2019 - Yard Kart Therapy

gegcorp2012

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Happy New Year all.

<Edit> Here is my test and tune video compilation (~10 minutes of yard track footage in November and December)
https://youtu.be/YlGP0D15dGM

My final update from 2019 is that we took the yard kart to an offsite location to drive on a .45 mile loop around a recently excavated area.

We have helmet cam footage (really a dash cam) but it is all upside down, and will take some time and editing software to process into a video.

It was good to ride in a wide open space as the sun was setting for the last time on 2019.

Photos show our yard mud on tires yesterday afternoon and different mud that what we brought back from the ride (it was dark when we got back so the third photo was from today)

To the staff at DIYGC...Thanks for hosting the site and having the build off contest. It has been a great learning experience and my son likes karting as new hobby besides his usual computers and tech stuff.




Tech specs go here:

DIYGC 2019 Thunder – gegcorp2012 Yard Kart Therapy


Specifications

Type: Fully suspended yard kart
Weight: 300 lbs(190 lbs rear 110 Front)
Wheel base: 73 inches
Front track: 46 inches
Rear track: 43 inches
Front tires 18x8-7 Maxxis AT
Rear tires Kenda radial 20”
Engine: Predator 212 CC stage1 prep
Clutch TAV2 CVT clone 6”/7”
Genuine Comet belt
Sprockets 10t/60t #40 chain
Frame: 3/4” pipe, pie cut bends
Seat: Plastic racing bucket
Steering: ATV 110 CC with 3” arms and Ackermann set for new wheelbase
Steering wheel: Kandi kart
Front suspension: Dual A-arm coil over ATV 110CC - Peace Sports
Rear Suspension: Monocross ATV 350 CC - Yamaha Warrior
Brakes: 110 mm Peace OE disks on front, ___ mm Yamaha single disk on back
Master cylinder:Two piston with stop light switch
Drift/parking brake: Modified Yamaha rear foot pedal assembly

GPS verified performance with 254 pound rider:

Carb Jet, air cleaner, header pipe
30 MPH on pavement (with governor... took a long time to wind up)
18 MPH on yard track (with governor)
Governor deleted
41.45 MPH on pavement (4750+ RPM)
26 MPH on yard track (no governor, 6" driven)

KartInfo link
3800 RPM 6"/7"
KartInfo by kartcalc.net:
Code:
[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]Kartname [/I]: [B] gegcorp2012 DIYGC Thunder[/B]
[I]RW diameter [/I]: [B] 20 in[/B]
[I]Weight [/I]: [B] 554 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Engine type [/I]: [B] Predator 212[/B]
[I]HP [/I]: [B] 6.5[/B]
[I]Torque [/I]: [B] 12.86 Nm | 9.48 ftlb[/B]
[I]RPM [/I]: [B] 3800[/B]
[I]Governor removed [/I]: [B] true[/B]
[I]Assummed HP [/I]: [B] 6.66[/B]
[I]Mods [/I]: [B] carb jet, header, air filter[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]System [/I]: [B] Torque Converter[/B]
[I]Clutch sprocket [/I]: [B] 10[/B]
[I]TC type [/I]: [B] series 30 7" driven[/B]
[I]TC sprocket [/I]: [B] 10[/B]
[I]Axle sprocket [/I]: [B] 60[/B]
[I]Final Ratio [/I]: [B] 6:1[/B]
[I]Lowest Ratio [/I]: [B] 18.78:1[/B]
[I]Highest Ratio [/I]: [B] 6.72:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Min Torque [/I]: [B] 86.42 Nm | 63.74 ftlb[/B]
[I]Max Torque [/I]: [B] 241.51 Nm | 178.13 ftlb[/B]
[I]Acceleration [/I]: [B] 2.12 m/s² | 6.96 fps²[/B]
[I]Top Speed [/I]: [B] 54.15 km/h | 33.65 mph[/B]
[/INDENT]
[/FONT]
__
Sent from my SM-J700T using Tapatalk
5500 RPM 6"/7"
KartInfo by kartcalc.net:
Code:
[FONT="Verdana"]
[INDENT][B]My Karts
[/B]
[B]New Kart
[/B]
[B]Quick Calc
[/B]
[B]Tacho
[/B]
[B]Settings
[/B]
[B]Other Karts
[/B]
[B]Help
[/B]
[B]About...
[/B]
[/INDENT]
[INDENT][B]Support[/B]
[B]Donate[/B]
[/INDENT]
[B][U]KART[/U][/B]
[INDENT][I]Kartname [/I]: [B] gegcorp2012 DIYGC Thunder[/B]
[I]RW diameter [/I]: [B] 20 in[/B]
[I]Weight [/I]: [B] 554 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Engine type [/I]: [B] Predator 212[/B]
[I]HP [/I]: [B] 6.5[/B]
[I]Torque [/I]: [B] 12.86 Nm | 9.48 ftlb[/B]
[I]RPM [/I]: [B] 5500[/B]
[I]Governor removed [/I]: [B] true[/B]
[I]Assummed HP [/I]: [B] 7.25[/B]
[I]Mods [/I]: [B] carb jet, header, air filter[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]System [/I]: [B] Torque Converter[/B]
[I]Clutch sprocket [/I]: [B] 10[/B]
[I]TC type [/I]: [B] series 30 7" driven[/B]
[I]TC sprocket [/I]: [B] 10[/B]
[I]Axle sprocket [/I]: [B] 60[/B]
[I]Final Ratio [/I]: [B] 6:1[/B]
[I]Lowest Ratio [/I]: [B] 18.78:1[/B]
[I]Highest Ratio [/I]: [B] 6.72:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Min Torque [/I]: [B] 86.42 Nm | 63.74 ftlb[/B]
[I]Max Torque [/I]: [B] 241.51 Nm | 178.13 ftlb[/B]
[I]Acceleration [/I]: [B] 2.12 m/s² | 6.96 fps²[/B]
[I]Top Speed [/I]: [B] 78.37 km/h | 48.7 mph[/B]
[/INDENT]
[/FONT]
 
