Is it a bad idea to run too lean?

nikims

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My 2 stroke 66cc engine runs well up until a certain point, then it starts 4 stroking horribly and is basically unable to accelerate further. Setting the needle clip to run at the leanest option got rid of the four stroking(when none of the others did), but I'm worried that the engine might overheat. How bad of an idea is it, and would it be okay if I run at a mixture with more oil?(Currently running 40:1).
 

DAMIEN1307

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I wouldnt run lean I'd say it will ovrr heat
Where you put the needle valve C clip to position it depends alot on what your altitude is as well as what your running for a motor.

What is your altitude that your operating your bike motor???

Don't starve your 2 cycle motor of oil at a 40:1 mix...Add a little more oil to have a 32:1 mix if the motor has already been through the break-in proceedure.

If your still breaking it in, than you should be at a 25:1 mix until break-in is completed.
 

nikims

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Where you put the needle valve C clip to position it depends alot on what your altitude is as well as what your running for a motor.

What is your altitude that your operating your bike motor???

Don't starve your 2 cycle motor of oil at a 40:1 mix...Add a little more oil to have a 32:1 mix if the motor has already been through the break-in proceedure.

If your still breaking it in, than you should be at a 25:1 mix until break-in is completed.
About 600 meters during the day, up to 1500 at night, I like to ride in the mountain :D.
 

ImpulseRocket89

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A plug chop will be the best way to tell if you are running lean. Generally speaking being a little lean at part (about half) throttle won't cause too many issues as long as you are also not too thin on the oil mix. It might make the roll on throttle a tad touchy but otherwise there isn't enough load on the engine to be terribly detrimental. 3/4 to Wide open though is where the issues will start to arise. Specifically if you are holding the throttle there for any real length of time. That is when pistons start to soft seize or even start to melt. As long as that plug has a light tan to medium brown color to it after a plug chop you should be ok.
 

nikims

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A plug chop will be the best way to tell if you are running lean. Generally speaking being a little lean at part (about half) throttle won't cause too many issues as long as you are also not too thin on the oil mix. It might make the roll on throttle a tad touchy but otherwise there isn't enough load on the engine to be terribly detrimental. 3/4 to Wide open though is where the issues will start to arise. Specifically if you are holding the throttle there for any real length of time. That is when pistons start to soft seize or even start to melt. As long as that plug has a light tan to medium brown color to it after a plug chop you should be ok.
Well, I am running at WOT most of the time, because I have the stock sprocket and I can't reach very high speeds.But am I really running too lean if running at the leanest option is the only thing that makes the 4 stroking go away?(will check plug a bit later)
 

ImpulseRocket89

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Well, I am running at WOT most of the time, because I have the stock sprocket and I can't reach very high speeds.But am I really running too lean if running at the leanest option is the only thing that makes the 4 stroking go away?(will check plug a bit later)
There is no single correct answer for your situation. These are simple mechanical slide carbs with a single jet. The needle adjustment provides small adjustment capability to the main jet function. The needle being on the leanest setting on a jet that may be too big could work out just fine. It may still be a bit rich for all we know. Only a full throttle plug chop is going to answer that question.
 
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