Author Topic: Port timing  (Read 7938 times)

0 Members and 1 Guest are viewing this topic.

Offline RoostiusMaximus

  • Sr. Member
  • ****
  • Posts: 301
    • Millar Racing Engines
Re: Port timing
« Reply #15 on: July 25, 2011, 04:15:19 AM »
Is there a Connecting rod length difference in any years of these engines?

Offline kwakman

  • Hero Member
  • *****
  • Posts: 879
  • Kwikasfuki KX500
Re: Port timing
« Reply #16 on: July 25, 2011, 04:18:07 AM »
no.same bore stroke and rod length.
And lo, I did loft the front wheel and carried it forth to the unbelievers, and cast it down before them and said unto them ''look now upon the might of my throttle control ye pitiful cretinous ones''
And the unbelievers did quake in their boots....

Offline RoostiusMaximus

  • Sr. Member
  • ****
  • Posts: 301
    • Millar Racing Engines
Re: Port timing
« Reply #17 on: July 25, 2011, 05:55:50 AM »
i'm guessing no one is worrying about changing port timings when using the 1mm shorter CR rod in these engines?

Motorrad

  • Guest
Re: Port timing
« Reply #18 on: July 25, 2011, 11:50:22 AM »
i'm guessing no one is worrying about changing port timings when using the 1mm shorter CR rod in these engines?

Every time I have seen a cr rod used.. Was to counteract a stroker crank.

Offline RoostiusMaximus

  • Sr. Member
  • ****
  • Posts: 301
    • Millar Racing Engines
Re: Port timing
« Reply #19 on: July 26, 2011, 02:50:02 AM »
Hmmm, I'd read in a PDF

"The typical modification in the early 90's was to use a honda cr 500 connecting rod as it was larger and did not break as easy as the standard kx 500 rod"

Offline DoldGuy

  • Hero Member
  • *****
  • Posts: 1,198
Re: Port timing
« Reply #20 on: July 26, 2011, 03:36:52 AM »
Its Never too Late to Have a Happy Childhood!

Offline RoostiusMaximus

  • Sr. Member
  • ****
  • Posts: 301
    • Millar Racing Engines
Re: Port timing
« Reply #21 on: July 26, 2011, 04:51:51 AM »
I'd read that, dudes make no sense. 1mm is .040" so having the piston .040" further down the hole is not going to make it run off the exhaust port, the piston will be further on the port. I haven't measured the length of the KX piston yet. I'd better hold out until i yank these motors apart tommorrow night and see whats up. i have both versions of the CR500 rod in stock so we'll see how it goes.

Offline DoldGuy

  • Hero Member
  • *****
  • Posts: 1,198
Re: Port timing
« Reply #22 on: July 26, 2011, 09:02:57 AM »
CR500 piston has 2.5mm (or .100") positive compression height versus the KX500, so if you run the CR Rod (-1mm / .040") you still have a positive height of 1.5mm (.060") which leads to the base plate like Don46 has mentioned.
DoldGuy
Its Never too Late to Have a Happy Childhood!

Offline RoostiusMaximus

  • Sr. Member
  • ****
  • Posts: 301
    • Millar Racing Engines
Re: Port timing
« Reply #23 on: July 26, 2011, 09:20:45 AM »
ah, I was expecting to bore the pin bore on the kx piston.