Weiiird problem today...

[Iliketogofast]

I think it's because of the sparkplug I was using. It was a BR9 instead of the usual 8 and it was iridium.

But anyhow, the quad was acting funny. I would have to rev it a little to keep it idling, and when I did it would hang where I revved it to for a few seconds. After doing that 4 or 5 times it revved to 15k (according to my tach) and just stayed there. It wouldn't do anything. I hit the killswitch and I even pulled the coil, NO EFFECT whatsoever. After about 30 seconds of it I ripped the carb off and it died of course.

I suspect the plug got really, really, way too hot and caused the motor to run like a diesel or something. My compression is really high anyways, so I figured that helped it to keep going a bit but I can't understand how the hell it got enough gas to rev that high when the slide was only letting enough through for it to idle!

I changed the plug out from that Iridium one and it's fine.

What are your guys' thoughts on it?

[hang1p]

wooo!!!:eek2: :huh I think if my bike reved upto 15k it would granade

[Iliketogofast]

The tach says "Max RPM 15,540" and it was stuck there for a good 45 seconds, if not a full minute before I finally pulled the carb. When I ripped the coil off and it didn't work I coulda crapped myself :blah:

And it was really odd because there was no fluctuation. It was the exact same RPM the entire time, no cutting out, no bogging, nothing.

[bsjoe]

but how does that happen when you dont have the throttle open.. I may be acting liek a desile.. but it still was getting very very little air and not enough to rev that high I'd think..

[Iliketogofast]

That's why I asked. The throttle wasn't stuck, and the cable hasn't snapped or anything. When I ripped the carb off the slide was in idle position!

[csr250r]

that is pretty weird, maybe it was ur ignition is acting up if your killswitch didnt work. i think that the BR9s run hotter but im not positive on that, i run a br9 in my 250r and in my sled.

[Iliketogofast]

It wasn't the ignition... Like I said, I pulled the coil off the plug and it didn't have any effect.

[csr250r]

ohh my bad i read that wrong.

[Iliketogofast]

No prob.... Does anyone know what happened? I'm afraid to ride it now.

[wilkin250r]

It's been known to happen. It's usually called a Lean Runaway, because the problem feeds on itself.

I don't know why YOU saw it, or if it was related to your spark plug, but I can tell you how MOST people see it.

It's called lean runaway because that's where the problem starts. It often happens when people shut off their petcock, but then feel the need to run their bowl dry (why, I have no idea). As the fuel level drops in the bowl, the mixture gets lean, and creates more heat. This creates a hot-spot in the engine, usually the spark plug ground strap.

Then, exactly like you said, the engine begins to diesel. It doesn't run off the spark, it runs off the hot spot. This is why the killswitch doesn't work, nor does pulling the coil. The engine revs, which creates more heat, which causes more ignition, which causes the engine to rev even more. The condition feeds on itself, which is why it's called a runaway.

The only way to stop it is either cut the fuel (like you did), cut the air (pull the filter and plug the air intake), or the easiest is to manually stop or slow the motor. Most people that know what they're dealing with will just jump on, put it in gear, step on the brake, and let out the clutch. Since the slide is closed, it's not producing a whole lot of power, and it's pretty easy to stop.

Lean runaway. But your particular case is confusing, because the BR9 is supposed to be COLDER than the BR8. However, since the hot spot is usually the ground strap (not the electrode), the heat range doesn't have a whole lot to do with it.

[Iliketogofast]

Do you think that running it so fast for so long hurt anything?? The temp guage only got to 204F.

And I think that it had to do with the iridium type spark plug that it was. It has such a small, sharp electrode (?) that it must have been easier to heat up. Less surface area means faster warm up time.

[wilkin250r]

As far as hurting anything, you'll have to find out on your own. However, it should be pretty easy to spot. You either warped or cracked something (which would show up as a loss of power and rough running), or you had a seizure (which would show up as loss of power and rough running).

If the motor seems normal, I would say there was no damage.