KDXRIDER.NET

I can no longer ignore the voice at the back of my head that's repeating... "Change the piston, change the piston" - mine being a pretty stock 220, so plan to strip everything down and order a Wossner kit, double-quick! Thanks kdxrider.net for the warning/tips/suggestions.

Now, seeing as the bike's running and sounding pretty well spot-on, I guess I'll only replace the piston if it proves to be the original factory item. TBH, I'm finding it difficult to accept that a '94 bike running so sweetly can still be utilising its original piston, BUT the bike really doesn't appear to have been used much... heck, it was still on its original Nissin-branded front brake pads until a few weeks ago so, who knows!?

So, is there a definitive way to ID the stock piston? Does it come with factory-specific markings/stamps, or any other way of determining its origin?

The bike's a '94 Japan Market 220 :: Engine No. DX220AEXXXXX2

As ever... thanks in advance for any suggestions.

Peace

Stock should have a letter marking on the top of it. Like "A","B","C","D". But it might be worth just putting the new piston in then you will know what you have.

If well maintained you may be surprised how long a stock engine can go without being opened up for any reason.

KDXohio wrote:If well maintained you may be surprised how long a stock engine can go without being opened up for any reason.

You may be surprised how quickly a stock 220 can grenade when the stock piston drops it's skirts.

Julien D wrote:

KDXohio wrote:If well maintained you may be surprised how long a stock engine can go without being opened up for any reason.

You may be surprised how quickly a stock 220 can grenade when the stock piston drops it's skirts.

I always thought skirts dropping was a good thing? Maybe I'm thinking of something else.

99% of the time, a skirt dropping is a beautiful thing. The other 1% is a KDX220 saying "OUCH!".

Depends on the size of the skirt

KDXohio wrote:Depends on the size of the skirt

Plus size skirts need love too.

It's not whether or not you would, but whether or not you will tell anyone.

something about mopeds comes to mind

An elderly man on a Moped, looking about 90 years old, pulls up next to a
doctor at a street light.

The old man looks over at the sleek shiny car and asks, "What kind of car ya
got there, sonny?"
The doctor replies, "A Ferrari GTO. It cost half a million dollars!"
"That's a lot of money," says the old man. "Why does it cost so much?"
"Because this car can do up to 220 miles an hour!" states the doctor proudly
The Moped driver asks, "Mind if I take a look inside?"
"No problem," replies the doctor.
So the old man pokes his head in the window and looks around. Then, sitting
back on his Moped, the old man says, "That's a pretty nice car, all right...
but I'll stick with my Moped!"
Just then the light changes, so the doctor decides to show the old man just
what his car can do. He floors it, and within 30 seconds the speedometer
reads 150 mph.
Suddenly, he notices a dot in his rear view mirror. It seems to be getting closer !
He slows down to see what it could be and suddenly WHOOOOSSSHHH!
Something whips by him going much faster!
"What on earth could be going faster than my Ferrari?" the doctor asks himself.
He presses harder on the accelerator and takes the Ferrari up to 180 mph.
Then, up ahead of him, he sees that it's the old man on the Moped!
Amazed that the Moped could pass his Ferrari, he gives it more gas and
passes the Moped at 200 mph and he's feeling pretty good until he looks in
his mirror and sees the old man gaining on him AGAIN!
Astounded by the speed of this old guy, he floors the gas pedal and takes
the Ferrari all the way up to 220 mph..
Not ten seconds later, he sees the Moped bearing down on him again! The
Ferrari is flat out, and there's nothing he can do!
Suddenly, the Moped plows into the back of his Ferrari, demolishing the rear end.
The doctor stops and jumps out and unbelievably the old man is still alive.
He runs up to the banged-up old guy and says, "I'm a doctor.... Is there
anything I can do for you ?"
Out of breath and pale as a ghost, the old man whispers,

"Unhook my suspenders from your side view mirror!"

Finally got round to changing the piston on my 220 today.

Thanks for the pointers and guidance everyone - the piston was indeed stamped with the letter "B", so the original item. Overall condition of the piston was amazing... no scoring, marking or fractures, save for a small amount of carbon on the crown... same for the cylinder - in absolutely A1 condition. Anyways, now replaced with a Wossner forged and Teflon-coated item, along with wrist-pin, genuine small end bearing and gasket kit.

When you consider that the bike's near-on 20 years old, had amazing compression, made no worrying noises and pulled like a train, it's pretty amazing how well things have stood the passage of time - particularly when compared to the piston-change schedule of more modern stuff, no names mentioned!

Just one question... I'm going to struggle to get my torque wrench and socket combo to access the cylinder bolts (head bolts will be fine)... are you guys just torquing-up by feel (manual states 25NM), or is the use of the wrench essential?

Enduro_Mayhem wrote: Just one question... I'm going to struggle to get my torque wrench and socket combo to access the cylinder bolts (head bolts will be fine)... are you guys just torquing-up by feel (manual states 25NM), or is the use of the wrench essential?

I think you need to use a crow's foot with the torque wrench for those.

You have to use a crows foot adapter to torque it properly. Keep in mind that adding an adapter changes the amount of torque applied (i.e.: if you set the wrench to 18 ft-lbs and your crows foot extends the length of your wrench by 2 inches, then you are actually torquing to like 22 ft-lbs). To properly determine what value to set your wrench to you need to do a little math:
L = length of your torque wrench (measured from center of socket pin to center of where you put your hand to apply force
E = length of the crows foot adapter from center of socket hole to center of the crow foot
Ta = Torque value actually applied to the nut (the factory spec, or for this application 18 ft-lbs)
Ti = Torque value indicated, or what you actually will set the torque wrench to so that you get 18 ft-lbs

the formula is:
Ti = (Ta x L)/(L + E)

so for example using my wrench (which is 15 inches long) and adapter (which is 3 inches long), and looking to get 18 ft-lbs on the nut, I would actually set the torque wrench to:

Ti = (18 ft-lbs X 15 in)/(15 in + 3 in) = 270 ft-lbs-in / 18 in = 15 ft-lbs is what I need to set the wrench for.

The bonus is that this formula works for any kind of adapter you want to stick on the end of your torque wrench that extends its length.

Bufftester's way would work ok, but I prefer to use this method http://www.belknaptools.com/support-lib ... alculator/

Same thing but it does the math for you. You can down load it to your computer for quick reference too.

Just looked into this and the calculation works equally well for measurements in metric, too...
So, length measurements in Metres (m) and torque measurements in Kilogram Metres (kg-m)

Thanks guys... absolutely amazing information and help AGAIN!

Motion Pro makes a special torque wrench adapter specifically for this task. It is a 12 & 14mm box wrench with a 3/8" square hole in the middle for use with your torque wrench. The wrench came with conversion instructions to allow for the extra length. Their P/N is 08-0134.

I posted this very question earlier this year, and this is how I found about this wrench. Unfortunately, I'm not savvy enough to cut and paste that thread here.

pumpguy wrote:Motion Pro makes a special torque wrench adapter specifically for this task. It is a 12 & 14mm box wrench with a 3/8" square hole in the middle for use with your torque wrench. The wrench came with conversion instructions to allow for the extra length. Their P/N is 08-0134.

I posted this very question earlier this year, and this is how I found about this wrench. Unfortunately, I'm not savvy enough to cut and paste that thread here.

Even better... many thanks for this info.

The Motion Pro wrench is readily available in the US, less so in the UK... BUT I've discovered that DirtBikeExpress can source them, with a delivery lead-time of 2-3 days.