Ktm Flat Tracker
Sherman Desrosiers
In the 1930s, as the board tracks faded away, flat track racers appeared: street bikes modified to race on dirt or clay ovals. Past icons include the Harley-Davidson XR-750, but others include flat trackers from BSA, Norton and Triumph. This style is still popular today, with interest spurred by an intense rivalry between Harley-Davidson and Indian.
Flat Track handlebar 22mm manufactured out of steel, it enables you to get a more comfortable driving position and a better look. This handlebar has much pullback to the rider, and his flat Track look will make your bike handle better.
Traded a fella the other day for a plate 1997 XR600R that I'm planning to build out to resemble an older flat track bike. Something like that vintage_addiction xr600 with the harley tank. Here's the plan:
Ordered a set of rims from chapmoto.com (excel takasago 19x2.15) For the XR600R hubs it's a 36 hole front and a 32 hole rear. Spokes are on order from Buchanan spokes. Going to try my hand and building them. If it goes south I'll send them over to Chris at Wheel Works in Hayward to get them laced up.
Awaiting the champ tail section from Saddlemen which should be here in about a week. Pretty amped about it. Going to do some work to put in some low profile lights and signals which will likely lead to a new shape that we'll make a mold of so we can iterate on.
Tonight I got into more teardown and measuring for the suspension changes I need to do. Wanting to lower the whole bike by just a shade under 3". To do this I needed to know what max extended length the rear shock would need to be to get the right ride height so I measured the stock height (shock is 380mm long at full extend and the rear swingarm drops 20 degrees from horizontal) then moved the swingarm to the desired angle (somewhere closer to 12.5 degrees) and took a new measurement. The new length is somewhere around 360mm OAL so I need to add in an 20mm spacer on the rebound side to get it into the right spot. Since the swingarm is 550mm long this should lower the bike by about 550mm*(sin(20)-sin(12.5)) = 69mm (2.72in). Since the steering angle on these is somewhere around 25 degrees the front will have to drop by 2.98/cos(25) = 76mm. Here's the idea on the rear swingarm.
Turned a spacer down for this build. My math turned out to be a good bit wrong and I ended up with way to long of a spacer (20mm). Going to have to fix this. But here's the spacer I made. I'll probably take this and shorten it a bit but for now I'm going to run with it to see how things shake out.
Looking at these FTR250's it's pretty amazing how near horizontal their swingarms are. With this new spacer I was getting somewhere around 8 degrees when on the stand. We'll see what it gets to under static sag once the wheels are built.
Want to find a sand blaster nearby and give those hubs a blast and recoat before the wheels go together. Rims and spokes should be here this week so the clock is ticking. Tracking numbers also say the tail section should be here on Thursday. Next week should be assembling wheels and getting into the subframe.
Went back and forth on whether to polish or paint the hubs. Ended up doing both more or less. After a good amount of polishing i realized i still had a lot left to do and a complete other hub so i went the painted route.
When lacing up the front wheel i noticed the drilled holes were not lining up quite right so. Looks like I ordered a rear 36h rim instead of a front. here's what that looks like up close in case anyone else is doing that kind of thing.
So I took that wheel back apart and will be seeing if i can swap it out for a front version. Thing i'm worried about is that I can't seem to find the right part number for the front 19" x 2.15" rim. What I have is the GES422 and I'm not sure if they even make the front. Shot excel an email. Hoping they get back to me tomorrow.
Should be able to get into the rear section modifications this week if Halloween doesn't get too in the way. Seat pan showed up and the gas tank should be here sometime around Wednesday. Should be another great weekend. Goel on that is to get a new tunnel built up for the old sportster tank. Then, once that is close to in shape. Cutting out and welding in a new subframe with a small compartment for hiding all the reg/rect circuit and battery. Here's hoping that goes together a bit smoother than the wheels.
Great idea. You may want to consider completely cutting each segment (if you haven't already) as this would allow for more complex (multi-axis) bends upon mock-up / final assembly. Something like these... -cuts-1 Looking forward to seeing more about this!
Yeah. I'm aware of those, that's why I came up with this idea. I want a way to make "kits" that you could weld up for your own bike if you'd like. That way it's not just a one off piece. Also working on a way to get the shape in a digital format quickly and cheaply but that's farther down the road. The new system is interesting as you don't have to worry about clocking each segment or getting the segments in the right order. They're all attached ahead of time. So just break off the tabs and hand bend to shape, tack, check, weld up. Here's an intermediate shot of the process.
