Melted spark plug

[cbrnadt]

Hey guys, I ran into a strange situatuion over the weekend with my 86 250r. I just bought the quad a few months ago and have been doing some suspension work before I got a chance to ride it very much. Last weekend I took it to the dunes in Oregon and everythig was good for 3 days of riding (about 20 gallons of fuel), but on the 4th day it lost power and about 5 minutes later wouldn't idle, then 1 minute later wouldn't run at all. After towing back to camp i pulled the spark plug and it had bent the side electrode down untill it was in contact with the center electrode - obviously no spark was why the engine wouldn't run anymore. I put a new BR8ES plug in and it ran fine at camp but when i took it out the next day it ran good for about 30 minutes before the new plug did the same thing.

What is up? Seems like it must have gon lean and gotten hot to me, but why?

Anyone have a better explanation?

Thanks,
Chris

[DPR250R]

What color is the plug when you pull it?

Any way to post pics?

I would start by pulling the tank and check the top of the piston for pitting with a flashlight.

[hang1p]

that happened on my dads snowmoble, the culprit was a piece of the piston top broke off and hit the spark plug closing the gap this happened 3 or 4 times before i pulled the head and saw the damage

[BKex]

I'am having this same problem on my 88R happened this weekend. Electrode on plug was bent in put in a new plug and ran great up untill the end of the ride were it happened again.

[cbrnadt]

Thanks guys,

the lat time i looked at the plug was before the trip last weekend and it looked good. I shut the bike off from full throttle in 5th gear and looked at the plug color - the electrodes looked normal and the porcelain was a medium brown color, and since the bike was pulling hard at all engine speeds and had a good stable idle and up to that point hadn't fouled plugs, I figured the jetting must be pretty close.

I will try to take some pic's of the plug and upload tomorrow (I have to do it from work)

later,
Chris

[BLACKeR]

what do you normally do to shrink the gap on your spark plug? will it down with mind rays, heat it up with a torch, or tap it with/on something? im guessing tapping it, why? because thats the most logical way to close the gap. so what would make the gap magically close inside your engine? something tapping it. which means debris of some kind had to be inside your cylinder. you need to fix that problem first. wether you got a stone in there, or much much more likely you have eaten a rod bearing of somekind or started to lose pieces of your piston.

i dont post this the way i did to be or sound like a jerk. im trying to encourage mechanical and logical thought to fix a problem whatever it may be. certenly very unexplained bizzar things do happen on engines, but frequently its simple, nothing happens magically. try to figure out what would have rationally caused the problem and go from there.

maybe you dont have debris inside your cylinder, but that would be my first guess. and continuing to run the R with this as a strong possibility it only desroying more that is already broken.

again i must stress i dont mean this to sound belittleing, or mocking. i do all my own work, and ride a lot so i break a lot of things, i have delt with and fixed just about everything. im trying to help you logically thing this stuff out.