R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 02-25-2008, 03:50 PM   #1
Tech Rookie
 
Join Date: Feb 2008
Posts: 5
Default new to nitro....

hello people, fellow racers...my background is this. i raced back in the early 90's, all electric...traxxas Hawk, losi JRX-T, ect. then one day in 96' i sold it ALL. now i come here to ask this....i just bought a Losi 8ight T two days ago, can someone please inform me the best way to break in this motor being my first nitro? i can read the book it came with but is thit the best way, 1 tank at idle? 2 tanks at idle? then circles and easing in and out of full throttle? last thing, the dude at my LHS sold me odonnell 30% fuel? should i return it? i need 20% right?


thanks for reading and maybe you can help
mental_one is offline   Reply With Quote
Old 02-26-2008, 05:34 AM   #2
Tech Master
 
petevette's Avatar
 
Join Date: Sep 2007
Posts: 1,243
Trader Rating: 13 (100%+)
Send a message via Yahoo to petevette
Default

I find that the best way to break in an engine is to do 2 tanks at idle, but let the engine cool off between tanks. Make sure you engine is not at top dead center when you shut it down between tanks. The piston has to be at the bottom of the sleeve. After two tanks at idle, using a very rich setting, I put 4 more tanks using figure eights or circles and using 25%, 50%, 75% and 100% throttle on each tank as the engine starts to breakin. Again, let the engine cool down between each tank and check the piston to make sure it is at the bottom.

Use a head shim to reduce the compression a little during breakin. After your sixth tank total, always making sure to check temperature to be under 210 degrees, I run about half a gallon through it before I start to lean it out. After half a gallon, I then go to a race tune. 30% fuel should be fine for breakin. Make sure you engine is at bottom dead center each time the engines shuts down to make sure the piston doesn't stretch the sleeve up top and you lose compression.

Also, you can do a search on this forum for engine breakin and I am sure you going to get tons of info.

Hope this helps
petevette is offline   Reply With Quote
Old 02-26-2008, 05:47 AM   #3
Tech Master
 
Join Date: Sep 2007
Posts: 1,080
Trader Rating: 5 (86%+)
Default

Just wondering, roughly when does the 'pinch' dissapear? And there are some blogs and break-in method that contradicts the 'first tank at idle'...is the idle method the best way to prolong the engine's life? I'm asking because i would love to try a different method for my next engine. Thanks guys
razor_clawzz is offline   Reply With Quote
Old 02-26-2008, 07:45 AM   #4
Tech Master
 
petevette's Avatar
 
Join Date: Sep 2007
Posts: 1,243
Trader Rating: 13 (100%+)
Send a message via Yahoo to petevette
Default

There is going to be more then one contradiction to what I said. If you ask 10 people, your going to get 10 answers. I have heard everything from using 6 tanks at idle to going full thottle on the first tank.

Your going to have to use your best judgment, but the method I described (heat cycle) is what I use and seems to work. I tried the 6 tanks at idle once and didn't get much run time from the engine. If your very conservative and dial in a very rich setting and keep it at 25% throttle, you can do less tanks at idle. You will probably see a reduction in pinch at about 1.5 - 2 gallons. Keep an eye on engine temp, you want to run it about 200 degrees - not too cold, not too hot.

Maybe someone else will chime in with a method that works for them for comparison. However, at the end of the day, you may want to pull your hair out with all the variations of breaking in a engine.
petevette is offline   Reply With Quote
Old 02-26-2008, 01:25 PM   #5
Tech Rookie
 
bte214's Avatar
 
Join Date: Feb 2007
Posts: 7
Default

If you ask 10 people you'll get 10 different answers. But who knows your engine best? Some random guy on the internet's method or the people who acctually made your engine? Read the manual and do it by the book. You'll be rewarded with a powerful engine with longevity.
bte214 is offline   Reply With Quote
Old 02-26-2008, 01:47 PM   #6
Tech Elite
 
mblgjr's Avatar
 
Join Date: Sep 2006
Location: AL
Posts: 2,175
Trader Rating: 86 (100%+)
Default

Most all modern RC manufacturers offer VERY detailed instructions compared to what they did 12 years ago...READ 'EM!

