Blipping throttle ?'s...what's the right way of riding 2 strokes?

[dinkyguitar]

Hi All,

So while I'm rebuilding my 87 KX250 I'm coming across all sorts of information about dirt bikes and 2 stroke motors.

Today I came across a video of a CR500 on the dyno and after all said and done, the piston winds up seizing.

A few said it's was the air fuel mixture, the owner said it was the narrow stinger section (not sure what that means) followed by others.

The 1 thing that sticks in my head was someone mentioned blipping the throttle on deceleration because you need to "quench and cool the cylinder".

So how should you ride a 2 stroke? Is blipping necessary?

dinky,

[Oblivious Maximus]

If this is your first ride on a newly rebuilt 250 in a while you won't have to worry about blipping anything. It'll do it itself.

[sandblaster]

Without pics of the piston it's hard to say what his problem was.
Too lean?
Depending on the piston being ran Cr500's need to be relieved at the exhaust bridge, or oil holes drilled in the piston, was it?
Improper piston to cylinder clearance.
Incorrect oil ratio in the fuel or bad oil.
To hot of plug range, ect....

But running it up on a dyno I would not think it would need the throttle blipped because there is very little deceleration resistance, so slowing it down takes just a few seconds and I would not think that would cause a problem. Hopefully some of the guru's here will chime in...

Unless you are running it wide open in top gear for a while and then letting off the throttle and coasting in top gear you should not have any problems.
But, if it makes you feel better, blip the throttle, I do because it sounds cool 

[Brute]

Speaking of blipping the throttle... I rode the KX5 to work and there was a 'nervous wrist' Harley guy blipping his throttle at every light. I was a lane over and a length back. I started blipping the throttle every time he did.  
About two lights of that and he quit doing it. Guess he did not like the sound of the big 2 stroke much.  
Back to topic though, don't you think with the oils we have now 'blipping' is not needed?

[dinkyguitar]

Thanks everyone....

So as far as how to ride a 2 stroke goes.....just ride....nothing special.

dinky,

[treedodgingfool]

There's a lot of possibles to a seizure, but there is one thing I will always do whether coming off of a long grass-track section, dirt road, or otherwise long sustained high RPM use (as a saftey precaution) prior to closing the throttle.  I always hit the kill switch while the throttle is still wide-open (or turn it wide open) to hit the piston with cooling fuel & lubricant.  Remember, 2str's carry their lubricant in the fuel.  A hot, still revving piston suddenly starved of lubricant and fuel can seize (the term 3 or 4 corner seizure depending how many sides stuck to the cylinder). This is why I always mount my kill switch dead next to the clutch side grip.  

Beyond that trick, other ways to minimize a lean/lack of lubricant seizures on a mechanically tight & well cared for bike are using as high a flash point pre-mix oil available (my favorite blended variety is Maxima Super M, it's flash-point is one of the highest for a synth/org blend & likes mix ratios of 32/1 or 40/1, ideal for KX's). Do not using ANY castor bean pre-mix oils UNLESS you plan to dump your gas out after the weekend (degrades within a day or two once mixed, loses it's ability to lubricate & doesn't stay mixed in cold temps).  Proper jetting & a spotless filter so no debris clogs a jet (knowing what pinging/crackling sounds like is important too).  Jetting for & using 110 leaded race gas (your crank seals will thank you for it, but in addition it's always consistent unlike pump gas & the higher octane offers a bit of fudge factor & a performance boost too if jetted for it).

[sandblaster]

If your jetted correct or even rich, the motor is in good shape, and you use a good quality premix then you have little to worry about.

[Foxx4Beaver]

If your jetted correct or even rich, the motor is in good shape, and you use a good quality premix then you have little to worry about.

that sums it all up right there!