axial .28rr carb problems

[86toy]

i have a axial .28rr that i cannot get to tune i have tried everything i know including sealing the motor with rtv and also bought a seal kit for the carb and cleaned it out and installed the new seals. i can get it to run great a full throttle with the high speed needle and with the low and mid at factory settings it acts like it's lean at idle (revs really high after a high speen run and overheats) if i richen up the low end then it falls on it's face from a start but it doesn't overheat or rev high after a high speed run. it seems to me like an air leak somewhere. i spent 2 tanks of fuel on this the other day playing with the adjustments and just can't get it. their isn't a gallon of fuel through this yet so i know it's not worn out. and i'm not new to this i have been messing with these things for years. so what i want to know is does anyone know of another brand carb that will fit this engine? or some kind of idea what my problem is? i'm running byrons gen2 20% fuel and a axial med. cold turbo plug. and it's in an aftershock if that makes any difference

thanks,
Mark

 

[Scrogg]

The HPI K4.6 engine's carb will fit it but it's made by Axail too so it's the same thing basically.
The STS .21 to.30 carbs fit Axials as well, but they are some of the worst carbs on the market.
You either have a leak or you are leaning the HSN too much and overcompensating by richening the LSN.
Those .28rr's have a rep for running hot, 280F-300F.
The best advice I can give you if you are sure there is no leaks, is to first replace the crappy front bearing in that engine. Buy a good double sealed front bearing from Boca or find a Mach .26 front bearing. Either will work. The bearing size is 7X19X6mm. Switch fuels to Byron's 30% Pro Blend and retune.
What pipe are you using? I hope it is not the Aftershock muffler. Try a Losi HT or HS pipe on it.

 

[86toy]

i have the losi ht pipe. i tune by starting at factory settings wich is very rich on the hsn. once i get good top end then i start to mess the the low needle in all reality i shouldn't even really need to touch the low and mid needle much. i'll try the front bearing and i was also thinking of trying a new fuel tank i have heard the primer in these tanks are known for leaks

 

[Scrogg]

Yes the fuel tanks on them are prone to leaking. you can remove the primer and fill the hole with silicone. as far as the LSN, ALL engines need this adjusted. The MSN no, leave it at factory.

 

[86toy]

i understand that all engines need the LNS adjusted some but this acts like it's WAY out at factory settings and it should be at least close i know it was when the motor was new. are the HPI carbs 3 needle?

 

[Scrogg]

They are the same except for the placement and the HSN plastic adjuster is not there on the HPI carb.
I have had to richen past factory settings on many an engine. Listen to the engine and give it what it wants.
Axial claims flush on the LSN setting. One of mine required the LSN to be out past flush. Poor manufacturing tolerances are to blame. I even tried 3 different carbs, different exhausts, different fuel tanks and put the engine on different cars. Hell I even replaced the block and bearings! Same results on that particular Axial. It always ran warm but it was still running with tons of pinch 5 gallons later.