2005 crf250 rebuild.

jj584

jj584

PR Addict
I just bought this bike in July, it’s been a great bike, runs strong and always starts 1-3 kicks hot or cold. My 110lb 13 yr old has no trouble starting it. My only complaint, it will puff some white smoke at startup for the first minute. Valves were checked and are in spec, doesn’t make any noise. My questions. Is the puffing normal? I’m going to put a piston in it over the winter and have the head inspected for good measure. Should I just put a crank in it just in case while it’s apart? Should I even touch it at all?
 
White smoke is usually a coolant problem or head gasket. Do you use a pipe plug when washing? Maybe you're just getting some water in the exhaust pipe. Check coolant level. Are you talking a little smoke or thick enough you can't see thru it lol. As far as the crank goes if it's within tolerances and bearings are good or no signs of wear it should be ok.
 
A few puffs of light smoke, goes away when the bike is at temp. It does not vent or use coolant, I haven’t had to top it off at all this season. I wash it with butt plug in but he’s washed it before when I’m not around and he’s 13 so who knows. I need a bleed down test to see where it’s at I suppose. Side note, my 08 kx450 doesn’t puff and it’s ok all the same maintenance cycles.... apples to oranges I know.
 
When you have it apart I would pull the valves out of the head and change the valve seals. A lot of time a puff of white smoke at startup is due to a hard (failing) valve seal and once warm oil hits it the seal loosens up a bit and creates a better seal causing the smoke to stop
 
My plan is to pull the head have it and the jug inspected, new timing chain, piston/rings gaskets and seals. Bike runs phenomenal and that little puff was my only complaint. It’s a great bike for my tall 13’ old to ride and feel out the bigger machines.
 
I would say new valves seals and springs if you were going that deep, I always use Honda OEM. Has the bike ever been rebuilt?
 
C Hudak said:
I would say new valves seals and springs if you were going that deep, I always use Honda OEM. Has the bike ever been rebuilt?
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I’m not sure of the history as it is new to me this year and has changed hands a few times. The head does look new though as the aluminum looks brighter and cleaner than the rest.
 
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