I think I cooked my evo. .46 today I was running 2 of them in on a Defiant when the rear engine started knocking and quit.I leaned it out but backed it back down I thought was enough,it now has no compression.........I took it apart and it looks new but no compression.Would a few seconds lean cook it?I guess I need a new sleeve and piston.Both engines I bought at a swap meet as new and they where new as far as I could tell.

I think there are two different ones?

46NT

46NX is the current one

I don't think they made any significant changes. I bought one of the early models, and 6 new ones last year for a part time job. The only thing I noticed is that my engine squealed when turned it over by hand the first time. The others don't have as much pinch, imo. I've run 3 of the new ones, and I did notice one seems far and away more powerful than the others.

The high speed needle valve knob has a pressed pin as a stop instead of the original collar. I like this method better because that pin grinds down easily.

I must not be the only one that this happened to because Horizon has the piston and sleeve back ordered.I did'nt think about it being the rear engine so it may not got enough air to cool it setting still.

No way to tell about the shortage as to whether it is due to production runs in China, a high number of bearing failures, etc. The prices are sure good though. Have you tried any other places that may have them in stock?