Break-in(some details will vary from person to person, but the heat cylcing principle remains..)
1.) Take the glow plug out. Look down in hole, rotate flywheel to point where piston is at bottom-most position. Then, mark a notch or spot at say 12:00 on the flywheel(with a screwdriver, body reamer, whatever.. 9:00 is easier on a Savage maybe.. Just matters that you know the location of the notch on the flywheel which corresponds to the bottom position of the piston. Or, permanent marker maybe..) Then later you can just rotate it to that position and know where the piston is. During cooling the piston should always be at BDC - bottom dead center. Put the plug back in.
2.) Wrap head in alu foil, or sock. Or both. Might as well do both for starters if it's coolish out. SH engines (LRP, Losi, Dynamite Nosram, etc..) and other RTR engines (Force like the Savage X4.6 etc..) especially can be reluctant to get up to temp during break-in...
3.) Preheat engine with a cheapo hair drier to 200-225F. With the head wrapped I can get an engine to 200ish in about ten minutes with a cheapo €7 hair drier..
4.) Start engine once it's warm. See how it idles. Don't be afraid to blip it to keep it running. You want temps to get up to 200-225 for a few minutes, then shut it down, let it cool completely, then repeat. For the first tank you can let it idle with the wheels up in the air(propped on a box or something) - if temps get to that range just idling, fine. If not, I would plop it on the ground and run it in figure-8's very lightly til temps get up there. Max 1/4 throttle in slow pulls back and forth.. Once it's been at 200ish for a few minutes, shut it off. Rotate piston to BDC immediately. Leave it til it cools completely. Break-in for the first few tanks is boring.. Bring a magazine or book or yo-yo or something.. I do this cylcing of running, getting temps to 200-225, shut off and let cool completely with piston at BDC like 5-10 times with an SH or other non-high-pinch engine.. Getting it up to 200 though might not be easy.. So I usually end up having to blip the throttle a tiny bit.. Maybe even lean the HSN a tad.. Remember, it's all about the temps, and complete cool down at BDC.. This is "heat cycling"..
Once it's cooled completely after the previous cycle, preheat again, and repeat. From cycle to cycle you can extend the running time. Over the years I've become less particular about it - so that nowadays I do the first few cycles for more extended periods - like half tanks. From the third cycle, assuming temps are good, I might even do full tanks. You can do it how you want - the original OS heat cycling method was more precise - first small cycles, then slightly longer, but afaic it's just about the temps, being rich and well lubed, and getting fuel through it..
So yeah, I do that, going easyish for the first liter or two - i.e. no extended WOT bursts(probably not even anything of half-throttle for the first two liters - on a race engine anyway. For an RTR or basher engine you can probably go to town after 6-8 tanks..) After a couple liters are through, then I just floor it like I want to, making sure temps stay around 200-240... Some higher pinch engines like Go's and Alpha's might like it a bit higher..
You have to be a bit patient and somewhat cautious for the first few tanks, but in theory and principle I don't believe in babying engines.. Just heat cycle the first half gallon with temps in the right zone, then let'er rip...
As for tuning, just lean the HSN a tiny bit at a time - as in 1/12 increments til it gets more crisp. The idle gap has to be very small - like less than 1mm. As you close the idle gap the idle might go down. Counter this by slightly and gently leaning the LSN..
Extra tips for nitro would just be, don't floor it til it's like 170F or so.. That's about it really..
Last edited by HerrSavage; 04-03-2014 at 09:55 PM.