YERF DOG 3020 Restomod

[GRIFFKART]

Howdy guys and gals.



I’m a longtime car guy and love almost everything that is fast, fun or dirty. American muscle cars, Jeeps, trucks, boats and even a few Gambler 500 races. As a father, I constantly strive to involve my kids and impart my passion and skillset to them. They are now 6 and 8 and its time for them to start wrenching and enjoying on their own project!



I’m working on a budget and I want to develop their mechanical skills and pride in their own hard work so I didn’t want to just buy a new kart. I was lucky enough to have a buddy gift me a 2000’ish Yerf Dog 3020 that his kids had enjoyed, abused and eventually outgrew. The kart had been sitting under a tree ignored for several years and is need of some TLC. Here’s what we have already accomplished:

• Replace the tiny handcart tires in the front with 145/70-6 knobbies
• Converted the front to 3-bolt hub
  • Ordered the wrong size 3-bolt hub and had to drill the wheels to match
• Replaced the worn out PowerSport 5.5hp with a Predator 224
  • Original motor was old enough to buy alcohol and had a broken pull start, cracked fuel tank and was full of varnish
• Replace the rotten 18x9.5-8 tire in the rear
• Struggled and failed to remove the rear wheel from the 1” keywayed shaft
  • Humbling
• Repair frame crack on driver rear
• Rebuild steering pivot that was rusted solid to the frame
  • Lots of heat, beating
  • Broken retaining bolt
• Clean and reassemble the Comet 30 series (?) torque converter
• Disassemble and rebuild the front spindles

Our first test drive yesterday was an overall success! Even with the throttle limited to 30% my son had an ear-to-ear grin! We also confirmed that the steering is horrible, super heavy and dangerous! I know this gen of Yerf Dog was part of the steering recall and that is the next project. Anyone got a good thread for Yerf Dog steering fix?


Once we get all the bugs worked out and the kids have a good grasp of safe operation we are already talking about some upgrades

• Bellmouth, filter and jet upgrade
• Remove governor
• Header and muffler
• Add Nerfbars
• Paint-kids Choice
• Rebuild seat

 

[BaconBitRacing]

Thank you for taking the time and building right and safe. A few members here have 'Dogs, and I know @Sandrion is actively upgrading his. @panchothedog has multiple fast, safe 'dogs and he should have some info. Have fun!

 

[GRIFFKART]

Thank you for taking the time and building right and safe. A few members here have 'Dogs, and I know @Sandrion is actively upgrading his. @panchothedog has multiple fast, safe 'dogs and he should have some info. Have fun!

I want them to have fun and build a love for this kind of stuff, but safety is always #1. It may seem overkill but we ordered DOT moto helmets for the kart as well. Plus if anything happened to them my wife would kill me so it's in my best interest.

Thanks for the recommendations on Sandrion and Pancho. I searched 3020 and came up with a few useful threads, but mostly dead ends. Thanks!

 

[BaconBitRacing]

NOT overkill at all for those helmets. Karts can be dangerous, even with cages.

 

[BrownStainRacing]

Howdy guys and gals.



I’m a longtime car guy and love almost everything that is fast, fun or dirty. American muscle cars, Jeeps, trucks, boats and even a few Gambler 500 races. As a father, I constantly strive to involve my kids and impart my passion and skillset to them. They are now 6 and 8 and its time for them to start wrenching and enjoying on their own project!



I’m working on a budget and I want to develop their mechanical skills and pride in their own hard work so I didn’t want to just buy a new kart. I was lucky enough to have a buddy gift me a 2000’ish Yerf Dog 3020 that his kids had enjoyed, abused and eventually outgrew. The kart had been sitting under a tree ignored for several years and is need of some TLC. Here’s what we have already accomplished:

