For future reference, all of Team Mugen's notes on the .12 that have been posted here since the engine's release, are now in the .12 Engine KB in the Engine FAQ section. This includes break-in, engine temp and recommended plug for nitro %.

Quick nitro noob question. I run the #6 Ninja plug in my .21 buggy on 30% O'Donnell. It works great with no problems. But I hear about guys running a hotter or cooler plug for certain fuels and conditions. What plugs are hotter (higher number or lower number) and when would you change? What makes them different? Is it more or fewer coils? Like I said. The #6 is what I was told to run and it's been good. I just want to have a good understanding.

Is anyone known what size is rear bearing for MR-21R01A?

The higher numbers are colder.

14mm x 25.4mm

I believe that size is the same as Novarossi, am I right?

It is like changing the timing on a real car. The hotter the plug the sooner the fuel will ignite. Most engine companies give you a very hot plug to break in the engine but after that you will want to change to a colder plug.

Most of the colder plugs are made with a larger size of wire. Not that you can see a big differance but I notice that the colder plugs usually last a lot longer then the hotter plugs.

Mike Swauger- you have a PM.

Who ever is considering a Ninja- get on the bus!! The power is for real and the tuning band is wide

Thanks guys.

Hot Tip.....

When using an Exergen DX501 with the Ninja you need to place an exhaust gasket over the Exergen head or else the gun's window WILL contact the plug electrode and cause damage. Push the gasket up as far as it will go- this will stop the sensor window from hitting the electrode. I think the DX501 is the only Exergen model that has this problem with the Ninja's head.

Exergen has been made aware of the situation and will be informing the engineers of the problem.

My sensor window has plug material on it from the contact. They were kind enough to offer me a repair/replacement/calibration for informing them of the Ninja's head design.

nope, your correct (or we see it the same way :P)

My serpent clutch has kyosho weights, stock backplate and stock shoe, JP spring and normal gap settings.
But when you try it....nobody home...nobody home.... engine starts to make serious rpm.... and kaboem your car launches towards the horizon (or the closest fence :P)
It's what we call a "Italian" clutch, gives a massive punch!

it requires a well set up car, coz it's more like a switch....
depends on drivingstyle if you like it

that is right my friend..even the front..its the same as the nova RO1 wc bearings.

Hello guys, I am trying to find The cheapest And fastest shop to get a ninja r01 the first version crank shaft for a friend of mine. If some one could post some links it would be much apreated. Regards Jeremy.

Seems like the carb on the mr12 likes to come loose? I lost the carb screw today. I think its because the insulator is tapered so it kinda gets squeezed up and out. I replaced the screw and tightened it down good, didnt move after that. Another guy on the track running the ninja also had his carb move upwards out of its socket.

Anyone else had anything like this happen?

I'm trying to get a handle on tuning this MR12 I'm finishing up the break in on. When I nail the throttle, it's a slight bog, then the engine falls flat on it's face just about when it's set to shift into second. When I let off the throttle, the idle hangs up a bit then goes back to normal. I'm pretty sure the engine was not overheating (temp aroung 215 on a +-60 degree F afternoon). Are both needles set too rich right now?

Also, can anyone comment on the power band on these engines? Should I gear it short like the CRF (I'm guessing nowhere near as short as that engine, but still) or will it pull whatever you give it?

All I know is compared to my NSR12, this thing seems (and sounds) silly fast.