It really works!!! I had given up trying to use those short springs and was using the long ones till I tried the fuel tubing. It can really be a challenge getting the fuel tubing over the springs tho. I suggest trying to do it with a few beers so your not frustrated and throwing things in a few minutes

I use JP-3 on the Force JL .21 and it works great, they says these are pretty much the same engine. Believe or not its good on fuel JP-3 is not know for being a gas miser, but seems these too like each other.

Does anyone know the correct amout of shims for a C6. I have .30 right now and i run 30% nitro. Thanks Speedy

The engine comes standard with .30 of shims, this should be with two shims. RB recommends that you add a .10 shim for a total of .40 to run 30%. How much fuel do you have thru the engine with those shims? If it is pre detonating you can pull off the head button and look at the piston to check for pit marks. Your altitude will also play into the equation some. Are you racing at sea level?

Ok mine has four shims It should have only two?

Well it also depends on what size those shims are that are installed. RB has shims that are .10 and .20. Since they recommend to have .40 to run 30% at sea level it is possible your engine has 4 .10 shims. Stock from the factory there should be one thicker brass shim and one thin brass shim. If you are at sea level and running 30% you may want one thick and two thin shims, or the 4 thin shims. You can also try one thick and one thin with the 30% to see how it runs for you as a lot of people run with .30 of shims with 30%.

If all of your shims are the same size you may want to use some calipers and measure to see whats in there.

chris did you run the shark motor yet. if so how did the motor feel.

OK thanks!! Im running 25% so I will take one shim out.

Hey man, sorry I have not raced the Shark yet. Here in Colorado we have been burried in snow for over a month now and LUCKY to get over 35 degrees. I am gona go race in Az this weekend but will probably only practice with the Shark as it's only got 6 tanks on it for now. I will let you know how it ran for that but it's gona be a full gallon of fuel before I can see what the Shark really has.

Yeah take one out for sure..... If you have one thick and three thin shims you should pull out two of the thin ones for 25%.

Jud they are talking about the C6 not the K9. A stock C6 would only come with two shims. If you are unsure how to take a shim out I will do it for you. LOL

The motor has 3 gallons on it. I had another .20 shim so i put it on like u said. The top of the piston IS Black is this good or bad no marks on the top that i can see. I heard steel wool was good to use to clean the top of the piston an button up is this true?

Thanks, also do you run the motor in a buggy or truggy.

The top of the piston being black is actually a good thing, just means there has been plenty of lubrication in there as that's from the oil burning. If it was pre-detonating you would see pit marks on the top of the piston and would be able to feel them as well. After 3 gallons you would see a lot of them if it was a problem, so I would just run it like it was with the stock shims if it was performing well for you without killing glow plugs or flaming out.

For cleaning the black from the top I usually use Brasso. You should fully pull the piston out of the engine to do this. Then just put a small dab on the top of the piston and rub it in with your finger. Let it sit for a few minutes then rub it off with a cotton cloth. If there is a lot it may take doing this 2 or 3 times to get clean. Also try not to do the sides of the piston at all just the top. After you clean it be sure to spray it down really well with motor spray to make sure there is no Brasso left anywhere in there. Then oil it up and put it back together.

I will be running it in my buggy, I run the C6USA in truggy because that thing is a monster with a 2020 pipe.