Been playing with a few of my nitros and have 2 engines with similar issues that I cant resolve. I think I know my way round tuning by now but you never know. They both run sweet with wheels of the ground but when on the ground, they have a mid range bog. Tried different carbs, pipes, glow plugs but cant get rid. I can only think the piston sleeves are getting worn out, however I think one of them is fairly new. They start and restart when hot so no obvious issues. They run well initially for the first few passes from cold then the bogging starts.
Too many nitro Savages, nitro Hypers, brushless Savage, brushless Hypers, Xmaxx, some old Tamiyas for fun
Hmm, interesting Sounds to me like a mixture issue? But I also know you have some experience with them so shouldn't be that? Almost sounds like it is running out of fuel. And so when it is cold the engine is happy running a little richer (like having the choke on in a car) but then when it gets to operating temperature the mixture is just a bit rich around the change between low and high speed jets? I might try turning each a little leaner (one at a time and only a little) and see how it goes? But also I am sure you can tune them pretty well, not like it would be your first go with nitro. Can't think of anything else it would be but I never played with nitros that much.
Also gearing with the savage possible to be the issue? As it is a big and heavy rig if you geared it high maybe it just doesn't have the power. Not sure. Let us know how you get on.
I am a mad RC loving lawn mower racing lunatic with a desire for over-powered RC's.
I resealed the backplate while waiting for a bit of dry weather and some time. It didnt have any old rtv sealant so hoping that a small air leak maybe the issue, as the idle was also erratic. Had a quick run this morning and retuned from rich, so far it seems to run right. This was with last of the old fuel and now have some fresh 25% optifuel race. I've left the gearing as before and the performance is okay. Hopefully perseverance pays off.
Second run this afternoon and performance ok but idle is still erratic, going up and down. Will try another carb.