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Video demonstrating detonation

By ScootMcGoot,
in Honda 2 Stroke

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Grand Master

ScootMcGoot

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Hey guys so I was finally able to get a little seat time on my EG engine that I recently assembled and I seem to be experiencing what I think is detonation still but I am not 100% sure if that is what I am hearing. I would only hear it coming off the throttle and it sounded like a weird idle that I experienced back when I lost all my coolant and the bike was running super hot. This sound lasts only 1-2 seconds and then the bike idles normally.

I tested the bike in 25-30 degree weather but I fattened my PWK from 45 to 48 on the pilot and 175 to 178 on the main and a jd blue needle in the middle. I am trying to figure out I this noise I am hearing is a result of the bike STILL being a touch lean or if this is being caused simply by too much compression and pump fuel.

I originally tested the compression of the motor before the first start and got 180 psi. I will test again when I get a chance and see if the compression has raised since the rings should be seated now.

Does anybody have a YouTube video with an example of what detonation sounds like?

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yellowdatsun

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In a car engine with more cylinders it sounds like shaking marbles in a tin coffee can. They call it "pinging", but it doesn't sound like a ping.

 

It is almost always limited to the engine being under load. So if you're hearing something off-throttle, it's most likely NOT detonation. It would be under acceleration or under load.

 

It will never happen off-throttle, if it isn't also happening under load. Plus, if it is happening off throttle, your engine has some real serious problems, or really bad gas. It's also helped (a LOT) by high temperatures. Rarely happens when it's cold out.

 

Running the engine lean, or on too low octane can definitely cause it. But based on your description of when it's happening, I don't think that's your problem.

 

The three worst things you can do to an engine are: no oil, overheating, and detonation.

Edited by yellowdatsun
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Grand Master

ScootMcGoot

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In a car engine with more cylinders it sounds like shaking marbles in a tin coffee can. They call it "pinging", but it doesn't sound like a ping.

 

It is almost always limited to the engine being under load. So if you're hearing something off-throttle, it's most likely NOT detonation. It would be under acceleration or under load.

 

It will never happen off-throttle, if it isn't also happening under load. Plus, if it is happening off throttle, your engine has some real serious problems, or really bad gas. It's also helped (a LOT) by high temperatures. Rarely happens when it's cold out.

 

Running the engine lean, or on too low octane can definitely cause it. But based on your description of when it's happening, I don't think that's your problem.

 

The three worst things you can do to an engine are: no oil, overheating, and detonation.

 

Thanks for your response, Yellowsatsun!  After reading your post I can say for sure that it does not sound like a can of marbles rattling around but I still don't know what is causing the sound.  I just remembered that I had recorded an uploaded a video to youtube with my bike making the exact sound I am experiencing now but the issue in that case was that the bike had a small leak in the rads and the engine was running too hot.  You can listen to that video here...

 

 

If you listen to the video you can hear the engine make a "bung bung bung" idling sound rather than the normal sounding idle.  Essentially what I am experiencing now is nowhere near as bad as that youtube video.  I will come off the throttle and it will go "bung bung" like in the first video maybe twice and then instantly return to a normal idle.  Just for reference this is what I call a "normal" idle...

 

 

I know the issue is not with the rads because I just filled them and can confirm that they are not leaking.  That only leaves me with jetting right?  I already fattened it up to what I think is correct after reading through many peoples listed specs for their PWK carbs in similar temps and elevations.  I am thinking I can try a couple things.

 

1. Drop in some 100 octane cam2 with no jetting changes and see if it behaves differently

2. Decrease the air screw from 1.0 turn out to .75

3. Increase the pilot another size

4. Drop the clip on the needle

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Grand Master

frdbtr

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Hey guys so I was finally able to get a little seat time on my EG engine that I recently assembled and I seem to be experiencing what I think is detonation still but I am not 100% sure if that is what I am hearing. I would only hear it coming off the throttle and it sounded like a weird idle that I experienced back when I lost all my coolant and the bike was running super hot. This sound lasts only 1-2 seconds and then the bike idles normally.

