Beta Backyard Kart 0.17.5

Update 0.17 includes many new parts, name changes, and new/updated meshes so you may need to clear the cache to resolve missing or misplaced textures/meshes. You can also delete the folder "0.30/temp/vehicles/bigkart" if you prefer not to completely clear the cache.


Full changelog for update 0.17 can be found in the Updates tab or in the link to the forums post below. I will also be taking any suggestions or bug reports there as well

Backyard Kart Changelog

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Here is the backyard kart!

It is a kart based on a real-life kart I rode as a kid back in the late 90s. My dad, luckily, hates throwing away anything he built, so he still had bits of this kart around so I could verify dimensions and more closely estimate the weights.

It has independent front suspension and a rear axle that is welded to the frame, so while it is designed for off-road driving, it is not designed for high-speed off-roading and is very uncomfortable at speeds above 20mph.

IRL pics

Spoiler

Here it is back right after the 350 was put in compared to the model in-game:


I thought the seat might have been placed more to the rear when the engine was offset, but nope:



And here is an action shot of me at around 8 years old on the 250 version:

This comes with an optional dummy that has a camera in its forehead. If you do not want the dummy, select the "No Driver Seat". The weight of the dummy is still applied at the dummy's center of gravity to maintain the balance of the kart and if you wish to not have the weight at all, choose the "Driver Seat" and remove the dummy.

There are three versions of the dummy: Static, Dynamic, and Dynamic (lean out).

The static dummy is like any other in that it will flop around when cornering or under acceleration.

The dynamic dummy will resist g-forces in all directions and try to shift its center of gravity opposite of the direction of said forces. For instance, when turning left, instead of leaning to the right, the dummy will instead lean to the left. What this does is attempt to move the center of gravity towards the inside wheels to prevent flipping as well as improve stability.

The lean-out dummy reacts in the opposite way laterally, a technique used by racing kart drivers to further get the weight off of the inside tire.



The kart went through several iterations over the years as parts broke and the intended purpose changed. So far, I have the three most relevant versions of the kart:

• Honda CH250
  • IRL Lore
    Spoiler

    [*]This kart was designed to ride in our quarter-acre yard which already had a figure 8 course worn in. The initial build used the entire drivetrain from the scooter, so it initially had three wheels with only one in the back. This was quickly scrapped after one of us ran into the house on two wheels. This kart lasted a little more than a year before the block cracked.
  • This had the driving position offset to the left and the engine placed to your right.
  • This was meant to be driven only on tight dirt courses, so it did not have brakes.
  • 
• Honda CB350 K4
  • IRL Lore
    Spoiler

    [*]This kart was designed after the previous engine broke. The seating position was changed since the engine no longer fit next to the rider and new tires were fitted to match the higher torque. This engine eventually gave out after a couple of years of service.
  • This one is more standard where the driver and engine are mounted in the center.
  • 
• 1987 Dodge 1.5L I4
  • IRL Lore
    Spoiler

    [*]This is the lowest-tier engine for that year. Being carburated, it puts out a whopping 85 horsepower! However, this is not an issue since after the final drive of the automatic transmission, it is further reduced by a factor of 4.27 thanks to the rear axle bringing the total reduction to around 13:1.
    [*]It initially was made to have half this reduction, but it quickly became apparent that a tractor does not need to go 90 mph
    [*]It is not designed with high-speed performance in mind and was designed to be a tractor that was used to flatten out our pasture and to build the track we raced other karts and other small off-road vehicles on.
    [*]
  • This one is not designed for high performance, but for high torque applications. This version was the last before it was converted to a new frame and could no longer be loosely called a kart.
  • 

Driving Tips:

Spoiler

• 250cc Base Configs (Better for keyboard drivers)
  • Standard Frame (Independent Front Suspension)
    • This one requires very little throttle control due to its balance and low power
    • Since there are no brakes by default, starting a slide before a corner will slow you down enough in most cases.
    • The rear will bounce around on uneven surfaces due to the welded rear axle. Due to this, gentle steering is required on really bumpy terrain at high speed.
    • Due to the off-center driver, right turns are much more sensitive as the right rear tire will lift up more easily.
  • Standard Frame (Welded Front Suspension)
    • This one handles very similarly to a standard race kart.
    • On most courses, you can scrub enough speed simply by turning
  • Independent Rear Suspension Frame
    • This one also requires very little throttle control and you can pretty much hold it full at all times
    • Sudden or oscillating steering may flip the kart
• One Wheel Rear
  • Don't turn

