four stroke that smokes like a two stroke

rogue · Post by **rogue** » Thu May 21, 2015 10:09 am

So my ktm 250 f will smoke from the crank vent when it's cold. I start it up and smoke comes out of the vent hose and smells of burnt oil, then goes away after it warms up. Is this normal???? So not a Four stroke guy.

Post by **Rider Eh!** » Thu May 21, 2015 10:39 am

I recommend she switches to nicotine patches or those new vaporizers, may help kick the habit.

Post by **AJRJ** » Thu May 21, 2015 11:03 am

Usually a few seconds on the rev limiter will clear it right up. The key is to start it with the throttle pegged.

Could be nothing, could be rings, valve seals etc etc. A leakdown test will help, but doing a piston as PM is a good idea, if it's not been done.

Post by **dirtyboy** » Thu May 21, 2015 1:44 pm

Mine doesn't do that.

cedric · Post by **cedric** » Thu May 21, 2015 3:06 pm

I think it might be time for a set of rings, are you getting oil coming out of the breather?

Post by **axel99** » Thu May 21, 2015 4:11 pm

Time for a top end refresh.....I hear just the parts are $500

Ahamay · Post by **Ahamay** » Thu May 21, 2015 7:45 pm

Blow by. Rings at a minimum. Get ready to open ur wallet.

rogue · Post by **rogue** » Thu May 21, 2015 9:08 pm

Ok thanks boys. I'm OK with with a top end, that's just part of riding.

I was worried it was something else.

Post by **axel99** » Thu May 21, 2015 10:02 pm

Do it right with piston, wristpin,wrist pin bearing and rings. Popping new rings on a used 4T pistion seems like bad idea to me, if the rings are shot so is the piston. Too much work and risk to save the cost of a piston.

cedric · Post by **cedric** » Thu May 21, 2015 10:14 pm

Measure the parts, I'm sure you have the tools....

Post by **malcolmzilla** » Thu May 21, 2015 11:40 pm

If it doesn't smoke warmed up, might be by design. My YZFX uses a single compression ring and until warm, blows smoke. It's what they do to wring every last 1/3 hp out of these little buggers.

markvfr · Post by **markvfr** » Fri May 22, 2015 7:15 am

Ahamay wrote:Blow by. Rings at a minimum. Get ready to open ur wallet.

Yup, a whopping $170US for a piston kit...

Ahamay · Post by **Ahamay** » Fri May 22, 2015 8:12 am

markvfr wrote:
Ahamay wrote:Blow by. Rings at a minimum. Get ready to open ur wallet.
Yup, a whopping $170US for a piston kit...

Valve train failure and valves/seat and guides are very often also associated with blow by too. This is where the 'open your wallet' comment comes in.

Why do you seem so confrontational?

markvfr · Post by **markvfr** » Fri May 22, 2015 8:54 am

Ahamay wrote:
Why do you seem so confrontational?

'Cause I don't like Yamahas.

rogue · Post by **rogue** » Thu Jun 11, 2015 11:07 am

New piston and rings and she is ready to rip. thanks guys.

Rocky Mountain Dirt Riders

four stroke that smokes like a two stroke

four stroke that smokes like a two stroke

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Re: four stroke that smokes like a two stroke

Re: four stroke that smokes like a two stroke

Re: four stroke that smokes like a two stroke

Re: four stroke that smokes like a two stroke