In 2017-2019, I undertook one of my more ambitious projects to date; updating and upgrading my Suzuki DR350SE to make it a more capable and more modern lightweight dual sport. I didn't do a build thread at the time, but every time I post pictures of it, I get a minor flood of questions and requests for more information, so I figured this winter would be a good time to post a build thread.

This was a very gratifying build for me, because it really helped further my skill set and I learned a huge amount in the process. It took me from being a bolt-ons, minor customization, and minor fabrication type to being willing to re-imagine a vehicle, tackle more extensive mods, and go through every subsystem with rebuilds and improvements for my intended use. Of course by the time I was done I was looking at all my work from early in the project with a critical eye and wanting to re-do much of it!

The nickel tour: I took my almost completely-stock DR350SE and swapped an RMZ250 fork and CRF250R swingarm onto the bike. I repaired and tidied up the welds and brackets on the frame. I built new footpegs that failed miserably, and then bought some that work well. I updated the plastics, modified a rack, upgraded the kickstand, and added soft luggage attachment points. I added a fairing/windshield/lighting/dashboard upgrade. I put LEDs, reflectors, and running lights where practical. I re-loomed the stock harness along with some repairs and said upgrades, plus USB charge ports, hidden kill switch, voltmeter, heated grips, integrated trickle charger plug, and more. I built my own bar risers, upgraded the seat, brakes, and more. I replaced most everything rubber on the bike. I de-burred and powder coated almost everything I could. The powertrain remained mostly stock, save some carburetor and exhaust tweaks.

Starting point:

Result:

 

I'll be updating in installments as I dig through the archives and remember the details.

1SlowVW
1SlowVW HalfDork
12/2/20 6:39 p.m.

Cool bike, I had one with a decked head a good valve job and a few other tweaks, it was a 90+mph dirt bike that could power wheelie in 3rd. 
The suspension and kick start only were real draw backs as mine was an earlier model. Looks like you have both of those issues addressed! 
 

Professor_Brap (Forum Supporter)
Professor_Brap (Forum Supporter) GRM+ Memberand UltraDork
12/3/20 5:40 a.m.

Following, been reading up on the fork swap for a while.

mazdeuce - Seth
mazdeuce - Seth Mod Squad
12/3/20 6:22 a.m.

Is that bike posted somewhere else? ADV Rider? I swear I know that bike. 

Professor_Brap (Forum Supporter)
Professor_Brap (Forum Supporter) GRM+ Memberand UltraDork
12/3/20 7:06 a.m.

In reply to mazdeuce - Seth :

There is a picture of it in my DR250 thread. 

There are a few photos of it on the advrider.com forums, mostly in the DR350 thread and in Villain's DR350 Supermoto build thread.

A little history: my grandfather started regularly commuting to work via motorcycle during WWII (to help with fuel rationing) and got hooked. My dad has always had motorcycles around and when I was a kid the time Dad made for himself was to go out riding. I guess I came by it naturally, and I learned to ride before I learned to drive. My first-ever project was a cheap non-running early-70's Honda CR125 when I was about 13 years old. Once rebuilt and running, I scared myself silly ripping around the sheep pasture on that thing.

Fast forward a few decades, and I'm in my 30's and hadn't ridden in forever. I don't know why, I suppose things got in the way like school and cars, and work, etc. I was sitting around at work at the end of the day with my best friend. Every year for years when spring came around I would suggest it might be fun to get a bike, but never seriously. He was really goading me into it this time, telling me about all the fun we would have riding together, and how he knew I was really a bike guy at heart. I humored him briefly with something like, "Well, I suppose if a cheap bike fell into my lap..." at which point a co-worker walked in from another room shaking his head and hanging up his cell phone. He said, "Man...my wife is going to KILL me! What am I going to do?" I asked what was wrong, and he said, "I've been hiding a motorcycle she doesn't know about at a friend's house. He's been bothering me about picking it up for a few weeks, and now he says he is going to put it out on the curb! I'll probably take a bath on selling it, and where am I going to find someone to dump it on quickly? I'd let it go for CHEAP!" I took this as a not-so-subtle sign from the Universe, and within a day or two the '97 DR350SE was in my possession.

