Maintenance & Technical > KX500 Original
First Ride, weak
SweetTea:
Well I finally got home to my new/used (completely stock) 00 KX500. It's in great shape all & all, no big problems on the exterior, everything looks new almost actually. It rides good, although it vibrates more than anything I've ever owned lol, the suspension is good, shifts through all the gears perfect and its torquey, just no snap of power at all.
I took it for a spin this evening and it has less power than my ol' KDX220. The potential is there however I know it, I just need to work on it. It was a gravel road I rode on, and it did leave ruts in the road, so hookup could be part of it but I'm thinking theres more to it than that.
One thing, jetting seems to be lean, i'm getting a surge on midrange and when I let off the gas, so I'm gonna try jetting first. The intake boot on the reed valve side is dry rotted a bit, but I don't think its sucking air, but I'm going to replace that pronto anyhow.
I still need to check the compression and reeds, will do tomorrow. If compression is low I'll go ahead and do a topend. I guess if jetting doesn't help the power I'll check the KIPs as well.
I'll post more later, I just drove 14 hours straight and I'm a bit worn out and probably not making sense.
Any other suggestions while I'm going over her?
Thanks guys.
jonny500:
remove the kips cover, run engine, and see if it moves when engine is reved
SweetTea:
Thanks Jonny. I checked the KIPs and it appears to be working like it should, the rod goes in and out freely when reving the engine. Reeds are good. I checked the compression and it appears to be 95psi. So looks like the rings/cylinder are worn pretty good. Looks like I'll be doing a topend. I should have known, the thing kicks easier than a XR50, I could literally do it in my flip flops.
I took it for another spin after swapping the Turbine Core silencer out for a pratically brand new stock silencer and it ran a lot better. This thing handles great, feels like it handles better than my 07 WR450! There is decent power even with such low compression, it will bring the front wheel off the ground pretty easy and dig deep ruts.
Another question though. The jetting appears to be good, but when letting off the throttle it still surges, like I've experienced on other two-strokes under lean conditions. But I think I've read on here somewhere, that it's common to the KX500, any truth to this?
I know I can't truly jet the bike until I do the top end, so I'm not going to mess with it now. One thing at a time.
I'll be pulling the jug here soon!
Thanks!
flyingfitz:
Fixes for your issues based on my experience:
Do a top end. Make sure the cyl plating is good. Window piston is a good mod if funds are available.
The seals in the bottom could be bad. Something to consider. You have to split the cases to replace the seals. There are leak methods posted on this forum to check.
The surge has many theories. My throttle speed screw was all the way in to get the bike to idle at a reasonable speed. I jetted down until the engine would idle too fast with the idle speed screw all the way in. I then adjusted the idle speed screw out to get a reasonable idle. I then turned the air bleed screw in richening the bottom only to a point where the engine would not surge with the throttle at idle after revving. I am running a 52 pilot with a fresh cyl and window piston. N82r needle in center clip. 600 ft elevation. The settings I have work ok from 45 to 80 degrees. The plug does not foul and the color is brown. The bike does not surge and is very reliable. I also set my float level to 18mm. Hope this helps.
Fitz
martinfan30:
--- Quote from: flyingfitz on November 07, 2010, 07:09:36 AM ---Fixes for your issues based on my experience:
Do a top end. Make sure the cyl plating is good. Window piston is a good mod if funds are available.
The seals in the bottom could be bad. Something to consider. You have to split the cases to replace the seals. There are leak methods posted on this forum to check.
The surge has many theories. My throttle speed screw was all the way in to get the bike to idle at a reasonable speed. I jetted down until the engine would idle too fast with the idle speed screw all the way in. I then adjusted the idle speed screw out to get a reasonable idle. I then turned the air bleed screw in richening the bottom only to a point where the engine would not surge with the throttle at idle after revving. I am running a 52 pilot with a fresh cyl and window piston. N82r needle in center clip. 600 ft elevation. The settings I have work ok from 45 to 80 degrees. The plug does not foul and the color is brown. The bike does not surge and is very reliable. I also set my float level to 18mm. Hope this helps.
Fitz
--- End quote ---
So whats your main # in these conditions?
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