• Replace the tiny handcart tires in the front with 145/70-6 knobbies
• Converted the front to 3-bolt hub
  • Ordered the wrong size 3-bolt hub and had to drill the wheels to match
• Replaced the worn out PowerSport 5.5hp with a Predator 224
  • Original motor was old enough to buy alcohol and had a broken pull start, cracked fuel tank and was full of varnish
• Replace the rotten 18x9.5-8 tire in the rear
• Struggled and failed to remove the rear wheel from the 1” keywayed shaft
  • Humbling
• Repair frame crack on driver rear
• Rebuild steering pivot that was rusted solid to the frame
  • Lots of heat, beating
  • Broken retaining bolt
• Clean and reassemble the Comet 30 series (?) torque converter
• Disassemble and rebuild the front spindles

Our first test drive yesterday was an overall success! Even with the throttle limited to 30% my son had an ear-to-ear grin! We also confirmed that the steering is horrible, super heavy and dangerous! I know this gen of Yerf Dog was part of the steering recall and that is the next project. Anyone got a good thread for Yerf Dog steering fix?


Once we get all the bugs worked out and the kids have a good grasp of safe operation we are already talking about some upgrades

• Bellmouth, filter and jet upgrade
• Remove governor
• Header and muffler
• Add Nerfbars
• Paint-kids Choice
• Rebuild seat

Welcome!!!

It's always nice to see kids twisting wrenches and learning how mechanical things work together. Seems to stick with them their whole life.

You mentioned the governor removal on the pred 224. I really recommend NOT doing that. That's an oddball size wrist pin, the rod and piston in that area seem pretty weak compared to the standard clone size wrist pin, rod, piston combos.

The 224 makes alot of low rpm torque with the extra 3mm stroke, compared to any 212. It doesn't need high rpm and big gearing to jump weight outta the hole and keep pulling.

Theres a couple small adjustments, tweaks and cheap parts that really wake the 224 up, it might end up being more then you asked for, with the governor still working, stock air box and stock muffler.

Theres a member here working on his, jus moving the governor spring over 1 hole, gained another 600 rpm for him.
Post in thread 'Newbie Yerf Dog 30032 Need Advice' https://www.diygokarts.com/community/threads/newbie-yerf-dog-30032-need-advice.47403/post-594414

You can drill out the stock .028" main jet out to a .031" with a 1/32" drill bit, they are real lean outta the box.

The stock air box and muffler will handle 5300 rpm very easily.

There's a $40 flywheel, that can be added for safety and performance. It takes 2lbs off the crank, and a very noticeable increase in acceleration.

Install a .027" thick headgasket will bump the compression ratio from 8.8- 9.3:1, that's a ez, cheap way to pick up a lil extra power. The stock gasket can be .045"-.052" thick

Setting ignition timing to 28* BTDC, always helps in the mid to upper rpm. Stock is 21*-22*, ....if you're lucky.

The stock coil will start pulling ignition timing out around 4500-5000 rpm. If planning on turning more rpm, jus replace it with a performance coil. I only recommend coils from Dover Power,.....I KNOW THEY WORK AS ADVERTISED.

These are simple, ez, mods that will make ANY clone style OHV governored engine pick up more torque in the idle to 5000 rpm range. They are cheap and will not hurt the engine at all. And will out perform any of those crap stage junk kits out there.

Good luck, have fun, and be safe!!!!

 

[Denny]

Welcome! Have fun but I agree with your wife that hurting or killing the kids would be bad! Axles and rims, the great humbler! Will make a strong man weak, a smart man stupid!

 

[GRIFFKART]

@BrownStainRacing
I love sharing this stuff with them! They help in the shop and we have a lot of fun out on the trails.

Thanks for the 224 building knowledge bomb! You hit the nail on the head with the reliable and cost effective power is the goal! I look forward to introducing the kids to modifying for performance gain!

@Denny
Busting and installing the tires was tough but not horrible. Struggling and failing to get off a baby rim was the humbling part!

 

[Denny]

@BrownStainRacing
I love sharing this stuff with them! They help in the shop and we have a lot of fun out on the trails.

Thanks for the 224 building knowledge bomb! You hit the nail on the head with the reliable and cost effective power is the goal! I look forward to introducing the kids to modifying for performance gain!

@Denny
Busting and installing the tires was tough but not horrible. Struggling and failing to get off a baby rim was the humbling part!

