Narrow Case 250 Race Bike Build

[SwampApe]

Well, I've decided I need another hole in my head... errr... I mean, a 250 Ducati race bike built from the ground up...

I figured it'd be fun to document the process start to finish so here we go!

I got a motor, frame, and all kind of high performance bits from a local long time Ducati racer. Hoping to end up with a half fairing race bike similar to this without all the road legal bits and with a lot more performance equipment (gofast parts):



Here's a picture of the motor, and a few images of the teardown process. I have been out of commission for the past few months, just getting back into my shop and and getting things cleaned up.









New crank with the carrillo rod:



The soon to be tricked out head. Going to go with heavy duty springs and titanium valves:



Oh, and just for good measure here's a shot of me running supermoto at Barber with WERA this year in the 80gp class. Hope to make it out there on the Ducati for the next vintage fest:



If anyone has experience with narrow case race bikes please chime in! This should be a fun project for me and I hope to be hitting the track early next year with it.

The parts I have and will be working into this bike (besides a total rebuild of this motor and head) are:

JE 77m racing piston
Titanium Valves
Carrillo rod
Mikuni VM32
Airtech Bodywork and tank
Motoplat Electronic Ignition
Excel wheels
35mm Marzocchi Forks

[SwampApe]

Some interesting bits I've gotten in the mail.

Marzocchi 35mm forks. Need cleaned up but seem like they're in good shape:



Excel front and rear wheels. AHRMA limits wheel width to WM3 for this class. I went WM3 on the rear and WM2 on the front. Hoping maxing out the tire size on these rims will give me enough meat to work with on the track. If anyone has suggestions on tires and tire SIZE please let me know:



Running the stock 250 hubs since 4LS stuff is unobtanium. If I could list what was SECOND to good suspension I'd say braking ability (maybe later in this story I'll get into how poor braking mixed with a little stupidity led to me breaking my leg and scapula and ending up in the hospital). Anyway, going fast isn't fun if you can't stop fast. That's where you make the passes anyway right? I'll be digging more into how to get the most out of these stock brakes down the line:





Yummy race piston:



Stock for comparison:


Frame with tail section I currently have:



My first little bit of carnage. Snapped the head off this stupid clutch screw. not sure how that happened. Got it out with some creative angles and pointy vise grips. Over all I was pretty surprised by what good shape the clutch basket was in:

[SwampApe]

Getting these cases apart, getting the crank out, and getting everything cleaned up. I'll be replacing every bearing in this thing.

I started with good old brake cleaner and a toothbrush, which got things relatively clean then moved on to using our shop's ultrasonic cleaner. The problem being that it's way too small to fit the whole case in there. I've essentially been plopping it in there and rotating it like cooking a turkey. The cleaner uses heat, ultrasonics, and what my shop mate calls a "witches brew" of cleaner to get everything nice n' clean.



Since the case is already heated up in the ultrasonic bath, all it takes is a tiny hit with the torch to get the bearings out with a bearing driver and mallet. I know you're not supposed to use a torch on these cases, but since it's a quick little blast of heat it shouldn't warp them:




What you end up with is something like this. A little more elbow grease and it should be factory fresh and ready for new bearings:



You might notice the previous rebuild used gasket maker (yamabond type stuff). Since I hear these motors are extremely sensitive to shimming I've decided to peel all that off and replicate the process instead of using the factory gasket. This way I can hopefully avoid having to re-shim everything a million times.

Shims:



More shims:



Even more shims:



OKAY WE GET IT WITH THE SHIMS:



More shots of the cleanup process. I should have taken a before picture, because this part of the engine with all its little nooks and crannies was disgusting. Now it just needs some polishing. Okay, lots of polishing, but that's the fun part:



This side needs more time in the witches brew but it's getting there:


Shifter forks look pretty good:



Seems like the original crank bearings in this puppy. Going with some nice new replacements for the sake of reliability:


This bearing had a weird seal/shim on it:


Aluminum flywheel. After much deliberation, I think I'll be going "total loss" on this bike. It should offer quick revs and drop weight (rotating mass). I'm a little apprehensive about it, but I think it's the way to go for a quick bike. Racers in the crowd, can you chime in? Total loss? Full battery'less stator setup? What's better?



What a mess!



Next shop night I should be taking a break from this motor and getting into the frame, forks, and wheels.

[Eldert]

Hello

nice project . the motoscrubs website has a tech section . have a look at :

how to build a vintage Ducati racing single ( in a million easy steps )

that will answer a lot of your questions .

Eldert

[boobby]

hahaha, it took me a sec to figure out what these familiar items where on this build thread.