[2 stroke] TransBetxí: Cultivators Rally

Hi everybody
In the first place reported this document was conceived to give to know this peculiar and interesting race so famous in my village and the area, but so almost unknown everywhere. I also share this information and these images that I think are interesting and may be of interest to many people.
In the second place I would like to apologize that this page is French, but I hope that no problems here we communicate in English, aside from which my English is very bad...   I'm sorry.

Well, without more extend, I will present this singular rally which takes place every year since 1989 and that 2014 will fulfill the 26° edition on Betxí, a village in the province of Castellón (between Barcelona and Valencia). As I have said is celebrated every year, always the second weekend of Easter, which is usually about the month of April, in 2014  this will be exactly April 25th and 26th.

The peculiarity lies in this rally that competes with vehicles a little different... cultivators to plow a field fully modified for racing to make a relatively high level. These cultivators were used many years ago for our grandparents to plow the fields of orange, which at that time was, along with ceramics, the axis of the local economy.

Obviously, at first, many years ago, the idea of going to four stages with standard cultivators and character totally festive and very uncompetitive with years consolidated quote and every year he adopted a a more competitive, but do not lose the feeling of friendship that also characterized until today, which is a fully fledged race with serious (including the FMCV Federation Motorcycle of the Valencian Community) . So much so that today, though most teams are local, also sell competing teams from neighboring towns and even further, for example, since about three years ago Germans also sell teams.

Logically the competition rules has a certain established rules, some of the most important are that the cultivators can make all kinds of modifications but always respecting the original spin system, ie the whole machine front where the engine and all change and transmission to the wheels should be all set to turn with respect to the chassis where they placed the pilot and copilot forbidden systems individual twist on each wheel like a car, quad, buggy... And another rule is that the engine must be the original that bears walking tractor, ie, you can make all the appropriate modifications but you have to respect the engine displacement and the external appearance of the original engine, which is why almost 100% of vehicles are brand Gyrmet, who they mounted a Bultaco 250cc two-stroke engine.

Below are some pictures of the evolution of vehicles, from standard cultivators to current machines:
1989:

1992:
1995:
1998:
2000:
2003:
2005:
2007:
I’m, 2011:
2012:
I’m, 2013:
2013:
I’m, 2013:

And this in a video on-board a special stage of the year 2013, on youtube you can find many more:

https://www.youtube.com/watch?v=3OTzpZA5aV8
Also a few captures of the rally in 2013:






https://www.youtube.com/watch?v=rLLQaXmLbb8

Technical and mechanics evolutions:
Over the years, the cultivators have evolved from simple devices to plow the fields to the current racing machines. This has been possible thanks to the continuous evolution of cultivators each year by the teams contrive to try to beat their opponents.
Now I will explain some of the most important developments in each part of the vehicle:
The transmission housing has been one of the keys in this historical trajectory, initially box brand Gyrmet consisted of a 3 gears (one very short to plow the fields and the other two for the displacement of the walking tractor for roads) also a gear to behind the rotating shaft against. Then had a cascade of gears to speed desmultiplicar axis with gear and a giant oversized gear to save the distance to the axis of the wheels, as shown in the image (without the gear for plowing up and without the march behind):

The first changes were made consisted of eliminating the short first gear so the gearbox as it was only used to plow and remove the rear gear ant his contra-rotating. Then also delete gigantic gear to replace it by a chain from the third axis to the axis of the wheels also were modified the two gears of the gearbox to make the transmission longer and less gap between them:


Standard cultivator has no suspension system simply was a rigid axle shaft end he has to leave change and harvested directly on the wheels, then began to install suspension systems completely handmade, using in many cases joint shafts (which breaks down cut to fit them to the separation of the wheels) and stub shaft car. Install dampers installed a quad bike or even trapeze system is handmade.
The next step was to cut the box Gyrmet to lower the center of gravity of the vehicle, thus being a lower chain length, as shown in the following image:



Gear selected readers have also built various levers of change and drive for the gearbox, but this is not so much a standard Cossa, each team or driver door system change what he likes even pilots are retaining the original with minor variations.
We go now to the transmission crankcase primary Gyrmet the cultivator engine has a transmission Bultaco primary chain double, like old Bultaco, and a simple single disc clutch cork.
As would increase the engine power, the mono-discs cork singe, so the first modifications were coupled there a simple multi-disk came especially for these engines. Although they were not too good and had great pressure to adjust each spring for the pressure plate separated alike also had a very sharp and little operating order, although this still people who are still using. Later adapted clutches started full of motorcycles today.
Regarding the primary transmission, most cultivators still wearing chain series, although there are teams that are manufactured transmission system primary gears, one on the crankshaft and clutch each other against parasite rotating between the two to save the length between the crankshaft and the primary axis and also to maintain the direction of rotation. In this field, last year in 2013 I produced a completely new primary crankcase machining from a block of aluminum, I did make two units, two machines for our team, can be viewed here:




