If you use an os plug get the p4 its abit cooler than the p3. I use the o'donnell 97t plugs in all my go engines (3 port, 5 port, 7 port). 33% nitro will be fine if thats what you normally run. I run 30%, but i'm guessing 33% is what locals in your area are using.

+1 on the O'Donnell 97T, especially if you are going to run 33%
With that percentage you will want nothing more then a medium temp plug.
Run the stock .5mm shim stack, and if you start blowing plugs add another .1 or .2mm of shims.

I'v only just started playing with shimming, so still new to it.

My 1st MG66 lasted 11.5 months with 62ltrs throu it before the ORIGINAL rod let go (did not change to 2nd rod on purpose as we were doing an experiment) main bearing didn't need changing untill the 40ltr point and I didn't change the shimming either from stock and still got great performance out of it.
This 2nd MG66 I decided to remove just 1 .1 shim to see how it goes and found it perform like its on 30% so I stopped there.
I feel once I find "what works for me", why change it !
I may try removing another .1 after the scheduled bearing and rod change.

I can only post based on my own experiances, I do not speculate or assume what others do or why !!

I'll let MM elaborate on his shimming guide.

But yes, so far I have .4 shimming, not .4 head space.
I don't understand the head space thing, I just know what shims I'm running.

That is why this is such a good helpfull thread, because the people helping only comment on what they have had experiances with.

Spot on Flanno

Both Flanno and I run the .4mm shim stack because we have experimented a bit, and have found this set up works best with the fuels etc we use. Performance and reliability is brilliant. There are a few others on here who run the same shim set up as well. It works for us, but may not work for everyone, so experimenting to find the ideal set up for you is the key.
Massive's .1mm set up works for him, but you will also read he has a custom venturi fitted etc. Like Flanno said, you would need to consult with Mark at Massive Mods if you want to vary from what he has listed in the Shimming 101 guide on his site.
My suggestion of the standard .5mm shim stack (plus additional shims if required) to start with, is just a safety thing seeing as you are going to be running 33%. I have no experiance with fuels over 30% so would hate to advise something different and have your motor damaged. PM Massive and have a chat with him about it.
Personally I would drop the 33%, and source some 25% or 30% fuel. That's all you need to get the best out of these motors.

i was just wondering, i was told by MASSIVE that the MG66 motor is built to handle things most motors cant do..and thats why you can run a smaller shim stack....so will this still work for the GX series motors aswell?...

thanx guys for infos, you are all very helpfull.
and yes , just wondering what will be the runtime of mg66 compared to 5 and 7 port gxr engines?
I just decided to run 2072 pipe as 086 is not EFRA legal, and using 25% fuel just for safety reasons.
I will be using MG66 in losi 2.0 EU.
Thanks again

I run the .4mm stack in my GX motors and the MG66. Works well for me.

Run time is a tricky one, as there are so many variables. I seem to get slightly better run times from the MG compared to the stock GX motors, but I don't think my driving is consistant enough to say there is a definitive difference.
On a good day I can get 10 min stops with my MG in the X-Ray buggy on an average length track at sea level. .4mm shim stack, OD97T plug, 30% fuel, average driving skills and some sort of effort to be smooth on the trigger . That last factor is probably the most important one when it comes to economy. Hope that gives you some idea.
One thing I can guarantee, is the 66 in the Losi 2.0 EU will be very quick

There aren´t too many videos of the mg 66 on at youtube.

Could you make some of your mg 66s ? I´m really interested in this mill

Flanno has a good one of his Mugen Truggy going hard with the MG66. Was posted a while back. He might post it again if you ask nicely

I run my Go engines with the 1 silver shim and thats it...

im going to run my GO .21 5.5 at my last big race of the year, im running 30% byrons, what shimming would be best? kinda confused on the whole shimming thing, right now there is 3 shims 2 skinny ones and a thicker one...lol

August 2009 ACT states ( yellow/red and white "BCE MBX5T

http://www.youtube.com/watch?v=5OLOdoYbDUs



Janruary 2010 Maitland/Newcastle (Same as next lot of clips but clearer so ya know what car to look out for, starts filming me at 1min 20ish

http://www.youtube.com/watch?v=F7ScmRZJewc

December 2009 Tasmania (Yellow/red and white with yellow wing. :"not the yellow with black wing." see the previous clip to get to know the car colours.

http://www.youtube.com/watch?v=Vud56Td6VZA

http://www.youtube.com/watch?v=88Ht_...eature=related

http://www.youtube.com/watch?v=jXgwY...eature=related

May 2010 NSW State tittles. (Yellow/red and white with white wing.

http://www.youtube.com/watch?v=kIqaAgfEY1k

August 2010 Australian nationals (Flame front and pink/white with white wing

http://www.youtube.com/watch?v=BucFOIkwSsc

Nice Video clips !! Thanks

Thats one loose track. I think i would have run paddles!

is that on 30%?...and what plug do you use?