I tested the bike in 25-30 degree weather but I fattened my PWK from 45 to 48 on the pilot and 175 to 178 on the main and a jd blue needle in the middle. I am trying to figure out I this noise I am hearing is a result of the bike STILL being a touch lean or if this is being caused simply by too much compression and pump fuel.

I originally tested the compression of the motor before the first start and got 180 psi. I will test again when I get a chance and see if the compression has raised since the rings should be seated now.

Does anybody have a YouTube video with an example of what detonation sounds like?

 

You need that needle in the 4th position at those temps.

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Grand Master

frdbtr

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Thanks for your response, Yellowsatsun!  After reading your post I can say for sure that it does not sound like a can of marbles rattling around but I still don't know what is causing the sound.  I just remembered that I had recorded an uploaded a video to youtube with my bike making the exact sound I am experiencing now but the issue in that case was that the bike had a small leak in the rads and the engine was running too hot.  You can listen to that video here...

 

 

If you listen to the video you can hear the engine make a "bung bung bung" idling sound rather than the normal sounding idle.  Essentially what I am experiencing now is nowhere near as bad as that youtube video.  I will come off the throttle and it will go "bung bung" like in the first video maybe twice and then instantly return to a normal idle.  Just for reference this is what I call a "normal" idle...

 

 

I know the issue is not with the rads because I just filled them and can confirm that they are not leaking.  That only leaves me with jetting right?  I already fattened it up to what I think is correct after reading through many peoples listed specs for their PWK carbs in similar temps and elevations.  I am thinking I can try a couple things.

 

1. Drop in some 100 octane cam2 with no jetting changes and see if it behaves differently

2. Decrease the air screw from 1.0 turn out to .75

3. Increase the pilot another size

4. Drop the clip on the needle

 

Ok, mine makes the exact same sound that the 1st video makes when the bike is too lean on the needle.  Like I said above, move your needle clip to the 4th position.  My 06 likes the red needle better than the Blue needle.  with the 48 pilot you should be fine with the red needle (if that was what you were using in warmer temps), just put the needle clip in the 4th position.

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Grand Master

ScootMcGoot

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Ok, mine makes the exact same sound that the 1st video makes when the bike is too lean on the needle.  Like I said above, move your needle clip to the 4th position.  My 06 likes the red needle better than the Blue needle.  with the 48 pilot you should be fine with the red needle (if that was what you were using in warmer temps), just put the needle clip in the 4th position.

 

Thanks so much for the response!  Yes I usually run the red needle when the temps are a bit warmer.  I will make the swap this weekend and try again.  Hopefully that is it! :-)

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Grand Master

CamP

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2-stroke detonation sounds like TV static.

 

The dung-dung-dung at decel is a lean pilot, and/or a needle that is too wide(lean) on the straight section. Running a high idle makes it worse.

Edited by CamP
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Grand Master

frdbtr

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Thanks so much for the response!  Yes I usually run the red needle when the temps are a bit warmer.  I will make the swap this weekend and try again.  Hopefully that is it! :-)

 

One other thing.  I didn't understand this when I first started using JD needles, but the blue needle is exactly the same as the red needle with the exception of the Red needle is leaner from 0 - 1/4 throttle.  So if you do put in the red needle in the 4th clip position and it still feels lean off the bottom, just put the blue needle in in the same clip position and it should clear it up.  My 06 "blubbers" a bit off of idle with the blue needle and it very crisp off of idle with the red needle so that is why I like the red needle.  Technically once you find the needle that your bike runs the best at, it should work with that needle year around just by adjusting the clip and other jets to compensate for weather.  Having said that, you never know how each individual bike will react to different things, that is why it is nice to have 2 needles.

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Grand Master

ScootMcGoot

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2-stroke detonation sounds like TV static.

 

The dung-dung-dung at decel is a lean pilot, and/or a needle that is too wide(lean) on the straight section. Running a high idle makes it worse.

 

I see a lot of posts from you about using the CEJ/CEK needle.  How do these compare to the JD Needles?

