??? Gas Octane: What does the Huasheng F142 4-stroke like?

[Max-M]

I just swapped a Huasheng F142 4-stroke engine from my first build to my second build. I'm having some idle problems.

I don't remember what octane I used in the very short period of time that I ran that first bike, and I've got 93-octane in my new build. I'm working my way through the possible causes of the bad idle. I haven't read anything on what octane is specified for these engines. Can it be that the high octane is causing my problem? I know that the higher the octane, the slower the fuel burns. I learned this years ago when I decided to "splurge" on high-test in my Toyota Tercel, and I found that it wouldn't rev high enough to idle unless I kept my foot partially on the gas pedal. Like most people, I thought that the opposite would happen, but then somebody explained octane to me!

 

[motorbikemike45]

Unless your engine's manufacturer calls for higher octane fuel, don't use it. As you noted, it burns slower in lower compression engines and it doesn't atomize(vaporize) as well, especially at lower temps. In an engine with very high compression ratio, high octane is needed to lower the ignition point and slow the burning process to prevent pre-ignition(pinging) which will cause damage to the engine. Otherwise it works more poorly and is a waste of money. Pick the correct octane for your engine to keep it happy and running well for a long time.

 

[motorpsycho]

the majority of these engines (2 and 4 strokes) have relatively low compression.
so, burn the cheap stuff (87 octane) to get the best results.

 

[saw]

these engines are designed to run on 87..if you read the manual that comes with it will tell you the same thing

 

[CrazyDan]

Believe it or not, but I find that my 144f runs better on 91. It would ping a bit once the engine warmed up a little on 87. I assume this is because of the factory overbore, don't think they increased the volume of the head, so it would have higher compression than the 142f. Didn't notice a decrease in power, seemed to run better all around.

 

[Guest-269626]

Believe it or not, but I find that my 144f runs better on 91. It would ping a bit once the engine warmed up a little on 87. I assume this is because of the factory overbore, don't think they increased the volume of the head, so it would have higher compression than the 142f. Didn't notice a decrease in power, seemed to run better all around.

Thanks for the heads up. I just drove that engine today.