Dec 16, 2000
I have a 1991 kdx200 and its completely stock except for a weighted fly wheel...its in MINT condition and has a little more than 1000 miles on it....i got it about 4 months ago and i ride every weekend because sports take up most of my time after school. but my question is: why is there white smoke coming from the exhaust for the first 5 minutes I have it started??? I mix it 40:1 and i use a "ratio rite" mixer so i know my mix is good. and i shake the bike before i start it because i know the gas has been still for a week.
so why is this happening?? It doesn't seem to effect the performance of the bike....but it doesn't seem normal either....and help would definitely be appreciated THANKS!

Canadian Dave

Super Power AssClown
Apr 28, 1999
If I understand what you're saying it sounds normal. When you first start the bike the engine is cold and combustion is very poor. Much of the gas entering the engine is condensing in the bottom end and on the cylinder walls. Once the engine and pipe come up to operating temperature fuel atomization is greatly improved and much more of the fuel is burnt. The white smoke you see is the result of incomplete combustion and poor cylinder scavenging. Make sure you take a couple minutes to warm the bike up properly then gently ride the bike until it comes up to temperature and off you go.

Coolant entering the cylinder can also cause white smoke but its often present the whole time not just at start up. If you are conserned you might have a coolant leak monitor the rad level and insure its not going down and do a plug reading at WOT to make sure its not running lean.

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