other parts.

[twoofeach]

Both four strokes and two strokes get very hot. The Thumpers will start spewing out coolant. The two strokes will just take it like a man and not say anything. If you're not riding it, shut it off.

Circulation of fluid and air like Woody mentioned previously.

[Blitz393]

guess what happened to me- same thing, wouldnt run and sounded like my grandpa after an all night chili fest. turns out a peice of debris destroyed the ring and it wouldnt start (kick or otherwise) and was nothing to push it while in gear. the plug was much darker than it normally was but not black, but i contribute that to the extremely sudden compression loss, yours still runs/ran so the incoming fuel/air that wasn't getting combusted coated the electrode.

a slower moving bike, two stroke or four, air or water cooled, will run hot. it won't be the entire reason the engine fails, however it could be a big playing factor for it to fail. in my case, it was a peice of steel about 1 mm long and half as wide that destroyed the crown of the piston, piston ring, and scratched the cylinder wall.

the best, and also easiest way to find out exactly what went wrong is to simply open her up. take off your seat and tank, clean the underside of the frame really good, clean the engine good, and take off the cylinder head and inspect the piston crown. if it looks ok, then you may have to remove the cylinder to inspect the rings. you can check the cylinder wall for damage by slowly pushing the kickstarter down until the piston is at the bottom of the stroke, and shine a flashlight in the bore to see what's going on in there. there should be no nicks, scrapes, scratches, or scuffing. it should look relatively shiny and smooth. run a *clean* finger in around the bore and if you feel anything other than "smoother than a babys bottom" then you may have a problem. dont go crazy and start replacing cylinders for a little cold-seize scuffing or the random scratch from a peice of dust but use common sense. if you can't find anything wrong, then i don't know what to tell ya.

i guess i should have put this at the beginning of this post but be sure to check the carb for anything foreign BEFORE you go tearing into the engine. even if you don't find anything wrong inside the motor, you will be out about 20 bucks for the head and base gaskets and coolant that you would have to drain before removing the head and cylinder.

basically, my bet is on at least replacing piston and rings. you might have blown the main bearings also, but i doubt that. it does suck though, i had that happen to me in a race once...

Rob

[pragmatic393]

Guys, I understand the lack of air flow will contribute to a hotter running bike.
What I don't quite agree with is the idea of running at higher RPM's (on the pipe) at lower speeds equals cooler temps>Same air flow.