Is the above good??? lol. But seriously, what would cause this?
YZ250, top end is getting old. Probably 20+ hours. 50/50 c12/mrx02 fresh fuel mixed at 32:1 with 927. Been riding pretty hard on mx track- last week was several motos in deep mud, and as many this week on a fast dry track.
Bike has ran superb as always, seems to be jetted quite well, and always has had clean filters. The bad- plug probably had 15 maybe even 20 hours on it. Packing was burnt out after 5 hours, but I’ve been running it pretty hard.
It ran perfect yesterday, when I came home and washed and drained fuel to flush with pump water, I typically start to warm up and get fuel though system and it just backfired and wouldn’t start. Fresh plug made it fire right up and purrr like a kitten.
So is this normal wear, or did I start the bike with a broken electrode floating around? I did pull the pipe and from what I could see, the piston on the exhaust side looks fine.
thoughts? Thanks!!
Take a pic of the burn area of the plug.
It would appear the center electrode is missing, or you have one hell of a gap on it. Or is that what you are asking, how could this happen? I'm a little confused.
Yep, it’s missing the center electrode!!!
(I posted the question as a bit of joke)
I’ll post a pic when I get back into town next week. Ran awesome, then wouldn’t start on the stand at the end of the day after washing it. New plug, and it started fine.
wondering why the center electrode is gone….
mote pics to come.
If you got lucky it spit the broken piece out the exhaust?
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
As kijen said, maybe you got lucky.
I have seen them break in a backfire event.
You said, "washed and drained fuel to flush with pump water". This has got me totally confused. What do you mean, or what are you doing?
I run race fuel (mrx02). You can’t leave it in the tank. I drain the race fuel, and flush out /restart with pump fuel (pump water… because local fuel is garbage). It was after the flush with pump fuel, that it wouldn’t restart, and backfired and just generally was being a pain.
I tossed in a fresh plug, and it started fine with pump fuel. Have not raced or practiced with in since this episode.
my initial post was why the center electrode was broken off or otherwise missing. I’ve seen the main electrode gone during a meltdown event- but that’s not what happened here.
I really home that missing part is out of my engine. Guess I’ll know next practice.
If it's laying in your pipe you could suck it back in. Plug brand?
Stock cylinder and head ?
No. Full mod engine from Pro Action.
Pulled pipe and couldn’t find the electrode. Guess I’ll just send it at Wednesdays track day and see if it holds together. Shrug
Blast it up and down the street or in a field a couple times and you’ll know. It’ll save you a drive to the track.
Did you look at the piston and cylinder through the exhaust port when you pulled the pipe?
What’s your jetting?
Post a reply to: Please read my plug…