Running lean, pinging?

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scooper77515

scooper77515

freebie fixer
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What does pinging sound like on these skis, specifically 96 XP with 787 Rotax?

I just put new spark plugs in and took it out to adjust the idle up a little, and when I got on the throttle on the water, I heard what I initially thought was the ripples on the water hitting the hull at 45 mph. But I noticed it changed a little in sound when I let off the gas.

After about 10 miles of this, I started to wonder if I was hearing "pinging" so I headed back to the dock and pulled the plugs and they were very white. Even though they are new, I had just put about 20 minutes and 10-12 miles on the ski and expected more color than that. There was just a little of the expected tan color deep down on the cone of the plug.

Another example of what it sounded/felt like was--imagine that you have a couple grains of sand in a wheel bearing and there is no grease on it, maybe just a light penetrating oil. Now spin it about 500 rpm and you can hear and feel the grinding. Now amplify the sound to where it is loud enough that you can hear it if you listen closely to the engine while putting around at 45 mph. Is this pinging or should it be higher pitched like on a car engine?

IF it is pinging, can the high-speed jets be reached without taking anything off the ski?

I know where the low speed jets are, and can reach them by touch...are the high speed jets just as easy to reach?

One more thing, I am running bosch 2-electrode plugs that fit a Mazda 4 cylinder (that is what i had when my last set got dropped in the water, and have used them since, only this is a new set and the first were 4-electrode). Are these maybe too hot?
 
Plugs ....!

Your plugs are burning your engine too hot. We've gone over this in a thread somewhere. Plugs are designed to be low speed plugs or high speed plugs. They have different heat ranges to provide combustion. If your not careful, running an off spec plug in your motor will burn a hole in the top of your pistons..........
Go get the NGK plugs, nuber BR8ES....gapped at .020-.024 in..........
 
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Will do...even though I just bought a set of 4 Bosch platinums for $16:boxing_smiley: Maybe dad can use them on his car...that is where I got the old ones from anyway.

I know these are running too hot, because I never had this problem until today, right after I swapped them in. I really didn't want to start messing with the mixture after it had been running so well.
 
Just FYI...

I was running the NGKs that were in the ski originally, and one day when the water got cold, they started to foul up so you couldn't even start it (no choke on my ski).

My dad had just replaced his plugs in his 2004 Mazda so he had 4 of these Bosch platinum +4 plugs sitting around. We compared them to the NGKs and they were the same diameter and depth, so we put them in and the bike ran fine, even though I still needed to lean out the idle mixture due to the cold water making it run rich.

So, last week, I bought some new Bosch plugs for this season, but got the +2 (two electrodes instead of the 4 in the +4 plugs). This is when I started to notice the pinging and white plugs.

The +4 plugs still work, but they were black and oily and quite fouled after every use. The +2 plugs, supposed to be for the same car, ran white and dry.

I just thought I would throw that out there for FYI. That the plugs that are supposed to be run in the same car may run quite differently in our 2-stroke skis.

Did I ever mention that I love to experiment with stuff:D My folks, friends, and wife wonder why I keep "wasting" money on parts that end up not working...I just want to prove to myself that they don't work, and why not...
 
Scott, sometimes when you experiment it can cost you a lot of money in the end. These engines were designed to run with all the correct components in place. The engineers spent the time and knowledge to "experiment" before the product was in the market for use by us, the end users. If you change the products by using something not recommended, it could be a very expensive experiment.

Karl
 
Pinging...

From what your describing Scott....it could be. It's hard to tell without actually being there to hear it. But yeah, that's either pinging or something definitely close.....
Read you NGK plugs after a few hours run time.
Oh, just because a plug has the same thread and depth, means you can use it. Plugs are sold by the amount of thermal power they generate
 
In all honesty...

...when I used the Mazda plugs the first time, I still didn't think I would get this thing running half as good as it does now, and didn't think it would make it through the winter. PERIOD. So I just used what I had handy.

But now that it is running like new, I guess I better start treating it like it is new...

Good point on "the engineers already did all the experimenting". I never looked at it that way. I tend to work on older cars where there IS lots of improvement available, and I guess I had the same mentality on this ski.
 
Not mine but seems to be wise. By Group K. Determining proper fuel mixture by inspecting the color and condition of the spark plugs can be very helpful in situations where the engine is being operated constantly at full rpm under full load. "Reading plugs" for perfect fuel mixture is very common in high speed auto and motorcycle racing where the engines are nearly always run at full rpm and full load. Closed course pwc racing, however, requires as much "partial throttle" operation as full throttle. Furthermore a pwc racing engine seldom experiences full steady loads because of the rough water conditions. This means that spark plug readings, done on a pwc that is being ridden on a rough water course, has very questionable accuracy.

