TIMING A / 2 STROKE- JETTING CONDITIONS

[RdsOnly]

Not that I know a thing about 2 strokes.. 37 years tuning.

Compression/timing vs heat- long pull @ max rpm
  Octane= fuel more compression higher oct.- Lead we need [ave gas 100ll]
      Mixed with Non-ethanol fuel 91 oct with 100ll= 97-98 oct [average fuel in 1975]


#1 RD Battery= 11vdc - timing
        TIMING is everything [almost] to a good running 2 stroke.
---1- battery vdc -OK

  Timing @ 1.8-2.1mm btdc
  Depending on compression [PSI-vs ratio google] 13/1to 11/1
  Most RD's will be in the 12/1-high 11/1 ratio depending on mods

#2 Compression
   Head squish or moded = ratio [PSI] most in 125psi- OK at leaded fuel
   Over 126psi -130  Fuel- higher octane needed [prevent deto]= detonation

1 Timing /compression= compromise of 135psi- 103oct fuel ll, max 2.0Btdc
   NOTE: More advance snapper throttle response, quick= fun

- Timing is always 1st- advanced jet for rick deter deto, short runs spunky.
    Long runs WFO [high rpm]retard iggy

-1.7-2.1  mm btdc depends on set up
    More advance = fun [no deto= octane]

SO we have a parameter - timing VS compression /octane

  We get that with out jeting -feels better

Now  jet
Low end = idle - off line exit a/s air screw 1/2 out - 1.75
  pilot= to small / air screw in .5 to 0 runs better
  pilot to big /air screw 1.5+ idles higher- runs better

Sorted 25.7-30 pilot RD250350/400 {most}

Now main jet - Fuck the middle we will deal with that later!!!!!
1/4 throttle chop to WFO stumble --- does it clean out rev past 5k-12k?
  Trouble shoot- add choke when not running out= if better go bigger on main.
                                                                          if worse smaller main jet
OK you got that close feel good revs out

Now work on low end- pilot jet up hill down hill.
                                 up hill does it hesitate up hill? ba..ba barap go- to lean
        adjust air screw before new pilot 1/2 turn out= bigger pilot needed TEST
                                   down hill 0 throttle bang --bang--bang to fat pilot
                               adjust air screw or go down on pilot and adjust a/s
You have your Main close,
pilot OK, mid range is needle and nozzle jet

   1/4-1/2 throttle - WFO [chop]
       Falls on its face? Hit choke-
      if better need more main go down on needle clip bring needle up 2 pos.

      If goes then stalls and goes call me- or any other tuner on this forum.

OK all is well now you have a spunky off the line bike that runs out to 10k now
Do  a long WFO run kill switch- clutch in. Replace plugs with new.Go to shop.Do plug chop???? remove the other threaded part from the ceramic OR use a loop X10 ceramic down low in the plug you should see dark to light brown rings.Good tuned main jet 2 stroke.
   ... Go ride have fun- tunes as you ride- most ride you will not turn back to the shop, tune and ride again when you get back makes you want to ride more.

love a good running RD/RZ

  Compression#1
  Octane#2
  Timing #1
  Jetting #3
  HAHA 2 #1 old bikes need lead in fuel- octane See KLEEM vintage on octane

  JT
Ride it like you sold it!!!!!!

[RdsOnly]

My hope to to help you- if it confuses you please call me. I am here for my 2 stroke friends.

JT
512-718-9570

[m in sc]

im not sure what kind of dynamic compression numbers & cyl pressures you are running to require leaded fuel in an rd or rz to have to overcome the detonation threshold in unleaded. Its better of course, but no way do i agree its required unless its a full bore race application.