Losi is one of the best as well.

For general use and ease of tuning; it would be safer and slightly easier on yourself if you went and got 20% fuel; but 30% is fine as well. It would be best to add a .10mm head shim if you intend to run the 30%.

Prior to firing ensure all fuel lines and the tank are clear of debris. Check to make sure the glowplug and ignitor; as well as radio and receiver packs are all charged to save yourself any potential first-time-starting issues.

I personally prefer to run 1-tank very rich on the starter box. Wheels off the ground; with the engine very fat. Basically in a "high-idle" state; while s-l-o-w-l-y varying the throttle; not to exceed 50% (stay well below that actually).

Second tank run about 1/2 tank in the same manner; then shut down and allow the engine to cool. Run another 1/4 and shut down; then run the last 1/4 and shut down. Basically heat cycling the engine.

When the engine is new and you shut it down; make sure the piston is off TDC when it stops.

After the first tank and shut down; pull the plug and see how tight the 'pinch' is to gauge how much progress you've made compared to when you started.

After the 3rd tank you should be able to lean it down slightly and start making "parade" laps with the truck; with it still plenty rich where it slows/bogs when you dip into the main circuit.

Mostly; READ the mfg. recommendations and BE PATIENT.

Have fun while you're at it!
mblgjr is offline   Reply With Quote
Old 02-26-2008, 02:17 PM   #7
Tech Rookie
 
Join Date: Feb 2008
Posts: 5
Default

Word-for-Word Break in procedure:
The first three tanks of fuel should be run with the high and low speed needles notieably "rich" (see explanation below). There should be a slight sluggishness and thick smoke from the exhaust pipe. Run the 8IGHT-T RTR on a flat surface in an oval pattern. Ease into the throttle as you accelerate on the straight sections easing off as you approach turns letting the model roll through the turn before easing back on the throttle. This will allow you to get a feel for the steering response and handling characteristics of the truggy. You can also break in the engine by placing the truggy up against a wall or fixed object and allow the engine to idle through two tanks of fuel.

thats that...so it says i can run it on the 1st tank but ease into the throttle ect.
mental_one is offline   Reply With Quote
Old 02-26-2008, 02:30 PM   #8
Tech Rookie
 
Join Date: Feb 2008
Posts: 5
Default

"make sure the piston is off TDC when it stops".....what is this and why? thanks for all the help so far,
mental_one is offline   Reply With Quote
Old 02-26-2008, 03:20 PM   #9
Tech Master
 
petevette's Avatar
 
Join Date: Sep 2007
Posts: 1,243
Trader Rating: 13 (100%+)
Send a message via Yahoo to petevette
Default

The piston can not be at TDC, top dead center, because that is where the cylinder has the tightest pinch. If the engine stops or is shut off while the piston is at TDC then the sleeve will cool with the piston at top where it is tight. This will damage the sleeve. The piston must be at the bottom or where you don't feel any compression. That way when the sleeve cools and retains the pinch for good compression.
petevette is offline   Reply With Quote
Old 02-26-2008, 03:53 PM   #10
Tech Regular
 
Mugen MBX-5's Avatar
 
Join Date: Oct 2007
Location: canada
Posts: 354
Default

Quote:
Originally Posted by petevette View Post
The piston can not be at TDC, top dead center, because that is where the cylinder has the tightest pinch. If the engine stops or is shut off while the piston is at TDC then the sleeve will cool with the piston at top where it is tight. This will damage the sleeve. The piston must be at the bottom or where you don't feel any compression. That way when the sleeve cools and retains the pinch for good compression.
little clarification from a noob: i dont think it has to be at exact BDC, it can be anything BUT TDC. you can leave it like halfways and thats just as good.

as easy way to tell wether your TDC or not is to spin the flywheel with your hand, or if you have a pullstart, TDC is when the flywheel gets very very tight, if you keep turning it, that tightnesss will go away and it will be very easy to move from there... thats where you want it. never leave the flywheel at the point where its hard to turn because that means its at the top of the sleeve, which is bad.
__________________
I dont race. Please dont assume I race. I only bash around.

