DS800X Rally Coolant Change & Cooling System Bleed

The DS800X Rally cooling system is a sealed pressurized loop with a small expansion (sub) tank, a single-speed cooling fan, and a thermostat that opens at 82 deg C and is fully open by 95 deg C. Per the official service schedule, coolant is replaced every 2 years regardless of mileage (or at the 24,000 km major service interval).

The job takes about 60 minutes including the air-bleed cycle.

Specifications at a glance

Item	Value
Coolant grade	G48-spec OAT (e.g. GLYSANTIN G48-24, BMW LSL coolant equivalent)
Mix ratio	1:1 with distilled water (50/50)
Coolant capacity (full system)	~1.5 L (workshop manual does not specify exact total - fill to MAX on sub tank)
Service interval	Every 2 years, or at 24,000 km major service
Thermostat opening temperature	82 deg C (+/- 2 deg C)
Thermostat fully open at	95 deg C
Thermostat valve rise	At least 7 mm
Water pump cover bolt torque	11 N.m (M6)
Water pump impeller installation nut	12 N.m (M6)
Thermostat cover bolt torque	11 N.m (M6)
Water/oil exchanger bolt	59 N.m (M20)

The G48 specification matters. The KEL800 engine workshop manual doesn’t explicitly call out a brand, but the engine is built on the same Loncin platform that uses GLYSANTIN G48-24 in its DS900X sister manual, and the seal materials and aluminium components are identical. Don’t substitute silicate-based “universal” coolants (most green or pink products) - the silicate accelerates water pump seal wear and can block the radiator passages over time. G48 is a hybrid OAT (organic acid technology) coolant compatible with motorcycle aluminium engines.

Never use tap water for the dilution. The minerals in tap water cause scale buildup in the radiator over time. Distilled water is widely available at supermarkets and pharmacies.

What you need

• 2 L of G48-spec coolant concentrate (some products come pre-mixed; if so, you need 2 L of pre-mixed)
• 1 L of distilled water (only if you bought concentrate)
• One new flat washer for the water pump drain bolt
• 10 mm socket for the water pump cover / drain bolt (M6)
• Phillips screwdriver for the radiator-area bodywork
• Drain pan (3 L+ capacity)
• Funnel
• Paper towels and rags
• Coolant disposal container

Critical safety check before starting

The engine and radiator must be completely cold. Touch the radiator cap with the back of your hand, then with your fingertip; if you feel any warmth at all, walk away and try again later. Hot coolant under pressure will eject through the cap opening and cause serious burns. The official Voge warning: “the coolant may inject or splash out and get [you] injured.”

Don’t trust the temperature gauge on the dash. After the bike has been parked, the gauge can read low even when the upper radiator hose is still hot. Touch the parts.

Procedure

1. Park and prep

Park on level ground. Open the centre stand. Engine cold.

Remove any bodywork covering the radiator cap and water pump (typically the right-side fairing and the lower belly section).

2. Remove the radiator cap

Slowly turn the radiator cap counter-clockwise. If you feel any pressure releasing (hissing), STOP and let it cool further. A genuinely cold system will release no pressure when the cap comes off.

Set the cap aside on a clean rag.

3. Drain via the water pump bolt

Locate the water drainage bolt on the water pump cover. It’s an M6 bolt with a flat washer underneath. Place the drain pan beneath it.

Loosen and remove the bolt. Coolant will flow out steadily for a few minutes.

Once the flow has fully stopped, install a new flat washer and refit the drain bolt. Torque to 11 N.m.

4. Mix the new coolant (if using concentrate)

Pour 1 L of G48-spec concentrate into a clean container. Add 1 L of distilled water. Stir gently. You now have 2 L of 50/50 mix.

If your product is already pre-mixed, skip this step.

5. Refill via the radiator filler neck

Using a funnel, pour the 50/50 mix into the radiator filler neck slowly. Stop when the level reaches the bottom of the filler neck.

Don’t install the cap yet - the system needs to be open during the air-bleed cycle.

