OK, it's been 6 days since we last heard from the OP. I wonder if he's tried the easiest "repair", yet.....a bottle of dry gas.

 

[QUOTE=REELAV8R;1602310719]I don't buy it. Maybe for engines that never warm up fully or maybe direct injection engines and build up on the valves which could possibly lead to hot spots, but generally speaking I don't believe it's a real thing.

My anecdote;

(1) My 97 Ford Thunderbird DD with ~180,000 miles failed a smog test...excessive nitrous oxides. My mechanic actually suspected carbon buildup was increasing the compression ratio retulting in excess nitrous oxides and he recommended adding a bottle of Chevron Techron to maybe a 1/4 tank of gas, run it on the freeway and re-test. Did that, and barely passed.....nitrous oxides were just barely below the limit.
(2) I stopped using Chevron 87 octane, and began using Chevron 91 octane, because Techron was a 91 octane additive.
(3) Car was damaged by a collision while parked. Insurance company oaid $5000 (totaled the car) and then I paid $5000 extra to repair the car......$10,000 total . Then because of being totaled, I had to get a salvage title and redo the smog test! OMG! What if the car now fails the smog test.....I could be out $10,000 if I can't pass the test.
(4) Upon re-test, nitrous oxides were now reduced to just moderate.......the Techron, designed to prevent carbon buildup, was working very well.

Supposedly my nitrous oxide problem was due to carabon build up increasing compression ratio, Techron removed the carbon build uo, and nitrous oxides dropped very noticeably. Based upon this notion, I give credence to the Hot Rod magazine article.

 

I agree with the 'bad gas' as the most likely cause. As also suggested, since the premium fuels are more expensive they sit in the tanks longer underground where they accumulate more water.
The addition of alcohols into the fuel increases the water vapor in the fuel potential. Add some chemicals to dry the gas and then drive it all out of there when you have the time to enjoy doing so.
Low compression engines work best with lower octane gas. The higher the octane rating the more energy is required to burn all of the gas. So unless you have high compression, great spark and a need for high test fuel you are wasting money..... just my opinion.

 

I was actually told by the dealership when I bought my air cooled bike years ago that running higher octane fuel in traditional air cooled engines such as the bike, or lawnmowers and even my watercooled rotax-jetski motor was not recommended. I know when I did the whole seafoam down the carbs and throttle body routine on both my air cooled vw kitcar and my old 96 dodge ram I had a LOT of smoke the first time and hardly any when performing the procedure a second time... and neither engine burned oil. It was also my understanding that the ZDDP in the oil often used on these older engines created enough carbon to mess with 02 sensors which is why it was originally phased out as time when on so wouldnt there be the possibility of more of this buildup in these older engines?

 

If he was referencing a low performance (ie low CR) air cooled engine he would be correct.

Air cooled or water cooled it's a matter of heat and pressure that can cause detonation.
Deposits can develop no matter what fuel is used if the engine tune is not good. Some chamber designs are poor so they will always develop some deposits.
My two stroke engines on my race bikes were always spotless except a very thin tan deposit on the top of the piston. Good tune.
I worked on other guys' bikes (same make model) whose pistons and chambers were covered with a black deposit. Poor tune.

 

I still love watching folks with a Toyota Prius' putting 93 octane in it telling me that it goes faster with it. Octane only helps if you need it. Higher octane fuel burns more slowly which is why I use it in a 12.25-1 engine.

Hello REELAV8R,
On the engines I worked on from the 1960 era they all seem to develop some type of layer of deposits on top of the piston crown. Since the era of fuel injection the deposits are less.
My Cessna 172 had the Continental O-300 6 cylinder and the pistons tops were always clean.
My 1968 C3 always has some deposits on the piston crowns and they are controllable.

What kind of 2 stroke bikes? I still have a 1984 Yamaha RZ350 that I love dearly. I learned to ride small machines and I love showing these idiots with their new Ducati's what Blue smoke exhaust smells like. I have been having trouble with little white ***** of paraffin forming in the fuel bowls on the carburetors. It has been going on ever since they came out with the oxygenated Fuels. I am not sure why but it limits my rides until the little white ***** fill the float bowl and stop the engine from getting gasoline. Having rubber intake manifolds might be aggravating the situation. I have been letting the engine get fully warmed up and even then I get the little white ***** in the float bowls. Never had this issue while flying using auto gas or aviation fuel. To make matters worse they don't have regular gasoline around here, I have to drive over an hour to get plain old gasoline.

 

In the 60’s carbs of course were used, so the tune would have been worse due to changing atmospheric conditions and chokes were anything but accurate delivers’ of fuel when the engine was cold. So I would expect more soot on the pistons and heads simply due to those factors. Fuel injection being much more precise should and does do much better in that regard.

