Originally Posted by Rsickles

The original VZ was designed to run a 8mm and 9mm venturi. The real question you have to ask yourself, does running a smaller venturi mean you're on the gas more? Driving WOT on a smaller venturi burns more gas than learning throttle control on a larger venturi. The tuning window also closes on smaller venturis... So if you tune in the cold dewy morning, by hot and dry afternoon, you'll have to retune.

Did you install the extra .1 brass shim the engine came with? You must run one .1 brass and one .2 aluminum shim no matter what.


Here's your problem. These pipes are fuel hogs.

Originally Posted by Crash Test Dumy

When it's cold and the plug is out, if you can turn the engine over and do not feel any mechanical pinch, then it's time to remove the break in shim.

Cheers
Brian

Originally Posted by Mark Erce

good info...thanks!!! so when is it a good time to remove the break-in shim? and what carb restrictor were you using?

Originally Posted by JamminSP

Once the mechanical pinch is gone is a safe time to remove the shim. Mine was never installed to begin with but at approx 1 gallon I removed the thickest of the 2 installed shim. This incresed the compression thus increasing run time and performance. I didn't see the need to install the extra shim because there isn't enough pinch to warrant it IMO. I'm also down to a 7mm restrictor but thinking of going down to a 6.5mm.

Originally Posted by Mark Erce

ok thanks guys. I just ordered mine today. I thnk I will install the shim and then remove it after break-in. just to be on the safe side. I might have to try removing the thicker of the 2 shims as well....is alot of ppl doing this? the engine should be ok with leaving it in right?

Originally Posted by mikenix

Adding the extra shim for break in the way to go. I got my latest one to come around much quicker so there is less fuel wasted with a motor that isn't performing as good as it should. I removed it after 1/2 gallon. I probably could have stayed as there is still massive pinch. Please start with it and you'll have a better experience. I highly recommend using heat indefinately.

Originally Posted by Jaz240

I've been really pleased with all the positive feedback so far. It's great to here all you guys having good outings with this motor. Special thanks to Mike Cleary for all you do for me and for Team Terribles. You made a great call bringing in these engines. I am going to be sending a couple out to Lance at RC Renew. He is going to run half a gallon of fuel through them on a break in bench with computer controlled variables and monitoring. I will then have them available for sale as ready to rip! Just remove break in shim if you want and race tune! Drop on the track ready without the added cost or time of the break in process. Prices will still be less than the original V spec or the new blue XZ

Originally Posted by akiyama77

here's my setup

6.5mm restrictor
nova 9901 pipe w/ 41021 headder
sidewinder strike 30%
steel flywheel 2 comp w/green springs, 2 alu w/ gold springs (std losi setup)
os p3 plug
13/48 gear ratio
motor has about 1 gallon on it, and i took out the break in shim before the race
we ran a 20 min main, came in at 10 min, and took only 100cc, I used a Losi fuel gun.
Hope this helps

Originally Posted by Mark Erce

there's a 2mm(silver) shim and 2(copper) 1mm shims. always keep the silver one and one of the copper ones in at all times. the extra copper one is for break-in. you can remove it after about a gallon.

Originally Posted by jewn_beef

The shim that comes in box with motor can be used for break in
I did not use it for breaking in mine just make sure you get motor up to temp before attempting to start for first time or first gallon or so u will also notice that motor stays really tight for around 2 gallons once loosens up all the way run times get better
good luck with it.