I'm new to the site and the sport so any advice will be greatly appreciated. I bought a 99' yz 125 at a yard sale for a few hundred bucks, and my buddy who talked me into it was kind enough to rebuild the motor (new bearings, crank, basically everything). A brand new procircuit spark arrestor for a yz250 came with it which he modified to fit my bike. Other than the pipe, all is stock as far as I know. Yes, total low budget project but its my first bike, was only ridden 1 season, and basically brand new. First time out I got exactly 3 miles until melting a hole in the piston (already replaced) and I don't want it to happen again. I was told its way to lean and needs to be rejetted. Here's the kicker, I live at 8,650 ft and the trails i want to ride ascend and descend between 8,500 and 12,000ft. The shops I've asked are pretty tight lipped without handing over a bunch of greenbacks and having them do it for our base elevation. Any advice (other than getting a bigger bike or 4stroke) on what jets to install for high altitude would be great. I have to figure this out myself or I'll spend more getting it jetted every week than I have in the bike total. Thanks for any help!!!!!
High Altitude Jetting Help Please!!!!
- Thread starter DH2MX
- Start date
If you get it jetted properly at the elevation you live at you'll be fine at the other elevations you mentioned. If you go down to sea level you might have to richen the jetting.
Here's a link to one of Eric Gorr's really complete Carburetor tuning articles that should get you started on the process.
http://www.chicagostories.net/ericgorr/EG_Carb Tuning.html
Before you start jetting you'll want to make sure you have a properly packed silencer, and carefully verify that you have no air leaks around the carb, reed cage, and the ignition side crank seal.
Here's a link to one of Eric Gorr's really complete Carburetor tuning articles that should get you started on the process.
http://www.chicagostories.net/ericgorr/EG_Carb Tuning.html
Before you start jetting you'll want to make sure you have a properly packed silencer, and carefully verify that you have no air leaks around the carb, reed cage, and the ignition side crank seal.
jaguar
~SPONSOR~
It's most likely that you have an air leak at the places Rich mentioned. Find the leak and then double check the jetting. When my piston top was eroding away on my AX100 (air cooled) it was a leak at the base gasket and head gasket. But with water cooled engines the base gasket is not the problem.
