MT250 Knobby Vintage Streetfighting Cafe Scrambling Rat Tracker

The steer tube for the GSXR triples had a little shoulder that didn't allow the bearing to slide down far enough. The bottom triple also hit the bottom of the head tube. So I had the steerer tube pressed out and machined down, and also had a spacer made to go below the lower bearings. I took that moment to have the triples and clip-ons media blasted. They turned out awesome, but the surface absorbs grease stains like crazy, so I'll have to have the powdercoated or something before this build is done.

Here's the bottom, before I had a spacer made.

Once I got it all straightened out, I was able to mount the wheel and get the bike of the stand, and finally see what it looked like with the pipe on it.


With a spare KTM seat just sitting on it:


With a Ducati Monster seat:


I think it's looking pretty scrappy in just the way I was hoping it would.

The GSXR fork has been grafted to a Narrow Glide Harley hub pretty frequently, but the majority of the posts that I read were using a new GSXR fork. I had chosen the 1991 because it was really long and would hopefully preserve some of the original geometry. That turned out not exactly to be totally true because the real measurement that matters is from the axle to the top of the bottom triple. No one measures that so I just hoped that some of the 1991 fork being super long was in the dimmension. But because I chose this fork over the more modern ones, I wasn't sure if the wheel swap was going to be simple. I found a Narrow Glide Hub at a local salvage shop and brought it home to fit up. I had to order some bearings from All Balls Racing again, but when I fitted them in the hub everything seemed to be lining up OK. I ordered a black powdercoated 18" 40-spoke rim from some supplier that I found online. But when I went to order spokes from Buchanons it was so ridiculously expensive that I thought maybe I'd find them on Ebay. I didn't find them, but I did find a whole 19" wheel with a small dent in the rim for $60. It turns out that the 19" drop-center rim uses the exact same spokes as the 18" rim. So I bought the whole wheel with the intent of stealing the spokes. When the wheel arrived, the hub was as good as the one I had already bought, so I zip-tied all the spokes together and just transplanted my black rim onto the new hub/spokes.

The 19" rim on the bike:


Bolted a piece of aluminum to check rotor alignment, and the calipers clear the spokes.


All zip-tied together:


Dismantled:


Transplanted:

On the bike:


Tomorrow, rotors...

this is hell build!

can't wait to hear it

just a thought or three

~kop

just a thought or three

~kop

Those are pretty killer. I think they are MT125's. I actually saw a restored version at a local Honda shop here in Portland.

Rotors

So we have the Harley wheel on the Suzuki Fork on the ancient Honda. Now it's time to make the brakes work, and I can claim no originality in this department. Others have sorted this out, and as much as I resisted the urge to use what others had already done, I didn't find too much room for creativity.

The issues that need to be sorted out in this step are finding rotors that are the right diameter and offset for the calipers. The original GSXR used 310mm rotors with 22mm offset and a 64mm inner diameter. This website was super useful in researching all the different brake components: http://metalgear.com.au/mgear-brake-disc-front-gold-centre-p-6317.html.

In the end, I sourced rotors that were as close as I could get from Ebay. They were 310mm and 0 offset, but had a larger inner diameter and incorrect bolt hole pattern. They were for an older Vstrom, I believe.

Here they are on my spare hub.



You can see that the issue is that the issue is not only do I need to drill a smaller bolt hole pattern, but the rotors need to be concentric to the hub. This is normally taken care of by the fact that the surface of the disc's inner diameter is in contact with a flange on the hub. Without this to maintain concentricity, it's only the bolt pattern that keeps it all centered. Honestly it's probably not that big of a deal if the rotor is a little off center, but it'd bug me.

Initially I dreamt up a design for a hub-centric ring that would also overlap the outside of the rotor and give me a little more material to hold the rotor on while also centering it. It would have been awesome and I even had plans to anodize it. But when I went to the machine shop to have a couple made they were going to be close to $350 and that was the end of that idea. The machine shop however was able to take my hub and rotors and drill the new bolt hole pattern precisely in the rotors for $80. This turned (machine pun intended) out to be well worth the money. I could have spent hours at home with the drill press trying to make it perfect and still messed it up. It took them about 2 hours and is spot on.

That brings us up to current on this build. There are few things that I haven't mentioned that I thought were cool little things. When I got all the front end stuff off of Ebay, I scored some clip-on bars, but I was not sure I wanted to use them. They were swept down like most clip-ons and clubman bars. I wanted to maintain some dirt bike elements, but the upper triple clamp was already pretty high in reference to where the tank and seat will end up. If I put dirt bike riser bars on the top of the triple, they'd be way up in the air. As much as I like some elements of the tracker style, I was really trying to avoid big monster bars.

