Don't mean to sound like a jerk, but why go nuts over why your end result is improved bro? There are so many factors that change so frequently...

• Not all plugs are created equal, even the same exact model #
• Not all wear states are created equal, and it always changes
• Not all engines are exactly identical
• Weather changes hourly
• Fuel is not guaranteed to be 100% consistent batch to batch in the same brand
• Break-in and startup methods
• Heat saturation states
• Clutch setups
• ...to name a few

All of this stuff is just theory and practice. Even a scientific mechanical engineer couldn't get you a 100% infallible answer bro. Too many things change when looking for the answer (but he'd probably be a killer pit guy when he was done...lol). I completely agree though: this IS counter-intuitive. Why? Who knows... and enjoy your cooler temps, better bottom, more top, and longer runtimes. Woot! Woot!:D

As a tuner I can say that a cooler plug gives you a wider tuning window. Perhaps you were at the rich edge of that window and only experiencing 80% of that engine's potential. When you found the sweet spot in the narrow hotter window you are now experiencing the engine's FULL potential.

Great job tuning by the way!

.

Oh well, guess I'll take this as a learning experience. It just seems backasswards. It goes to show u that you never stop learning new things in this hobby and not all tuning rules are written in stone. But for now it looks like I'll be buying some OS plugs.

As always, THANKS FOR THE HELP.:)

So So True

new main bearing
 

any tips on how to change the main bearing in gx-5r?

DO YOU KNOW HOW TO TAKE THE PISTON/SLEEVE AND ROD OUT?..

if soo...then take them out...remove the carb and take the motor COMPLETELY apart....with NOTHING in it but bearings....then toss it in a preheated oven of about 350 degrees!....then when it reaches that temp just pull it out(wearing some thick gloves) and they should just fall right out...if not it will only take a little push with the end of a paintbrush or something NOT metal or plastic;)

yes, i've rebuilt the 7 & 5 port a couple times minus changing the bearings. thanks for the advice. 350º is enough? doesn't stress the metal any to heat that much?

assuming I should put new bearings while still hot, or should i wait to cool a little so they can seat in perfectly square/flush?

As a millwright I can tell you thats not enough heat to change the heat temper of the the metal. 350 is a safe heat.

Here's a couple videos of someone showing how to remove the bearings, and he makes it look super easy. I wish I would have seen this a few weeks ago, because a buddy destroyed his plus 21-4 case trying to get his bearings out.


http://www.youtube.com/watch?v=WhpwsjYoxM0
http://www.youtube.com/watch?v=Q3xIWcdQFiE

I thought we told him to use the oven but it was too late.... Didn't we?

just make sure you put the new ones in WHILE its still HOT...and you can use the crank to make sure the bearings seat all the way in ;)

we put the new bearings in the freezer too, goes in easy :nod: .... learned that little trick racing motocross for 10+ years

Just wanted to clarify something as I have been having a few tuning issues wit GO-5R

On break in I added the extra shim for the whole break in and then removed it after around 10 - 12 tanks. I am now running on Bryons 25% fuel and last night at the track I had a decent tune using the settings from GO NZ website of 1.25 - 1.50 turns in from flush on the LSN and a few mins turn on HSN needle from flush. The car was running great after a few laps but seemed a little slow on take off on the bottom end so I leaned a little bit more and then it was just so rich and wouldnt hold the idle. I moved the lsn back to what I had before the break and it was same :cry: Would the cause of this be anthing to do with my plug going off? I did get a shunt from behind which caused my servo to jump a cog.

your motor just finally BROKE IN....thats why the sudden richness ....