How to tune an engine.

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lillightingboy21

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Quote from nitroaddict,

"In case you like to adjust your engine to optimal settings this is the route you can follow."

"First close the high speed needle and then open it 3 full turns anti clockwise. This will do generally for all brands of engines."
"Press the engine against the starter wheel and choke the engine by closing the exhaust for about 4 seconds. This is to assure that the empty fuel line is filled with fuel."

"Now connect the glow-plug igniter and start the engine without opening the throttle. If the engine does not start, turn the stationary (idle) screw by 1/8 turn steps (clock-wise) until the engine fires up."

"Now if the engine is running at stationary (idle) speed OK, check if oil splashes and smoke are coming from the exhaust.
If not! Open the bottom speed needle by 1/4 turn steps until it does. If it is running richer (the engine stalls with a rumbling sound) turn the idle speed screw clock-wise until the engine runs stationary (idles) OK. Again check if oil splashes and smoke are coming from the muffler. Do not touch the high speed needle yet!
Now, let the engine warm up first to about running temperature of 90 degrees Celsius."

HIGH SPEED
"Try to run the engine at average speed on the track. We are not yet looking for the clean rev up of the engine we only like to adjust the top speed."
"So it might be that the engine is going from idle to full speed with a 4-stroke rumbling sound we take care of that later!
If the engine is not running rich (4-stroke), no smoke and no rumbling sound, open the high speed needle again by 1/2 turn steps (counter-clock-wise) until it does."
"In all cases smoke should leave the muffler when the throttle is opened fully."
"Now close the high speed needle in 1/8 turns steps clock wise between each lap until it sounds right at speed and still smoke is leaving the muffler."

BOTTOM SPEED
"If the engine is running stationary (idle) for 5 seconds and the throttle is opened fully the engine should pick up rpm's without any rumble or hick up."
If it tends to rumble close the bottom screw by 1/8 turns steps (clock-wise) until it picks-up OK.
"If it tends to hick up (grasping for air) then open the bottom speed needle by 1/4 turns steps (anti clock-wise) until it rumbles again."
"Then close the needle by 1/8 turns steps (clock-wise) until it picks up rpm's OK.."
"Still check for the oil splashes and smoke from the exhaust. Keep checking the temperature of the engine and smoke trails coming from the muffler."

IDLE SPEED
"When adjusting the BOTTOM SPEED needle it might be needed to change the idle speed too as the BOTTOM SPEED is of influence of the IDLE SPEED needle."

"During engine settings check the engine temperature for abnormalities "

"TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS"

"TIP 1 ! The break-in period is 80% the key for a good running engine and a long lifetime. Try to stay below all maximum settings of the engine performance. If you are just running your car for fun, then be sure that the engine is running always at a richer setting."
"Try to warm up the engine for 2 minutes minimum by running the car at medium speed (rpm's) before asking the maximum power from your engine."

"TIP 2 ! When your engine was running fine before and it does not want to start, then this is the golden rule. Open the throttle fully."
"Start the engine without connecting a glowplug igniter for 3 seconds. Lift the car and then close the throttle. Now put the glow igniter on and the engine should start, easily. If not check for fuel, defective glow-plug or whatever. But do not touch the needles. Only minor changes (all within a 1/2 turn) could be needed if the external circumstances are changed. A good running engine, does not need frequent needle changing."

"TIP 3 ! Always check the engine temperature frequently, by putting some spit on your finger and then on the cooling head. If it does not evaporate the engine temperature is around or below 100 °C. You may close the high speed needle a little if required. If it stays for 3 to 4 seconds the temperature is OK. If it evaporate direct, then open the high speed needle until the temperature goes down."
"An engine temperature system is a nice feature and can prevent premature engine failure due to overheating."

"TIP 4 ! After using your engine these are the things to do:
Remove all fuel in the engine and carburator by taking off the fuel line and let the engine run until it stops. Then put some after run oil in the engine and run the motor for 3 seconds on the starter box so the oil is spread inside the engine well. This will prevent rust building up inside the engine if not used for a long period."