 

One other thing.  I didn't understand this when I first started using JD needles, but the blue needle is exactly the same as the red needle with the exception of the Red needle is leaner from 0 - 1/4 throttle.  So if you do put in the red needle in the 4th clip position and it still feels lean off the bottom, just put the blue needle in in the same clip position and it should clear it up.  My 06 "blubbers" a bit off of idle with the blue needle and it very crisp off of idle with the red needle so that is why I like the red needle.  Technically once you find the needle that your bike runs the best at, it should work with that needle year around just by adjusting the clip and other jets to compensate for weather.  Having said that, you never know how each individual bike will react to different things, that is why it is nice to have 2 needles.

 

This is incredibly helpful!  I never realized how the red and blue needle relate to each other.  I just though one was for cold weather and the other for warm weather.  When I bought the carb it came with the blue needle installed and blubbered really bad on the low end.  I would basically have to pull the clutch in the tight stuff and whack the throttle to clean it up.  Red was MUCH better and that's what I ran all summer.  Good to know that I should be able to use the red needle year round with slight jet/clip position changes.

 

Getting alot of great informative info from this thread!! I love it!!  Carters2, whats you elevation? I am curious, as your set up is pretty much what I just swapped mine to for winter, and I havent had a chance to try it yet.

 

According to the map I am looking at here I am about 500 feet above sea level.  My riding areas can take me anywhere from sea level to probably around 1200 feet above sea level depending on where we decide to go that day.

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Grand Master

frdbtr

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I see a lot of posts from you about using the CEJ/CEK needle.  How do these compare to the JD Needles?

 

 

This is incredibly helpful!  I never realized how the red and blue needle relate to each other.  I just though one was for cold weather and the other for warm weather.  When I bought the carb it came with the blue needle installed and blubbered really bad on the low end.  I would basically have to pull the clutch in the tight stuff and whack the throttle to clean it up.  Red was MUCH better and that's what I ran all summer.  Good to know that I should be able to use the red needle year round with slight jet/clip position changes.

 

 

According to the map I am looking at here I am about 500 feet above sea level.  My riding areas can take me anywhere from sea level to probably around 1200 feet above sea level depending on where we decide to go that day.

 

I have the JD needles and the CEJ needle for my 06.  I can't tell you exactly how the CEJ measures up to the JD needles as far as the tapers and straight sections but I can tell you that the CEJ needle felt nearly exactly like the JD red needle as far as how crisp it ran with the same jets.  I decided to use the JD Red needle instead of the CEJ needle because I felt like the bike was a bit smoother as far as power delivery all through the power curve whereas the CEJ needle felt a little abrupt off of the bottom end.  The JD needles are triple taper needles and the CEJ/CEK needles are single taper needles.

 

I wish some of the guys who are more knowledgeable about needles and how they measure (with a caliper) would get a set of the JD needles and compare them to the other popular needles though.  It would be very good info.

 

Edited by frdbtr
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Grand Master

ScootMcGoot

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I have the JD needles and the CEJ needle for my 06. I can't tell you exactly how the CEJ measures up to the JD needles as far as the tapers and straight sections but I can tell you that the CEJ needle felt nearly exactly like the JD red needle as far as how crisp it ran with the same jets. I decided to use the JD Red needle instead of the CEJ needle because I felt like the bike was a bit smoother as far as power delivery all through the power curve whereas the CEJ needle felt a little abrupt off of the bottom end. The JD needles are triple taper needles and the CEJ/CEK needles are single taper needles.

I wish some of the guys who are more knowledgeable about needles and how they measure (with a caliper) would get a set of the JD needles and compare them to the other popular needles though. It would be very good info.

Once again thanks for the info! I wasn't looking for actual dimensions of the needle just how it performs in comparison to the JD needle so that's exactly what I was looking for. Sounds like sticking with the triple taper JD needle is the way to go considering smooth power is what I am going for.

Man I don't know what I would do without thumpertalk!

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Grand Master

mynewcr250

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this is the best example i have ever found online of what detonation sounds like. you'll hear it at 17 seconds in when the guy floors it. its the metallic/rattling sound.

 

as stated detonation happens under load (as you can see in the video). unfortunately, detonation and pinging are the probably the most overused terms and 90% of the time, what's being described is not pinging or detonation. my orange bike sure loves to do this...

 

17 seconds in, really bad at 22 seconds when he backs off and then gets back on it hard

Edited by mynewcr250
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