Proper break in of your engine is an important step in ensuring you have an engine that is easy to start, runs well and lasts a long time. The break in process if done correctly takes three to five tanks of fuel and will require one to two hours of time.
The object of the break in period is to give the engine parts a chance to wear themselves in, to mate to each other if you will. Most Nitro engines are of a lapped piston and sleeve design. That means that the sleeve bore gradually becomes smaller as the piston moves up. At TDC the piston is pinched in the bore which forms the seal to keep fuel and gases from getting past the piston when the engine is up to its running temperature. If the piston gets worn down it will not seal correctly and the engine will prematurely require an overhaul. The piston can get worn down quickly if the engine is not brought up to temperature because the sleeve will not expand and the tight fit will cause the piston to wear faster. The break in process is done to try and get these parts to mate togeather with the least amount of friction. Once the break in is done the parts will have mated themselves to each other and the tolerances will be better maintained.
The break in consists of heat and cooling cycles. The object is to get the engine hot enough for the sleeve to expand and the piston to seat itself with the least amount of wear. If you have a temperature gun you want to watch the temperature of the engine it should run at least 190 but less then 250 degrees. 250 degrees or higher means it is running to lean and you need to adjust the mixture. We use a temperature gun and try to keep the temp around 190-230 during break in. Temperatures will vary with location, humidity, outside temperature etc.
First off it is important to have a fully charged glow plug ignitor when running the engine for the first time. You should also be sure you have fully charged batteries in the controller and vehicle. Also don't forget to fill the fuel tank and leave the body OFF of the vehicle! Another good idea is to put a mark on the flywheel when the engine is at BDC so you can easily move the piston to this spot.
You should read any manuals that came with the vehicle first, especially if this is your first nitro powered vehicle. The engine should be ready to run from the factory. You should not have to make any adjustments before starting the engine. When you are ready to start the engine for the first time, first turn on the controller, then turn on the receiver on the vehicle. Make sure everything works, steering servo, throttle servo. Most controllers have a trim adjustment that lets you trim the servo's. Make sure the throttle trim does not have the throttle open to far.
Next prime the engine. Without the glow plug ignitor attached pull the starter a few times (2 or 3) and watch the fuel line, you should see fuel being pulled into the engine. Don't overdo it or you will flood the engine. If no fuel is moving through the fuel lines then put your finger over the muffer exhaust and try again. Remember don't over prime or you will flood the engine and possibly lock it up. If the engine does get flooded remove the glow plug (watch you do not lose the sealing ring), turn the vehicle upside down to get the fuel out of the engine.
Once the engine is primed attach the glow plug ignitor to the glow plug and start the engine. Note: If the engine does not want to start, before you adjust anything on the engine try using the trim on the controller to open or close the throttle 1/16 to get the engine running. See owners manual for how to start your engine. If this is the first time the engine is run leave the glow plug attached and let the engine run for a minute or so to get everything warmed up then remove the ignitor.
With the engine running and warmed up, slowly rev the engine up to about 1/4 throttle for two seconds and watch the exhaust. (vehicle should be on a stand when you do this) If there is a nice plume of bluish smoke coming from the exhaust it means your mixture is set correctly. If there is no smoke or the smoke is light white it means your mixture is too lean and you need to adjust the air/fuel mixture needle a 1/16 turn only to the rich side (usually counter clockwise) then repeat the 1/4 throttle run again. Do this until you have a nice plume of bluish smoke coming from the exhaust. The fuel is the lubricant for the engine if the engine is running lean it will get too hot. A good quality fuel is important also.
Once you get the blue smoke coming from the exhaust put the vehicle on the ground and continue to run this 1st tank of fuel out not going over 1/4 throttle and not for more then a few seconds then braking. This is a good time to practice your figure eights...Try not to let the tank run completey dry, when you notice it is almost empty pinch the fuel line to shut the engine off. Note that if the engine stalls when you let off of the throttle try braking to a stop and then slowly releasing the throttle for this first tank (engine is probably running very rich and will stall easily) Let the engine cool for 10-15 minutes. You should NOT let the engine cool with the piston in the TDC position. You should always try and keep the piston in the BDC during the cooling down periods. This should be done to keep the sleeve from contracting around the piston while cooling.
On the second tank of fuel slowly increase to 1/2 throttle for 2-3 seconds then slow down. Do this for the whole tank of fuel. Again when the tank is empty let the engine cool for 10-15 minutes.
On the third tank you want to run at half throttle for 3 or 4 seconds then slow down. You may notice sometime during this run that the engine is idling faster and the vehicle wants to keep movingl at idle. This is a pretty good sign that the engine is loosening up and breaking in. You will have to make an idle adjustment 1/16 turn then do a few 3-4 second 1/2 throttle runs and check how the idle is. If necessay make SMALL idle adjustments (1/16 to 1/8 turn max) until the vehicle remains still while at idle. Again once the tank is empty let the engine cool for 10 minutes or so.
On tank four you are ready to go to full throttle for 2 or 3 second bursts then brake. Accelerate smoothly and don't stomp on it, yet.. After this tank the engine should be just about ready to go.
Tank five smoothly slowly accelerate to full throttle then hold it there for two or three seconds if you have the room, many do not. Run the tank normally with a few seconds of slowly accelerating to wide open throttle every three minutes or so. When this tank is gone let the engine cool down. Your engine should now be completely broken in. And it should be ready for a long life with less misery for you.
You could now tune up the engine to give better performance, but remember a little blue smoke is a LOT better then none or white. Don't lean out the mixture so much as to have very high RPM's but no blue smoke. This means the engine will run too hot and will ruin itself becasue of lack of lubrication. The blue smoke means the engine is getting enough oil to lube itself.
Taking Care Of Your Engine.
Once you are done running your vehicle you should do after run engine maintainance. This is pretty simple and will keep your engine and you happy for a long long time. It's a simple three step process. 1. With the air filter ON clean the outside of the engine especially the cooling fins. 2. Then clean your air filter and add after run oil to the engine. I've used Marvel Mystery Oil for years in all my model engines. A few drops into the carburator, turn the engine over once or twice and you are done. Also there are special RC Vehicle after run oils on the market that you can purchase and we do sell some on our web site. 3. Another good idea is to NOT let the piston sit at TDC when it's sitting cooling down or if the engine is not going to be run for long periods of time. The reason being that when the engine cools the metal could contract enough to pinch the piston. Then the next time you go to start it you could score the piston and or cylinder walls. Or if it's stored with the piston in the TDC position the oil could drain down and the piston and cylinder becomed dry where they meet. Then you you go to start it you could damage the piston and/or cylinder walls. Doing these maintainance items faithfully will keep your engine happy and a happy engine is a good engine....
When you have a new vehicle another good thing about breaking in the engine is that it lets you get used to driving the new vehicle. So it helps break in the driver too letting him/her gain confidence without having to go full out right out of the box. Especially helpful for new drivers
NOTES: There are as many ways of breaking in an engine as there are engines and drivers. This is the way we do it. Some say engine break in is not really needed just take it easy for awhile. Others say go for it right out of the box, no break in required.
We have found that engines that are broken in on average last longer run better and cause less headaches then those that were not. Less tinkering with needle valves etc. Of course taking care of the engines after running them makes a big difference too.
We highly recommend engine break in, and the use of some type of after run oil and keeping the engine and the rest of the vehicle clean. RC engines and vehicles can be a substantial investment, takeing care of them insures you get the most out of them both money wise and fun wise.
Shopping Cart