Not too much later I was registered for a Basic Rider Oregon class (on the school's TW200) that would get me back into it, and get me my endorsement. I picked up a used jacket off the advrider forum and got some pants, boots, and helmet new. My dad loaned me some of his spare gloves for the time being. The DR started, idled, and revved, and it came with some spare parts, so my dad came to visit and helped get the bike up and going. We cleaned and inspected the rotors, replaced the pads, and bled the brakes. We checked the tires and they looked good, and tested all the lights. We changed the oil and installed new chain and sprockets. Woohoo! I was having a blast, and I hadn't even really ridden much.

paranoid_android (Forum Forumer)
paranoid_android (Forum Forumer) UberDork
12/4/20 2:59 p.m.

Cool, another DR owner!  I'll be following too smiley

This next few posts will likely rapidly cover a span a few years time involving minor tweaks, maintenance work, and lots of riding before we can move on to the meaty part of the build. On a fairly early ride on the bike, a longish section of high-speed slab must have been more vibrations than she had seen in a while, and I lost the float bowl's drain plug! I realized that there was a fuel leak fairly quickly and shut off the petcock before getting anything worse than a bit of gas on my boot. I needed to call for a rescue as I didn't happen to have a spare fine-pitch Mikuni carb float bowl drain plug on my person, and had given up after a while of searching back down the shoulder of the highway. I pushed to a gas station where I bought some refreshments and the jerk of an owner informed me that he had zero interest in my problems and that I was not welcome to stay or to leave the bike. I called a buddy and sat in the shade for a bit while consuming the stuff I bought at the gas station. I also called Jesse Kein at Keintech (also in my home state of Oregon) to see if he had the parts. Jesse sold me some carb upgrade parts as well, and while waiting for my ride, the pump attendant came over while his boss wasn't looking. He confirmed that the boss was indeed an shiny happy person, and offered to let me stash the bike inside the locked dumpster area for a few hours while he was still on his shift. Motorcycles seem to have the ability to bring out the worst in a small segment of jerks, and at the same time also bring out the best in a large segment of riders, former riders, future riders, and dreamers/admirers. I got back to the shop, found a spare float bowl screw, got back to the bike and reclaimed her, and got back home and prepared to do some carb work. At that point I also found this damage on the throttle cables:

I got some cables on order and got the carb parts from Keintech. I figured that "while you are in there, might as well," which lead to this:

And eventually to this:

It took quite a bit of trial-and-error fiddling, but eventually the bike got even better with the new throttle cable, rebuilt carb with new seals, new jets, and increased idle adjustment capability. A previous owner had already opened up the airbox, which at the time I took as a bonus, but in the future I wouldn't be so sure. I only mention this here to help provide a counterpoint to the mountain of marginal BST33 tuning information constantly reguritated around the internet. Those thirsty for DR350SE knowledge need only do a little Googling to find a massive amount of hack-apart-your-airbox-and-replace-all-your-jets will instantly "improve" your bike types of posts. In hindsight I think the bulk of the improvement was down to the carb clean, new seals, and the new non-broken cable. The other stuff just created more adjustment to screw things up with, and the need to keep adjusting things to keep it running just right, which may or may not be better than a reliable-as-an-anvil bike that works pretty OK all the time.

Professor_Brap (Forum Supporter)
Professor_Brap (Forum Supporter) GRM+ Memberand UltraDork
12/5/20 5:43 a.m.

Drs are not like a drz with a 3x3 sadly. I haven't seen one that didnt requio some serious fiddling to run even half way decent. 

 

Now that I was neck-deep into this thing, I started haunting Craigslist and eBay for parts, and scoured the internet for information about possible upgrades that could be adapted from other bikes. I've always loved researching and parts hunting and I was really going bonkers on the DR, buying stuff that came up at a good price for spares or just in case, as well as some stuff that I might be able to adapt.

With my carb tweaked, I figured I would see what I could do about the exhaust. I found a few references to folks using Honda CRF motocross exhausts that were close-ish to fitting, and they came from Honda with a titanium headpipe and aluminum repackable muffler, versus the non-serviceable all-steel stock setup on the Suzuki. I found a likely eBay candidate for cheap and here they are side-by-side. The split between the two parts is in a slightly different place, but the total length isn't much different, and the fasteners are even in the right general vicinity:

It needed an adapter bracket for the rearmost muffler mount and some ovalizing of the holes on the header flange. Lesson number one: motocross exhausts are deafeningly-loud when compared to dual sport exhausts. It was no bueno. One five mile ride with earplugs and my ears were ringing...I couldn't hear as well for a little while afterward. I was setting off alarms on parked cars, and every pedestrian's head was whipping around to see what the hell was coming. It was awful for something used on the street...and it really didn't fit that well in the end. Lesson two: titanium and aluminum are sexy and lightweight, but not practical for me to modify in my garage as steel.

