The real OW – YZM400
1997/98 Blended Yamaha with OW – YZM400 Works engine.
Check out the article in Moto Magazine UK. May,2015 issue 115.
This is the “First Generation Prototype”
OW-H2 Works Engine with electric start,
raced by Andrea Bartolini
This is one of the OW – YZM400 Works Engines
which began the four-stroke motocross revolution
and changed motocross history forever.
One of the most historical motorcycle works engines of all time. The Holy Grail
Same Works engine like one used by Doug Henry to win
1997 Las Vegas Super Cross. First four stroke win.
This is the only known existing electric start OW – YZM400 works engine
Here is Bartolini on the #72 OW – YZM400
winning Castiglione, Italy 1997 Castiglione, Italy
Compliments from my friend Trond from Norway
Nice article by Rick Sieman on Off-Road.comOff-Road
Advanced Racing Technologies
Paint by Auto body Master – Mike Carter, Oklahoma City
Thanks to Doug Dubach for fantastic custom made carbon fiber muffler. Doug used the same carbon fiber used to build Doug Henry and Bartolini muffler. See photo below.
Doug was instrumental in the early development of the YZM400. I am honored to have him on-board. One of Doug’s many claims to fame, is being the first racer of the new production YZ400F.
I extracted this article from Pulpmx.com. Put best by Dan Lamb about how historically significant this engine is and how rare it is for years to come. There never will a be anything like it ever again.
<<<<There is no works bike before or since that changed the history of motocross like Doug Henry’s 1997 YZM 400, the only “true” works bike in the AMA since the inception of the production rule. The production rule was put into effect in ‘86 to protect privateers from having to battle $100,000 engineering marvels, but Yamaha somehow worked out an exemption and worked within the highly lopsided double-displacement rule with the AMA to further four stroke development. I’m not going to turn this into a two-stroke four-stroke debate, but this bike was a 100% prototype machine and went against every production rule in the book. Because of these freedoms, Doug Henry’s YZM 400 was the trickest handmade machine to ever shred a motocross or supercross track. >>>>>
Having said that, the plan is to utilize this engine to something it deserves, instead of sitting on a shelf as a trophy. The project here is to use a production 1998 YZ400F motorcycle for this beautiful YZM400 works engine. I plan to simulate as many components as possible, as found on Andrea Bartolini or Doug Henry’s bike. My way of salvaging some very historical technology.
To the best of my knowledge ,this is only prototype works engine with electric start, known to exist. This is the engine that revolutionized motocross world in 1997 by Andrea Bartolini in European world motocross championship and Pete Johansson and by USA champion Doug Henry. The three other non electric start engines are in the only two existing motorcycles that I am aware of. One owned by Doug Henry’s bike, one owned by Bartolin’and other is the bike in Yamaha museum.
As you will see, it is an amazing engine design by Masakazu Shiohara. The main case is CNC machined out of one block of aluminum. The brown side covers, believe it or not are billet machined titanium. All the bolts are titanium. The 396.9cc engine is supposed to be rated at about 60 HP and redline up in the area of 12,000 RPM. The engine is also a wet-sump with only .7 quart capacity, not like the production bike that is dry sump and uses the frame as the oil reservoir. The water pump runs off the cam not like the production engine using the crankshaft. Another unique feature on the YZM is the exhaust it dual port and merged into one, where was the production bike is single port. Piston is 95mm x 56mm stroke but the production engine is smaller 92mm but longer 60.1mm stroke. The YZM has four gears, but production has five gears.
If you would like to read about the YZM400 motorcycle in old magazines, here is small list of ones I have gathered. There may be more.
Dirt Bike Feb 1997 – Motocross Action June and December 1997 – Dirt Bike December 1997 – American Motorcyclist June 1997
In the Dirt Bike issue December 1997 you will see large photo of this engine.
Here is a good article on the history of YZM400 evolution on Pulpmx.com.YZM400
Now on to the project……….
Sept 2012 – Purchased 1998 YZ400F donor motorcycle.
Custom decals and graphics by Senge Graphics out of Pittsburgh. Steve has done a great job. Check him out.Senge Graphics
Pulled the engine from donor bike. Weight comparison – YZM weights in at 54 lbs. and production engine came in at heavy 61 lbs.
