The break in shim is a .2mm copper.

CHAOS - just check the 7 Port and make sure the .3mm alloy shim is not stuck to the top of the sleeve. Sometimes it gets really stuck on there and it looks like you only have the copper shims installed.

Just a reminder - some of the early GX Series engines came with 2 x .1mm shims, as opposed to the single .2mm shim - just to confuse the issue. But as Matt said, the stock shim stack is .5mm and you can run up to 30% nitro with this.

Thanks Grizz that makes sense.I have the .1mm x2 shims.Not sure what happened to the alloy shim for the 7p but looks like could have been a assembly error.Glad I pulled it apart before I fired it up.

The break in shim idea seems to be exclusive to Go yet it works great.Wonder why other manufacturers don't recommend this.

When do you recommend I pull out the break in shim ? I usually run 500cc - 1000 before I pull it out.

People have varied thoughts on this. If you leave it in too long (like until the pinch has pretty much gone) the motor will run flat.
I normally suggest removing the shim around 12 or so tanks into the break in, as it is only really there to relieve compression on those first few really tight tanks to make things easier on the motor and on you.
So in a buggy say around the 1.5 litre mark, before you start to tweak things a little leaner.
There was a popular misconception a while back that the extra .2mm shim in the box was for running 30% - but this is incorrect. The motors are shimmed at .5mm from the factory and will run 30% no problem like that. In fact you can run 30% with .4mm no problem as long as you are a reasonable tuner and don't get on the ragged edge of too lean.

I'm about to run in my Go GXR 5 port. Do you have to use the extra supplied shim for run in? or can you run it straight out the box?

if you are pre-heating every start it's not required, but if your not your rod will last longer with the break-in shim.

It only takes 2 min to fit it. It just makes life easier on you and the motor - heating or not. You really should be removing the head and smearing some oil around the bore etc anyway before you start the motor, so may as well fit it while you have the head off.
The new GXII's don't come with an extra .2mm shim, but I still fit one for all break-ins on the break in bench, and advise customers to fit a .2mm shim if they have one lying around. It does make a difference on those initial tanks:cool:.

hey Shane, just wondering if my new GX II has had the extra shim fitted?

run in was a peice of cake with you having done 4 tanks on the run in bench, it still needed another 10 tanks of running rich to get to that point of being able to turn it over from hot, had it in my old X6 and on the dry dusty track it was a handful but a lot of fun to drive, with the new carb and all that compression I had heaps of punch and power... it going to be a beast in the truggy at the nationals.

Good luck Craig, our Truggy Nats are this weekend also.

cool thanks. The engine (GX5R) factory settings are HSN (Flush) and LSN (Flush). Are these the correct settings for run in?

Also I'm going to run this in my Hara D8. How can you tame the bottom so it's manageable in the buggy.

Front and Rear bearing
 

What are the dimensions of front and rear bearing for GX 5R and GX 7R.
Any recommendations on front and rear bearing?

Hi Craig. I fitted a .2 mm shim for bench run-in, but removed it when I stripped and checked the motor before you got it.
Yep, the run-in bench is da bomb. It relieves that initial real hard pinch so much faster than running in the buggy. You can feel it when you turn the motor over hot with the prop by hand after 3 or 4 tanks - it is starting to free up nicely by then. 8 - 10 tanks on the bench and the motor is fully bedded in and ready for whatever tune you want to throw at it.
Despite the "quicker" run in, the bench is actually easier on motors because you can control and maintain the temperature of the motor throughout the whole process so much more accurately, so wear on the other internals is greatly reduced, as is the time spent running with significant pinch.

Soft clutch springs, and maybe a combination of alloy and carbon shoes, or even all carbon shoes depending on the track surface.
Maybe run one tooth bigger on the clutch bell to deaden the bottom end a little. The 5R is a very strong motor down low. You will need a smooth trigger finger to keep the buggy in line:nod:.

Front 7 x 19 x 6
We only run steel in the front due to dust and dirt being forced up into the bearing under the flywheel. Dust and dirt are the mortal enemies of ceramic bearings. Plus front ceramics don't like the shock loading from the starter box when cold. The front bearing is small in comparison, so you are not gaining a huge amount by going to ceramic here.

Rear 14 x 25.4 x 6
Run either stock or ceramic here. We have been using the Answer Si3N4 silicone nitride ceramics and find them excellent and very long lasting. The Avid ceramics are also a very good bearing. Both have good ABEC ratings.

thanks shane. so .09m springs the way to go?

This GX 7 SCREAMS baby,unreal!

Thanks Flanno, hope you have a good one as well.

The best way to tame an engine down is with your throttle finger,if tractions low just feather it off the line, personally i hate 0.9 springs on any motor unless your shoes are worn, they bog the motor down off the line giving you no punch for short runups to jumps etc and its a lot harder getting the tune right with the lsn...another option is to run a pipe thats a bit softer down low than the 2072 if thats what your running.

Thanks Shane, I'll leave it as it is when i fit the new head back on, fingercrossed the weather doesn't effect the weekend too much, may have to do well saturday incase $h!t happens sunday :rolleyes: alway a fun trip away regardless of how the racing goes :cool: thursdays going to be a big day! practice into the night, pig on the spit and a band! we'll have to stop at the wholesalers on the way being that far out in the sticks.
looking on the map its a long way down south,I wonder will there be any banjo player in the band :lol::lol:

GX 7R is an awesome motor, i still have a good one running and love the power in a buggy, can't wait to see what the GXII 7 HO will be like

:nod:, best buggy engine ive ever had!! its controlable with a heavy finger unlike the GXII in buggy.:D