Suspension woes

The DT1 has been sitting in the closet collecting dust quite literally. It’s in my closet with my clothes…

I’d purchased some forks on ebay off a 94 YZ250. Awesome, inverted KYB creations with an insane amount of travel and awesome look.

For some stupid reason, Yamaha decided that the 94YZ was going to be a rarity as far as forks go.

Stupid YZ forks. So pretty, though...

The forks themselves are 43mm at the stanchion, not 45 or 46 like most newer versions.

The steering stem itself is most troublesome…28mm in diameter.

The old 1971 steering stem/lower part of the triple tree 

 

Comparatively, the dimensions of the stock steering neck on the DT1 are this:

Upper bearing seat- 43mm.

Lower bearing seat- 49mm.

Not a big deal…this means that I need a tapered roller bearing for the top that is 28mm Inside Diameter by 43mm Outside diameter, 28 x 49 for the lower.

Except that doesn’t exist. Anywhere. Ever. It’s not a roller bearing, ball bearing, tapered or un, that was ever made or will ever be made for a price that I can afford.

So my struggle has been multi-fold.

Options-

Find different triple trees with a 25mm stem that will fit the awesome forks from the YZ250

Adapt the DT1 frame to accommodate the only 28mm ID tapered roller bearing made (28x52mm)

First option is out. Almost an model YZ 85 forks meet my 25mm stem requirement

(I spent a fair amount of time sourcing dimensions from allballracing.com and their fork swap app. It doesn’t directly tell me anything useful since my model isn’t supported, but it does tell me the bearing dimensions for all the other models it supports, and this, in turn, tells me steering stem diameter and overall neck diameter choices. All balls also has a list of all of its bearings, so I can see what my general options are)

I could use YZ85 trees, but I’d also have to get YZ85 forks since the bodies are a smaller diameter than the ones I have. Also…YZ80/85 forks are expensive because punk brat rich kids use this model of motorcycle to learn/train/race little wee-person motocross.

Option 2 is out because I don’t want to modify the frame at all. I want this all to be bolt on/off.

So I took a long shower last night. It was a cold night. I shut the light off in the bathroom. Closed the door, lit a candle, and brooded in the hot steam and water. I had to decide what I wanted to make this bike.

I’ve long wanted a TW200…a Yamaha fat tire monstrosity of a motorcycle. They’re hard to find for a reasonable price. But parts are not…And as it happens, TW200 forks meet my diameter requirements in that the stem is 25mm. The forks themselves are antiquated, traditional models with not a whole lot of travel. But in the end…I’m not building a motocross bike.

 Stock TW200 photo. 

Stock TW200 photo. 

I just really love those YZ250 shocks. I’m keeping them anyway because YZ forks are a direct and popular swap on the BMW F650GS’s and it turns out, I’ve got one of those.

So for $40 I got some TW200 triple trees on the way from ebay. For another $40 I’ve purchased the correct (in theory) tapered roller bearings. The TW and the DT used loose roller bearings back in their day, but cartridge tapered roller bearings are easy enough to find, theoretically better at handling loads, and I wanted to use them.

The choices at this point (there are always choices) are what forks to get? The TW200 supports 33mm forks, and there were not many 33mm fork options. The TW200 units will more than suffice, and no doubt they’ll be better than the old 1971 technology, though the 71 forks had 34mm stanchion tubes.

Further, the TW200 long used a front drum brake. Within the past 5-10 years, the newer models (this is a bike that’s seen almost no change since the 80s) feature a disc brake. The only change that was made was on the casting of the left fork.

So theoretically, I can find a newer style left fork that will allow me to put a hydraulic disc front brake set up on, any old right fork, a TW200 front wheel with a disc brake hub, and I’ll be in good shape.

Decision B- what to do with the rear? I can adapt a TW200 rear swing arm (maybe, researching dimensions on this) and put a monstrous tire on there.

Problems- TW200 uses a mono shock, the DT frame is set up for dual shocks. 

The bike may look cool with an 18x3 tire up front and an 18x3 tire in the rear, though. We’ll see…

 

On the engine front, decided to get back to work because I’m tired of parts sitting on top of my fridge and under my sink. Bearings are on order as is powder for coating the cases.

Going a different route on color…

 The color of garbage. 

The color of garbage. 

Originally they were going to be a crinkle blue (think valve covers of the 5.4l supercharged engine in the Ford GT) I went so far as to order the color and begin coating...and then I realized i was sent the wrong color. And I lost all heart, and have not touched anything since then. 

Now they’re going to be a two stage candy with flat black accents. The frame is matte black. Triple trees will be candy blue. Body work, if I ever get there, will be carbon fiber. 

Best since Day 1.