uh owe sparkplug hit

[cannondale4life]

ok today i was ridin and outta nowere my r just shut off,so new to the 250r/2 strokes so i figured i fouled a plug or sumthin so i arrived home and i pulled the plug i see it was hit,so not knowing what to do i threw a new plug in er and it fired right up?????so im very confused and not sure what caused this so any input would help greatly please/thank you


ps.i have a fairly new HOTRODS crank........

[Honda 250r 001]

im not sure what you mean when you say "hit" but if it was white then its a lean fuel air mixture and you will blow up your top end if you keep running it like that. to fix that you need to run a bigger main.

[cannondale4life]

sorry i didnt explain myself clearly the sparkplug looks like someone tapped it physically with a hammer or something the gap is completely gone the electrode tip is bent down to my electrode i dont know if you can over revv it and it would cause this or what,hope you can make sense of this

[Honda 250r 001]

maybe your spark plug is too long and its hitting the piston, what plug are you running? run a b8es

[cannondale4life]

im am running that plug?

[hondamancbr03]

If you are running the correct plug there is no way the piston can reach the plug.....You could have had something get into your motor and it hit your spark plug before it was pushed out.

If i find a bent plug on any of my motors the head is coming off to see if the cylinder wall was scared......I head gasket is not that much money just to get a piece of mind.
Here's a picture of a head....As you can see the spark plug is recessed up in the combustion area so the piston could not reach it.

[leager-n-ky]

Check your compression, i have had a ring break off, get on top of the piston and beat the HE DOUBLE HOCKEY STICKS out of everything.

[cannondale4life]

ok hondamancbr03 thats makes alot of sense to me ill probly check it out tonight and laeger-n-ky should i still sheck my compression even if the quad still runs the same as it did

[leager-n-ky]

I would, mine still ran too.

[BKex]

I had this happen to me on a long trip and just kept on re-gapping or throwing a new plug in. right when i got back to the truck it seized on me. The top-end rod bearing cracked and came apart on it, causing extra clearance and pieces of the bearing coming up and hitting the plug. I would pull the cylinder and check it.

[cannondale4life]

ok thats possible but i have a brand new with maybe 5 hrs on it hotrods crank????

[hondamancbr03]

Having only 5 hrs on the motor makes for a better reason to pull the top end.....If something is happening in there or did happen in there, the sooner you find out the less the cost for repairs could be.

Like i always say....Gaskets are cheap compared to crank and rods.

[cannondale4life]

ok im probly gonna pull the top end tonight is there anything i should look for besides scaring of my cylinder

[fulltiltrider]

You just got this right, it had alot of compression didnt it? Sure its not detonation? That could do that I guess? Did you ever check your squish height? What fuel?

[hondamancbr03]

High compression or pre-detonation would not cause spark plug damage.....But it would turn the end of the plug a light gray color which would be material from top of the piston sticking (or melting) to the plug. While you have your head off, i would check for pitting on the top of the piston (center mostly) and on the head, that's usually a sign of high compression running low octane fuel.

[cannondale4life]

ok so i pulled my head and cylinder off and wow,the piston was very very pitted also the piston skirt was almost completely gone the ring was bent and that being bent scarred the hech out of my cylinder and it appears the piston was in backwords

[hondamancbr03]

Can you post a picture of the top of the piston? Some pitting is caused by parts being pounded between the head and the piston, pre-detonation is a totally different kind of pitting....Sorry to hear about the break down.

[outacontrol]

wow that sucks dude, glad the trade never went through, i wouldnt have been a happy camper!

[cannondale4life]

nah sorry i dont have a pic pistons gone now but i think it was a piece of my piston skit that hit my plug

[86 Quad R]

Originally posted by cannondale4life
nah sorry i dont have a pic pistons gone now but i think it was a piece of my piston skit that hit my plug


just curious....... how many hours is/was on the topend, namely the piston?

[cannondale4life]

probably 5 or 6 hours on the topend has two races on it and 2 practice sessions thats about it

[86 Quad R]

.....and this was on a forged piston? in most cases a broken skirt results from piston "slap" (exessive piston to bore clearances) and is very common on "cast" material. ........... that is most unusual for a piston skirt to break that soon unless....... you sure there isnt something else going on in there?

[cannondale4life]

i honestly have no idea

[All250R]

Originally posted by 86 Quad R
.....and this was on a forged piston? in most cases a broken skirt results from piston "slap" (exessive piston to bore clearances) and is very common on "cast" material. ........... that is most unusual for a piston skirt to break that soon unless....... you sure there isnt something else going on in there?
Well, the piston was in backwards. I laughed a little when you posted that. :) Sometimes people have more confidence than is good for them. 2-strokes are amazing... In this case the ring ends are going to be hitting the roof of the exhaust port an causing the rings to bulge into ports more than normal. It's not a good thing. I don't know how much pin offset exists in these pistons, but if its in backwards, the piston may see excessive rocking as well.

I've never run an engine with the piston in backwards. How well did it run?

[cannondale4life]

haha yea i have no idea what that guy was doin he must have been doin some serious drinkin or something whem he putt it together lol and as far as how it ran it seemed to me like it ran well but i dont think it was all there,it doesnt help the fact that i came off of an 400ex to this haha

[Honda 250r 001]

believe me, this thing will rip once you get the piston back in correct. for a 250r, any cut aways in the piston, ANY!!! go twords the intake side. The exhaust should be a plain longer rounded at the bottom skirt. The intake should either have a thumb size hole or a cut away about the circumfrence of a pop can. (There is also a little arrow in the top that points to the exhaust) lol

[ny250r]

Same thing happened to my piston during my last race (only my piston was not backwards). Exhaust side piston skirt below wrist pin broke into a million pieces. Top-end had maybe 6 hours on it. Made it 12.7 out of 12.8 miles through my first lap when it began to cut out and died. Thought I fouled a plug, which I have NEVER done on my R. Pulled the plug and found the ground strap was making contact with the electrode. Tried to kick it over and got about 1/2 kick before it was stuck. Found that a piece of the piston was keeping the crank from rotating as it was wedged in the bottom end between crank and case. Piston to cylinder clearance was .0028" at rebuild time and piston still looked great other than the skirt. Was running an OEM Honda piston at 66.50 mm. Still not sure why it came apart...

[86 Quad R]

Originally posted by All250R
Well, the piston was in backwards. I laughed a little when you posted that. :) Sometimes people have more confidence than is good for them. 2-strokes are amazing... In this case the ring ends are going to be hitting the roof of the exhaust port an causing the rings to bulge into ports more than normal. It's not a good thing. I don't know how much pin offset exists in these pistons, but if its in backwards, the piston may see excessive rocking as well.

I've never run an engine with the piston in backwards. How well did it run?

dohhhhh!! :huh i flat out missed that post. :ermm: i feal like a tard