Engine Trouble Knocking at Higher RPMs

[Arty]

The number one cause of pre-ignition, or "knock", is low octane fuel. Buy the highest octane you can get, and if possible, find a service station that will sell you pure gasoline, and not gas that's been watered down with ethanol, these engines weren't designed to run on it. And most gas stations sell E10 only, now, and they don't have to tell you.
I usually put napthalene moth balls in my gas, because those will boost the octane up considerably. The secret with those is to read the label, most moth balls sold as such now days are made from paradichlorobenzine, not napthalene. Paradichlorobenzine is urinal cake, don't put that stuff in your fuel. I'll probably take all kinds of flack for saying it, but the fact remains, I always got a 50% fuel economy improvement over regular octane, undiluted pump gas. The results will be considerably less with E10 fuel, but still better than straight from the pump. I noticed they now sell little cans of gasoline at the hardware store, next to the 2 stroke line trimmers, that will be undiluted, high octane gas for the exact same reason, these engines don't care for what they sell at the gas pump these days.

Green Mantis:
OK - here's my two cents worth. I just tried the moth ball treatment in my two stroke mix. I haven't quite burned through a full tank, so take it with a bit of a grain of salt, but so far I'm really impressed. The bike seems to start easier, run way more cleanly when cold, generally seems to pull better, and has a more reliable idle.
I'm going to continue with the treatment at least for now.

 

[GreenMantis]

Higher octane will do that. You should get substantially better mileage out of it, too, if you can measure that. In addition, it will stay fresh longer in the tank without decomposing into whatever stale gas is. Before they started putting alcohol in the gas, I always saw a 50% improvement in fuel economy, plus it made my motorcycle go faster. If you were to use any of that stuff they sell in the bottles at the auto parts store, it would do exactly the same thing, and it works. It's just way, way over priced in the bottles. All that's in that stuff is mothballs, read the label on any one of them. Keep in mind that it will be listed as an "inert ingredient" which is just horses**t, naptha IS the ingredient. Then there will likely be some more horses**t about "proprietary secret ingredients" which don't really exist or they would have to put it on the label.
Anyway, good on you to try it for yourself. You'll see when you finally burn off that tank, by how long it actually takes you, that it's getting you a lot farther than it used to. The only real trade off is that air cooled engines tend to run cooler, that's not a problem, really. And you aren't alone, EVERYONE who EVER tried it for themselves noticed a big difference, in my own experience. The fact that we are being scammed at the gas pumps is one of my pet peeves. And we are, I can assure you. I knew a guy who was a fisherman, in a small boat he towed to the boat ramp on a trailer. He kept meticulous records for his taxes, and marked the page in his notebook when he started using mothballs in his gas. He got 50% better fuel economy for years ever since, so there was no mistaking it. He admitted that he still didn't understand it, but it worked, no doubt about it. Oh yeah, the other drawback is that it will make engines that run at the same speed all the time, like a generator, or a lawn mower carbon foul faster, since they run cooler. It's not an issue on an engine with a manual throttle, though.

 

[HeadSmess]

lol, naphtha....

lighter fluid. the naphthalene is the solid, as in mothballs.

straight naphtha is lighter fluid.

buy it as zippo fluid from a tobacconist? overpriced. but watch them carefully...they go to the drum of shellite and fill empty cans up...

twenty cents of lighter fluid sold in a branded tin for $10....

most of the octane improvers are just things like naphtha, acetone, toluene, xylene...

another one that works is that stuff they use on solid fuel camping stoves... forget its name.

i still run the lowest octane i can get and just let the engine rev. no worries about knocking or detonation then. detonation is caused by low speed running at full throttle/load.

i dont run ethanol crap in twostrokes though, unless i run castor oil as lube. ethanol and standard oils dont mix.

 

[GreenMantis]

lol, naphtha....

lighter fluid. the naphthalene is the solid, as in mothballs.

straight naphtha is lighter fluid.

buy it as zippo fluid from a tobacconist? overpriced. but watch them carefully...they go to the drum of shellite and fill empty cans up...

twenty cents of lighter fluid sold in a branded tin for $10....

most of the octane improvers are just things like naphtha, acetone, toluene, xylene...

another one that works is that stuff they use on solid fuel camping stoves... forget its name.

i still run the lowest octane i can get and just let the engine rev. no worries about knocking or detonation then. detonation is caused by low speed running at full throttle/load.

i dont run ethanol crap in twostrokes though, unless i run castor oil as lube. ethanol and standard oils dont mix.

Exactly! But you shouldn't run the low octane gas, the difference in fuel economy more than offsets the lower price. You'll get more miles to the dollar using premium. Unless you put some mothballs in it. They don't sell low octane fuel cheaper to save YOU any money. They do it because people can't help themselves, they are willing to spend more on gas to get a lower price.
I used to like to ride my motorcycle out to the municipal airport, and buy avgas, which cost half over more than pump gas, but I still ended up saving a little bit on it, since I got so much better mileage off that stuff. Then, when I learned about mothballs and started doing that, it ran just as well, and got the same mileage as the avgas, but cost a lot less. Then I was saving big bucks, and have been ever since.

 

[Arty]

Green Mantis:
I'm thinking that "camp fuel" - the stuff you buy for the old coleman camp stoves and lanterns (also called white gas) might also be a good alternative. - Ever tried it?

 

[KCvale]

Octane is not a fuel burn enhancer, it's a suppressor for high compression engines to stop compression caused pre-ignition, (knock).
We don't have to worry about that with our little one cylinder engines.
When I first started out I ran everything on Premium thinking it was best. I don't now ;-}