Due to the high temperatures in the exhaust and the combustion residues in the exhaust gases, the exhaust valve is certainly one of the parts that should be checked and maintained most frequently. Regular maintenance is not complicated and can save you from a lot of trouble.
The main problem is “only” combustion residues, which can stick to the outlet slide and around it and make the valve difficult to move. This problem occurs especially with restricted bikes with semi-synthetic oils, where the slide valve must be cleaned regularly even though it is not actually used when driving.
The maintenance and care actually consists only of
- Remove and Disassembly
- Check smooth running and function
I recommend maintenance of the exhaust valve at least twice a year, but after 3,000 km at the latest. To make this as easy as possible, it is recommended to replace the screws with stainless steel (A2) screws, no special strength is required. This saves trouble with stuck screws. The threads should also be lubricated with copper-based anti-seize paste or a separating paste. The screws are tightened with 10 Nm and under no circumstances are they “banged down”.
Cleaning of the outlet slide
Before removing the slider, the area around the slider must be clean to prevent crumbs from falling into the motor through the slotted hole.
For maintenance the gate valve is removed and carefully cleaned of combustion residues with a cloth, if necessary with a brass brush. If the part is left overnight in diesel, the combustion residues are usually very easily removed. Under no circumstances should a hard wire brush be used.
The clean slider must not show any cracks. Theoretically even a broken slider can’t get into the piston, because the slot is not deep enough, but a few defects on the sides are not enough to prevent this. A broken slider can cause engine damage.
Cleaning of the slot in the cylinder
The cleaned power valve should be sliding very easy inside the slot. If this is not the case, the slot needs to be cleaned.
The elongated hole on the cylinder can be cleaned with a round tube brass brush. You can set the piston to TDC and connect a vacuum cleaner to the exhaust pipe (the piston is set to TDC to avoid fuel mixture being sucked in by the carburetor, which gives an explosive mixture!) to draw air through the sliding slot. If you now brush the slot clean with a nozzle brush, the dirt will be sucked outside.
Make sure that no dirt gets into the motor through the slot of the slider.
When closing, the slide is accelerated into the slot by the spring and then hits the cylinder without any damping effect, like hammering with metal on metal. It is therefore advisable to replace the original paper gasket with another one so that the paper gasket dampens the impact. All you need is some sealing paper, preferably not too thin.
The replica gasket corresponds to the area of the metal on the cylinder, as shown in the following pictures:
In some gasket kits such a gasket is even included, but it is intended for the RAVE2 – but that doesn’t bother.