2019 - Yard Kart Therapy

gegcorp2012

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Thanks @landuse.

I have a couple of items to work on before I get all my tic marks for the build off.

Next day out will be after brake bleeding, adding a kill switch.

Optionally, I hope to re-drill my tiny 110cc wheels and try the shorter tires for better starts, and add the Ackerman angle on the steering to tighten the turning radius.

oh, and my free sticker !


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gegcorp2012

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I thought the kart quit last weekend because it was out of gas.

After taking a closer look, I noticed the choke lever was gone and the carburetor was loose. I found one of the nuts inside the top of the carburetor.

Glad it was too big to drop all the way through !


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I must have left them loose when I put in the jets and the air filter adapter.
 

gegcorp2012

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Ackermann built in ? I want to improve the steering radius, so I am checking to see if the steering knuckles can be optimized for the new wheelbase. the front end was on a 110cc quad, and now it's on kind of a stretched kart .

So I tied a string in the middle of the rear carrier and stretched it to the kingpin bolt to see how the steering knuckle lines up....



some close ups of the front...




Looks to me that the kingpin angle is making it so the tie rod is in line with the string.



The one thing I noticed is that with the small steering wheel, it's kind of hard to turn. I am thinking I may try to make the knuckle another inch longer for more leverage. I would do a similar mod to the steering end as well.



That is if I get around to it.
must...stay..focused...

Bleed the brakes again and add kill switch then I can call it done.


OK, so I got a nice toggle (kill)switch, and made a console out of sheetmetal. While I was at it, I added another hole for a light switch.


Since I had to take the steering wheel off to do the console, I couldnt let the opportunity pass by without doing something about the steering.



I added about 3/4" to the steering arm so that it will push the steering knuckles a tad more.
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gegcorp2012

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Added the kill switch and a 9" LED off-road light.


I noticed the LED light says 12 or 24v, so I decided to try some tool battery packs. I added some alligator clips and tried a 18v ni-cd pack, but decided to go with my 18v Ryobi Li-ion pack since I have a few of these.


I used a tie wrap around the top of the Ryobi pack to hold the alligator clips in place. that makes the back of the alligator clip stay in contact with the battery contacts.



...karting into the night








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itsid

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Ackermann built in ?
...

So I tied a string in the middle of the rear carrier and stretched it to the kingpin bolt to see how the steering knuckle lines up....

Looks to me that the kingpin angle is making it so the tie rod is in line with the string.

mean.. unfortunately the "pivot" you're interested is essentially the kingpin at the height of the spindle axle..
(that's there the string ideally should end up)
ackermann-kingpindilemma.jpg
so you are slightly off.. maybe half of the knuckle head,
but since the angle doesn't change too much
I'd still say your geometry should be okay
(assuming the string is indeed perfectly straight)
it might not be absolutely perfect alright,
but certainly far better than many other setups we've seen ;)

'sid
 

gegcorp2012

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Thanks @itsid
It's not right as it could be... I may have made it a little works lengthening the steering arm.

Here is a better photo to show the axle and arm.

Looks to be about 90*, so I will see about adding some material to make the arm longer and move that knuckle head over.


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gegcorp2012

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Test and tune... Working on instrumentation.

I added a tiny LCD tach, and a cell phone holder for hands free operation of the GPS speedometer. Also trying out a dash camera that my Sister gave me last year... my Son is a techie and he suggested I use a rechargable USB battery and it works (!)...

I will try to upload a video then see if I can mount the dash cam somehow and take a video going around my track in the yard.

The GPS is saying 16 mph tops on my yard track, so I wanted to add some instrumentation to figure out what is going on and what to work on next.

I hope to monitor the TC and see if it is shifting the driven clutch all the way. With a 10t driver sprocket and a 60t axle sprocket and 20" tall tire, I should see about 1mph per 100 RPM... so either the engine is not hitting 3800 RPM or the TC is staying in low gear or its slipping due to tall overall gearing (even downhill?).

Once I get this sorted out, I will pull the governor.


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gegcorp2012

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Got it back together last night and put on a few miles today.

