High Altitude Tuning

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Norm will probably have an answer for me and I could have PMed him but maybe there are a few other guys who live in areas of high altitude who might benefit from some advice on tuning for this condition. I live near Denver, 5280 feet above sea level but my neighborhood is closer to 6100 feet. The engine is a CH-80, 2 stroke. I've got about a 100 miles and three tanks of fuel under my belt, running 24:1 after an initial break-in period of 16:1. Even though the engine runs good, pulls me up hills easily and starts great, especially when warm, my spark plug and exhaust trail tell me I'm running rich so my question is; can I expect to see a dryer plug, and maybe more performance, simply by moving the 'C' clip up, or is soldering and redrilling the jet in my future?
I have a set of orifice drills and I know how to solder so I'm not concerned about that task but before I go to that extent maybe someone who lives in these thin air places has found the answer. Any assistance will be appreciated.
Easy Ridin'
Tom
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
I would move the clip up a notch to the top. You may get it set right for your altitude. If not, you can buy a smaller delorto jet, or solder and re-drill your.
 

2door

Moderator
Staff member
Sep 15, 2008
16,326
123
63
Littleton, Colorado
Joe,
Raising the clip seemed to improve things noticably. I haven't pulled the plug yet, I want to put a few miles on but I just made a run to the hardware store and the engine sounds and feels different. It breaks into a nice 2 cycle, runs smooth and has a little more power. Thanks for the advice.
Tom