??R-4,R-5??

[JamesThomp101]

What is the difference between a r-5 or r-4, etc. needle jets?

[TZ925]

The smaller the number, the leaner. I have as low as R-3 but couldn't see using them on my Y2K TZ. The ranges I've heard for Y2K's is R-7 through S-0. My 93 and 94's used the R-6 to R-8 range. All motors are different and of course weather and altitude will affect your settings as well. Keep in mind that a leaner nozzle also changes your main jet setting. These ranges are an example of what has worked for me, I can't say what your bike would need without riding it.
Good luck.
Monty Warsing

[Bill Cole]

Just to piggyback Monty. If it is a 125 your talking about you will find that the R-6 is the nozzle of choice. If it is really hot go to the R-5. You will never use an R-4 unless you are running Sunoco maximal or crazy fuels. You also may want to put a one size larger main in it if you go leaner on the Nozzle.

Bill Cole

[dave_432]

Depends on the bike. I ran an R-6 in one bike, and 2 hours later I had to go to a R-4 in the other bike to get the same type of mid-throttle jetting.
I keep the nozzle rich though. If it's really rough and studders at partial throttle I'll go one size leaner and keep it there.