This 066 Grenaded........What The Hell Happened???????

[windthrown]

One question I can answer is that gasoline octane is definitely reduced with the addition of premix oil. From information posted out there, including BP, Yamaha and Rotax, octane drops about 2 points when oil is mixed with gas at a rate of 50:1. It varies somewhat with the type of oil used.

Also the piston top pitting is not the only damage you can get from running low octane gas. Scoring and scuffing often occurs, and looks a lot like the damage from straight gassing or overheating (running lean). This is because of flaring and uneven burn pressure at TDC, which causes piston tilt and excessive scuffing. I had a series of photos showing this, but I cannot find them. Madsens has a good photo of an example of really low octane damaged piston though:

http://www.madsens1.com/saw_fuelmix.htm

Also from what I can glean from the detonation photos here, the majority of detonation pitting is on the outer edges of the pistons. If the typical MM saw has a much narrower squish band, as shown in many of his porting threads, the reduction of the outer squish area would lower the effects of detonation and uneven flaring, because there is less compressed fuel volume out there in the squish at TDC and hence less force causing pitting or piston tilt. Detonation may well be still happening with lower octane gas, but its just on a smaller scale and not noticeable with the naked eye. The modified cylinder also focuses more fuel at the center of the piston head, and hence more downforce at the center of the piston which would cause more even pressure, even if the burn were more uneven. This would help to avoid pitting and piston tilt from flaring.

My thoughts anyway...

 

[Walt41]

Randy, you should subscribe to "machinery lubrication" it is a trade magazine that has tons of useful information, in one of the previous issues it covered the film layer requirements for caged bearings as static and dynamic loads were increased.

 

[Dan_IN_MN]

Sorry if this has already been brought up. I got to page 9 with 10 to go and there wasn't any more talk about the bearings.

Does it look like the rod scrapped the bottom of the crankcase? If this is true, that rod is way out of concentric from the crank pin!

 

[Mastermind]

It hit the case after the bearing fell apart.....

 

[SierraWoodsman]

There are a few oils like that. Redline doesn't have as much dye as I'd like to see in an oil. The best oil I've seen for that is the WoodlandPro synthetic. It turns the fuel BLUE.

Redline / Belray H1R are both hard to tell by the color even @ 32:1. I would much prefer that they turned the mix a more distinct color.
Now I Dymo-label the fuel container with the mix ratio/Oil type/fuel date/octane rating. This may be overkill for some but I like to keep it straight in head.
What ever it takes I don't want to make the straight gassed mistake.

 

[komatsuvarna]

I got to thinking about how little oil is even in 50:1 ratios. Thats 1 ounce of oil, for every 50 ounces of gas! At 50:1 that's 2% oil.

32:1 is just 3% oil, that dont sound like much, but it sounds a lot better than 2% .
40:1 is 2.5% oil.
80:1 is 1.3% oil.

 

[shootingarts]

Redline / Belray H1R are both hard to tell by the color even @ 32:1. I would much prefer that they turned the mix a more distinct color.
Now I Dymo-label the fuel container with the mix ratio/Oil type/fuel date/octane rating. This may be overkill for some but I like to keep it straight in head.
What ever it takes I don't want to make the straight gassed mistake.

One thing for sure, I don't want any red two cycle oil! My off road diesel is dyed red and I'm pretty sure it won't substitute for pre-mix. I have designated cans but I also sometimes have more fuel than fits in the designated cans, that is when the trouble starts. I was scratching various parts of my anatomy the other day since I knew I had mixed a little red diesel and gas together and the best two-cycle oil I could buy with a quick grab was red too. I start looking in cans and I had used the blue two cycle for the last mix, problem solved! Still need to work on that. The new diesel doesn't stink nearly as bad as the old stuff, even farm diesel, and my smeller seems like everything else, not as good as it used to be. Used to be a quick snort told me what was in what can. Smell that is, not shot!

Hu

 

[windthrown]

Yah, on the ranch we had tax-free red dye (off-road) diesel for the tractor, clear taxed diesel for the on-road Ford 250, plain regular gas for the lawn mower, cars and ATV, and super E0 gas that was mixed with 2-stroke oil. Mobil 1 premix was a pain because it was clear. The ex could not tell if it was mixed or now. When they stopped selling Mobil 1 in the US I switched to Elf, which has a blue dye in it. So then we had red, white and blue fuel around the barn in different sized containers. I spray painted the series of gas containers with red, white and blue streaks to mark them, and the plain gas had no paint.

