In terms of motorcycle, overhauling refers to dismantling the engine completely, inspecting it and replacing the necessary components. Generally, new engine doesn't need overhaul work. If the motorbike gone through 10-15 years, its good to do a overhaul work. It is generally done to maintain the engine in good shape. Here, overhaul work is generally carried out before FC work or if the motorbike face any problems. But, regularly we have to do overhaul work based on kilometers or years. Here in this post, we'll discuss something about engine overhauling and why it is done.
When a engine is overhauled, few things are done to maintain the engine in a good condition. Basically, upper and lower half of the engine is dismantled and reconditioned. Components like connecting rod, piston, bearings will be inspected and replaced. Cylinder sleeves will also be inspected and re-bored to make sure that the piston rings do its job properly. After that, everything is assembled back together and engine's life will be restored back to the good condition. There are several reasons for the overhaul work to be done. Let's see them one by one.
Time
If you are having a motorbike for more than 10 years, its better to overhaul your motorbike's engine. Because, as we know, there'll be number of moving components inside the engine. As you use it regularly, the moving components will undergo wear and tear. If this happens more especially between piston and cylinder, motor oil leaks into the combustion chamber producing black smoke, oil deposits will be formed and cause irregular combustion. So, overhauling work ignores these kind of problems completely.
Damage in piston rings
If piston rings are damaged, during the movement of piston, engine oil escapes via piston rings and enters the combustion chamber and it burns in the combustion chamber with fuel air mixture. This produces black smoke and all the oil sludge will be deposited inside the exhaust pipes, valves and in header pipe. You can easily find out this by just inserting your finger in the exhaust end pipe. If you see sludgy black deposits, you need to recondition your engine. If you tend to ride continuously, you can expect loss in mileage and lubrication in cylinder wall will be affected.
Bearings
Moving parts are connected to bearings as they move freely and they are lubricated by engine oil itself. Bearings are built to withstand more kilometers and to sustain in hard conditions. Even though, when the engine runs with poor oil quality or with no oil, it boosts the bearing to wear more. If this happens, clearance will be created and this leads to shake in the bearings. You can identify this easily by hearing weird engine noises. At this condition, you have to overhaul your engine and replace the bearings.
Engine seizure
If your engine is seized without oil or low quantity of oil, you need to overhaul the engine. Though it makes you to spend more money, you have to do it to bring your engine back to life. In this case, without oil, piston will seize in the cylinder by metal expansion due to heat. New piston and cylinder kit have to be installed or you can rebore your cylinder. Every manufacturer will have another two standard dimensions for bore. You have to rebore according to that and replace the piston with respect to the new bore dimensions.
Compression
In another post, i've explained about how to check the compression of the engine. Remove the sparkplug and just insert your finger in the plug sleeve. Make sure that you are not reaching till the end. Try to start the bike. If you hear the hissing air sound, there's compression. If there's no compression, you have to inspect the parameters related to compression. If the gasket is damaged, its hard to find it out. For that you have to dismantle your engine and find the source of compression loss.
You have to be careful while doing overhaul works. Because, if you forget to assemble any small part, everything fails. Experienced person can do it without any errors. If you fail to align the gasket properly, compression will leak and oil passage could block. If you fail to install dowel pin, bore will not align properly. So, you have to be careful while doing overhauling work. If you don't have any experience, you can head for authorized service center and its very important to do overhauling works for old engines.
When a engine is overhauled, few things are done to maintain the engine in a good condition. Basically, upper and lower half of the engine is dismantled and reconditioned. Components like connecting rod, piston, bearings will be inspected and replaced. Cylinder sleeves will also be inspected and re-bored to make sure that the piston rings do its job properly. After that, everything is assembled back together and engine's life will be restored back to the good condition. There are several reasons for the overhaul work to be done. Let's see them one by one.
Time
If you are having a motorbike for more than 10 years, its better to overhaul your motorbike's engine. Because, as we know, there'll be number of moving components inside the engine. As you use it regularly, the moving components will undergo wear and tear. If this happens more especially between piston and cylinder, motor oil leaks into the combustion chamber producing black smoke, oil deposits will be formed and cause irregular combustion. So, overhauling work ignores these kind of problems completely.
Damage in piston rings
If piston rings are damaged, during the movement of piston, engine oil escapes via piston rings and enters the combustion chamber and it burns in the combustion chamber with fuel air mixture. This produces black smoke and all the oil sludge will be deposited inside the exhaust pipes, valves and in header pipe. You can easily find out this by just inserting your finger in the exhaust end pipe. If you see sludgy black deposits, you need to recondition your engine. If you tend to ride continuously, you can expect loss in mileage and lubrication in cylinder wall will be affected.
Bearings
Moving parts are connected to bearings as they move freely and they are lubricated by engine oil itself. Bearings are built to withstand more kilometers and to sustain in hard conditions. Even though, when the engine runs with poor oil quality or with no oil, it boosts the bearing to wear more. If this happens, clearance will be created and this leads to shake in the bearings. You can identify this easily by hearing weird engine noises. At this condition, you have to overhaul your engine and replace the bearings.
Engine seizure
If your engine is seized without oil or low quantity of oil, you need to overhaul the engine. Though it makes you to spend more money, you have to do it to bring your engine back to life. In this case, without oil, piston will seize in the cylinder by metal expansion due to heat. New piston and cylinder kit have to be installed or you can rebore your cylinder. Every manufacturer will have another two standard dimensions for bore. You have to rebore according to that and replace the piston with respect to the new bore dimensions.
Compression
In another post, i've explained about how to check the compression of the engine. Remove the sparkplug and just insert your finger in the plug sleeve. Make sure that you are not reaching till the end. Try to start the bike. If you hear the hissing air sound, there's compression. If there's no compression, you have to inspect the parameters related to compression. If the gasket is damaged, its hard to find it out. For that you have to dismantle your engine and find the source of compression loss.
You have to be careful while doing overhaul works. Because, if you forget to assemble any small part, everything fails. Experienced person can do it without any errors. If you fail to align the gasket properly, compression will leak and oil passage could block. If you fail to install dowel pin, bore will not align properly. So, you have to be careful while doing overhauling work. If you don't have any experience, you can head for authorized service center and its very important to do overhauling works for old engines.