According to Novarossi website the 9 ports rev 900 RPM than the 7 ports. That makes it 1.4 MPH faster.

Here's a tip I learned last night. When the Nova head bolts are too tight, it's a real pain to try to get them off without stripping the slot.

I used a Hudy off road wheel wrench that sat on top (not locked into) the handle of my flat blade screw driver and acted like a servo saver. It allowed me to add sufficient downward force and enough lock to twist, if it was too tight, the Hudy tool popped off. Simply it allowed me a good handle on the downward pressure and reduced the turning force requied because of leverage.

Novarossi "pre-run" engines, does it mean we can go straight to racing with it right out of the box?

No. Pre-runned means the engine has runned a certain time on the bench so the most part is done. You still have to finish the break in proces.

Thanks for your reply.

What's the advantage of pre-run engines?

As mentioned, 1st difficult start due the tight pinch is gone so you will safe your starter box, and I believe you will get a fresh conrod.

but i have seen a brand new pre run engine with brownish conrod,maybe they depend on the conrod condition to do replacement

I did say "I believe"....
I thought I have seen it mentioned somewhere.

I suggest to run a couple of tanks rich before you start race tuning the Novarossi pre run engine. Although I have put engines I break in on the bench directly in the car, and start tuning on the first tank. Everything was fine, however it's always better to run some tanks rich to be safe. In fact, I always start a race weekend with a moderately rich setting on my engine. Then lean it over a couple of tanks.

A good pre run in engine can save a lot of time, and some fuel cost to the consumer. It can also give some performance data.

A new conrod is needed and a great idea but I have never had a pre-run Nova with a new conrod. No idea why Nova doesn't do it.

I usually change the rod after a few tanks. I had one pre-run engine conrod break after 6 tanks and have seen others go. FYI

Ive been told by a Novarossi World driver that witnessed the run-in processes at the the factory that they do install a new rod after they're done

I haven't seen too many but the factory pre-run Nova engines I have had thru here all have had wear marks on the connecting rod from being run

From few info from the player, it show that nova didn't replace a new conrod after break in,the nova driver you mentioned may not know the actual situation in the factory

has anybody tested both mito 9 on and mito 9 c ,how does they compared each other,wich one is revving more ,what pipes are you suggesting

The Mito 9C is just a Flash based engine and I believe Kurzbuch did win the worlds with this engine.