I ran mine about a week ago... It was a stock Ninja but had Ceramic Bearings. It went thru 1 day of practice, 3 rounds of qualifying, 30 minute B Main and a 45 minute A Main. The motor ran with no problems and good enough power. The track was pretty big. Geared it at 17/21 pinion and 49/45 spur on a Mugen MRX4-X.

Here is a picture of the car:

i now close the chapter on my ninja.

mine was the last of 3 that started last season in our club, to die.

2 rods and a piston cracking in half did ours in.

i have had sirios, novas, x12, and all have been abused at times. and they are all still running with NO parts changed.

i replaced the bearings in the ninja, and was due to replace the rod TODAY!, and it broke yesterday.

Good motors while they last. i thought mine would last.

Hope OS makes them better, what am i saying OS will make them better. Good luck

May she rest in peace. Shame to see one go. I can almost understand the rod going, given the pinch the engine has (which is why I'm not TOO mad my first one died after a year). Never needed to change the bearings, but I know one guy that had his bearing fail last year. I'm hoping my fresh one I just got doesn't meet an untimely demise, because it is far from slow. I will be getting 2 rods as insurance though...

well i have two new bearings, they were installed and ran for 2hrs? if u are interested. the good parts left are the block, carb, head button, head. the crank i will have inspected.

May not be a bad idea.

Hey guys I am new to onroad and just bought a mrx4x and a mr21ro1a and keep hearing about changing the conrod after break in.I was wondering why?I have broken in engines and they have lasted over 3 gallons and no problems.Is it because of the higheer sustained rpms in onroad use or something else?Thanks

It's that ninja con rods have a reputation for premature failure. Might be because of excessive pinch during break-in but who knows.

It's cheap insurance for the part that fails first i'm guessing 90% of the time.

Hi guys..

I am a newbie here.. so a little bit of excuse...

I am getting my Mugen MRX-4X tomorrow

and I have not decided what engine to get...

I tried ordering Ninja .21 7-port on-road, but it's been discontinued..

any recommend top-end motors?

any suggestions welcome

thanks in advance.

How longs a piece of string!

I am using the GRP Tuned engine at the moment, massive top end , could do with a little bit more bottom end, but for the price you can't beat it

any good places where i can buy motors?

Well I got my mr21ro1a fully broken in yesterday.She seemed completely broken in after the 12th tank.I had absolutely zero problems with break in.The one thing that shocked me with this engine was how fast it lost pinch.Like my picco .26maxx had about 2 times the pinch compared to my ninja and it lasted for about 16 tanks or more.I don't see how this break in could have weakened the rod but I will check it before I run it at the track.I ran a medium plug with 20% even though it was shimmed for 30% just because everyone was talking about the excesssive pinch.It was about 90 degrees outside with about 70% humidity.I will install a cold plug and run 25% for the rest of the engines life.I started tweaking the needles on the 11th tank and had it pretty good but still alittle fat on the top by the 12th.I don't think this engine is any harder to tune than other aftermarket motors but the tuning window is pretty small for that "sweet spot".Running it full blast like it would if it was at the track resulted in temps of 240 when the temperature outside was 80 because a storm blew over and cooled everything off.Maybe these guys are blowing there rods because they are more sensitive to lean conditions?

sorry if this question has been asked before..

what glow plugs other than the Ninja/GRP ones can i use?
will OS ones work?

i'm running the .28 truggy engine which i believe would use the same glow plugs as the B01A/R01A..

thanks in advance!

IDM, Sirio, Picco, OS, GRP.

No Nova or O'Donnell!

thanks stefan!

i can get OS plugs easily,
juz wondering which one is suitable for the .28?

would the OS P6 be the same as Ninja no.6?

Hello, I was wondering if anyone knows the factory settings for the Ninja .21 R01A 7 port onroad engine?