Yes. I understand the engine is tuned (manufactured) to run on 16% Nitro. Although adding 1mm head shim would be way too much.
0.1 to 0.2mm shim is what's needed. I would go with 0.1mm for 25% Nitro. Then re-tune.

Hope that help's.

Regard's
BM

Stupid question, I damaged a few fins on my Nova 35WC engine and was going to buy a new head, but like the look of the Mephisto head. Are novarossi heads interchangable or are they different?

The upper head (w/cooling fins) for the Mephisto is the same design as that for the Keep-On and the Flash PT. It is lower profile and the lower portions fit down around the case of the engine. Since some of those engine cases were dressed to fit the lower fitting head, I am not sure if it will fit around those cases that were not dressed. So you are on your own.

Novarossi WINS Euro 1/10 Nitro Speed, in Portugal.

Novarossi MITO WC versions with ceramic and steel bearing have different crankcases. How is it the effect on performance?

saw from the other post in this forum that the latest Mephisto is using the piston set from keep on? it that true?
i have a question, dated back to the era of keep on and pt tuned, what is the difference in performance? just xtra long stroke with keep on?

No, the partnumber of the the P/S set of the Ielasi Raptor is the same as the keep-on, the P/S set of the Mesphito has a new partnumber.

and how about the performance wise between pt and keep on?
noted the latest Mephisto is not super long stroke

Mephisto Backplate
 

Rolef, also notice that the Mephisto does not have the newer Backplate with the pointed taper facing the crankshaft as found in the Mito 35 engines, any guess why they went back to the old design?

That I do not know. The 2 side groove does make it a more stable running engine because the better flow of the fuel but I can imagine they want to have an as low possible crankcase volume. I have heard from a guy that his engine modifier does modify the rear cover to get it as close possibe to the crankpin to lower the crankcase volume.

Lower volume gives a better pump of the fuel through the transfer channels resulting more bottom power.

Yes, I've modified a few backplates by drilling a hole in the center and connecting 2 bypass holes in the top. Seems to make a difference in throttle response, maybe a little more top end.

Can anyone shine some light on performance between the novarossi 9886, 2052, and 2006? I'm a fan of the 9886 top end power but was curious about the newer pipes? Thanks

Need advice for which motor to get for onroad. Coming from GT and offroad back ground. Mito, Keep-on. or Flash. I can get all for the same price. Which one works the best?

My friend Dana Smeltzer ran a Mito at the GLC, I believe. If you run at the new Steel City track, the Mito or the Mephisto would be good choices from the Nova Rossi line.