I settled on modding the stock unit for now, but I still eyed any sort of lightweight serviceable muffler with envy. I started by grinding down the gigantic weld on the inside of the head pipe, and finished it off with a wideband bung for further carb tuning (plus removeable plug for daily use) and some high-temp paint.

The other parts I scored that were total game changers were these Supermoto wheels. $500 shipped! Stock hubs laced to Warp 9 rims with Buchannan spokes, brake rotors, and Michelin Pilot Power Cup trackday tires included!

With two wheelsets, I rode this bike EVERYWHERE over the next few years; urban and rural, paved and unpaved, valley floor and way up into the hills.

 

My parts hunting meant that spares and upgrades started piling up. I bought a wrecked one-owner very-low-hour dirt model from a local guy who had been waiting 20 years for the buddy who wrecked his new bike and said he would fix it to come back around and fix it...and finally gave up. Kinda sad! The dirt model came with the pumper carb and a complete spare engine, so the parts value added up to more than the purchase price.

I also scored another SE frame off eBay (can be registered for street use) as well as a selection of '04-'06 RMZ250 front end parts. As my riding skills progressed (plus with sticky tires) I wanted to upgrade the suspension. I got several stock and aftermarket triple clamps, DR350 and RMZ250 to play with and starte measuring, mocking up, and pressing stems in. Aesthetically I wanted to get rid of the dated purple/yellow color combo. A custom Fisher seat from Fisher Saddlebags in Eagle Idaho helped the looks quite a lot, and the long-ride comfort even more...worth every penny! You can see the black/white seat in some of the photos above. You can also see the Cycra universal Supermoto front fender I added. It sacrificed a little bit of protection from spray, but helped the looks over the loooong schnozz of an 80's dirtbike style fender that came stock. The smaller fender also added a bit of stability at highway speed. I bought some new Cycra handguards in white to replace the black Acerbis that came with the bike, and I carefully grafted some Zeta LED turn signals into them.

 

 

 

Now that I had my supermoto wheels for pavement fun, I decided I could go a bit more off-road aggressive on the tires for the dirt wheels, so I picked up some Michelin T63 DOT knobbies. I've always had good luck with Michelin tires for my two-wheelers, and feel they are usually worth the money.

I also got myself a present of some Giant Loop soft luggage. They are a local company specializing in lightweight soft luggage for adventuring, which seemed aligned with my sensibilities. Here is the first mock-up in the parking garage when I first got the stuff:

Another area I wanted to address was the stock headlight, which was fairly abysmal, and I also thought it would be nice to add some optional wind protection. I found both upgrades in one place with Britannia Composites. They are in BC, Canada and the reviews seemed really positive. HID lighting (at the time I ordered, these days it is LED) and a really cool style adventure fairing with customizable ABS dashboard. At the time I ordered, they were making a big push to replace their side-by-side lights model called the Lynx with a more modern-looking stacked-vertically lighting setup, but I managed to cajole them into making me one of the old style. Since then, they have brought that style back. smiley A nineties Japanese dual sport promoted with desert-racing tie-ins just wouldn't look quite right with a rally tower reminiscent of a recent KTM...I wanted something that harkened back to the Baja and Dakar bikes of the 80's and 90's. The windshield is a brilliant design that is height-adjustable on the fly with the turn of two knobs.

 

Since I bought the forks for the upgrade used, I figured I would tear them down to replace bushings, seals, o-rings, copper washers, and fork oil. Used motocross stuff is cheap if you are shopping in the roughly decade-old age bracket, and parts are still pretty well available. The catch is that most of it is *well* used, so I shopped around to find some that weren't too beat up, and planned to overhaul as a precaution. I used almost everything from the front end of the '04-'06 Suzuki RMZ250, same bike as the Kawasaki KX250F ('04-'05 for certain, unsure on '06 interchange.) I pressed the DR350 steering stem into the RMZ triples, and used the RMZ front wheel, axle, hub spacers, brake rotor, and brake caliper. I used the DR350 brake lever/master cylinder (the perch has a mirror mount, unlike the dirt bike parts.) The fork is a little taller, is waaaay beefier, and has slightly more travel than the stock DR setup. Part of my intentions for the bike at this point included the possibility of still switching wheelsets, and there is absolutely berkeley all for aftermarket front brake upgrades for the DR350, but there is decent aftermarket for most Japanese motocross bikes, so I could just buy RMZ250 supermoto parts...or so went the plan. More on this later...in the meantime we need to continue with catching up on the timeline of past modifications.

