Update:450 cam mod/found something strange?

6 replies to this topic
  • jimn

Posted November 19, 2004 - 09:07 AM


Tried to reply to old thread but it was invalid.02 yz426.I was the guy with the intake cam retarded one tooth from the factory.Finished cam mod(oem)last night(finally got shims)bike started 1st kick!It also seems that the intake cam being off one tooth was the root of my jetting issues as now I am running the jd blue needle where before it only ran okay with the red (leaner)and was rich as hell with stock needle.I had to adjust intakes also(tight).A BIG THANKS!! to Satch for the help on this one!Adjustments were as follows.
Exhaust /left from 189 to 210
right from 190 to 210
Intake /left from 194 to 185
middle from 194 to 185
right from 202 to 190
Stayed on the loose side on all.
Any suggestions on ride time before checking clearances again?Thanks,Jim

  • grayracer513

Posted November 19, 2004 - 11:09 AM


Satch is cool. :cry:

Depending on how stable the valve adjustment has been in the past (very stable, I assume) and your confidence in your work, recheck clearance any where between 1 ride and 10 hours, unless you hear noise, or it starts to develop idling problems (hanging, surging, etc. a sign of tight valves). If nothing's changed, you're back to normal.

  • Satch0922

Posted November 19, 2004 - 07:32 PM


Glad to hear you have the beast running....and running good! :cry:

I have rechecked my valves several times since the cam mod and they are still in spec......did the cam mod in 5-03 and I ride most every weekend (assuming nothing is broken.......on me that is! LOL)

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  • terrymc

Posted November 19, 2004 - 08:30 PM


How did the bike run with the intake off a tooth? I mean, did it make any power at all?

  • jimn

Posted November 19, 2004 - 09:55 PM


The bike ran okay and had plenty of power once I leaned out the needle(I ran the jd red but in pos 6)lean needle,rich position 168MJ 42 PJIam at 3500 ft ,N AZ.Too rich it would bog ,too lean stall.I could get it close but not quite right. I spent waay to much time messing with it.I'd have good throttle response but popping on decel and still have black plugs.I now get to start over again but it is already running better.It is a good thing because I may wear out seat/tank fasteners soon.I even called the yamaha customer satisfaction line to let them know about the timing being off.Thy said they made note of it.Well,now I feel much better, :cry: Jim

  • Satch0922

Posted November 20, 2004 - 04:48 AM


Jim that is strange.....maybe you got a "Friday" bike!? Let hope not. :cry:

  • grayracer513

Posted November 20, 2004 - 11:38 AM


Don't automatically assume your popping on decel is a fuel mix problem. It can also be because of an air leak at the midpipe clamp (especially if there isn't one, as with the FMF Ti4) or at the head. If that's the real cause, your pilot circuit will be too fat by the time you make it stop with the fuel scew.

Just a tidbit.

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