Maintenance & Technical > KX500 Original

Timing Question?

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gowen:
Thanks Doordie, I will be taking tomarrow to work with the timing. Went from jetting to timing now. :-) I need to find me a degree wheel.

Now, the formula I will be using is the Alt 2. Cause I do not have a degree wheel. :-( Just a dial indicator.

T=L+R*(I-Cos A)- "ROT"(don?t know word) L2-(R*Sin A)2

I'm unsure of the "ROT", but if I can find that missing forumla. :-) Would you happen to know the connection rod length? I don't have anything that has measurements besides tearing down the motor? It is a Hot Rod, but is stock length. Thanks

KXcam22:
Gabe,
   If you have access (of know someone) who has a CAD program, for an easy degree wheel you can draw one, print it on a large self adhesive  label (8.5x11 avery) and stick it a piece of tin (or even cardboard or an old CD if the hole is not too bid).  Over the years, i've made a few of these and they work quite well.  Heck you can just glue the paper on if you have no label.  If you're stuck, drop me a pm and I can email you mine (6") in a pdf or autocad.  You could print it off at home. As far as timing, Doordie and Paul are correct.  Think that as your piston approaches TDC the sooner the ign fires before the piston gets to TDC, the more advanced it is (the timing), therefore as you reduce to 2.2mm the piston is closer to TDC when the ign fires, hence retarded.  Modified 4-strokes like more advance, 2-stokes not necessarily - take a few tests to find the best setting. Although I always thought that retarding was better for bottom end power but likely depends on the engine.  Have fun.  I have too much snow to test anything now. Rebuild season.  Cam.

KXcam22:
Gabe,
  One more thing.  You might want to stay fairly close to the PVL specs.  Too much advance can torch a hole through the piston really fast.  You don't get much warning either. Bike kicks over quite easily afterwards though (Ha Ha). Cam.

doordie:
gowen,

Conrod lenght is 145 mm.

I think the word I mean is "squere rot" ,sorry if wrong spelling! :oops:

T=2.3mm (example)
P=R+L-T=43+145-2.3=185.7mm
R=86/2=43mm
L=145mm

Now YOU calculate it!

//doordie

gowen:
Hi Doordie, thanks, that helps alot and I understand now. I have a question though, I now run into a problem I never did with the stock ignition, the kick starter now kicks back on me while trying to start it. Is this normal? What does this mean? Thanks

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