Hey guys, we've got a ton of GX-5Rs, starter boxes, and coming in this week and next (two shipments). Get 'em while they're hot!

Also, we just ordered flywheels, clutch shoes, springs, 2 in 1 tools, and spare parts for starter boxes. I'll be carrying a lot of the belts, pulley gears, and a limited number of the structural parts (I dont see these needing to be replaced).

For those of you w/ the losi boxes that cant get gears or belts, our box uses those same parts.

+1 That article is very informative. If your thinking of experimenting with changing the shims from the factory ones, have a read of this article first.

are they any good?

Grizz, thanks very much for that.

I'm having problems starting my new GX-5R motor. I just finished break in but it turns over and over but doesn't want to crank. When it finally cranks it acts extremely lean at first. When its running its perfect. I took the fuel line off the carb and primed the engine and the line spits fuel but when its connected it acts like its not getting any fuel. I'm still in the trouble shooting stage. I've changed the fuel lines and pressure tested the tank. The gasket in between the pipe and the manifold has a little leak, it gets wet from all the priming I'm guessing, but it doesn't seem to be a material amount. Am I over looking something with the carb?

What are Stock settings after break-in ?

There aren't really any "stock" settings after breakin....too many variables like pipe/plug/fuel/weather etc etc..If at any time you need to retune maybe cause of a pipe or fuel change just start with both needles flush and go from there.the tuning of the long lsn has been repeated sooooooo many times on here..if in doubt look on the massive mods website.

Check the head bolts and pinch bolt screw and make sure they are tight. With a new motor the heat cycling during break in can cause things to bed in and leave the 4 x head bolts or the pinch bolt retaining screw a little loose - resulting in air leaks. Maybe check your idle gap too, and make sure it´s not too big (.7 mm is good).

Like Gizmatron said, there are no stock settings really. Your motor being a US distributed motor will have the shorter LSN needle, so it will tune like most other motors out there. Hazarding a guess to get you started, I would say try, LSN 1.25 - 1.5 turns in from flush, and HSN 1 - 1.25 turns in from flush. That should get you running anyway, then fine tune from there.
Contact Rex (22 Racer), he will know. We have the long needle carbs in our GO motors here, which have quite different settings.

Great info Grizz! I apologize for misinforming folks. I didn't know Go Tech motors were shimmed for 30% out of the box. I'll pull my break-in spacer out right now and retune! (.25 6-port) Oh, I forgot, I still need a 2072 pipe. I've been distracted by my electric buggies lately...too cold and wet for nitro around here now. I can feel the good weather on it's way...nitro-time!

neither did I. I think mark needs to chime in here and set us all straight on shimming. according to his web site after the engines are broken in you need to start removing shims in relation to the nitro %. and also short run times,pipes melting bodies[my problems] I put .2mm shim in my mg-66,with the .3 built in thats .5mm total. now instead of lsn being turned in 3.5 turns back to the 1.5 turns in. temps great,run times good,no more melting body. just remember the engine must be run in!!! or you will risk damage to crank pin and bearing rear. my 2 mg's came with long needles so needle settings should be almost like my gen 5.5 carbs. as far as needle settings.when it wasn't I remembered what was different,the shimming.

The thing to be aware of in Massive´s shimming 101 article is that the shimming size he is quoting (next to the plug choices) is SHIMS ONLY. It does not include the built in .3mm of the head button.

So for 25% you are looking at .4 - .5mm (std factory set up) of shims PLUS the .3 head button.

30% you are looking at .5mm (std factory set up) - .7mm of shims, PLUS the .3 head button.

As Matt said, you can reduce the shimming for slightly better run times and hotter head temps / cooler pipe temps.
I was just suggesting in my earlier post that for the average racer the standard shim pack of .5mm gives a motor with plenty of power that is easy to tune on 25 or 30% fuel - with no worries about detonation, killing plugs etc.
I have been running a new fuel blend at 30% for a few months now, using the standard .5mm of shims (so .8mm total incl head button) and a medium temp plug with excellent results. Mega power, not one blown or deformed plug and reasonable economy.

Everyone just assumes that the .2mm copper shim is for higher % fuels, but to the best of my knowledge the GO motors, right from the early days, have been shimmed to run up to 30% out of the box. That .2mm shim is purely a decomression shim from when the older motors were so tight and hard to start ???

I´m sure Mark will post soon and lay down the law to set us all on the straight and narrow

I see what you are saying grizz, to me the article is contradicting its self. If you read he is combining the 2 to get his total. then it states- So lets just talk about head shims VS Nitro % age and assume the engine is run in. Plug choice is next to each one

15 % .2 Hot
20 % .3 to .4 Med hot
25 % .4 to .5 Med
30 % .5 to .7 Med Cold
but then here is his setup;
My set up on my MG66 FT is this

Shim .1mm and 20% nitro, with med plug LRP #6 , 9.2 mm custom venturi 11.5 mins tank time at average tune , 12.4 mins at race tune. 125 ml; tank. EPA wide open. Turbo Head Button.
so the above makes sense to me,and following that train of thought works for me. so I am running 25% nitro with a .2mm shim pack,plus the .3mm built in gives me the ,5mm that makes my engine smooth and happy. know all that will change when I go back to my byrons 30%. I think I will add a .1mm shim for .3mm shim pack plus the .3 built in for a total of .6mm.
so when I ran the above 30% rule the way it's written I had a total of .8mm total shim stack,[.5mm plus .3mm already there]after run in had to lean the lsn 3.5 turns in causing me all sorts of problems that I never had with my other engines. every time I fired it up I was tuning it. the other engines,7-5ports no problems. set the needles and go. hell once they were tuned I don't think I ever touched them.

one word " THEY ARE AWESOME " !! ok thats 3 ...

I have been running .3mm of shims, 30% nitro and med. plugs
in all of my GO Engines. One copper .1mm and one copper
.2mm shim in each engine. All the amuminum shims never
made it back from the modders. When I want to run my
Clocked 7port in my on-road DM-1, I run .2mm of shim
and a cold plug.