T Lawrence is a scamming scumbag

Tonys Screws l carolinasrc.com l spektrum (?)
Mugen MBX-5 is offline   Reply With Quote
Old 02-27-2008, 05:35 PM   #11
Tech Rookie
 
Join Date: Feb 2008
Posts: 5
Default

allright....i did 1st tank at idle, 2nd i ran it in a little circle but when i tried to ease into it, it didnt go any faster, just got louder so i didnt try to do that much on the 2nd tank. on the 3rd i messed with the high and low and it got a little better. the 4th tank.....

if i sat at idle for maybe 15 sec. then hit the gas it would take off!! then after runing at maybe 50% throttle it would start to bog down and me giveing it more throttle dint help?


this is all in the high and low right, (rich and lean), its not that i f'ed up the engine is it? sometime it would fly then 1 sec. later it would bog down


i know that i am a noob and i thank you guys for all the help,
mental_one is offline   Reply With Quote
Old 02-27-2008, 06:45 PM   #12
Tech Master
 
petevette's Avatar
 
Join Date: Sep 2007
Posts: 1,243
Trader Rating: 13 (100%+)
Send a message via Yahoo to petevette
Default

I think your engine is fine. Seems to be running very rich which is good right now. As you put more tanks on it and lean it out you should see a huge improvement on performance.
petevette is offline   Reply With Quote
Old 02-28-2008, 07:11 PM   #13
Tech Regular
 
lowey79's Avatar
 
Join Date: Dec 2007
Posts: 356
Default

Was it blowing smoke out the exhaust when it bogged? if so, you've got a nice rich mixture. If there's no smoke, you've gone a touch lean... go back to factory settings.

If you've run 4 tanks thru it, you can now start to lean it out. Start from the factory settings, start and run the engine to get it up to temp. Now turn the HSN in 1/8 turn (no more than this at a time) and run the car for half a tank using short bursts of throttle then back to idle. Then go in another 1/8 turn on the HSN an run for another half tank.... Continue doing this, slowly increasing the amount of throttle used untill your engine will rev up cleanly and make close to full power while still blowing smoke. It may splutter down low, but this is because the LSN is still rich.

You can now adjust the LSN in a little at a time untill the engine will accelerate cleanly and rapidly from idle.

Generally, as you lean the LSN, the engine will start to idle faster. This is normal, as the idle air gap screw is set a little wide to compensate for the rich mixture. Once you have the LSN set about right, the engine will idle high 10-20 seconds after a high speed run before settling down. Now adjust the air gap screw out to lower the idle to just before the clutch starts to engage and you're good to go.

If you go too lean on the low, the engine will bog as you hit the throttle. Rich it up a little to stop it bogging

If you go too lean on the HSN, the engine will run hot and bog or flame out in the high rev range. Richen the HSN 1/4-1/2 turn and retune for optimum performance from there.

Remember, small adjustments at a time, and it wont hurt the engine by running slightly rich.
lowey79 is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
LOOKING TO BUY RC NITRO TRUCKS, CARS, BUGGYS, ELECTRIC OR NITRO CASH IN HAND jd267 R/C Items: Wanted to Buy 26 09-06-2008 11:25 AM
WTTF: mini electric or nitro (nitro perfered) and also looking at all nitro deals.... xxx-ntad2 racer R/C Items: Wanted to Buy 3 04-25-2007 06:53 PM
XM Ready radio and Nitro Buggy to trade for Nitro Rustler or Jato RTR NewNitro R/C Items: For Sale/Trade 1 03-17-2007 10:38 PM
FS/FT Tmaxx, Nitro Rustler, Nitro RS4 Racer, Nitro RS4 RTR, Losi XXXNT RTR ChrisR40 R/C Items: For Sale/Trade 24 03-20-2006 02:47 PM
FOR SALE:Nitro 4tec, Hopped Nitro Rustler, Parts lot, Picco .12 engine, plus more!!!! feel my impact R/C Items: For Sale/Trade 0 08-05-2002 09:41 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 04:04 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net