can someone please give me some figures for jetting a 1989cr125 with a fmf fatty pipe and powercore silencer. The bike right now is running to rich and fouling out the plugs.If you have done this year bike before, please gove me some jet specs? thank you
First, Jetting is very subjective. It varies greatly with temperature, humidity, altitude, and even riding style. So there really is no one specific "Correct" jetting spec for any bike. Your much better off actually learning a little jetting, the how and why's, and then doing it yourself. It not hard, and its very rewarding. So follow the link at the bottom of the page to Eric Gorr's Carb Tuning Guide, this will definatly get you started. Then go to your local dealer, know what carb you have, and buy a few jets. Good LUCK!
before you jet, i'd clean the carb good, including choke,and clean airfilter and inspect the reeds...a bike that old my need a new seat valve in the carb cause if that is worn, you'll be running extra rich..you may can buy that at www.bikebandi.com....a hotter plug may help also...
cobraR, I've got an '87 CR125 and I have leaned out the jetting. I moved down some on the main, up one size on needle(making it larger and letting less fuel through hole= leaner), and the pilot is stock. I also use a BR8ES, supposed to use a '9' but they just foul for me. Also make sure that your float bowl is at the correct height.
40 to 1 sounds about right, even 32 to 1 would be good, I wouldn't use less than 40 to 1. As for a plug, I'd go with an NGK, BR8ES. It'll resist fouling without being too hot.
The only difference in the plugs is the one with the 'R' before the number means its a resistor plug. Its supposed to resist interference from electronic waves or something, the one your using now is fine. 32/1 is less fuel to oil ratio than 40/1, I usually use 40/1 in mine because I ride in the woods most of the time, so I do not need as much lubrication as someone who is riding on a track at wide open throttle.
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