Lost power and significant compression

Discussion specific to the 1995 - 2006 KDX200 (H Series) and 1995 - 2005 KDX220R (A Series) models sold in the USA
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C George
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Re: Lost power and significant compression

Post by C George »

newbbewb wrote: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
Never got hot .

I honestly believe I must have had some debris someplace after porting the intake.
I used carbide cutting tips and then finished it off with a stone tip.
Looks like stone debris.

BUT , I don't know where it would have been after flushing the cylinder ????

I talked to Millenium Technologies today and a stk bore replate is $200.00
plus shipping both ways and 7-8 business day turn around.

Whats odd is that it ran strong and then suddenly when riding , you could hear a difference in the exhaust note
and most of the great 220 torque was gone.

I don't think the head gasket started leaking as the copper seal shows no signs of it.
05 KDX-220R / 06 KDX-225R / Maxima 927 / Millenium Tech / Ron Black / PC , FMF / Many 220 engine mods / 40 + yrs. of riding dirt bikes 🀟🀟
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Gotanubike
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Lost power and significant compression

Post by Gotanubike »

How is the play in the connecting rod?
1990 KDX200
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C George
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Lost power and significant compression

Post by C George »

Gotanubike wrote:How is the play in the connecting rod?

Seems fine ???
05 KDX-220R / 06 KDX-225R / Maxima 927 / Millenium Tech / Ron Black / PC , FMF / Many 220 engine mods / 40 + yrs. of riding dirt bikes 🀟🀟
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Re: Lost power and significant compression

Post by Postigo »

Check the spark plug. I remember back in the 90s a friend of mine got a similar problem and was caused by a piece of porcelain from the spark plug.
The Doctor says I have multiple personality desorder... But we are not agree...
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C George
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Re: Lost power and significant compression

Post by C George »

Postigo wrote:Check the spark plug. I remember back in the 90s a friend of mine got a similar problem and was caused by a piece of porcelain from the spark plug.

The plug is fine . The plug never had a good reading , always on the rich / oily side.

The rings probably never seated as they were wiped out in such a short time.

I know I'm going to have to send the cylinder out to do it correctly ,,,, just bad timing.
05 KDX-220R / 06 KDX-225R / Maxima 927 / Millenium Tech / Ron Black / PC , FMF / Many 220 engine mods / 40 + yrs. of riding dirt bikes 🀟🀟
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Re: Lost power and significant compression

Post by C George »

This being an 05 model , is it nikasil or electrofusion ?

I read somewhere that Kawasaki used nikasil after 2003.
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Re: Lost power and significant compression

Post by C George »

Thoughts on hitting it with a flex hone ??
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Re: Lost power and significant compression

Post by diymirage »

C George wrote:Thoughts on hitting it with a flex hone ??

probably not a good idea
the stock coating is so thin a flex hone will wipe it out completely

WD40 and a scotchbrite is the best you can do short or having it replated
newbbewb wrote:DIYmirage has it right.


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Lost power and significant compression

Post by adam728 »

Was ring end-gap checked when this bike was put back together? Really though, everything points to debris as you said though. What's up with the porosity on the damaged areas? Was the plating actually removed and we are looking at aluminum?


As for honing, aluminum oxide, 240 grit, brush or "plateau" hone, not a ball hone or stone hone. Ball hones can potentially tear plating away from the port edges, and stone hones can be deadly to your cylinder if one of the ends is allowed to enter a port area, tipping in, grabbing, and doing damage.

At any rate, on Nikasil they'll still just mostly be deglazing, with very minimal material removal. A lot of elbow grease with a scotch brite will net nearly the same results.

Image
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Lost power and significant compression

Post by C George »

[quote="adam728"]Was ring end-gap checked when this bike was put back together? Really though, everything points to debris as you said though. What's up with the porosity on the damaged areas? Was the plating actually removed and we are looking at aluminum?


As for honing, aluminum oxide, 240 grit, brush or "plateau" hone, not a ball hone or stone hone. Ball hones can potentially tear plating away from the port edges, and stone hones can be deadly to your cylinder if one of the ends is allowed to enter a port area, tipping in, grabbing, and doing damage.



Ring gap was well within spec. I think the picture is magnifying the damaged area to look like aluminum as the coating is still there.

I guess I'll stay away from the 400 grit flex " ball " hone I found today.
Last edited by C George on 04:13 am Jul 03 2014, edited 1 time in total.
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Lost power and significant compression

Post by C George »

I found an old wire cup brush in the garage that was slightly snug in the cylinder
and cleaned it up with that. "well oiled "

I'm riding next week " va-ca" with my son one way or the other , so it's going back together with
fresh rings and gaskets.


Image

Image

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Last edited by C George on 04:08 am Jul 09 2014, edited 5 times in total.
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Re: Lost power and significant compression

Post by C George »

Patiently waiting for rings and gaskets to arrive Monday.

Removing the sharp piston skirt edge allows a little more lubrication.


