How much compression

[KDXRIPPER]

Fitted a new piston and rings ,checked compression before the teardown to see before and after psi. Comp gauge reads 183psi? bike has 4400lklms on it, new piston and replate was done at 2400klm.
Cylinder looks good no scratches or marks. Has anyone got any readings from past rebuilds for the 200 1997. Does this seem high?
Cheers Peter.

[C George]

I'm not sure what the 1997 specs were , but the later ones show a max factory spec of 155 PSI.

What was the compression before the new piston , rings , replate ?

Has the head been shaved or does it have a thinner base gasket ?

Assuming the gauge is accurate and it wasn't tested rt. after assembly with a highly oiled cylinder , you
on the border of having to run 93-94 octane or blending in some race gas to keep it from detonating.

Yes , your on the high side but if I'd run it with the correct fuel in a heart beat.

[Marky360]

My 05 has 182 psi that's after a ride and hot I want to pull it down and see what it's like in side have had the bike 12 months

[C George]

My 05 has 182 psi that's after a ride and hot I want to pull it down and see what it's like in side have had the bike 12 months

Why would you want to pull it apart ? If my bike had those kind of numbers and had no issues , I'd run it. " with some good fuel "

My guess is some one modded the bike before you got it ,,,, not nessesarily a bad thing.

[KDXRIPPER]

Thanks for the reply C George

What was the compression before the new piston , rings , replate ? The replate was done by previous owner

Has the head been shaved or does it have a thinner base gasket ?

Not sure on the head may be shaved? ,I run cometic head and base gaskets

Marky360

My 05 has 182 psi that's after a ride and hot I want to pull it down and see what it's like in side have had the bike 12 months

I tested mine cold and was expecting/hopeing mid 140s, when it blew 183 i thought maybe its one of those "if aint broke don't fix it" deals. The piston i removed looked great could have gone straight back in.
I test rode it yesterday to bed the rings will wait till i have a couple of hours on it to recheck comp.
What state are you in
Cheers Peter

[C George]

183 cold sounds like your gauge may be off , as that's close to 200 hot

good motor un-modified ,,, 150-160 lbs

[Marky360]

Why would you want to pull it apart ? If my bike had those kind of numbers and had no issues , I'd run it. " with some good fuel "
My girlfriend rides the KDX more then I can and she is learning so I want to clean the power valves. Run 98 octane at 50:1 it's premium over here

Peter I live in Perth now grew up in NSW near parkes my dad rides a 97 kdx 200

[C George]

Must be nice to have good fuel available ,, my opinion is the pump gas in this country is terrible !
I mix my own to make sure the consistency is always the same.

[Jaguar]

I've read that 185 is the normal max. Don't worry, be happy

[Jaguar]

Quality of bearings must have improved since Jennings wrote that 175psi was the limit for production bikes if they were to be reliable.

ps- Ripper, I don't have enough posts to have the previlege to receive/read private messages. Click on my signature link and email me from my performance CDI page (at bottom)

[diymirage]

ps- Ripper, I don't have enough posts to have the previlege to receive/read private messages.

it isn't about post count, PMs are reserved for supporting members
technically it will only take a dollar to get PM privileges but that wont buy you a gold star

[adam728]

Must be nice to have good fuel available ,, my opinion is the pump gas in this country is terrible !
I mix my own to make sure the consistency is always the same.

Keep in mind Australia uses the RON octane rating, we use (RON + MON)/2. His 98 octane is about the same as our 92-93 octane.

Quality of bearings must have improved since Jennings wrote that 175psi was the limit for production bikes if they were to be reliable.

Yea, that was long ago and very generalized. A "modern" YZ250 (current gen engine, 2001+) will put up about 200-220 psi stone stock. Mine was heavily modified and was around 250 psi, and lived on pump gas.

[Jaguar]

1989-1994 KDX200E manual states 119-185 psi is the acceptable compression range.
1995-2006 KDX200H manual states 91-155 psi is the acceptable compression range.

[C George]

Must be nice to have good fuel available ,, my opinion is the pump gas in this country is terrible !
I mix my own to make sure the consistency is always the same.

Keep in mind Australia uses the RON octane rating, we use (RON + MON)/2. His 98 octane is about the same as our 92-93 octane.

