Lost power and significant compression

C George · Post by **C George** » 07:26 pm Jun 27 2014

My 220 , which I rebuilt over the winter with 180+ psi compression
lost a considerable amount of power the other night.
No real pull.

I just went and did a warm compression test and it's now at 150 +/-
after maybe 3-4 hours of riding.

Something must have let go like a ring.

I even pulled the silencer apart to see if some packing or core had come loose.

Post by **KDXGarage** » 08:14 pm Jun 27 2014

Is this the one with the super timing?

diymirage · Post by **diymirage** » 08:28 pm Jun 27 2014

Jason wrote:Is this the one with the super timing?

C George · Post by **C George** » 08:10 am Jun 28 2014

Jason wrote:Is this the one with the super timing?

No ,,, i't's not funny . This bike has been running just a touch past the advanced mark.

I'll tear it apart today.

The Timing deal works just fine !! If you run the correct fuel.

C George · Post by **C George** » 08:15 am Jun 28 2014

diymirage wrote:
Jason wrote:Is this the one with the super timing?

I don't see the humor myself.

diymirage · Post by **diymirage** » 09:54 am Jun 28 2014

C George wrote:
diymirage wrote:
Jason wrote:Is this the one with the super timing?

I don't see the humor myself.

if you happen to have kids you'll get it
you don't want to know how often ive told my kid that something isn't a good idea only to have him try it anyway and find out daddy was right

somehow, this feels the same way

Gotanubike · Post by **Gotanubike** » 12:36 pm Jun 28 2014

C George wrote:
Jason wrote:Is this the one with the super timing?

No ,,, i't's not funny . This bike has been running just a touch past the advanced mark.

I'll tear it apart today.

The Timing deal works just fine !! If you run the correct fuel.

I don't find it funny either. But post pics please! for science.

C George · Post by **C George** » 12:23 pm Jun 29 2014

I've got my 220 apart now and even though I thought I thoroughly
flushed the cylinder with soap and water it looks like debris hit the
exhaust side of the piston / cylinder. :( :(

Strange how they look like small fractures on the piston ?
But I believe if you look at the rings closely in the picture , the edge is
scared up.

Not sure what I should do at this point ,,,,,,,, just mad at myself.

Bore and replate with new piston ?? The most expensive.

Slap new rings and gaskets in it and run it ?? lousy for this new a bike.

C George · Post by **C George** » 12:56 pm Jun 29 2014

There's area's to the sides of the exhaust port where it looks like the
rings aren't even hitting.

Post by **KDXGarage** » 01:02 pm Jun 29 2014

I was not trying to be a smart ass. I was thinking you had two KDX's. Advanced timing might lead to advanced stress??

Again, I was not trying to be a smartass.

C George · Post by **C George** » 02:49 pm Jun 29 2014

Jason wrote:I was not trying to be a smart ass. I was thinking you had two KDX's. Advanced timing might lead to advanced stress??

Again, I was not trying to be a smartass.

NO worry's ,,,,,, Yes , we do have two , my son's 200 and my 220.

I took some fine emery cloth , by hand , to the cylinder and the scratch's did knock
down quite a bit.

newbbewb · Post by **newbbewb** » 03:48 pm Jun 29 2014

is that a wiseco piston, and is it still round?

C George · Post by **C George** » 07:09 pm Jun 29 2014

newbbewb wrote:is that a wiseco piston, and is it still round?

Yes ,,, and as round as any piston is. Not to be a smart ass but all pistons cold are not round
and are tapered because they expand at different rates.

If I follow your thinking ,,,, was it too tight for the bore ?? ,,,, not by measuring the ring end gap
it wasn't.

Before pulling it apart if had no torque and seemed to rev easy which still has me dumbfounded.

I really hate to just rering it and put it back together.

Hard to take a picture but the exhaust side of the piston looks like it's got small hair line fractures
that you can feel with your finger nail. Nothing visible on the inside. ???

Postigo · Post by **Postigo** » 08:10 pm Jun 29 2014

Check your air filter, It looks like something got inside your cylinder. As yo can see there is not seizure by heat expansion or timming. Looking at the photos I can distinguish the lubrication groves on the side of the piston and that is the first thing you loose during a seizure. Good luck

Gotanubike · Post by **Gotanubike** » 08:47 pm Jun 29 2014

Did you re-torque the head bolts after the first ride since rebuild? Did they feel loose coming off???

newbbewb · Post by **newbbewb** » 11:57 pm Jun 29 2014

check the water pump?

C George · Post by **C George** » 04:21 am Jun 30 2014

newbbewb wrote:check the water pump?

Explain ? I did notice that the resevoir level was lower.

Post by **scheckaet** » 10:02 am Jun 30 2014

i don't see why the water pump would be at fault there. Obviously something got into the cylinder to nick the ring and cylinder. Either when it was put back together or through the air filter (check boot, carb and reeds). maybe the end gap was way too big (doubtful)

newbbewb · Post by **newbbewb** » 02:13 pm Jun 30 2014

Water pump....as in did the engine get hot? Just throwing that out there. Ive seen a couple of water pump shafts break. Those bikes ran fine until it didnt. Doesnt explain the debris though

C George · Post by **C George** » 05:24 pm Jun 30 2014

Gotanubike wrote:Did you re-torque the head bolts after the first ride since rebuild? Did they feel loose coming off???

No and they were torqued at 20lbs,,,,, factory spec 18 ,,,, yes , I should have retorqued.

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