The good ol’ 0300 contenintal, yes flew a couple 172s with that engine. Sounds like it’s making tons of power but not really.
nice thing about an airplane is you can lean the engine out for changing conditions so you are in control of the mixture all the time.

I raced the YZ 125 and YZ 250. This was before the YZ 450f came about. Once those hit the scene it was a significant advantage over the two stroke.

fun factor was far greater on the 2 stroke however. Took more technique to get the job done.

I wonder if the ***** in you bowl are part of the fuel system somewhere getting dissolved by the ethanol?

maybe get fuel from a different vendor see if that changes. I always used straight gas vs ethanol blend fuel.

 

Well, another 7 days have gone by, and still no updates from the OP...................

 

Hello again REELAV8R,

I figured you had an idea what an 0-300 was judging from your user name. I had one for many years and Loved it. My mechanic signed off everything I did to the aircraft. I replaced the oil filtration system with an Oberg filter with a metal flake detector. It was built in 1958 and made it's maiden flight in March 1958. That Cessna had "Tubes" in the original radios under the dashboard and the best was the manual Flaps (barn-doors) that extended to 40* allowing easy landings over and over. The most fun I ever had was "Spin Training" with my 172. I emptied out everything extra and took it to 9000' over Fredericksburg VA and kept spinning that plane until I got to less than 400' to recover. The people at the airport thought I was nuts and kept telling my instructor that I did not have to know how to spin. He smiled and got in the plane. He saved a B52 for the USAF back in the early 1980's and won the McKay trophy down at the Smithsonian Air and Space Museum. My instructor required me buy an airplane and then he gave me lessons for $4 an hour with me paying for the gas and flying time. I am perfectly comfortable spinning an aircraft that is designed for it. My Cessna had on it placard that it was not supposed to do tight spins but knowing how to recover is a great thing to know. The FAA stopped requiring the spin training due to the number of fatalities. My Cessna would recover all by itself in about 4200' but that was getting too close to mother earth for my likes. I am a really good "short field" pilot however learning at a field with 1300' of runway. Due to a major back injury I am now taking Morphine every day and the FAA just smiled... I sold my Cessna and have missed it ever since.

I road raced a Bridgestone 200 back in the early 1970's for fun. I preferred motocross but ended up making my living on the motorcycle working as a courier in Washington DC. Over 140,000 miles worth of street riding and I still get a smile. I drove for ~15 months before retiring back to college. My RZ was the first and last water cooled Yamaha Street bike. It has "Power Valves" and is known to make a lot of horsepower. You hit 6000 rpm and the front end gets real light until you pass 10,000 rpm and the power drops off. It is a very fast little two stroke bike. That was until my brother bought a Suzuki V twin 2 stroke 250 with water cooling and Suzuki's idea of power valves that will run circles around my 350. Mine makes about 63 hp from what we can tell. I do keep the 2 stroke oil a bit higher than I should just so the people who don't remember or have never seen blue smoke that smells good (YamaLube). I had a neighbor follow me in his car flashing his headlights, I stopped and he wanted to tell me that I was burning a lot of oil, I smiled and suggested if he ever saw "no smoke" to let me know right away.. I also road a Suzuki RE5 back in the day, the rotary engine was a blast to drive but gets worse mileage than my C4 does. That darn bike was smooth as glass but got 20 mpg all the time. They called it a 500cc bike but in fact it was 500cc on each side of the rotor so a 1500cc bike would be expected to get 20 mpg.

The little white ***** I believe are paraffin which is used in making of gasoline. They squish easily and are not hard at all. They are perfect shaped like little BB's and they literally fill the float bowl. Since the intakes are rubber there is little heat getting to the float bowls. I have tried going further only to have the engine start to act up due to the lack of fuel getting through. I put an extra filter on the gas lines and still nothing gets caught until the float bowl. I might have to heat the float bowls to drive normally. The RZ is Fast and Fun but it is clearly not a beginners bike. Finding experienced mechanics for these two strokes is getting harder to find kind of like carburetors. Finding new riders with expensive fast bikes and showing them the power of a little 350cc engine is always fun.

What I want to know is why don't the little ***** of paraffin cause automobiles any trouble?

Are you by chance a commercial pilot? I always wanted to grow up and be a fighter pilot for the Navy. I was signed up for OCS and they found out I am color blind and I have a hearing loss. They would not let me sit anywhere in the front of an aircraft. The Army and Marines tried to get me to switch over to helicopters...not. I am a private pilot who can't fly at night time.

 

Steel tanks on motorcycles have an interior coating on them often to prevent rust. I have no knowledge of paraffin being used in gasoline. I know it’s used in diesel and diesel like fuels.
could it be from the yamalube? Although I used yamalube also never had that happen.

I do fly for a living. ATP rated pilot. Cargo is my game. Very good place to be in our current Covid-19 world.

Been quite a while since I’ve flown GA . Would like to get back to it though. It’s where the real fun is.

Talk about off subject, Lol.