Quality of bearings must have improved since Jennings wrote that 175psi was the limit for production bikes if they were to be reliable.

Yea, that was long ago and very generalized. A "modern" YZ250 (current gen engine, 2001+) will put up about 200-220 psi stone stock. Mine was heavily modified and was around 250 psi, and lived on pump gas.

One of the biggest problems with todays pump gas is the inconsistency of quality. Many a regular gets pumped into Hi Test tanks
as the average automobile consumer will never know the difference.

[adam728]

One of the biggest problems with todays pump gas is the inconsistency of quality. Many a regular gets pumped into Hi Test tanks
as the average automobile consumer will never know the difference.

Any proof or just going by popular rumor? I always read on the internet how terrible modern fuel is, or how proper octane isn't maintained, or how ethanol content is always WAY above the allowed level. Truth is these are well monitored and non compliance can mean big fines for stations, distributors, refineries, etc. I'm a dad by night, but a fuel system engineer by day. Knowing what's out there so we can calibrate to it is a big deal. I've yet to see E30 in place of E10, or premium coming out at a lower octane than regular, or many of the other "this happens all the time" claims of the internet.

[KDXGarage]

DON'T YOU COME IN HERE WITH FIRST HAND EXPERIENCE!!

Thanks for sharing the knowledge.

[C George]

One of the biggest problems with todays pump gas is the inconsistency of quality. Many a regular gets pumped into Hi Test tanks
as the average automobile consumer will never know the difference.

Any proof or just going by popular rumor? I always read on the internet how terrible modern fuel is, or how proper octane isn't maintained, or how ethanol content is always WAY above the allowed level. Truth is these are well monitored and non compliance can mean big fines for stations, distributors, refineries, etc. I'm a dad by night, but a fuel system engineer by day. Knowing what's out there so we can calibrate to it is a big deal. I've yet to see E30 in place of E10, or premium coming out at a lower octane than regular, or many of the other "this happens all the time" claims of the internet.

I'm not questioning your engineering knowledge at all. My sources are many a trucker customer who questions what there filled with at the rack.
I'm told the ethanol is added there also and mixed at a close approximate 10%.
I'm open to to learn something everyday.

[C George]

1989-1994 KDX200E manual states 119-185 psi is the acceptable compression range.
1995-2006 KDX200H manual states 91-155 psi is the acceptable compression range.

Thoughts on this ?? Why did Kawasaki drop the compression so much ?
Did the E series have that much more torque and the H series more top end ?

[Julien D]

Yes the E bike has a bit more grunt than the H series motor. Probably had more to do with a difference in the KIPS design than anything. The biggest difference between the H and E engines seems to be the KIPS design. Id have to check the manual to compare, but there are two different compression ratios for each, one with the resonator chamber open to the cylinder, and one with it closed. I'm betting the E bike has a bigger variance. Never thought to look at that before, but it will be interesting to check.

*checked

My E series manual states 7.7:1 (high speed), 9.2:1 (low speed)

Interestingly enough my H manual only shows 7.9:1.

*Another edit:

I found another source, although no factory documentation to support, claiming 9.4:1 compression for the H. If 7.9:1 is correct and 9.4:1 is correct, we could take that to mean that the H has higher compression ratios for both high and low as compared to the older E bikes. This to me does not make sense given my impression of the two bikes. The H seems more responsive and snappy in the upper RPM range, while the E bike has a smooth and harder pull from the bottom. That would indicate the opposite of what these numbers are showing, yes? I'm sure some of the differences are in the exhaust valve itself as well as the cylinder porting. Even that does not explain the service limits for compression being so much higher for the E, if it does indeed have lower compression ratios for low and high RPM. Someone smarter than me is going to have to analyze what data we have. It would be nice to find a definitive source from KAW on what the high/low speed ratios are on the H series bikes, if anyone has that.

[KDXRIPPER]

A quick update on the new piston for the Kdx 200. Compression test 200psi ?. I also tested my 2005 kx 250 it has 203psi. and tested my brothers 97 Kdx200 untouched original piston 138psi.
My 11.4 to 1 390 stoker small block mopar has 170psi.

KDX200 below

KX250 below

Some of the herd 1997Kdx200 2005Kx250 2003Kx250 1997Kdx200(purple seat) 2004Kx 85 2001 Kx100