Fuel/Oil Ratio

[bramuno]

I've been struggling with this issue for years and keep getting different answers from everyone I talk to so maybe someone here can help.

I have a 91 KDX200 that has always had black smoke coming from the exhaust. Also, black oil sometimes spues from the tail pipe. I was told I needed to adjust my fuel/oil ratio. I've adjusted this many times to run leaner and richer and nothing seems to work. Does anyone know the best ratio to mix that could help out with this issue? I've tried finding the factory recommendation but have been unsuccessful. Any suggestions would be much appreciated!

[Gotanubike]

If you are running the 158 main it might be a good choice to go down to maybe 150, maybe leaner depending on your elevation. I am at 45/155 at 300ft, and still slightly rich. Most use a 40;1 fuel mixture

[scheckaet]

please read newb info in my sig and follow the jetting guide.
In a nutshell: pick a oil/gas ratio (most use 40:1 cuz it's easy) and jet your bike accordingly. period.

[bufftester]

The factory recommendation is 32:1, but as noted above, most these days are running 40:1 or 50:1. The ratio is not the most important element though. Jetting to the ratio you choose is. So pick a ratio (40:1 is convenient here in the states where a standard gas can is usually 5 gals = 16 oz (1/2 a quart bottle)for the oil) and then jet the carb to that ratio. If you ever change anything (ratios, changes to intake/exhaust, new top end, etc) you will want to rejet. This should eliminate 90% of your oil issues, but there will always be a bit, it's the nature of 2 stroke motors. Of course, it goes without saying (so I'll say it) that before you jet your bike you make sure that intake/exhaust tracks are mechanically sound (no tears/holes in boots, reeds good, top end god, muffler repacked/drained, exhaust clear, new filter/plugs, etc) and properly adjusted.

[SS109]

please read newb info in my sig and follow the jetting guide.

This!

I still run 32:1 because I ride my bike hard all the time in the AZ desert. I like knowing I have plenty of lubrication. I don't have a spooge or smoke problem.

[KDXGarage]

Search here and all over the world for information on jetting.

Welcome to the forums.

[bramuno]

Thanks for the info! Been running at 32:1 but sounds like the spuging might have to do with my jetting. Need to pull the carb out and clean it soon so I will give this a try and get back to you all with the results.