Draining the old oil.

Putting the parts out in order as I take them out helps make sure I put it back together correctly.

Side by side with the stock fork for comparison.

 

Professor_Brap (Forum Supporter)
Professor_Brap (Forum Supporter) GRM+ Memberand UltraDork
12/22/20 7:27 p.m.

Interested in fork details, been on my list for a while. 

Here's some details on the fork swap I did. If I had it to do over again, I would investigate possibly slightly easier swaps that would net a similar gain by using '99 DR350 cartridge forks or Suzuki RM forks instead of the Suzuki/Kawasaki joint-venture RMZ forks that I used.


As I mentioned before, the forks I got for cheap, so I was interested in making them work even if it took some modification. Here's a comparison by the numbers.

2004-2006 RMZ250
48mm Upside Down Kayaba: 20mm axle diameter, 25mm triple clamp offset, lost my notes, but from memory, either 32mm or 34mm axle offset, 300mm travel, 55.9mm upper clamp diameter, 59.1mm lower clamp diameter, brake caliper bolt spacing 102mm between hole centers

1997 DR350SE
43mm Conventional Showa: 15mm axle diameter, 20mm triple clamp offset, ~38mm axle offset, 280mm travel, 43mm upper clamp diameter, 43mm lower clamp diameter, brake caliper bolt spacing 78mm between hole centers

The key takeaways are that the total offset (triple clamp plus axle offset) between the two are very close which means little change to the handling. The RMZ forks are a little longer, with slightly longer travel, but with sag adjustments plus adjustment of the fork height within the triple clamp, totally doable. The axle measurements and fork measurements meant that it was going to be a full front-end swap of wheel, forks, triples, and brakes.

I found some useful information at HScarborough's DR350 Fun Build on advrider.com and Kezza's DR650 RMZ fork upgrade also on advrider.com.

Thankfully, the DR350 stem and the RMZ250 stem have the same diameter at the lower triple clamp, so I was able to press a DR assembly apart and press the stem into the RMZ lower triple. NOTE: the DR350 stem has a roll pin retaining it that must be drilled out before pressing. I used a 20-ton hydraulic press along with a propane torch for heating the aluminum triple clamp and put the stems in the freezer before reinstalling. This is not a job you are going to accomplish with a bench vise or a sledge and a scrap of 2x4!

At this point in the project, I went through several revisions of triple clamp setup, but I'll stick to high points. I started with the stock RMZ triples, which had a couple minor problems: the upper triple clamp bolts were on the back, which isn't a good location for a triple-clamp-mounted handguard mount (which I was set on using at the time) and didn't offer much adjustability for handlebar position without going to aftermarket risers. So I went to an aftermarket Pro Taper triple clamp, which features upper bolts on the front outside, great for a handguard mount, a nice rubber mount with adjustable durometers for rider preference, adjustable position (but not adjustable height...more on that in a bit!) as well as sexy machined/anodized looks and stiffer structure (in theory.) The next hurdle was that the Pro Taper lower triple clamp has cinch bolts on the backside, which were fouling the oversize tank, so I ended up going with a stock Suzuki lower clamp plus the Pro Taper upper clamp.

Another note on pressing the DR stem into the RMZ lower triple: the RMZ triple clamp is thinner at the point the stem presses through, or it allows the stem to recess further into the stem than the stock triple clamp. The result is that the bearings sit too high on the stem. Without machining or spacing the stem downward slightly, the bearings won't have a surface to sit on once installed in the frame, and it won't be possible to get a satisfactory steering head bearing adjustment. I know some folks have included a spacer on top of the lip on the very bottom of the stem, and below the lower triple, but since I have a lathe, I turned mine down slightly. The machined surface used to end at the red arrow.

This picture shows the completed combo assembly on the right next to the original DR350 lower triple just to the left, and you can see the similar overall architecture in the lower triples. Don't mind the undoubtedly lead-filled paint flakes that fall from the roof of my rental workshop when people move around upstairs! laugh

And here is a front view of the completed assembly with stock DR350 lower seal and bearing installed.

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