After I stared at the clip-ons for a while, I realized that I could flip them upside down and swap them left-to-right. Ta-da! Clip-ons that are swept up and about the right height to keep all of the aesthetic lines about right.

It's the little things.

Before:


After:

Need New Axle

The front end is still not entirely done. In fact there is one big step before I can totally sign off on that part and move on. The GSXR axle has a big shoulder on the right-hand side that pushes the hub against a spacer on the left. Since the Harley hub is wider than the original Suzuki hub, the axle doesn't need to push it as far to the left as the original. So when I thread the axle in only a few threads enter the left-hand drop-out (that's a bicycle term, but I'm not sure what you call that part of the fork on a motorcycle). I could take the axle to the machine shop and have that shoulder turned down, but I'm afraid there's not enough material there to do that, so I think that I need to have a whole new axle made. Bummer, but the guy that did my rotor was an ex-GP racer from a million years ago, and seemed interested in my project. He told me to bring the whole fork/wheel down so he could make it right.

I spend so much time thinking about and tinkering on the Scrapper, that sometimes I wonder if I actually like riding motorcycles. Luckily the Oregon racing series has kept me honest...

While I take a breather from the whole fork/wheel/rotor sub-project, I decided that it's time to consider the tank/seat operation. I'm no photoshop master. In fact, I suck at it, and if I was going to be totally honest, I'd admit that I don't have photoshop, but I found some rinky-dink photo editting program on the web and started messing around with ideas.

I stole a photo of a 1974 CR 250 because the pipe was in the right place.



And messed around with it, adding parts until I got to here:



It's crude for sure, but sort of where I think I'm headed.

When I realized sort of where I was going, I bought a cheap/thrashed Ducati Monster seat from ebay for $45, but the foam was intact and the seat pan was fine.

As much as I love cafe racers and trackers, I've always disliked the whole nothing-for-a-seat look as well as the big rear hump thing. It always seems like someone has poured themselves into the details and made something super cool, only to slap on some under-designed foam and cover where you need to sit. Before anyone offers up their defense of this, it's just my preference from an aesthetic and comfort standpoint.

At any rate, I think that the shape of the foam is right, and I intend to put a seat cowl like the one in my mock-up over the rear of the seat where a passenger might otherwise sit.

Obviously the seat is just resting on the frame and needs to come way down:

Loving all the updates.

Your big tire obsession reminds me of the TW200 custom crowd.

I think that it must be a universal experience when building a bike to have a bunch of big parts all ready to go, but be held up by little things. I can't really sort out the seat until I have a tank. I couldn't really sort out the tank, until I knew where the bars were going to be. I couldn't do that until the fork was done, and arguably should wait until I get a front tire on. I was reluctant to buy a front tire until I knew how big my rear tire was going to be. And my wife was slowly catching on to how much $$$ i was spending on my $400-bike. That said, I pulled out a 140/80 dirt bike tire I had lying around and wrestled it onto the rear wheel. Surprisingly, it cleared the swing arm! That means I can have a 120/80 on the front (awesome!), and I felt like I had enough of an idea where I was going to find a tank.

I don't entirely dislike the original MT tank, and I really like the original silver/orange/black color scheme, but when I look at all my inspiration pictures, they seem to share in common a bulging, crotch-rocket style tank as opposed to the 1970's-era tear-drop tank. It has been a challenging to know where to sprinkle bits of modern parts and where to retain some vintage soul. I love the forks/wheel/rotors, but I thought that now I needed some counter balance, otherwise I'd have a old frame with a bunch of modern stuff on it.

So here's my argument. See if you agree. I think this tank is the vintage version of the new crotch-rocket style tanks. It is humped up in a similar way and has the indentations for your knees.



Additionally, it's just plain cool. Bonus points for being Honda.

$70 later, and reported to be in the mail from SoCal.

LBC said:

Loving all the updates.

Your big tire obsession reminds me of the TW200 custom crowd.

Click to expand...

I've never mentioned it out loud, but I love the TW200! I even convinced a friend to buy one and we've had some fun adventures together (http://www.advrider.com/forums/showthread.php?t=558242). But sadly I'm 6'3", 200#, and the TW200 is too small. You could say that I'm making a TW200 for big people.

Another favorite:

That thing is going to look super aggressive with those big knobs front and back. And that pipe echoing down alleys... oh hell yeah!

LBC said:

That thing is going to look super aggressive with those big knobs front and back. And that pipe echoing down alleys... oh hell yeah!

Click to expand...

Thanks! It's going to be totally obnoxious!

So, I've been plugging away on the Scrapper, but have been going so slowly that I never felt like enough had happened to merit a new post. But I let over a year go by without updating my progress, so here goes.