KDX1989 - Compression

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KDX1989 - Compression

Postby Dogeatgod » 11:31 am Jan 17 2015

Hi All

I recently brought a 1989 KDX200 and thought the low end power to be a little weak.

Being a bit of a bellend I measured compression whilst the bike was cold (120 psi).

Having then taken spanners to the bike the problem looks to be that the power valves were not working (the lever comp govenor had fallen off - was also bent - new one ordered). There is no wear on any of the parts, so I reckon everything has been overhauled recently.

My question is:-

I've not removed the cylinder but looking at how shiny everything is reckon all is good - would the low compression reading be due to being cold or should I replace pistion rings and examine further whilst engine is out. (Basically I want to stick back together and pull wheelies as soon as possible).

Thanks

Rick
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Re: KDX1989 - Compression

Postby Dogeatgod » 12:39 pm Jan 17 2015

12005A 12005-1121 - Ah, need a LHS exhaust valve - any ideas where to source?
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KDX1989 - Compression

Postby Gotanubike » 01:12 pm Jan 17 2015

Usable range in my manual for compression is 120psi-185psi with the engine warmed up

I was going to say it's likely that a subvalve has had it's gear teeth chewed up and is no longer turning. Most new owners making a comment about having no bottom end range or no top end power range is usually due to the broken valve(s) being stuck open closed.

Looks like Kawasaki recently discontinued the valves unfortunately but they can still be found. I can still get them from my local dealer who orders them from the warehouse in Toronto, but maybe not for much longer. They are not much more expensive to but online
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Re: KDX1989 - Compression

Postby Dogeatgod » 02:41 pm Jan 17 2015

Thanks for reply Gotanubike.

They are a discontinued bit; luckily after a bit of trawl found a clone here - http://www.cmsnl.com/products/valve-exh ... Lq5pEesV8G

As the heads off will also replace rings, glue it all back and see if compression has improved.

Cheers

Rick
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