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landuse

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To the staff at DIYGC...Thanks for hosting the site and having the build off contest. It has been a great learning experience and my son likes karting as new hobby besides his usual computers and tech stuff.

You are welcome :D It is just awesome seeing people getting into the garage and building things!!
 

gegcorp2012

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Update : New 4 lug wheels and tires, front suspension rebuild, better brakes.

With the 2019 build-off in the rear view, its time to look down to road and upgrade the Yard Kart for more safety at speed and better handling.

Understeer was the biggest issue at >20 mph on grass with the very worn tires on the front and the large paddle tires and live axle on the back.

The repeated thrashing on the yard track and 30+ MPH runs on a chert excavation site has flushed out the need for 4 lug front rims, better tires and new bushings on the control arms.




Look at that slop !

I replaced the worn and sloppy bushings with CPVC fittings that pressed right in and just needed to be drilled amd cut down to fit.




I used the CPVC fittings because that was the closest thing I could find at the local hardware supply, and these will eliminate all of the slop. That is a fix in my book.

Next stop is brakes:

Something is not right with this caliper, since the outer pad is showing a contact patch less than half of the size of the pad. It may be the casting is not square or the pad is rocked out a bit.

I am waiting on 128mm brake rotors for the new hubs, and I also have a better master cylinder to do next.

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gegcorp2012

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The 128mm rotors came in last week and quite naturally did not work with the existing 110mm calipers... so I had to order couple of different caliper sets until I got the right ones.

If you are considering using Chinese ATV suspension and brake parts, be sure to skip the 50/70/110 cc class parts and start with the 125/250/300 cc class parts because they are beefier and more suited for the extra weight and stresses the kart will generate.



I chose to modify my uprights to hold the new calipers as the new parts result in a wider arrangement.

I drilled 4 short pieces of 1.5x3/16 flat stock to make new caliper mount brackets and assembled for a test fit, then tacked them on. I removed the calipers before bringing the heat.



I will brush them down and trim them so they look better and paint them next.



Also changed the mounts for a new 3/4" bore Polaris master cylinder for plenty of volume and line pressure.



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gegcorp2012

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With the Covid-19 shelter in place restrictions, I have less travel to cover my territory, so that means more time around the house.

Since I work from home anyways, and know I'm not going to be flying or driving anywhere soon, I have time to tie up some loose ends.

I found out the soft pedal issue was being caused by my attempt to use two master cylinders... the main one on the foit pedal and a rear brake operated by hand (drift or parking brake). It turns out the line pressure is pushing up into the other master cylinder... and the result is a mushy pedal and weak stopping power. I can plug one of the tee fittings to fix that today.

I ran into a space issue on final assembly of the new calipers, spindles and wheels. Not exactly sure how it happened, but I welded the caliper mounts slightly different, so one side was grabbing the rotor screw heads and the other side was rubbing the caliper against the wheel.

I had to spend a few hours "clearancing" with a grinder (and mask). Got it done last night.

Beware of the lug nuts shown on the wood block. I was using these and one of them siezed up on the stud and chewed up the threads, which caused me to put this project on the back burner in Feb.

I replaced the lug nuts with the kind that has ridges on the bottom flat rather than the "thread cutter" up at the top.

Just need smaller castle nuts and a 12mm bolt to bypass the brake line for the rear brake handle, and Im ready for another season


<Edit>
More photos from 2020:

October - My daughter from TX visited and I got to take turns on the yard track with my grown-up sized kids.
Screenshot_20210109-090618.jpg Screenshot_20210109-090407.jpg
August 2020 - Added a roll bar and mounted the fuel tank to the frame so the fuel does not slosh onto the CVT belt.
20201029_165904.jpg 20201022_194459.jpg Screenshot_20210109-005551.jpg

New Year 2021 - Burn out video
 
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