To get an accurate plug reading on a pwc, a fresh set of spark plugs should be run in the machine for 3-5 minutes at full throttle/full rpm on relatively smooth water. At the end of the full throttle running, the throttle should be chopped and the kill button pushed simultaneously (called a "plug chop"). If the engine is run at partial throttle for even 3 seconds after the full throttle run, the plug reading will be invalid.

After the full throttle running, and the plug chop, a combination flashlight/magnifying glass must be used to view the carbon deposit at the base of the porcelain (down inside the spark plug where the porcelain insulator and outer steel spark plug casing meet. A ring of dark brown at the base of the porcelain denotes ideal fuel mixture, light brown is lean, and a ring of black is over rich. This is the only area of the spark plug that accurately indicates fuel mixture. Furthermore, this reading only indicates full throttle fuel mixture. No part of the spark plug can indicate low speed or mid range fuel mixture. The upper part of the spark plug porcelain (by the electrodes) is often very light or white in color, however this coloring is mostly affected by additives in the gasoline and oil. The coloring of the end of the porcelain in no way indicates appropriate fuel mixtures of any throttle range. The cosmetic appearance of the spark plugs can defiantly help a pwc mechanic to quickly diagnose the symptoms of a major operational problem. But as far as carb fine tuning for personal water crafts is concerned...reading plugs qualifies as a very questionably accurate way to fine tune the carbs. Very few professional PWC engine builders recommend their customers to do carb fine tuning based on plug readings...and even fewer engine builders do it themselves.
 
That is how I did it

I ran it about mile or 3 up river, turned around and put it pretty much full throttle until I got close to the dock and cut the engine and coasted in. According to this documentation, I should be running just right, but I need to add in that sound that I think is detonation...

Still, I will put in the correct plugs because I think these are running "too hot".
 
if engine fails and you remove head you will see what looks as if termites ate around the outer edges of domes in head if you had detonation. I believe a lean carb is one of the ways this can happen.
 
Spark Plugs

BAD SCOTT...BAD BAD SCOTT!!!!!
Do not play with spark plugs!!!!!
DAWG
I totally agree with the other posts.
DAWG
 
let us know if the new plugs fix the problem. at least you could hear it my hearing is so bad it would take a rod nock or somthing that loud to get my attention.
 
Intelligence!....

Oh, how I love to see the intelligence in the replies pick up to the extent that we can pass on things to one another.........Dawg, Robin...Great.....Scott......(walking away with tails between legs...):rofl:
 
Got them!

Got 4 NGK plugs, but haven't had a chance to put them in yet. I bet it will fix it. I will probably have to readjust the idle mixture...
 
Not Pinging...

I swapped the plugs, and ran it quite a bit over the past 2 weeks. Today, at the beach jumping waves, I think I figured out what the sound is...

...since the exhaust is usually under water, there are times at higher speeds where it is above water and the tone of the exhaust noise changes.

I have pretty much figured out that what I am hearing is periodic bursts of un-muffled exhaust sound as the exhaust outlet rises above the surface of the water.

Kinda hard to explain, but at very high speeds, an indentation in the water behind the ski will open up in such a way that I can hear the exhaust without the muffled effect of exhausting through water. Do this 5-10 times a second at high speeds and what I am hearing sounds like a rattle.

I was able to do this on purpose today on the rough water, and was able to pay better attention and verify that it is a normal sound, that I was assuming was pinging...

To verify, plugs are nice and dark, maybe a little too dark, but probably because of me adding that extra oil.

Ran GREAT for the 3 hours we rode it in the waves, and then the 20 minutes I rode in freshwater on the way home just to rinse off all the salt and sand.

Just an FYI update...
 
Cool!....

Cool, thats nice to hear Scott........you got a nice ride for practically nothing and look where you are now. A nice toy for you and your dad for the summer and look at how much you learned through the winter months......
Now, stick around for the summer months.........that knowledge will help others..........Spread the love!................:rofl::cheers:
 
Hey Scott, I hope the learning experience was as good for you as it was for us...lol
It's great to hear of a good response from a long winter of troubles and aggravation to have a happy beginning for the summer. Now go have fun ...you deserve it. Remember to come back and and visit often.

Karl
 
It is running great!!!

But just because it is running doesn't mean I am done visiting.

I keep reading about things to watch out for, mods to make it run faster and better, etc. So I am not going anywhere!!!

I also need to get some air pictures to post on that other thread...:reddevil:
 
I knew you couldn't stay away...Heck all of mine run great most of the time and I can't leave this place for a day...afraid I'll miss out on something...lol

Karl
 
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