 

[Jimmy in NC]

That has to be one of the first that I have seen to not score the piston but to break a rod bearing due to not enough oil.

Thank you for sharing this information, Randy. I've been running 40:1 with Stihl Ultra. I think it's time for me to switch.

I just got a little hand held blower in 3 weeks ago. It lived 8 short days.. ran low on fuel, they added straight gas to it and it locked the crank up tighter than I can free up. Piston, ring, cylinder are mint. Knew it was straight gassed but this confirms it was poorly mixed/low on oil.

 

[066blaster]

200psi= 200 pounds per square inch. The more square inches there are the more pounds required to push the piston through the compression cycle. A 660 has more square inches than an 044.

And Brad is right that if the pull cord wraps around a pulley of larger diameter, you will have a greater mechanical advantage.

then why is it when i break a pull rope and reatach the handle they pull over really easy with less rope coiled up. pull rope length does affect ease of start up and ease of pull doesnt always reflect the amount of compression it has.

 

[Hinerman]

would not be an Arboristsite thread without a thread derail

fixed it for you

Great thread by the way. I use Amsoil at 40:1 in my saws at the moment. I have some Stihl Ultra at 50:1 I use in my trimmer, edger, backpack blower, etc. Everything is going to 40:1 from now on regardless of what oil (or equipment) i use.

 

[VINIFIREWOOD]

Very interesting and informative thread. Thanks to everyone that contributed.

One question for Randy. Your honest opinion here, do you feel it was the oil itself or simply the lack of oil in this engine?

 

[Mastermind]

Very interesting and informative thread. Thanks to everyone that contributed.

One question for Randy. Your honest opinion here, do you feel it was the oil itself or simply the lack of oil in this engine?

Nothing at all wrong with Amsoil Saber. There just wasn't enough of it.

 

[VINIFIREWOOD]

Nothing at all wrong with Amsoil Saber. There just wasn't enough of it.

That's kinda what I thought but I didn't want to assume anything.

One misconception a lot of people have with Amsoil's 100:1 recommendation is that this is meant for the home owner running stock unmodified equipment on a weekly or monthly basis. If one were to read the label, they recommend 80:1 for "Professional" use in unmodified equipment. Now to most of us even this seems waaayyyyy to lean of a mixture, even to me as an Amsoil user and dealer. And in a situation like this in a modified engine obviously more oil is needed. Trying to run 100 or even 80:1 in this saw is like trying to run your average 5w30 in a Sprint Cup Nascar. It just aint gonna work. Bottom line what I'm getting at is like you said, it wasn't the oil just the lack there of. I think it would be safe to say that any oil, in this situation, would have failed to give sufficient lubrication at that mix ratio.

 

[CR500]

I'm sure it's been contested MANY times. Opti-2 does the same thing.

My BIL bought a new Yamaha Banshee in 1989. We road together for years. He ran Opti-2 at 100:1 from day 1. The Banshee is the highest revving, most powerful 2-stroke quad ever made. He road it like he stole it. I'm talking speed shifting wide open runs in the sand dunes, icy country roads, circle track racing in fields, etc. Over the years, I did the topends on it twice. It never once seized. It finally locked the main crank bearings up after nearly 20 years. We replaced the crank and he's still running the same mix today.

I tried many times over the years to get him to switch oils and mix ratio. But what he is doing has worked so long that he won't switch. BTW, his quad is 100% stock.

On the other hand, my Banshee was highly modified and I ran Maxima Castor 927 at 32:1, exclusively. I never seized a piston or damaged a crank.

To this day, I can't understand how that machine runs like it does. It's still going today.

I would NEVER do what he's done, and would highly recommend against anything similar. While it's contrary to most everything we think we know...it's worked for him. However, it does make for an interesting story to those of us that are far more anal and careful about these kinds of things.

Not to doubt you Brad but what about the Suzuki Quadzilla??? The Quadzilla was nicknamed "Banshee Eater." The Zilla was a 500cc 2 stroke quad.

I ran R-50 in my sled at 32:1 and I have been inside 2 720 motors and I could tell which one was ran on Polaris synthetic and Klotz R50.

 

[blsnelling]

They didn't rev as high.

 

[CR500]

They didn't rev as high.

True... but they were fast. I used to have a banshee before I got into bikes lol