6. Bleed the system

This is what makes the difference between a good coolant change and one that overheats two weeks later because trapped air kept the thermostat from sensing real coolant temperature. The Voge procedure is short:

1. Shift to neutral. Confirm with the dash.
2. Start the engine. Let it idle for 2 to 3 minutes. Watch the radiator filler neck - bubbles will rise as air works its way out. The coolant level will drop as air is displaced.
3. Snap the throttle 3 to 4 times. Just blip it - rev to maybe 3,000 to 4,000 rpm and let off. Each snap forces a slug of coolant through the system and helps dislodge trapped air pockets.
4. Stop the engine. Wait a moment.
5. Top up the radiator to the bottom of the filler neck if the level dropped during bleeding. It usually does.
6. Refit the radiator cap. Hand-tight, then a quarter turn with the cap tool / by hand. Don’t over-tighten.

7. Fill the sub tank

Locate the expansion / storage tank (visible through the bodywork). Fill with 50/50 coolant mix to the MAX line. Don’t overfill - the sub tank needs headroom for thermal expansion.

8. Verify after a real warm-up

Take the bike for a 10 to 15 minute ride that gets the engine to full operating temperature (you’ll see the cooling fan kick in at least once). Park, let it cool fully (overnight is safest), and check the radiator level.

If it’s dropped (it usually does as residual air finds its way out), top up with 50/50 mix. The expansion tank should also still be at MAX; top up that too if needed.

A second top-up after the first proper warm-up cycle is normal and not a sign of any problem. If you find yourself needing to top up repeatedly over weeks, that’s a sign of a leak (head gasket, water pump seal, or hose) and you need to investigate.

9. Reassemble cosmetics

Refit the bodywork.

10. Disposal

Used coolant is toxic to humans, pets, and wildlife. Pour into a sealed container and take it to a hazardous waste drop-off. Most municipal recycling centres accept used antifreeze for free. Never pour coolant down a storm drain or onto the ground.

Common pitfalls

• Skipping the bleed. Trapped air keeps the thermostat from opening at the right time, and creates hot spots that can damage the head gasket. The 2-3 minute idle plus throttle snaps is non-negotiable.
• Tap water dilution. Mineral scale builds up over years and reduces cooling efficiency. Distilled is cheap; just use it.
• Wrong coolant. Silicate-based “universal” coolants in green or pink will react badly with this engine’s seal materials. G48 spec or compatible is the rule.
• Reusing the water pump drain washer. Voge specifies replacement. The old washer has compressed and won’t seal as well; you’ll get a slow weep.
• Over-torquing the drain bolt. 11 N.m means 11 - finger-tight plus a touch with a torque wrench. The water pump body is aluminium and the threads strip with surprisingly little extra force.
• Forgetting to fill the sub tank. The radiator level alone doesn’t tell you the expansion bottle is full. If the bike runs hot after a coolant change, the first thing to check is whether the sub tank is at MAX.
• Refitting the radiator cap before bleeding. The system has to be open to the atmosphere during the bleed cycle. If you cap it, the air can’t escape.

Cross-reference

The KEL800 cooling system shares architecture with the KEL895 in the DS900X but uses different torques:

Spec	KEL800 (DS800X Rally)	KEL895 (DS900X)
Thermostat opening	82 deg C	83-87 deg C
Thermostat full open	95 deg C	95 deg C
Drain bolt torque	11 N.m (M6)	6 N.m (M6)
Water pump cover bolt	11 N.m (M6)	10 N.m (M6)
Water/oil exchanger bolt	59 N.m (M20)	(separate component on DS900X)

Both use G48-spec OAT coolant. The procedure (drain via water pump bolt, refill, bleed via idle + throttle snaps) is essentially the same.

Sources

• Voge DS800X Rally Engine Service Manual (English) - pages 26-32 cover the cooling system specifications, troubleshooting, and replacement procedure. This guide reorganises and condenses those pages.
• Voge DS800X Rally Owner’s Manual - confirms service interval cadence.
• DS800X Rally torque specifications - full table for cross-reference.

If you’ve found a useful tip we missed (e.g. a drain bolt access trick, a recommended G48 product available locally), send it in and we’ll fold it into the guide.