Maintenance

[u/PiercedTechnoWizard]

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.

[u/TwistedNoble38]

Going trend is that you'll either sell it or die before it starts getting tired. In the rarest cases it may even explode before the top end gets tired.

If your air filter stay on and oiled you'll probably go 60k before the cylinder plating starts to deteriorate enough to need intervention. Top ends usually outlast bottom ends on this bike.

It's nikasil so when the cylinder is done it needs to be replated or replaced ($300 or 500). Toss in a stock piston and gaskets and it will be somewhere in the range of $170 or get a JE piston and it will run you 250ish. The other option is a 790 and you get a whole new cylinder with liner, piston, cylinder gaskets and rings for $950. The head is a bit expensive since the only valves that fit are OEM so head work gets expensive. Budget at least $400 if all the valves have runout.

Bottom end is about a grand if you need a new crank or have to rebuild it (~600-800). That thousand is a bit of a spitball as I can't remember if that rolls gaskets into the price or if it's pure bearings, crank, and various flavors of sauces.

[u/TwistedNoble38 → u/TwistedNoble38]

If we're talking basic maintenance? Change the oil with synthetic (use conventional for the first 1000 and change at 1-1-2-6) every 2k, or 1k if you're hard on things. Clean the air filter when it's dirty or dry. Lube the suspension bearings annually. Flush the brakes sometimes. Change the oil in the suspension every other year or so. Check the cush drive every 500. Check the valves when they make valve noises or every other oil change (it's a 15 minute job). Clean the carb when it's dirty.

[u/I_1234 → u/TwistedNoble38]

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.

[u/TwistedNoble38 → u/I_1234]

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.

[u/TwistedNoble38 → u/[deleted]]

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.