Carbon Analysis On Piston Crown

[Gypo Logger]

Brad, it could just be a Stihl thing, we husky dudes have never experienced a problem such as what you're describing. Lol. The stihls unlike the husky's seem to missfire alot, causing carbon buildup on the piston crown which increases compression, thus exasperating the problem exponentialy, especially when running fatter mixes with cheap fuel.
I'd go husky for awhile and see if the same type of symptoms show.
I've also found this type of carbon arising when a two ring piston is used. It's just an EPA thing. JMHO
John

 

[Fog1965]

After loosing a saw to the EPA and ethanol, I looked at Klotz R50. But, it won't work in the Houston area as all the gasoline has ethanol in it. I called Klotz about the alcohol compatibility and after talking to them decided it wasn't worth the risk. It is "iffy" - should mix with low amounts of alcohol, and a maybe at around 10%, but no definite it will mix.

I can't find any spec sheets on the Stihl oil, so I won't be using that anymore. I have raced high performance two strokes for over 30 years, so I am going with what I have used in the past - Klotz KL200, I can get the spec sheet on that. It is a different ratio/percentage (way more than 32:1/3%), but it mixes with nitro, alcohol, and gasoline - so ethanol won't be a problem. I'm just not sold on the 50:1 oils, already tried thin oils in racing and they didn't work either.

The main function of the oil is to protect the piston and liner, the bearings are normally never a problem in getting lubed - and in some cases get too much. If the engine is set right, there is really no such thing as too much oil - only too little. And no amount of oil will compensate for too lean a setting, I have burned down a high dollar racing engine, that had 18% oil (5.6:1), when I got it too lean.

Fog
Gasoline is for washing parts, alcohol is for drinking, and Nitro is for racing,....

 

[Cantdog]

OK I'll Give it a Shot Too!!

Firstly I know nothing about klotz and have used just about every kind of 2 stroke oil in the past. And I always ran rich on oil probably around 30-32:1. Been running 2 strokes and mixing my own fuel since 1962 or so. Growing up on an off shore island you use outboards every day from a young age. In the last couple of yrs I changed my general habits concerning oil mixture. I am much more precise when mixing fuel these days because I 've seen how to much oil affects carbon buildup in 2 strokes.
I just looked at the piston in my 630 Super II that I put together last Aug and it has felled, limbed and fit about 15 cord of hardwood. I ported this saw to about 58% and opened the new Meteor piston up as well. More or less using your formulas and posts as my guide lines. This saw runs around 14,400 and is very strong for a 61cc saw. I am running Stihl Ultra in my saws now. The piston in this saw looks just like new. The top is still as shiny as when I put it together. I rather expected it to look just like yours. Not pluggin Ultra but it seems to burn very well and must be quite hi detergent to burn so clean.
The next thing I'm going to put out there will probably cause a lot of screaming but here goes.
I own and ride two Ducatis, a 900 SuperSport (2 valve air cooled) and a 916 SuperBike (4 valve water cooled) and occasionally consult the techs at BCM MotorSport in Laconia NH concerning tuning and injection mapping etc. BCM is one of the most well respected Ducati shops in North America. Now I must admit that when I used to fuel up the bikes it was ALWAYS Hi-test all the way. BCM techs recommend NOT running Hi-test at all on the road and only racing fuel on the track. They even discourage mid-grade as well. In other words reg gas for everything except all-out racing. The reason shows on your piston. Carbon. According to them Hi-test contains many additives that do not burn clean and cause carbon buildup on pistons, valves, valve stems and exhaust ports. The added pop of a higher octane does not out weigh the adverse ways it affects the motors it is run in and at some point will carbon up a motor to the point where it won't run as well as it would on reg gas. Not to mention the wear involved to pistons and valve trains. Like most hi quality saws Ducatis run nikasil cyls. Take it for what it's worth but I have taken their advise and only run reg gas in my saws and and Ducatis. So I do not know whether it's the Ultra or the reg gas or both that has kept the 630 nice and clean but I'm going to keep using what is working for me and my motors. Still run AV gas in the old Harley though I like the white exhaust pipes and the sound!!! Happy EarthDay!!!

 

[huskystihl]

I'm sure that you have had plenty of thoughts on this but looking at all my eqipment when I change the plugs I had a few saws that were like that cleaned up went I went from ultra to amsoil. I also had my bg55 blower carbon up in the same process, the blower has been like that for quite sometime yet is tuned perfect according to a tach since theres really no way to get it perfect by ear yet it runs as good as the day I got it. My dealer says it's nothing to worry about but it's still not pleasant to see. I know according to stihl, amsoil causes more carbon in the 4mix equip than ultra but my 660 was horribly carboned and a different oil solved it. the dealer also noted accessive idle could be the cause but my 200t is spotless while it's only ever seen amsoil and has spent half it's life idling.

 

[blsnelling]

LOTS of TREMENDOUS posts here guys. I really appreciate the input. But my mind's really in a whirl now. I'm going to put down some of my thoughts and let you guys respond again. These are not my conclusions, just thoughts and wonderings.

