Andrea Bartolini YZM400F engine and project.

[artracing]

50/50 works re-creation?

 

I noticed this thread the other day.

https://www.thumpertalk.com/topic/1059806-happy-birthday-thumpertalk/

 

It seems these YZM400F bikes may be the very reason ThumperTalk came to be.

That is something. Never would have figured. Glad they saved those videos. I have one on Bartolini on my website. Very impressive also.

If you start searching the history of the YZM400, you will see that its impact to motocross and motorcycle market is astronomical. It literally changed history and direction of motorcycles.

We can save the two stroke, four stroke debate for another thread but this bike did serious damage to two stroke but I think it was inevabtable.

[artracing]

Here is the link to one of Bartolini races that he won with YZM400, at Castiglione in 1997.

I think he was sand bagging and came out of nowhere. Impressive what the bike can do.

I had to put a programmable CDI on my 50/50 :-) which has more capability then what they had, ignition wise. Like throttle position, which they didn't have. Wonder what that would have done for them?

http://www.huskyrestoration.com/bikes/YZMcastiglione.mp4

[artracing]

50/50 works re-creation?

 

"50/50 Works"

I like that. I will use that.

Thanks

[rmxdan]

Ha ha, fair enough, and I thought the recreation / re-creation twist was the best bit...

 

Could be very useful having the programmable ignition to keep the engine running safely with whatever fuel you are going to use.

I dare say the works bike were probably pushing limits to maximise performance which could reduce engine longevity.

Have you calculated what compression ratio the engine is running, and what the cam specifications are?

[artracing]

Ha ha, fair enough, and I thought the recreation / re-creation twist was the best bit...

 

Could be very useful having the programmable ignition to keep the engine running safely with whatever fuel you are going to use.

I dare say the works bike were probably pushing limits to maximise performance which could reduce engine longevity.

Have you calculated what compression ratio the engine is running, and what the cam specifications are?

I have it setup with very mild timing curve to be safe. It appears the engine was freshened after last time it was raced and never raced again. Since I only have one head gasket, I never took the engine apart. Except for flywheel and clutch cover.

Clutch assembly is YZ250. Rumor has compression ratio at 13:1

The piston is 3mm larger at 95mm and stroke is short 56mm vs. 60.1mm stock.

Supposed to be close in ratio to Formula One cars.

[artracing]

This is from Yamaha Racing website.

Yamaha Factory Racing will mark the company’s vital role and place in the history of off-road motorcycle development by unveiling a dedicatory livery in the classic ‘red/white’ colours for the motocross Grand Prix of Italy at Maggiora this weekend. Works rider Jeremy Van Horebeek – currently third in the MXGP FIM Motocross World Championship with eight consecutive podium finishes – will run the scheme on his YZ450FM; the design is a near replica from that of Andrea Bartolini’s revolutionary 1997 YZM400F prototype that changed the face of motocross. Christophe Charlier is hoping to be fit for the Grand Prix of Germany on June 21-22 after minor knee surgery but his YZ250FM will also carry the famous colours in Italy while being displayed under the team’s awning.

[YZX]

Just noticed this thread, sweet bike.

[artracing]

This bike will be at AMA Vintage Days this weekend. I'm putting it in the, all motorcycle show Friday.

Keeping it at a friends booth in swap meet up the street front Penton booth until Saturday afternoon.

I'll be riding it around also.

Rob

[artracing]

I had an unfortunate breakage in the electric starter system which is more like a transmission. Had American Machine and Gear reverse engineer it and we are all,back to normal.

Here is a rare look inside the right side cover with clutch basket and part of starter mechanism removed

[artracing]

Finally got some good photos of the bike.

Rob

[YZX]

Finally got some good photos of the bike.

Rob

📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg

damn, thats one nice bike

[artracing]

Just saw the specs on the 2015 YZ450. At 52HP, it's still, after 18 years, under the 60HP of this bike.

[grayracer513]

Not that much.  In real life, the '15 has spun up dynos to the tune of 57 HP in stock trim.  Not to denigrate the YZM, but I wouldn't drag race for titles, if you know what I mean.  Besides, if I'm not mistaken the 60 figure for that bike was crankshaft power. 

[cowboyona426]

Finally got some good photos of the bike.

Rob

📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg📎image.jpg

 

Wow, the shot from the rear sure makes the shrouds look WIDE!

[artracing]

Not that much.  In real life, the '15 has spun up dynos to the tune of 57 HP in stock trim.  Not to denigrate the YZM, but I wouldn't drag race for titles, if you know what I mean.  Besides, if I'm not mistaken the 60 figure for that bike was crankshaft power.

You could be right. I have only seen data that media reported. Would love to get the Dyno report.

[artracing]

Wow, the shot from the rear sure makes the shrouds look WIDE!

They are wider, I used large Fluidyne radiators, same size as Doug Henry since it was the same engine.

[artracing]

Here is a nice article by Rick Siemans Super Hunky on my YZM400

http://www.off-road.com/dirtbike/tech/building-a-working-replica-of-the-yamaha-yzm400f-54136.html

[Baldwin]

What an awesome build. Has it ever been ridden hard or is it for show only? Curious to know what that engine is like compared to a production unit (from any year or manufacturer)

[bk29]

Man that thing is cool. Did you consider using the two stroke side plates like Henry's bike?

[artracing]

What an awesome build. Has it ever been ridden hard or is it for show only? Curious to know what that engine is like compared to a production unit (from any year or manufacturer)

It's the prototype engine for what evolved into YZ400F. This engine is holy grail of four strokes. I am told only three electric start engines were built. Other two are not know to exist as of today. Only three people have driven this bike. There is a video of it on my IG Huskrestoration

It has not been ridden very hard. There are no spare parts for it. They are all OW works parts. Custom made. I had a unfortunate gear fail in the starter transmission. Had to be custom made to the tune of $800