KX Riders

Maintenance & Technical => KX500 Original => Topic started by: I_Duddits on January 06, 2008, 04:04:40 PM

Title: What compression on your 500?
Post by: I_Duddits on January 06, 2008, 04:04:40 PM
I know my engine needs a rebuild but I'm running it while I rebuild my spare.
So on the bench (it's difficult to get a good kick on the starter) I get about 115psi. Is this going to be enough to start the beast? I reckon all assembled, when I can get a good purchase on the kick starter and kick it like I stole it, I should get a 135'ish out of it.

So is 115 to 135 gonna be enough?
How much is yours? I'm trying to get a feel for the average.
Title: Re: What compression on your 500?
Post by: CR480R on January 06, 2008, 08:57:22 PM
Are you holdin the throttle open?
Title: Re: What compression on your 500?
Post by: I_Duddits on January 07, 2008, 03:14:27 AM
Are you holdin the throttle open?
No throttle on the bike as yet, why would it make a difference to the reading?
Title: Re: What compression on your 500?
Post by: bigbellybob on January 07, 2008, 04:17:29 AM
Are you holdin the throttle open?
No throttle on the bike as yet, why would it make a difference to the reading?


yes it will make a difference and 135psi is low even for a 125.
Title: Re: What compression on your 500?
Post by: I_Duddits on January 07, 2008, 05:49:44 AM
Are you holdin the throttle open?
No throttle on the bike as yet, why would it make a difference to the reading?


yes it will make a difference and 135psi is low even for a 125.

So how much should I be looking for then?
Title: Re: What compression on your 500?
Post by: bigbellybob on January 07, 2008, 06:13:13 AM
some ware in the 190's
Title: Re: What compression on your 500?
Post by: I_Duddits on January 07, 2008, 06:50:17 AM
some ware in the 190's
And that's with a BIG kick and the throttle fully open ?
Title: Re: What compression on your 500?
Post by: bigbellybob on January 07, 2008, 07:16:59 AM
some ware in the 190's
And that's with a BIG kick and the throttle fully open ?

several big kicks and throttle fully opened dont stop kicking tell the gage stops moving
Title: Re: What compression on your 500?
Post by: bigbellybob on January 07, 2008, 07:18:09 AM
also the green cases look awesome

what is the elevation your testing @

you can expect a 3-5% drop on the gage for every 1000 foot in elevation
Title: Re: What compression on your 500?
Post by: I_Duddits on January 07, 2008, 01:42:44 PM
also the green cases look awesome

what is the elevation your testing @

you can expect a 3-5% drop on the gage for every 1000 foot in elevation
I'm at sea level. I'm going to change pistons and barrel and see if I can up the compression.