2010 FX450 Smoke on Startup

Companydamned · Apr 21, 2014

I've got a 2010 FX450 (70*) that I purchased used. Bike appeared to have low hours (original front tire, chain and sprockets, brakes, etc....) and I have since put about 20 hrs on it. My concern is that it appears to burn oil on startup. I first started noticing it about 10hrs riding time after I bought it but the funny thing is that it doesn't happen every time (maybe 60% of the time). Sometimes it fires up cold and the exhaust is totally clean and others it has quite a pronounced "puff" of grey/blue from the muffler and out of the joint where the muffler meets the headpipe. Usually it is just one puff when it first fires and then it is clear right away but on rare occasions it'll smoke a bit until its warm. It's quite annoying and I'd like to get it rectified if it isn't a major teardown job. I haven't overfilled the oil level (it's always at about 3/4 up the sight glass) and also don't think I've over oiled the air filter or anything (besides, one would think it would be smoking all the time if that were the culprit?). Any ideas? I'm looking at where to start in tackling this.... I'll do new rings and valve seals if that's what it takes but basically looking for advice and hopefully simple fixes at this point. Would a leakdown or compression test be a good idea? could the valves being out of spec cause this? Just thoughts...

Thanks a lot for the help

Johnf3 · Apr 22, 2014

3/4 up the site glass could be over-full. You just need the oil level at the bottom of the glass when the engine is cold. The crankcase breather vents to the airbox so excess oil will drip back down the intake and show up as smoke upon start up. This is most likely your issue.

My other piece of advice would be not to be quite so worried about it. Modern high performance four strokes start with a puff of smoke every now and then and it is not a big deal. Maybe try to not obsessively look at the exhaust every time you start it cold.

. You asked for a simple fix and this is the best one i can offer. Also, valve adjustment has nothing to do with what you see. Maybe valve seals, but not worth tearing apart, plus valve seals are really not a common issue.

My FX does the same thing, and has since new. I have 200 hard hours on it. It still runs great, and uses no oil overall. The valves have still not needed adjustment.

2010 FX450 Smoke on Startup

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