"TIP 5 ! Use a good airfilter."
If you disagree with these mothods post yours.
Nick
 
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Is it ok to adjust/tune the engine when its running? My manual said make adjustments with engine off. I have a hpi rs4 3 evo.

Thanks :smart:
 
You mean you're supposed to shut the engine off to adjudt the needles? Wow learn something new every day. I mostly adjust while the engine is running and have not had eny problems. I'm not talking changing the setting from break-in to running settings but an 1/8th of a turn here, 1/4 turn there and no problems.
 
Ya i never have had a problem with tuning while the engine was running. That is the first time that i have heard that you should shut off the engine before tuning. But all of us usaually leave the engine running while tuning the needles. If you hae any more questions about tuning please help your self to asking those.
 
There is no problem for tuning it while its on but when you do:

1. The adjustment will not function right away: this means you will have to rev it alittle each time you change a setting.

2. When you do get it tunned perfect, stall it, then try to start it up. If you can start it up, sweet, if not, then thats another reason you shouldnt tune when engine is on.

3. Untuned engines tend to stall when you rev (that means that 1'st reason wont work) and becomes a hassle. If you can't rev your engine when you tuned it runnig, then............. everything goes wrong.
 
wtf thats a new one on me tuning while the engine if off lmfao
 
The only time I do anything when the engine is off, is when someone brings me a car they bought used and know nothing about. Then I check throttle/brake servo travel, adjust the idle screw, and set the needles to about the factory settings.
I let them pull the cord or spin the starter while I tweak the LSN till it runs. When it's running, and idling at proper temp, I trigger the throttle up and down and tweak the HSN while they hang on to the back bumper. Aside from black skid marks on the work table by the track, I have no problems doing it this way. By the time it's on the ground, it's ready to rip. Works for me, every time.
 
great thread ...now i gotta remember all those tips for future use.
 
Hi still pretty new at this forum thing.
I have written previously about a Power Racing Swift 1/8 nitro buggy that i have had a lot of troubles with.
I threw a rear diff and replaced the centre diff when it turned a little sloppy, lots of the anoying things mostly simple and obviously i have learned a lot.
I really get tired of break downs i havent run more than 2 litres of the 20% yet and continue to have break downs. When the buggy is running it is very responsive and lots of fun. Today when i took it to a development site for a run it had used approx 1/3 of the tank when it laboured strangely and stopped.

You guessed it when i pulled the end off the engine the main bor big end bearing is gone luckily the crank dosent appear damaged,I think that the conrod and bearing will be the only damage.The engine still has free movement other than the main and rod.

The Manufacturer of the engine SH 21 claim that it is a very reliable and durable unit. I run after run in the engine after use the engine always has a good stream of smoke however i have experienced a fatality.
Ps I ran the engine in on 15% for approx 8 tanks at idle.

Do you think the engine failed because the fuel mix was to lean i ran at around 2 1/2 turns on the carb main jet give or take for the conditions etc. will i be able to replace the rod and main bearing provided the rest of the engine is good.

I am over the Swift and the unreliability issues. Please some advice re the Buggy Dramas
 
Thank for the post it will help me a lot
 
actually there are 2 mistakes on that visio document. the temps and the < and > need to be switched. i will fix it and make a pdf out of it if you want.
 
I read all of that lol, you can never read too many threads about tuning!
 
Well, I thought my himoto buggy with sh.18 was running fine, but no. (This is my first nitro and it has a 2 speed diff) I never realised until today I was never getting to 2nd gear even with full throttle in a local railway station car park. I have to run it with the hsn only 1 turn out or just under. Also leaned the lsn a quarter turn as I was getting bogging at low power before the thing took off properly. This is probably the reason I never had enough room to get to 2nd gear. Also now when I punch the throttle the front end of the buggy visibly lifts up which it didnt do before.
I am getting a nice trail of exhaust even with the hsn 1 turn out.
 
I think they say not to tune engine while its running because of safety reasons, but you know you can and need to tune while engine is running.
 
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