Carts or rear frames where they located the pilot and copilot are totally new manufactured, many years ago that began to replace the old standards for these new cars much lighter and the lower point of gravity and tilt independent on each wheel, drum brakes were adapted to the top of the car, but today many have already been more effective brake discs and light, also being installed teams front brakes every year, as growth had brakes only later. Another important point is the hitch wagon to the machine as standard is a steel bolt that slides directly against the steel of the machine, and with a simple pin that makes axle. But increasingly being installed bearings systems for a smooth rotation and eliminate power play that had the pins of steel against steel.
Already finally enter the engine. As I said earlier, the regulations prevents change the standard engine from another cultivator. Is for this reason that almost all the cultivators use this box incorporating a motor Gyrmet Bultaco 250cc two-stroke. Of course all kinds of modifications are allowed to the original except engine engine displacement increases (excluding rectifications on the cylinder liner) air cooling and respect the original moment is prohibited to install a water cooling system.
Engine Features Bultaco 250 standard are:
-Aluminum crank case double bearing near the primary transmission.
-Crankshaft stroke is 60mm with 116mm distance between conrod centers.
-72mm piston diameter (with rectifications of 0.25 to 73mm).
-Aluminum cylinder with cast iron cylinder liner, air-cooled load with only two transfers and a exhaust port with central bridge with a very low distribution.
-Admission to the cylinder by the piston skirt with a old 24mm Dellorto carburetor.
-Aluminium cylinder head air cooled.
-Without resonance exhaust pipe.
-Fixed ignition.
The whole undergoes profound changes and that is why the evolution of the engine increasing its power together with all the improvements mentioned above make this race that you have the level today and is so impressive to see it and live it every year.
There are many teams that keep admission to the cylinder piston skirt, but most of those are in more advanced positions as lead reed valves for admissions either the cylinder or crankcase made entirely by hand, mechanized or even CNC. Modern carburetors are mounted 36 to 39mm diameter. The cylinder will be adjusted distributions of escape and transfer areas and even make you some new transfers.
The cylinder heads are modified or lowered and are the new nocks outer casing Bultaco cleared with combustion chambers centered and squish band.
Various ignitions mount, either fixed or variable and programmable.
Obviously mounted exhaust resonance, be adapted to different cross or enduro motorcycles, there is a company that sells its exhaust especially for cultivators, and of course there are plenty of exhaust pipe made by hand. We have our own exhaust pipe development after some tests in bench tests.
The standard crank case:

My engine 2012-13:



I hope you liked it and I trust that any queries or have curiosity upload.
For more information you can also search the internet to rally for his name: Transbetxí.
Official Website: www.transbetxi.com (although it is in Catalan and a little out of date)
You can also find the facebook group TRANSBETXI.

Where can I put this topic?

  

Anyway, thanks for this unusual subject.

This is racing !!


  


Thx

 

  

Marc, ouvre une rubrique "agricole" peut-être, pour les motoculteurs de course et les Harley Ferguson ?

  

 

Hi, Piquer,
Terrific  vehicles !!   
Seems to be funny and more and more professionnal.

Ca ne m'étonne pas ! il y a 45/47 ans avec mon meilleur pote qui travaillait avec moi on attelait un sulky derrière 2 motoculteurs Honda F50 (haut moteur similaire au vélomoteur C200) on neutralisait le régulateur et comme en 4 ème il prenait normalement 20 km/h on passait à près de 40 ! et on se tirait la bourre sur la place de l'église du village !!

Excellent, Piquer !   
Good smell of fun   

yeah c'est top ça

Thanks, I'm glad you like it.   
You can see many more pictures here: https://www.facebook.com/groups/59162244965/?fref=ts

Here are some pictures of the crankcase machining for reed valve admission:



The admission blocks, inside with CNC machining and external contour with wire electroerosion:






Regards

Today was a day of testing!

The configuration of the engine with the curve is fixed ignition map and a rich carburization





More on that tomorrow
Regards

90KMH 

Edit:

With little wheel on the dyno!    

gozos a écrit:

90KMH 

Edit:

With little wheel on the dyno!    

Yes! the wheel diameter on the dino is 365mm. The race wheel is 440mm when it's new.
The equivalence is 110 km/h
And now the engine is better adjusted and more rpm