Yup! They’ll make a grown man cry! But it feels so good to cut it off with a torch or angle grinder!

 

[GRIFFKART]

First test drive complete! My son took 1 lap around the block and came back with an ear to ear grin! And all the neighborhood kids came running over to check it out!

New problem is the torque converter is dragging/engaged all the time. Even just pull starting the motor causes the cart to drive forward. I’m searching the forum for fixes and have a few ideas.

New belt based off the part # off the original PN: Comet 20359. It is A-symmetrical and seems to fit correctly based on the belt selection sticky.

I removed and cleaned the driver and DID NOT lube it. I sanded the rust off the pulley surfaces with an orbital sander.

the driven side is stuck on the Jack shaft. I can get the 15/16 nut off but not the retaining clip. So I cleaned it and sanded the pulley surfaces as smooth as possible.

Recommendations? Or link to applicable threads? Thanks.

 

[BrownStainRacing]

Here's some good advice, reading material, about t/c's.
Those parts, driver and driven, are really cheap on ebay and Amazon. That's all I use and my junk has lasted for years.

Jus dont be cheap on the belt. If it dont say "Bando" or "Comet" on it.....find one that does.

Comet 30 Series Torque Converters | Comet 30 Series Parts

Comet 30 Series Torque Converters for 3 to 8hp Go Karts and Mini Bikes. Comet 30 Series Clutches, Driven Pulleys and Comet Parts. Technical Information.

www.gokartsupply.com

 

[Denny]

You could try taking the belt off and soaking it with PB Blaster for a few days. The put the belt back on and drive it for a while and see if it frees up. Or just chisel it off and replace it with a Jungle store one.

 

[GRIFFKART]

@BrownStainRacing
@Denny

Thanks for the input, links and parts advice. I bought the best reviewed belt on Amazon, but I’ll hunt down a Comet or Bando if they make a difference.

Researching it more I think my flyweight assembly is worn out. I can pull the weights open my hand and the slide pins keep walking out. I also need to clean out the inside of the sheaves more now that I understand that that is where the flyweights ride.

Sounds like you guys both endorse the knock off torque converter? OE Comet stuff seems to demand a high price tag. I’d like to save a few bucks if possible.

Thanks for the input!

 

[BrownStainRacing]

@BrownStainRacing
@Denny

Thanks for the input, links and parts advice. I bought the best reviewed belt on Amazon, but I’ll hunt down a Comet or Bando if they make a difference.

Researching it more I think my flyweight assembly is worn out. I can pull the weights open my hand and the slide pins keep walking out. I also need to clean out the inside of the sheaves more now that I understand that that is where the flyweights ride.

Sounds like you guys both endorse the knock off torque converter? OE Comet stuff seems to demand a high price tag. I’d like to save a few bucks if possible.

Thanks for the input!

You're welcome!!!

I wouldn't recommend something I havnt tested, put thur a mud hole or 2, and use myself. I don't believe in wasting a man's time and $ over some bs parts I havnt tried,


The only problem I see in the cheapo 30 series drivers is the flyweights, they are not weight matched, usally 2 or 3 grams different. Comet is probably the same. Idk, havnt seen new Comet parts in few years.
I put em on the wire wheel on the bench grinder and weigh em to match. Most people wouldn't even notice the lil clinging.
I perfer the lighter aluminum flyweights myself. Seems to be a smoother engagement, then the heavier zinc ones, to me. I ran a lil more rpm engagement then stock.

As for the belts. I ran across a mini bike drag racer that said he gets 50+ launches outta a bando for a 30 series.

I figure if they can handle 18-20 hp methanol small blocks launching 5000+ rpms, surely they can handle my junk "turd motor" builds.

I figured right.... they last over 2 yrs, my son gets my old ones and he's never bought a belt,

My grandson buggy has comet belt, it jus works. It'll never get another brand.
It's been thur more mud holes and up the steepest hills then most would ever try.

They ain't garage queens or trailer queens. They get used, abused, and beat on....alot!!!