Is my bike pinging?

[2strokeHAWAIIAN]

So I went riding this weekend and bike was running good but on a long straight away I noticed a brief knocking noise. 

The noise occurred after a wide open run in 5th gear down straight away. After the bike topped out I got off the throttle and was flipping the throttle just to keep the cylinder lubed up. About the second and third "throttle blip" I heard a very audible knock in the engine. I'm not completely sure what the noise was but it sounded very similar to rod knock in a car.

Only did it those two times and at very low throttle opening. I got back into the power-band and the noise went away.

I did mix a gallon of fresh gas with some gas that was about 3 weeks old so I'm hoping it was just pinging but I'm thinking it could of also been piston slap or rod knock. After the ride as I was letting it run out of gas I did notice the engine seemed a little noisy but it seems that is common on the yz250.

Does this sound like pinging or is my old engine getting tired? 

 

[Nevada Al]

Pull it apart and look only takes 2hrs or so...  Should not detonate when blipping throttle like you describe and then be fine under load...assuming clutch in when blipping for fuel right?  Could it have been your pipe popping/ ie pipe bang?  I’ve experienced this in situations similar to what you describe.  

Edited to switch lube for fuel...lol

Edited November 14, 2017 by Nevada Al

[2strokeHAWAIIAN]

Clutch was not in. I thought you just blipped the throttle to avoid engine braking and lack of fuel. How does grabbing the clutch effect how gas goes in the cylinder? Not trying to disagree just curious

[Nevada Al]

1 minute ago, 2strokeHAWAIIAN said:

Clutch was not in. I thought you just blipped the throttle to avoid engine braking and lack of fuel. How does grabbing the clutch effect how gas goes in the cylinder? Not trying to disagree just curious

Running the bike out full on the main and then chopping the throttle UNDER LOAD will cause a lean condition...  pull in the clutch when you hit top speed then blip throttle to give it fuel under no load.. takes all of one second.. repeat.. 

[2strokeHAWAIIAN]

Very good info. Hopefully thats all it was and no damage was done. I will be sure to pull the clutch in after a wide open run from now on. Thanks for the tip!

[Nevada Al]

18 minutes ago, 2strokeHAWAIIAN said:

Very good info. Hopefully thats all it was and no damage was done. I will be sure to pull the clutch in after a wide open run from now on. Thanks for the tip!

Right on I’m sure it’s fine if just one or two times.   Think of your carb in terms of throttle position...  1-1/4 pilot jet, 1/4-3/4 needle, 3/4 to full throttle main jet...  Main jet work needs main jet fuel.  5th gear under load and blipping from 0-1/4 throttle equals not enough fuel.  A lot of guys go so far as to hitting the kill switch and blipping to full throttle to dump fuel/lube in hard conditions.  I think that’s ridiculous but am mindful of my fuel needs.

 

 

Edited November 14, 2017 by Nevada Al

[Gowey]

2 strokes need to be ridden difference then a 4 banger. A finger should always be resting on the clutch lever. Make sure you don't try use the engine braking method to slow down, especially on long downhills and after full throttle runs. Instead pull the clutch in, and use your brakes.

 

[bikedude987]

ignore this crap about blipping the throttle.  If you're running enough oil, and appropriate jetting, there is LOTS of oil circulating around the motor, and little chance of seizure. 

 

[Nevada Al]

41 minutes ago, bikedude987 said:

ignore this crap about blipping the throttle.  If you're running enough oil, and appropriate jetting, there is LOTS of oil circulating around the motor, and little chance of seizure. 

 

He wasn’t talking about seizure from lack of oil....He was asking about pinging, detonation from going lean.... 

[Woodsweapon350]

He wasn’t talking about seizure from lack of oil....He was asking about pinging, detonation from going lean.... 

 

"After blipping the throttle to keep the cylinder lubed up"..... that line in the original post tells me you're wrong lol and even you said the words "blipping for lube". There's no need to blip for lube

[Nevada Al]

 

2 hours ago, Woodsweapon350 said:

 

"After blipping the throttle to keep the cylinder lubed up"..... that line in the original post tells me you're wrong lol and even you said the words "blipping for lube". There's no need to blip for lube

Yeah, I was talkin about fuel and detonation...  I was parroting his terms is all and didn’t reread it.