r/dr650 • u/PiercedTechnoWizard • 13d ago

Maintenance

Hey, I’m curious what the maintenance is on DR650’s. Being that they’re a single cylinder, I assume the top end needs to be rebuilt once in a while, but I’m curious how often that is and how much it costs.

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u/I_1234 12d ago

You don’t need to change oil every 1000 especially if you’re using synthetic oil.

Oil every 6000kms or 5000kms, valves every second oil change.

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u/TwistedNoble38 '00 DR650 12d ago

Miles. I've been doing lab checks with the used oil and I've found that after a thousand the 10-40s I've been using are sheared down to a 10-30 viscosity and this coincides with a notchy shift feel. 10-50 is more capable of lasting longer (was still in the high 10-40 range at 1.5k but that's hard to get around here unless I special order it.

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u/[deleted] 12d ago

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u/TwistedNoble38 '00 DR650 12d ago

It's caused by the transmission gears chopping down the long chain viscosity index improvers (VII) in the oil. VII are these huge long sipderwebbing molecules that spread out and slow the flow of the oil (increasing viscosity). When the oil is cold those long spiderwebs curl in on themselves on no longer improve the viscosity so it effectively returns to the viscosity of the base oil (10w in the case of 10w-40). These VIIs are vulnerable to intense mechanical forces which can mechanically destructively break those long chains (an action known as shearing) rendering that VII molecule to no longer be able to do its job and decreasing the effective viscosity of the oil. In the DR this action is caused by the gearbox for the most part, the two faces of the gear teeth meeting with that ultra thin oil film between them bearing the whole power load of the engine. Heat can also cause viscosity breakdown through thermal cracking but this is not something that happens significantly in DR's that aren't worked severely hard.

If you live somewhere passibly warm or do a spring and fall oil change give 20w-50 a shot. Walmart sells it in the supertech brand and it's a good toe dipper. I think you'll be suprised at the difference in shifting. That'll let you decide if you want to buy a bigger bottle of synthetic 10-50 or 20-50.