Power Sports Store refunded my $25 2nd day air charge. :grin:
Last edited by C George on 04:11 am Jul 09 2014, edited 2 times in total.
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C George
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Lost power and significant compression

Post by C George »

[quote="C George"]I found an old wire cup brush in the garage that was slightly snug in the cylinder
and cleaned it up with that. "well oiled "


Image


Thoughts ???? I guess if it runs OK , then I'll leave it together.
Last edited by C George on 10:57 am Jul 07 2014, edited 1 time in total.
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Lost power and significant compression

Post by adam728 »

Looks fine to me. If it were mine I'd run it.
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Lost power and significant compression

Post by C George »

Trying to pay closer attention to detail , I noticed the stock base gasket fits very poorly as
it has a 1/16 to an 1/8th of an inch sticking in towards the transfer ports. It kind of defeats
the purpose of cleaning up the ports to have it like that.
I ended up cutting my own gasket from .010 material.

XX - Then I noticed the bottom end cases not lining up perfectly with the cylinder ,,,, oh well,
it's just a trail bike . :hmm:
Last edited by C George on 06:31 am Jul 08 2014, edited 1 time in total.
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C George
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Lost power and significant compression

Post by C George »

I was putting it back together untill I found that the ring end gap
at 3/4" down the cylinder is .018 and the gap at 1/4" is .020,,,,, DAM

The wire brush must have taken off more than I thought ???

The factory specs are .0059 to .0137 ,,, which is exactly what the wiseco site says for this bore.

Sticking with plan ,,,, We're riding this week.
Last edited by C George on 04:36 am Jul 09 2014, edited 2 times in total.
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Lost power and significant compression

Post by C George »

I feel that there was a couple things going on here.
After removing the old gasket from the head , the upper part had been
wiped clean from leaking coolant.
No I didn't retorque but the thing I'd forgotten after building my son's
200 was that the head was torqued at a higher than stock spec.
That I didn't do and when the gasket let go , I'm sure thats when I noticed
the exhaust note change. I won't publish my torque spec that I used today
as most things I do are experimental and thats what I asked RB for also.

The cylinder is way out of spec but I'll deal with that at another time.


XX - Note ,,, Ron commented that " ALL " his head mods are designed to work
with stock torque specs , so I'm sure that my problem was self inflicted.
Last edited by C George on 04:49 am Jul 09 2014, edited 2 times in total.
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Lost power and significant compression

Post by Gotanubike »

Torque them down! I know I have mine torqued to at least 23 ft lb, but no head mods
1990 KDX200
Bike Profile -> http://www.kdxrider.net/forums/viewtopi ... 61#p136315
Suspension Overhaul(Shock+89-92 conventional forks) -> http://www.kdxrider.net/forums/viewtopi ... 15&t=15255
96'-98' RM125 Showa 49mm fork swap -> http://www.kdxrider.net/forums/viewtopi ... 04&t=16994
KDXrider world map! -> https://www.zeemaps.com/map?group=186158
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Lost power and significant compression

Post by adam728 »

Cleanliness of the threads has a huge effect on clamping force for a given torque as well. If you torque to 18 ft-lbs with corroded threads you'll likely hardly squish the gasket. Do it with oiled threads and there's a ton more tension in the studs and clamping than dry threads. Put moly on them and you'll likely cause the stud to pull the threads out of the cylinder, or even neck and break the stud itself.

Just wanted to note. A lot of gasket failures come from improper fastener prep/interface/lube. It has a very big effect on what the clamping force is in the end. I read one time that dry vs moly-lubed on standard steel fastners requires about 80% less torque to reach the same bolt stretch and therefore clamp force. So before cranking 110 ftlbs on tiny head studs, make sure the threads are in good shape, or else all that extra torque won't do as much for the gasket as good threads would.
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Lost power and significant compression

Post by C George »

adam728 wrote:Cleanliness of the threads has a huge effect on clamping force for a given torque as well. If you torque to 18 ft-lbs with corroded threads you'll likely hardly squish the gasket. Do it with oiled threads and there's a ton more tension in the studs and clamping than dry threads. Put moly on them and you'll likely cause the stud to pull the threads out of the cylinder, or even neck and break the stud itself.

Just wanted to note. A lot of gasket failures come from improper fastener prep/interface/lube. It has a very big effect on what the clamping force is in the end. I read one time that dry vs moly-lubed on standard steel fastners requires about 80% less torque to reach the same bolt stretch and therefore clamp force. So before cranking 110 ftlbs on tiny head studs, make sure the threads are in good shape, or else all that extra torque won't do as much for the gasket as good threads would.

My threads were dry with blue Permatex gel Loctite.
I don't believe thread locker affects the bolt torque but
the threads should be chased with a die when taken apart next time.

Moly or any EP lube is something you have to be very carefull with , as I've seen
many an automotive tech break a wheel stud using their trusted torque stick.
Last edited by C George on 04:42 am Jul 09 2014, edited 2 times in total.
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