2007 EC300 Compression

[smallpuffydog]

I just ran a compression test on my 2007 300 with a good (borrowed a Snap-on tester) compression tester:
-Threaded the tester in.
-Held the throttle wide open.
-Kicked about 25 times (enough for the gauge to stop climbing).

The result was a reading of 205psi.

I live just about 500' above sea level.

Does that sound reasonable to you guys?

 

[gasgasman]

Not too bad.

Anything below 160 would need attention.

 

[GMP]

Really? That sounds high. My brand new broken in '12 measured 182 PSI. I thought most of the 300s were about 10 less than the 250s.

 

[gasgasman]

Really? That sounds high. My brand new broken in '12 measured 182 PSI. I thought most of the 300s were about 10 less than the 250s.

Yeah. You're right. Should be 160psi or less would need attention.

The 300s have that compression "release" port that would skew the readings some.

 

[smallpuffydog]

Compression

Yeah. You're right. Should be 160psi or less would need attention.

The 300s have that compression "release" port that would skew the readings some.

I was surprised to get 205 out of it.

I bought the bike used, so I am thinking that somebody might have shaved the head. I am going to measure the piston clearance and see what i come up with.

It may take me a couple of months to find the time, but when i do I will post the results.

 

[Mud-Ectomy]

Is this a engine hot or cold value?

 

[smallpuffydog]

Cold

Is this a engine hot or cold value?

I did the test with the engine cold.

Just took out the plug and did the compression test

 

[GMP]

Maybe it was set up for race fuel. Does it run OK on pump gas?

 

[smallpuffydog]

Maybe it was set up for race fuel. Does it run OK on pump gas?

I mix a gallon of Sunoco Race Gas with 5 gallons of premium...nothing like the smell of the race fuel and caster oil burning. I even put it in my push mower...

I have never tried to run it on regular pump gas.

 

[(F5)]

ok here is my take.

compression tests on 2 strokes are bull. You can get a bit of an idea of a failure, but that's it.

I'd bet your reading is influenced by some residue oil spat up sealing the rings better than possible. Hot will give you a lower reading which is of course silly.

Either way don't lose any sleep over it.

 

[Jakobi]

ok here is my take.

compression tests on 2 strokes are bull. You can get a bit of an idea of a failure, but that's it.

I'd bet your reading is influenced by some residue oil spat up sealing the rings better than possible. Hot will give you a lower reading which is of course silly.

Either way don't lose any sleep over it.

I'm with you! My tester uses an adapter before the check valve which increases the volume significantly enough to completely change the compression ratio. End result is low readings on the gauge. Its only good for comparison between a fresh top end and a worn one.

 

[Jiikoo811]

Test mine bikes yesterday... 10kicks cold engine, throttle fully open... 2009 300ec stock head and 90hrs run piston give result 12bar.
2008 300ec stock head 5hrs run piston 13bar and with s3 head with black insert (squish 1,15mm) 14.3bar

Sent from Razr MAXX

 

[honuki250]

compression

I dont know what the bar means.

I am in same boat. Cold engine 10 kicks 175 - 180. its a 2007 ec 300 bought used a few years ago. I only ride about 6 times a year mainly DS and trails.

Had carb issues but now that it is fixed bike runs great but I dont know when the last top end was done so was trying to see if it need it. It does not lack power or hillclimbing ability.