If all goes well, then I could fab up kits for other XR owners to weld up their own exhaust if they were interested. Instead of the old way of "figure it out, stupid". Hahaha. Also, one 90 degree bend (6 pieces for $60) is intense.
That seat pan may be the perfect place for this. I've sometimes wondered why cycle mfg.'s. no longer build hinged seats (as they did in the 60-70's. They were convenient for access to air boxes and/or fuse panels. Like these... Much more work initially but the added convenience could prove to be worth the trouble in the long run. Thats the beauty of a custom build, make it the way you want it. For some added inspiration, here is a link to Dirt Bike Mags write up on Dues Customs CR500 tracker they built for Dani Pedrosa. ENJOY! -cr500-flat-track-by-deus-customs-for-dani-pedrosa-two-stroke-tuesday/
Just off the phone with Excel. Turns out the GES422 (G - 19", E - 2.15" wide, S - silver, 422 drilling pattern 36H wide angle for rear) is the wide angle nipple hole but the GES410 has a narrower dimple and drill angle so it will hopefully fit much better. Rim will be here Thursday. I'll get it laced up this weekend and get some pics up on here.
Once I've got the forks back together it will be rear subframe time. Tricky part is having the bike at the house and the tool at the shop. Not enough space at the shop to keep it all there. Struggle!
Tomorrow I'm working on the mounting systems for the seat and the tank. Planning to add a plate to the top of the rear section that can handle bolting the tank and seat in the front (one bolt through both). Then the rear of the seat pan will also have a bolt. Haven't quite sorted out how I want to do that yet. I want something that will allow for easy removal. Perhaps, a simple single bolt then two studs on the seat pan so that the seat pad can be removed, then the bolt will be accessible. Hmmmmmmmmmmm. Decisions decisions.
Check out our CRF150RB Flat tracker. Just finished building it. It will be debuting this weekend at an AMA event in Upstate NY. www.electriccityriders.com Custom 17" Excel rims, custom spokes as nobody has any information on this yet including Buchannan. Maxxis tires, Sunstar aluminum sprocket, Renthal gold chain etc. This bike rocks. It will change everything. It will be running in the 85cc class. I believe it will be in the winners circle.
It's been ridden. This bike goes on a hard surface short track, not a mud pit for snot nosed kids. It hasn't been raced yet, just practiced on and when we are done with our equipment it gets completely cleaned and detailed.
That sounds like it might be a deal. I think, however, I'll order a cam and then send it to you so that I retain the stock profile to use for now. I'll call my Honda buddy today and get a cam coming. Send me a link to your site if you have one and I'll call you.
Both my kids are straight A students that sit on the Student Council Boards at their schools. They both wash and maintain their own bikes and help out whenever they are needed. They don't run around town and they don't get into trouble, because they love their sport to much to lose it being dumb.
I know of at least 30 families that race in the Midwest and surronding regions and they all have the same values as us. Maybe I'm wrong, but I'll never whack someone without first finding out about who that person really is.
Rims are too narrow for the Maxxis...should be WM4.5(2.75") That's what they were designed to be run on. Do you plan on doing the suspension? Don't forget to cover them footpegs! Good luck and nice looking bike. Tdub
This bike can run in the 85cc class at most flat track events because the rules are so relaxed and in flat track racing, unlike motocross, there are not enough riders to send people packing. It is also imminent that the rules will be changed very soon to accommodate this bike and the inevitable others that will follow. If the AMA has a clue they will get it done ASAP.
At our particular track, AMA sanctioned, we are going to allow it to run with the 85cc bikes. No doubt someone will scream but we want to be forward thinking and not backwards as most flat track organizations have been. It's forward thinking that made MX racing what it is today. We intend to move in that direction at our track.
The Maxxis tires work fine on 2.5" rims and especially considering that there is not enough clearance on a "mini" between the fork legs for a wider rim, thus increasing the overall width of the tire. That may be true on a larger bike but it's very very close right now with the 2.5" rims. .25" is not enough to make a difference when there are so many other factors that have a greater influence on performance than this incidental difference in width. Mostly, the person twisting the throttle.
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