I somehow got interested in putting an 18" on my relatively new-to-me DR650; and then as I looked into it, interest became obsession. I was confounded by how easy some made it seem and how little specific info there was on something that was supposed to be so easy. So here is my saga, er.. write up: I hope it helps someone. I have no great understanding of motorcycles, and I make no claims of expertise what so ever, at all. I consulted a friend of mine who owns a shop, and knows WAY more than me, several times to make sure I wasn't doing something unsafe to the bike/wheel. So fairwarning, if you know a lot or bore easily, move on
I was lead to believe that a dr350 wheel was a 'plug and play' solution to an 18" rear, so I set out to track down a such a wheel. Turns out, this is only partially true. The DR250's and DR350's both had models with hubs compatable to the DR650, but a person really wants the CUSH DRIVE. This is feature is found on 1990-95 DR250SE and 1990-96 DR350SE models (except the 'T' model). The hub part # is 64111-15D00. The non 'SE' model does not have a cush drive, and the rim and spoke set is different (trust me on this). A useful tool I found in my travels was the Babbit's parts site: you can find a part number, and then check what other bikes use that same part number and therefor crosscheck what bikes/years share parts. FWIW, ThumperTalk has the absolute lowest priced Suzuki OEM parts I could find on the web.
So I found a wheel on E-bay, and ordered it up. The spokes had a lot of what I assume was salt corrosion, so I figured I would replace the spokes. On the advice of people smarter than myself, I took a few steps at this point, before reaching for the bolt cutters. First, measure the off-set of the hub/rim on each side to make sure it gets back to the same spec. Second, make note of the [first] four spokes and their positions in the hub/rim, so when you go to re-lace the rim, its that much easier. I used colored zip ties. Third, save a few of each size spokes, for backup-- Suzuki only sells spoke sets (36).
Once I got my wheel, I decided that it needed some cleaning up. After the aforementioned considerations, and spoke removal, I took the hub and rim to friend's shop with a bead blaster, and, well.. bead blasted em. Then I buffed them with a pad on my die grinder. Cleaned em up quite nice it think:
: before I bought the 18" wheel, I looked up part numbers for both the 250/350 se wheel and the stock 650se wheel and found that most of the associated parts are interchangable; with the following exceptions: rim (obviously), hub, brake disc, spoke set, and cush bumpers. the other part numbers are the same. So bearings, spacers, the axle, etc. for the 650 work for the 250/350se wheel. I wanted to keep my original wheel mostly intact, in case this whole experiment goes horribly wrong, so for my new wheel I ordered a new spoke set, new sealed wheel bearings, and cush bumpers. Turns out, the cush bumpers on my stock wheel fit better than the ones I ordered for the new wheel. The sealed Moose wheel bearings are part# A25-1256, and are compatible with the DR250se, 350se, 650se.
To summarize, if you found the wheel, didn't need new spokes, and wanted to use your 650 bearings and cush pads, you are go to go, and now about here:
So now we get to the brake disc issue. The disc from the 250/350 wheel is smaller and has different fasteners. 250 Hub:
The mounting holes from each disc match up, but the 650 disc has a recess in both the disc and the hub:
The reason why this is a problem, is that the 650 screws need a recess because of this:
My solution was to shim with washers that fit both the disc recess and fastener shoulder, of these , the 2 serrated lock washers seemed the perfect solution:
So now we look like this:
OK, so now the wheel is good to go. The next thing is the tire. I really wanted to try a Mefo super explorer which is a 140/80-18 tire. People are talking about getting 6-9K miles on ktm 990's and the like, so I figure I should be able to get crazy milage on a DR. Also, I really like the tread; very similar to the heidenau K60, which I've tried but crappy mileage.
ANyWho, here's the wrap-up kids if you are still awake: The new wheel/tire raised the rear end 1" and is about 3 lbs heavier than the 17" with a mefo explorer. It looks badass, if that's what you are into. It also raised the gearing. (I had wanted to lower my gearing, even when the stock wheel was on the bike.) I put a 14 tooth front sprocket on to (a) get some more room between the tire and the swing arm, (b) to lower the gearing. Lowering the gearing to a 14t only maybe got me back to stock, now I have to go lower. Also, I need to add some links to my chain if I want to go with a bigger sprocket in the back. Here's some pics of the bike with the 18":
I'll have to put some mileage on this thing to see if the trouble was worth it. Another issue to consider, the 650 rim is wider than the 18", so a 140/80 is a big tire, and a PITA to spoon on and mess with.
Happy trails, Cheers, matt