I am currently working on modifying the frame and fabricating the custom exhaust. The engine is twin exhaust port, so the exhaust. has to be made custom. Production bikes are single port. As for the frame, The front down tube is notched for dual exhaust and left rear down tube must be modified due to the fact that the intake and carburetor are at different angle and interfere with the down tube Hence, the reason for the well recognized curved left rear down tube you see on Bartolini and Henry’s bike As you will see in the following photos, we had to duplicate that down tube to fit this engine.
1998 YZ400F donor bike. Frame, swingarm, seat pan, forks, lower tripe tree, hubs and calipers is about all that remains.
Titanium factory rear subframe
Titanium foot pegs.
90% of fasteners are titanium. 100% of Engine fasteners are titanium. Many components on the engine are billet titanium. Really!
Carbon Fiber custom engine mounts with titanium bolts
Carbon Fiber air box with customized air boot
Carbon Fiber chain guide
Plastic is all NOS 1998 European white with custom made decals
Since the original ignition system is unknown, I will be using a new programmable DC-CDI ignition system by Zeeltronic and utilizing the original prototype stator and flywheel.
Carburetor will be an original production Keihin CR but with some modifications. I’ll be using the throttle position sensor since the programable CDI uses one. To the best of my knowledge the YZM did not use throttle position sensor.
Seat was custom upholstered by Pirate Upholstery, Kingston NY. I used them for my Supermoto. Their work is superior. They do the seats for Orange County Choppers.
Radiators will be modified Fluidyne aluminum oversized. Needed for this engine, since the engine is wet sump with less than quart of oil.
New Excel rims
New Excel stainless spokes and nipples
New Pirelli MX tires.
New Front and rear brake disks with titanium bolts
New Afam rear sprocket with titanium bolts
New Billet GYTR compression release lever
New Cables customized
New Pro Taper fat handle bars. Same ones used by Doug Hemry
Billet aluminum top triple tree with fat bar clamps
New Fuel Tank
Authentic chain used by YZM, REGINA 135RX3-113L
Aftermarket kick stand
Unless noted, all other components are restored YZ400F
This is Andrea Bartolini YZM400F
This is the YZM400 Electric
Below is a photo of Doug Henry’s YZM400F. Same engine minus electric starter
This is a article in Dec 1997 Dirt Bike magazine wit Stephane Peterhansel holding this engine.
Doing quick fit of YZM400 in the donor bike.
Because the carburetor interferes with the left rear down tube on production frame, it has to be modified.
Look familiar? I made a actual size copy of Doug Henry frame down tube as a template. You can put the photo template in front of the frame, take it away, and you will not see a difference.
Things are being fitted up first and then the final welding. Here you see the frame is notched for dual output exhaust. The factory YZM frame was built with a front wish portion of frame to allow for exhaust output.
Yet another overlook detail. The sprocket cover is billet titanium
I had some of the original graphic decals custom made.
All the plastic on this bike is NOS. I had to go from USA to Australia to Europe to get it all.
This the rear sub-frame I’ll be using. All titanium. Spoke with Mark Jerman. He use to make these for Yamaha when her worked there on the YZM project.
The orignal YZM400F used larger radiators. I’ll be installing a set of Fluidyne custom radiators.
Along with NOS YZ400F air louvers with custom extensions.
DRD Doug Dubach Racing carbon fiber muffler, custom made to match the Henry / Bartolin bikes
Added a Carbon fiber air box
Check this out. They spared no expense with this engine. This is the smaller “Billet Titanium” side cover and below it titanium clutch cover. Ka-ching
Carbon Fiber Engine mounts
Bench tested Zeeltronic programmable CDI unit. Pickup coil and throttle position good.
Produced spark with high tension coil.
Due to the slight difference in engine from production and longer intake manifold
the carburetor air boot had to be shorted. Modified vs. Stock on right
Fits pretty good!
Completed fabricating the battery box which also holds starter relay.
Fits nicely under the seat inside the air box. Still plenty of air for carburetor.
Now we do the build. Assemblies ready. We go for paint and put it together.
Still a lot of work to do but I thought I would do a dress rehearsal.
Click here to see First Test run TEST RUN