Among engine parts, the crankcase cover and cylinder head cover are probably the parts that are most often viewed on a daily basis. Oil leakage seepage is a cause for concern, which is why, when those parts are removed, the gaskets should be installed, and the old gaskets should be treated and cleaned thoroughly.
Here, let's focus on the "points to be concerned about" when restoring the head cover of a Kawasaki middle 4-cylinder engine.
Shut off with liquid gaskets in combination
The tightening and restoring of the head cover must also be taken care of in the Kawasaki middle. The rubber cam end plugs must be replaced with new parts when disassembling and reassembling. Oil seepage from this part is common. Oil seepage from this part is common. The sealing part of the cam end plug has a silicone seal. The sealing section of the cam end plugs should be coated with a silicone liquid gasket, but apply it thinly and evenly to the cylinder head side, not to the rubber plugs. It is not necessary to apply it thickly, but it is correct to apply it thinly and evenly.
Oil leakage seepage point end plug
Since it was also right after the head cover was cosmetically redone to crystal paint specifications, the head cover gasket that was replaced at that time was reused. To prevent damage to the gasket, the old liquid gasket was cleaned with gasoline to wash out the old liquid gasket, and a new liquid gasket was used with the new gasket. The four head cover bolts, which are tightened through the cam end plugs, were tightened with a liquid gasket applied to the threaded portion. In many cases, engine oil rises up through these threads by capillary action, causing oil leaks.
The order of tightening the head cover is to tighten it gradually from the inside to the outside. The tightening torque was 12 Nm. Be careful not to over-tighten = over-torque.
Replace ticking hardened rubber parts with new ones.
Begin restoration of the air box. We often notice the deterioration and hardening of the inlet pipe when we do things like overhauling the engine waist and adjusting the tappets. Since they are often stiff and difficult to install and restore, we replaced them with new inlet pipes. It would be a good decision to replace it before the genuine part is lost. There are inner and outer inlet pipes, and the outer inlet pipe is set first. If the air funnel that goes inside the plastic case is crushed, it will cause intake resistance, which is not good. Check the work progress while making sure that the pipe is in good condition. After attaching the two outer inlet pipes, fix the two inner inlet pipes. If the inside is installed first, it will be impossible to visually check the installation status of the outside. Also, the inside is easier to install and less likely to be assembled incorrectly.
After assembly is complete, start with a compression check.
After restoring everything and checking the engine oil level, I disconnected the spark plugs, connected the booster cable to the battery, and turned the cell starter switch. The compression pressures for each cylinder were all the same data. Incidentally, this engine had undergone a bore up + combustion chamber modification, and to be honest, I was somewhat concerned. When you build a bolt-on kit, it is still safe, but since the engine had been bore-up based on our original idea, we were worried. The standard compression pressure for a normal engine is around 10-11kgf/cm2 (1000-1100Kpa) when cold, but this tuned high-compression engine showed 14kgf/cm2. We hope you will check the preceding report separately for the tappet adjustment procedure and know-how.
POINT
Point 1 - When incorporating gaskets, consider using liquid gaskets as well!
Point 2 - Rust-prone threads and bolts require countermeasures
Point 3 - Check the current compression condition before starting the engine.
There are tricks and know-how for any kind of work.
Here, we are assembling the twin-cam head cover of a Kawasaki middle 4-cylinder, and know-how also exists when restoring this head cover. Among the procedures in the normal assembly, the work area is the removal of dirt and surface preparation of the head gasket assembly surface. Old liquid gaskets can be cleaned more quickly with gasoline than with parts cleaners. For single parts, it is possible to soak and clean, but for large parts such as cylinder heads, it is better to soak a rag with gasoline and press it against the stained part, then wipe it off with the rag when the gasket is soaked with the gasoline. Also, when reusing a used gasket or using a new gasket, a liquid gasket must be used in key places. It is never necessary to apply a thick coat, so be sure to spread it thinly.
Some models have points where oil leaks and oil seepage symptoms are more likely to occur than others. In the case of this Kawasaki Middle, oil leakage from the area around the half-moon rubber plug at the camshaft end seems to be surprisingly common. This is because engine oil rises up through the threads of the bolt that tightens through the rubber plug by capillary action. When tightening this cam end plug section, it is said that it is a good idea to clean the threads with parts cleaner and then apply a silicone-based liquid gasket to the threads. This method was learned from a direct Kawasaki mechanic who has maintained many Kawasaki motorcycles.
Once the head cover is restored and the carburetor is restored, let's measure the compression pressure of each cylinder. In the case of a multi-cylinder system, it is important that all cylinder compression pressure data be consistent, whether it is two, three, or four cylinders, before the compression pressure values are known. If the pressure data is not consistent, the explosion balance will be off, and stable idling and acceleration performance will not be obtained.
For an engine that has just been assembled, if the numerical data for all cylinders are within ±5%, it can be considered a measurement error. The compression gauge is one of the special tools that the Sunday mechanic should own because it is easy to use when judging the condition of an engine that has been run over.
