Lets start a new thread on this motor. I have burned two pull starts during running in and third is running like a dream. Fourth is being run in on a prop and is going to be a killa! Post all good/bad experience here.

What I also meant was performance mods to get the best out of this motor without spending too much money or sending it to modifiers.

To tell the truth the engine is hopeless.Firstly the carb is made of aluminium and when the crankcase heats up the carb temperatures also rises. It pushes the fuel back to the fuel tank.If im not wrong this process makes the engine run lean and it overheats .

best bet is to change the carb from a os or a novarossi [ carbs that is half aluminium and composite ]to keep the temps down on the carb to get a stable idle and constant performance.

I agree on carb note you made as already installed carb from Nova motor. The stock pullstart motor is really performing now also with the Skyline VR 12 plus pipe and no mod work. Man I can catch TOP/Novarossi's! I do not know stock head shim size; Would you know the smallest I can go with 16% nitro? Thanks

16% nitro? I had a a few hours of a good run with a cold plug and 20% nitro. The cold plug is to keep the temps down.

Not sure what is best for 16% yet as i have not experimented with it.what plug did u use for your 16%.

i swear by O'Donnell fuel if u can get your hands on it. just last week some dude came to my track with a ten year old fresh 25% bottle and we tried it on the hyper engine and a rb matrix . it still is fresh ... well maybe the nitro content has lowered but the lubricant is still working wonders lol.

In our "Pullstart" class, we go by max 16% Nitro; I think to be consistant with Aussie rules. I don't know if I can get O'Donnell here in Australia but using a local brand 'Hot Stuff' and their recently changed formula. Its working well and has about 12% lube. The plug I used for combo was OS #8 @ 16% and running perfect. As long as the fuel comes in a plastic bottle with good seal you are o.k.. Engine temp??? as tuned for performance and ensured that body opening max size to our regs; front 50% window opening. Who knows possibly 240 degrees F on 22 degree celcius day.

Anyone else with engine advice? Has anyone grooved head button, that sort of thing? Chasing mods for more bottom end punch.

i would have to dissagree about the motor being helpless. i've had mine (do not run it often since my TZ) for almost 2 years. after i threw the manual away and tuned it to smoke and sound it was very reliable. it uses 30% with a duratrax gold "cold" plug.

i admit the carb was ver tricky at first but once you get it within its sweet spot its like any other good engine to where you dont need to touch the needles anymore. i got so good with the carb that i put the card in my old sirio.

i'm not saying this is the motor to put you in the a-main cause its not but it does run (well mine does)

I have one of these in my CD3, they not bad at all for the price!
i have done a few mods to mine tho and its really screaming now.
The carb is OK, just dont follow the manual, tune for sound and performance and make sure there a good trail of smoke and its all good, carb holds its settings well actually, dont need to play with them much.

vc05hdt, the best plug to use with this engine is the OS LC3 its a long reach plug, next time you have the head off check the distance from the bottom of the plug to the combustion chamber there will be one thread still showing.
I am running 16% with no head shim installed, but i am a 1600m above sea level.

vc05hdt, Check ur Pm's

Delta9, PM sent, Regards

What Os carby fits onto the Hyper 12? CV-X or 12TZ?

I have the pullstart hyper12 that came with my gpx4 and at first was kind of impressed, it started easy and ran consistently always, it still does. But lets face it, it cost asout about 90 bucks and has the power and speed of a 90 dollar engine. Don't get me wrong, it is a good engine for the price, and I haven't had 1 problem with mine. I just broke in a mr12t01a and believe me when I say it is a whole different animal. I say if your happy with it then run it till it blows and buy another, if you want real performance, take the next step and spend some coin and get a jlr red dot, mr ninja, sirio... They all have engines that aren't to much(jlr under 200, mr ninja under 300)and they really, really scream.

Yeah, the manual settings don't make it run well at all. I have tuned it similar to how I normally tune my motors, and it doesn't have the flat spot in first that it had before. I recon it has a lot of potential, it certainly seems fast enough for me! I have noticed that it'll spin the tyres quite easily.

What is the Os carb people have been using on this motor?

You may use Novarossi carburetor and 100% compatible.

I modified around ten Hyper-12 engines years ago and shared with friends, the performance is not bad (I used Novarossi carburetor).

If my memory is not wrong, conrod of Hyper 12 is same Novarossi 7600.