Still blows smoke!

[Curtis]

Picked up a old RMX250, was blowing heaps of smoke when I bought it, I replaced crank seal, sleeve and Oring on the gear box side. Still blows heaps of smoke. Im assuming main case gasket is leaking. What else could it be?

[sleepy]

Describe the smoke. When it is smoking. Does the smoke smell different to normal 2 stroke?

[shelpi]

a pressure down test will help, Alex showed a nice easy one on here ahh was it his RM80 resto?

[Curtis]

Yeah its definitely gearbox oil, crankcase was full of it!

[ty4]

your pipe will be as well Curtis...did you give it a cleanout....warm it up with the oxy...the neighbours love it

tony

[sleepy]

Yeah its definitely gearbox oil, crankcase was full of it!

Did you clean out the crankcase after the seal change?
Have you checked to see that all the case screws are tight?
So only things after those are gasket , broken case from a rod letting go in a previous life.

[Curtis]

Flushed the pipe, flushed the crank with fuel, turned the bike upside down cranked it out. Ran it in Neutral with no gearbox oil, cleared out! Put Gearbox oil back in, ran it, pumped out smoke from exhaust again. Gota be main gasket!

[pokey]

Burning gearlube stinks and the smoke is a different colour. Also the gear lube will usually look milky if its contaminated with fuel.
 centre gaskets rarely go but they do on occassion. if your in doubt just split the cases and change it and while your there make sure your right hand seal is correctly seated and not damaged.( insert a smooth pin or sewing needle between the shaft and the seal to make sure the lips are seated and not folded.. be careful)

[OverTheHill]

My "90 RMX250 enduro bike was like that when i bought it [smoked out the village lol], but had dried out in the pipe after a hard days flogging. Took my Ag100 [yes Ag100 lol] to a roadrace on a short circuit recently with 70cc minibikes [was a good match] & smoked so bad you couldn't see behind--till you caught it up next lap, but point being that it came right after about 10 laps & never looked back. all the noise deadening packing along the inside of the walls of the pipe get soaked, plus the tail pipe muffler. Used to burn them out at work but hell-you can't do that nowdays [in nz]. Cheers.

[OverTheHill]

sorry, i should have read the story--gearbox oil smell & in C/case. Cheers.

[Curtis]

Looks like the beast will be coming apart, probably not a bad idea too check things out properly. No christmas ride for the RMX 

[FourstrokeForever]

Looks like the beast will be coming apart, probably not a bad idea too check things out properly. No christmas ride for the RMX 

That's the go Curtis. Gaskets do dry out after a few years of holding back oil, fuel and air. The RMX are a top bike so you may as well make it as close to new as possible, that way it will last you for many more christmas rides.....

[evo550]

Interesting if it was crankcase gasket letting gearoil through, that when you ran it without any oil did it run lean, would think it would be sucking some serious air in?

[Andrew L]

Interesting if it was crankcase gasket letting gearoil through, that when you ran it without any oil did it run lean, would think it would be sucking some serious air in?

Agreed drain the oil in the gearbox and run it without riding it , if it revs up without throttle input would point to going lean and gasket failure probably show up more with the filler point open as well

[Curtis]

Good point. Yeah it did idle really high for a bit. May have leaned out.