• 350cc Base Configs
  • Standard Frame
    • The rear tires tend to suddenly lose traction at speeds above 50mph
    • Setting the rear tire pressure at or near 0 significantly improves grip and reduces bounciness
    • Once the rear end starts sliding, do not let off of the throttle, but keep it as low as possible. This keeps the weight from shifting to the front, which causes overcorrection.
  • Independent Rear Suspension Frame
    • This one is much more stable, but still requires a bit of fine control at high speeds

• All

• • Try the understeer assist. All street versions of the kart have an extremely small sweet spot for cornering and this system hits that spot.
  • Try the 4WD Transfer Case
    • Add the front diff to match the rear
      • Match the diff name to the engine size or use the adjustable ones
    • Put front tires that match the rear
      • Same rim and tire size required for speeds above 70mph as the different width tires expand at different rates, which will cause the thinner tires to actually slow you down at higher speeds.
    • This will help compensate for instances where the kart understeers
  • Try the different diffs
    • They significantly improve the turning circle
• Lower the rear tire pressure
  • Between 3 and 10 for the bubble tires
  • Between 4 and 10 for the kart tires
  • All others use standard pressures
    
  • This will allow the rear end to absorb bumps better and improve grip at the cost of top speed.
  • Lowering the pressure too much will cause the tires to rest on the sidewalls and significantly increase bounciness

Tuning Tips:

Spoiler

• Standard Frame
  • Standard suspension
    • Experiment with camber settings
      • There will be a lot of body lean when turning, so using negative camber can help with grip if it is understeering too much
    • Lower the front end
      • This is accomplished by using the adjustable suspension or choosing different tires
        
      • This helps put more weight on the front tires and reduces the amount of body lean, which allows the kart to pull more gs before flipping
  • Welded Front Suspension
    • Caster is the key for this setup
      • The caster can go quite high and the higher the caster, the more the front end will lever the inside tire up.
    • Experiment with the track width
      • The wider it is, the more the front wheels will lift the inner rear tire.
      • This will need to be balanced as a wider front track width results in more understeer
    • Try to keep the toe as straight as possible, erroring on the side of toe out rather than in.
    • Keep the camber neutral to very slightly negative
      • You may need to watch how the tires flex to see how much is needed. The bottom of the outside tire should be flat against the ground.
        
      • The camber setting will have to be very slight as there is very little flex in the front arms.
    • If the rear end slips too much or starts skipping adjust these in order:
      • • Reduce caster
        • Reduce toe-out
        • Reduce camber
    • The actual settings will depend on the tires you choose.
      • The welded front race setup has a nearly optimal setup to allow the rear end to slip at around 1.7Gs on flat road
      • The lower the rear end grip, the lower you will want the caster since there will be less need to lift the inner rear tire and having both planted increases stability
    • Try to use the raised rear axle and match the front and rear tire diameter
      • This will lower the center of gravity and allow for much sharper cornering before a flip
      • With 8 inch tires, it can get up to 2.3 Gs before rolling over.

• IRS Frame
  • This one tunes much like a rear-engine car
  • You want the kart to lean to the front so there is more weight on the front tires or it may understeer a lot since there is very little weight on the front.
    • This will have to be balanced with grip, as too much oversteer may flip the kart

• Tires
  • The order of tire grip on road from worst to best is:
    • All Terrain
    • Rally
    • Standard
    • Sport
    • Race
    • Kart
    • Kart Super
  • Off road:
    • Kart Super
    • Kart
    • Race
    • Sport
    • Standard
    • All Terrain
      
    • Rally
  • Not all tires have all of these options, but this is the order I had in mind when setting the names
  • All of the tires and wheels in this mod will fit on any vehicle that uses 3-lug hubs

There are 13 additional engines and 4 electric motors:

Spoiler

• 150cc Engine
  • This is based on the true original engine from a Honda CH150 scooter. I chose the 250 because this was too slow with the 2:1 reduction and I recently found the true reduction ratio just before uploading the engine mesh update.
• 450cc Engine
  • It is based on the CB450, but fitted with the same CVT as the 250
  • Really only put in to have a more powerful option with the same feel as the 250cc
• 500cc Engine
  • This one is based on the CB500 Four, which had the same transmission as the CB350
  • In the same vein as the 450, it was added to have more power with the same drivetrain as the 350.
• 600cc Sport Engine
  • This one is based on a Suzuki GSXR600
  • It has a torque curve that heavily favors high revs
  • The high-end exhaust makes it closely match FSAE-tuned versions of this engine

• 750cc Engine
  • This one is based on the Kawasaki engine that was on this kart's predecessor
  • It is almost exactly the middle between the 500 and 1000cc engines

• 900cc Engine

• This one is based on a 900cc Honda
• It is much more tame than the 1000cc engine while still being thrilling to handle

​

• 1000cc Engine
  • Based on a Ducati Streetfighter V4
  • The peak torque is equal to the High Rev 2, but the curve is much more manageable.

• High Rev Engine
  • This one is a silly engine that has an almost unusable torque curve.
  • 90 ft-lbs of torque and 300 horsepower make for a very challenging ride

• Predator Ghost 212cc
  • The first real kart engine in the mod
  • It is weaker than the 250cc, but the CVT has a much better ratio range for racing.

• Blue Shock Race 7KW Electric Motor (Electric Base Motor)
  • A very weak motor meant to power karts that weigh around a third of this one, but it works pretty well once you start moving

• Blue Shock Race 18KW Electric Motor (Electric Mid Motor)
  • This one performs very close to the 250cc

• Blue Shock Race 30KW Electric Motor (Electric Top Tier Motor)
  • Very fast. It needs fine throttle control around corners.

• Crazy Electric Motor
  • 1600 HP because why not?
• Civetta v10
  • No room for a driver
  • Because, why not?
• Autobello 1.5L
  • Has room for a driver
  • Low budget option for more power
• Vivace 1.2L I3
  • Has room for a driver
  • Barely fits the frame and is wicked fast
• Gavril V8
  • No room for a driver
  • Wanted to see what a low end torque monster could do

Recommended Maps:

Spoiler

Kartland
This is a multi-course karting map. It includes 8 unique courses. 4 real-world courses handpicked so they each provide a different experience and 4 custom-made courses, also designed to provide a unique driving experience compared to the others.

The 350cc welded front race config is tuned for the Lentola Course on this map and the 250cc and Predator configs are tuned for the indoor courses on this map.

Big Kartland
This is another multi-course karting map, but this one is geared more toward high-end karts. Each course is designed or chosen to allow the 600cc configs to reach 100 mph. This one is still very WIP, but one course is finished and that course has a ton of layouts for time trials.

The 600cc configs are tuned for the UMC course in this map

Motorsports Playground
The Kart course is very dynamic with high-speed turns, a hairpin after a long straight, and turns along hills. It also has a woods course that has a ton of really tight turns that are perfect for the offroad configs of this kart.

Elvedalen Gokart (I got permission to upload changes here)
This one is a standard course with a good mix of tight and open turns as well as two long straights

TRN Race Track LIDAR
It has both a fairly tight course and a few motocross courses, which fit the kart quite well

The mid-race configs (450cc and 500cc) are tuned for the road course

Simply Sideways School
This one is really nice. I used mesh roads to mark out a course (this is not my map, so the course will need to be added manually


Simply Sideways Motorpark
This one is more open, but is still pretty fun with a faster config

Utah
The kart has a fairly easy time going through the lower off-road areas. the 350cc standard config performs its best here

As usual, feel free to message me with any issues you encounter, and if you set up a tune that performs better than what I set up or fills a niche I neglected, send it my way and I'll either replace one of mine or add it to the list.

Credits:
bitelaserkhalif - Provided the new model for the 1 cylinder engines
Agent_Y - Provided the base for the new dummy
Meo - Provided model for sand tires
Raider - Provided the base model for the new kart tires