1. Maybe the excessive carbon buildup on the crown is due to the very high viscoisity of R50, the lack of detergents, and the very high flash point. Perhaps that dictates that it be mixed at a thinner ratio.

2. Maybe another oil would not cause carbon buildup like this at 32:1. But is the superior ester base of R50 giving more protection at say 50:1, than another oil at 32:1.

3. Is there a comparable oil to R50, ester based, that has higher detergent content?

4. I've run at 40:1 and then 32:1 because my saws are ported. But, aren't chainsaws really low output engines, due to restriction of such a small package, and the lack of a tuned pipe? Maybe I don't need that "extra protection" that I think I do.

I may call Klotz today and see what they have to say. I sent an email to Klotlubm last night. Maybe he'll pop in here.

 

[TRI955]

I think the doctor is over thinking the operation at this point....I have better things to lose sleep over.

What is wrong with Stihl Ultra???


Mike

 

[StihlyinEly]

I think the doctor is over thinking the operation at this point....I have better things to lose sleep over.

That's funny, Mike!

I've learned a lot about oil and combustion by reading carefully through this thread. Really, it's a lot more information than I NEED to run my saws, but it's been an interesting and informative read. Thanks to those who contributed, and who will continue to do so.

 

[Nitroman]

LOTS of TREMENDOUS posts here guys. I really appreciate the input. But my mind's really in a whirl now. I'm going to put down some of my thoughts and let you guys respond again. These are not my conclusions, just thoughts and wonderings.

1. Maybe the excessive carbon buildup on the crown is due to the very high viscoisity of R50, the lack of detergents, and the very high flash point. Perhaps that dictates that it be mixed at a thinner ratio.

2. Maybe another oil would not cause carbon buildup like this at 32:1. But is the superior ester base of R50 giving more protection at say 50:1, than another oil at 32:1.

3. Is there a comparable oil to R50, ester based, that has higher detergent content?

4. I've run at 40:1 and then 32:1 because my saws are ported. But, aren't chainsaws really low output engines, due to restriction of such a small package, and the lack of a tuned pipe? Maybe I don't need that "extra protection" that I think I do.

I may call Klotz today and see what they have to say. I sent an email to Klotlubm last night. Maybe he'll pop in here.

I do not think you should give any of this a seconds thought. I have 5000 miles on my Arctic Cat 570 (fan-cooled), oiling and running rich, no problems with carbon. On my Polaris XCR-800's (liquid), I've had as much as 6000 miles and very light carbon.
Right now my 394 has just a nice light coat like yours, and it is run in all different temps from -25*F to 65*F, but I do tune accordingly. I am running standard Husky synthetic oil.
The carbon will build to a point then stop accumulating. I think you have a good idea with using a very high quality oil, and running it rich isn't going to hurt a thing, most likely will keep your saws living for a very long time. For me, I've been running 40:1 just because and it isn't hurting my few saws.

 

[blsnelling]

I just got off the phone with a Klotz tech. I'm over lubricating for my application, period. R50 works best in high RPM, high load, high heat applications. I'm not high enough on that chart to dictate 32:1. If the oil isn't burnt, it has to go somewhere, and carbon on the piston crown is the result.

I have two options. Mix it thinner or go to another oil. He did say that 10K-12K RPMs is suffient to properly burn R50. He also suggested Motorcycle Techniplate or 50:1 Techniplate. Both are low ash content oils. Interestingly enough, these are both TC-W3 rated oil. We talked about that. That no longer means it's designed for water-cooled use. It has more to do with it being injectable. Not using it in our chainsaws is a carry over from old technology from years past. He was emphatic about NOT using Super Techniplate. He said carbon buildup would be WAY worse.

I asked him about the viscosity. R50 is the equivalent of a 50W engine oil. I asked him if that viscosity in and of itself dictated less oil in the mix, or gave it greater wear protection. The answer was no. It's the formulation of the oil, not it's viscosity, that makes it perform like it does.

 

[FATGUY]

I just got off the phone with a Klotz tech. I'm over lubricating for my application, period. R50 works best in high RPM, high load, high heat applications. I'm not high enough on that chart to dictate 32:1. If the oil isn't burnt, it has to go somewhere, and carbon on the piston crown is the result.

I have two options. Mix it thinner or go to another oil. He did say that 10K-12K RPMs is suffient to properly burn R50. He also suggested Motorcycle Techniplate or 50:1 Techniplate. Both are low ash content oils. Interestingly enough, these are both TC-W3 rated oil. We talked about that. That no longer means it's designed for water-cooled use. It has more to do with it being injectable. Not using it in our chainsaws is a carry over from old technology from years past. He was emphatic about NOT using Super Techniplate. He said carbon buildup would be WAY worse.

I asked him about the viscosity. R50 is the equivalent of a 50W engine oil. I asked him if that viscosity in and of itself dictated less oil in the mix, or gave it greater wear protection. The answer was no. It's the formulation of the oil, not it's viscosity, that makes it perform like it does.