I made a couple of videos today, first on the CVT assembly with the dash cam, but after a couple of laps, I lost the battery for the dash cam somewhere in the woods after turn two.

Here are a couple of stills from the CVT video... the driven clutch is kicking in... got up to 3800 RPM and 18MPH on the yard track. The second photo shows the camera battery dangling near the rear tire before it fell off in the woods somewhere.


Sorry for the file size on these... the smaller file option was giving me errors

Then I made a video of a couple of laps using the phone that ended with an unplanned demo of the kill switch - had to drop the phone at the end of this video to handle the emergency shut down.

https://youtu.be/RvFj7k9leO0

The wire for the spotlight wedged between the light and the gas pedal so the gas was stuck WOT and the kill switch saved the day.


Next, I did a road test and got to see a new high of 31.4 MPH (slight downhill grade) and backed it up with 29 MPH on the way back (slight uphill grade). I'm saying it is good for 30 MPH on pavement with the governor on.



I also did a offroad torture test driving over several 3x4 landscaping timbers, and the phone flew out of the holder on the second bump and bounced around on the floorpan then landed in the yard after the last timber.



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gegcorp2012

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Governor delete in progress.

That little clip holding in the governer wheel is the hardest part. Finally got it and all the pieces out. Also threaded the holes for the oil sensor and governor shaft.


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karl

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making great progress :thumbsup:

don't forget that terribly small washer that sits behind the governor wheel!

'sid

I did this to a predator, and when I opened it up 20+ hours- 2 years later I found out, and the washer did not move at all, right there on the shaft. :p

Good work on the build! A bit on the long side , how does it turn? The rear tires look cool.

I use a pick , shove it between the clip and governor shaft, tap till deforms and falls off.
 

gegcorp2012

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Thanks @all

... A bit on the long side , how does it turn?

Meh... well, I am prety sure my Tahoe turns tighter !

It ended up about a foot longer than I planned, so better turns are something that I am still working on.

Sid pointed out how to optimize the Ackermann a bit, and that helped with better cornering and +2mph speed on my yard track. Also noticed the rear end is now easier to break loose after the front end adjustment... I did a 180 in the gravel, but need more RPMs to get on around.

I'm hoping the gov delete will give me some "power steering" on the big back tires.

Also asked for a 7" driven pulley and yellow spring for Christmas for more low end.

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JTSpeedDemon

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Briggs governors don't have that clip......;):D:D:D:p:p:p
They just slide right off, pretty nice.

I'll probably build up a clone someday, but for now I still like flatheads the best. Glad that nasty little piece of plastic is coming out!!:cheers2:
 

J.S.@SMS

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Oh, you'll see a big difference with the 7" driven. I put one on my streaker a couple months back. Now it leaves streaks in the ground when you take off, and goes much better off road. And proper ackermann always helps.

Slightly related question, what year and body style is you're Tahoe? I've got a '98 (first gen) 2 door 2wd LS with the barn doors instead of the liftgate. Fun fact, the first gen Tahoe ('95-99, or '92-'99 for the Yukon) was the only generation to have a true small block chevy 350, and two door option. The LS has been used in Tahoes since then.
 

gegcorp2012

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^^^ My Tahoe is a '03 Z71 with the 5.3 LM7. Its a 4 door with a lift gate on the back. Hauls 12-14 foot lumber if I lay it on the dash (just a few boards). Pulls trailers nicely too.

Glad to hear the difference the 7" driven makes. Getting excited like a kid at Christmas now...

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gegcorp2012

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Throttle rod mod after #gov.delete


I put a reference dot in line with the hole next to the cable retainer
Then I put my needle nose pliars to the right of that dot and bent the rod upward 90 degrees.

Next, turn the pliers 90 degrees and bend the rod another 90 degrees towards the carburetor.

Make a dot on the throttle arm in line with that first upward bend and drill a hole. (the second photo shows the new hole drilled already)

Cut the rod a few mm to the left of the hole that is closest to the cable holder.


Threading the throttle and stop assembly on for a test fit...

Closed position
Open position


This allows me to keep using my existing throttle cable and keeps the throttle stop.

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