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OS .21 TM ultra hot

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O

Orph3o

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RC Driving Style
  1. Bashing
  2. Racing
Hi Guys,

I installed the OS 21TM in my revo.

Break in went bad, the HSN casing was unscrewed (didn't notice this) and so I had a major air leak during break in. Temps were skyrocketing before I could really get a grip on this. I always stopped before reaching the 300... found the problem fixed it and finished the heat cycle.

Since then, temps are always super high, even with a "conservative" tuning (meaning a lot of smoke, but decent performances).
Never had any "lean" symptoms (lack of smoke, engine bogging when WOT) even at high temps.

I sealed everything I could with proper sealant (the orange one), did everything by the book.
however, still have super high temps from time to time.
Added a second spring on exhaust manifold thinking it may move etc...
Did the whole engine with watery soap and blowing, not a bubble anywhere.

Last thing would be changing front bearing, but I have never did it, and am a bit anxious about this one :D

I am not a professional tuner, not a newby either... just in the "I know a couple things but could be better" kind of range.

What I find awkward is that HSN is pretty lean (if flush is factory, I am 1.5 turn in) however, LSN is super rich (1.5 out from flush).
Setting the LSN using pinch test.
Idle gap is set to 1mm.

so here is the question... is the engine crapped from bad break in?
I thought that with an air leak, I would have had lean symptoms...
I know you are not supposed to tune on temps, but it regularly goes into the 300, and I am not feeling comfortable with this.

Any suggestions?
I have already reset and retune from factory setting... HSN always WAY too rich, and LSN way to lean (less than a second on pinch test at factory default).

Thanks!

---------- Post added at 10:02 PM ---------- Previous post was at 10:01 PM ----------

Oh and everything is clear, driveline, tranny etc... I forgot to say.
 
MOrgan Sidewinder 25%
OS LC3 (Hot) plugs

Also forgot to say, gearing is 16/36. Thinking about adding two tooth on the spur...
 
How much fuel is through the engine? Is it still tight at TDC with the plug out? If it's still tight your break-in isn't complete and the temp spikes are from too much rpm too fast. I call it friction heat but once the pinch is mainly gone, the heat spikes should tone right down. I would set the idle gap for .5mm and re-tune from there, if it is broken in fully then you can follow my tuning guide in my sig. If you follow it word for word and the engine is still acting up then 1) it may still be too tight or 2) it has an air leak or something as a sound engine will tune perfectly with my guide.
 
thanks guy, will try that at the track. Break in is fully done (more than a gallon through).
 
Have you taken the carb completely apart? Wondering if with all the tuning you have frayed an o-ring causing it to give you an air leak. Or a torn one from the factory.

Might be worth getting an o-ring set and some associated green slime (AGS), tearing the carb down, cleaning everything really well, replace the o-rings, lubed with AGS, then seal the threads on the HSN and carb neck when you install.

That would be my next step.
 
Hsn lean with the lsn rich is called a false tune. You're running the hsn lean to compensate for the rich lsn.
 
I run an osp7 plug in my .21 vzb big block and it runs best on 30%, which is what the motor was broken in on. The idle is 1/8 richer and so is the bottom end, as is the main carb, and the trans * which I just blew up * was set for later shifts. Lots of minor tweaking to take place. Luckily i'm just a basher, and have a very well versed rc tech that lives by me and is breaking off to start/run his own store. I notice a difference from running 25% nitro /12% lubricante, it's extreme. Piston is always turned down @ turn off to defeat the heat disipation aspect. It took a good gallon to break in the motor and the factory plug didnt give me issues until after the tuning started taking place. I leaned the main carb 1/4 and the middle screw 1/8 rich and was fine, a few tanks and it pooped out and went with the osp7. With the starter box no more than 2-3 seconds and the truck is running and no issues.
 

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