I'm a little confused. Did he say not to run r50, or not to run it at 32:1?

 

[blsnelling]

I just got off the phone with an Amsoil tech and he recommended Dominator. He said start with the 32:1 I've been running and thin it out from there. It's designed for 50:1, but there is fine at heavier ratios. He found it ineteresting that I'm only seeing fallout on the piston crown. He would expect to see it throughout the engine. He could not confirm if it was an Ester based oil. It does have anti-corrosion protection built into it.

 

[Cantdog]

I just got off the phone with a Klotz tech. I'm over lubricating for my application, period. R50 works best in high RPM, high load, high heat applications. I'm not high enough on that chart to dictate 32:1. If the oil isn't burnt, it has to go somewhere, and carbon on the piston crown is the result.

I have two options. Mix it thinner or go to another oil. He did say that 10K-12K RPMs is suffient to properly burn R50. He also suggested Motorcycle Techniplate or 50:1 Techniplate. Both are low ash content oils. Interestingly enough, these are both TC-W3 rated oil. We talked about that. That no longer means it's designed for water-cooled use. It has more to do with it being injectable. Not using it in our chainsaws is a carry over from old technology from years past. He was emphatic about NOT using Super Techniplate. He said carbon buildup would be WAY worse.

I asked him about the viscosity. R50 is the equivalent of a 50W engine oil. I asked him if that viscosity in and of itself dictated less oil in the mix, or gave it greater wear protection. The answer was no. It's the formulation of the oil, not it's viscosity, that makes it perform like it does.

So I take it that you don't believe that fuel and what is in it plays any part in this?

 

[blsnelling]

I'm a little confused. Did he say not to run r50, or not to run it at 32:1?

He said Run R50, but to thin the mix. Just experiment with it. 40:1, 45:1, 50:1. Whatever works.

If I can confirm that Amsoil Dominator is an equally high performace ester based oil, I may go that route. It sounds to have a much higher detergent additive package. Maybe I can have my cake and eat it too, and run 32:1 and have a clean piston crown.

 

[StihlyinEly]

I just got off the phone with an Amsoil tech and he recommended Dominator. He said start with the 32:1 I've been running and thin it out from there. It's designed for 50:1, but there is fine at heavier ratios.

Hmmm, he recommended an oil used in high-performance oil injection engines (I use it in my Polaris snowmobile) for chainsaw use instead of Saber Pro?

Did he say why Dominator instead of Saber, Brad?

And I can tell you that after switching to Saber Pro 50:1 or 40:1, I've watched carbon deposits clear up nicely in engines that were running on other oils. I expect it's that detergent thing. The 028S I picked up awhile back had some definite buildup on top of the piston, and after about six tanks of 40:1 Amsoil, most of the buildup is gone.

 

[blsnelling]

So I take it that you don't believe that fuel and what is in it plays any part in this?

I don't know. But that's not really a variable I can control. I'm not willing to pay the price to run unleaded race gas in my OPE, and I don't like 100LL.

At this point I think I'm down to two choices. R50 at 50:1 or switching to Dominator. I think I'd start at 32:1 just to see what happens.

 

[blsnelling]

Hmmm, he recommended an oil used by high-performance oil injection engines (I use it in my Polaris snowmobile) for chainsaw use instead of Saber Pro?

Did he say why Dominator instead of Saber, Brad?

Saber is designed for 100:1 and the Dominator is designed for higher output modified engines. The detergent thing is what's enticing to me. I'm hoping that Dominator is an ester based oil. I would like to confirm that though.

 

[StihlyinEly]

Saber is designed for 100:1 and the Dominator is designed for higher output modified engines.

Interesting. Verrrrrry interesting.

 

[blsnelling]

A quick search shows that Dominator is NOT an ester based oil. It is a PAO. So who makes an ester based oil with a strong detergent additive package?

 

[StihlyinEly]

OK, I'll bite. Why is an ester based oil preferable? Oh ####, I posted my question before I used the "search" feature! :censored:

 

[edisto]

In other words reg gas for everything except all-out racing. The reason shows on your piston. Carbon. According to them Hi-test contains many additives that do not burn clean and cause carbon buildup on pistons, valves, valve stems and exhaust ports. The added pop of a higher octane does not out weigh the adverse ways it affects the motors it is run in and at some point will carbon up a motor to the point where it won't run as well as it would on reg gas. Not to mention the wear involved to pistons and valve trains. Like most hi quality saws Ducatis run nikasil cyls. Take it for what it's worth but I have taken their advise and only run reg gas in my saws and and Ducatis. So I do not know whether it's the Ultra or the reg gas or both that has kept the 630 nice and clean but I'm going to keep using what is working for me and my motors. Still run AV gas in the old Harley though I like the white exhaust pipes and the sound!!! Happy EarthDay!!!

Good info Cantdog! One of the reasons I have been rethinking the use of hi-test is the amount of time it spends sitting in the tanks at the station relative to the regular gas. You just made up my mind.

Again.

(I should be getting a PayPal invoice for the 630 tonight).