25+HP Predator 420cc Hemi Everything Billet Build ~ XXL Go Kart Engine

In today's video I take a stock 420cc hemi predator engine from harbor freight and show how to build it to 25+ HP - billet valve cover, billet 1.3 ratio roller rockers, chromoly push rods, billet side cover, billet rod, .308 cam, billet flywheel, billet killer bolt covers, 34 mm mikuni, msd style coil, 65lbs double valve springs, and block, head, and piston Cerakoted. We put the engine on the gravy bones kart. We give it a first start and a few revs. Subscribe for the next video of testing!!!
Parts Used On This Build -
420cc Predator Hemi - bit.ly/3qHtMdR
Stage 2 Performance Kit - bit.ly/33EiRpS
34mm Mikuni Kit - bit.ly/2PeTnL1
Muffler - amzn.to/3xZTOQ2
Top Plate - bit.ly/2NDP1fT
Chromoly Pushrods - bit.ly/3EMdhVY
Billet Rockers - Coming Soon
Billet Valve Covers - Coming Soon
Billet Piston - Coming Soon
MSD Coil - Coming Soon
Killer Bolts - bit.ly/2Fg1pAG
40 Series CVT - bit.ly/2Q6mjG7
40 Series CVT 2600RPM Stall - bit.ly/3kPFDEd
Billet Side Cover - Coming Soon
Head Studs - Coming Soon
Metal Head Gasket - Coming Soon
Starter Ring Gear - Coming Soon
Check Valve - amzn.to/3yeXmLJ
Tools Used On This Build
Maxima Assembly Lube - amzn.to/3xQJdqI
3/8" Torque Wrench - amzn.to/3ixDZbg
1/2" Torque Wrench - amzn.to/36pwLx2
Piston Ring Grinder - amzn.to/2ROOvOr
Ring Tool - amzn.to/2sp60tT
Ring Compressor - amzn.to/2YITNwr
Plasti Gauge - amzn.to/3CzouYu
Soft Jaws - amzn.to/3q3aQZ5
Merch & Events - bit.ly/33YbmtO
Check Out Go Power Sports for all your Go kart needs! bit.ly/2viX9vP
Parts & Tools used on the channel - amazon.com/shop/redbeardsgarage
Quantum Machinery- Siegmund Welding Table - bit.ly/36PHm6G
- Nargesa CC60 Bender - bit.ly/2xWDVxj
Prime Weld Tig 225x - bit.ly/2EbSIqK
Prime Weld MIG180- bit.ly/2Q44l5V
Benchmark Abrasives (cut-off wheels, flap discs..) bit.ly/2SENg4f save 10% REDBEARD10
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Red Beard's Garage
P.O. Box 572
Sweetwater, TN 37874
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Instrumentals by Chuki Beats - / chukibeats
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*********Disclaimer*********
Please do not try to re-enact or recreate anything you see in these videos. We are trained professionals. Red Beards Garage does not take any responsibility for injury's created by doing so.
#RBGKarts #RedBeardsGarage

[@CJLeTeff]

RB you’ve got the best, ‘How To Build’ videos for small engines! 👍👍🎉🎉🎉🎉🎉🤘🏻🤘🏻

[@OppoOppo-cn5no]

ผมอยากชื้ออะไหร่จากคุณ

[@kennethlizarondo7699]

@@OppoOppo-cn5no hjbbbZkhgyhs vb

[@brettmoore3194]

Generator

[@andriyanto5112]

11

[@dashlamb9318]

Have to agree. Straight forward, to the point, and detailed.

[@sibirty]

I’m getting some serious “Trucks!” On HotrodTV in the 90’s vibes from this video!

[@Skiridr22]

Professor RB this is the best how to instructional video I have ever seen, 👍🏾👍🏾👍🏾👍🏾

[@trumpfancardanostakepool4737]

Love watching these engine builds. That thing looks sweet.

[@Thewatson77]

Anybody would be absolutely thrilled to rip this beast! Great work as always guys 👌🏼

[@tmurray1972]

That is the baddest mini bike engine I’ve seen.🔥🔥🔥🔥🔥

[@hanapilibang6163]

I really like seeing the results of the resin

[@CODOutdoors]

That motor sounds so angry, love it! Great video!

[@Dlokey4315]

Fantastic build video RB great video shots tips and tricks to get the most of the engines performance. Your the king of small engine repair and fabrication. 🤘💀 Ride Fast!

[@samsgarage1716]

Wow that’s amazing.I can’t wait to hook up my 459cc engine.Great video.

[@kenyatasims6991]

Man that engine is sick‼️

[@jamesroberts1800]

Having been a race mechanic for *more* than a few decades I have to compliment you. Nice vid, solid camera work, clean and concise directions/instructions. Not too much or too little of anything, well done. Now you just need an old fart like me to show you how to port a 2 stroke so it screams, I have my tricks :) but they are my tricks and I choose not to share too much. Hey, a guy has to have a few secrets, right ? I learned from the old legends like Terry Drake (Drake Offenhauser) and Louie Unser (Al Unsers brother, Bobby's uncle). Kinda surprised I haven't seen you mess with a Zenoah engine or two....or a bigger Honda twin like a GX 690 or sumpthin ? From what I've seen, not too bad of a shop, still need a few things, but it appears you're getting there.

[@robgto7051]

its not a 2-stroke

[@jamesroberts1800]

@@robgto7051 duh ?

[@jessehawks1849]

Best videos for learning and i seriously hope to have the common knowledge of you one day

[@ismailusman6058]

Nice work and tools 👍

[@christianmanuba7583]

I hope one day I have a machine like yours♥️

[@mavericknonconformist69721]

That is a gem.

[@juliusgreen7495]

Great job guys great video

[@jesseshelby4383]

I love this build. Should have done this video on 420 👌

[@ExcitedCoconut-cz5rq]

I'm putting one on my mini bike build cause it's 420 erryday

[@maycoamaro3346]

Parabéns ficou muito bom seu trabalho com quantos HP ficou depois que você trocou as peças

[@117moose]

Thats interesting about the ground strap.

[@sagenbabin8786]

I can confirm The valve spring compressor I used on my klx 110 and a friend used it on a Honda foreman 500 it works perfectly

[@leoarc1061]

How many hours can these small engines do before a rebuild (approximately)?

[@sagenbabin8786]

@@leoarc1061 idk aproxomatly but my bike is an 03 and it has the factory bottom end so it’s 21 years old I’m gonna rebuild it in a month because I have an oil leak. But the reliability just depends on the maintenance I run the shit out of my bike tho it’s bored out with a race head and a rev box and it’s run this way for 2 3 years

[@boycabatomixvlogs]

Great engine ..maybe this is good to install to a small boat ..good for fishing adventure...

[@brighambaker3381]

What's crazy is that your predator 225 from the other video makes over 20 with just over half the capacity!

[@gonracn]

That is gorgeous

[@finishingfinishing1543]

Amazing job 👍

[@steveschnuck2457]

Straight beast. God bless

[@brianrhubbard]

A very high quality video

[@masseralisane3711]

Idol im watching your videos...very power your engine set-up

[@Hamsa3600]

what a beauty man soo nice

[@Just3adventures]

That thing is SICCKKK!!! 🔥

[@user-hl2ke2kk2y]

Thank you.🥰👍🙏

[@ryanbrown5214]

Man this is awesome. Just subscribed and excited to see new videos. Great job brother and God bless!!

[@RedBeardsGarage]

Thanks for the sub!

[@dennymedia]

Good job👍

[@vichetdragoncars3186]

Proud of your skills

[@jhonsoliejhonsoy9434]

I love your work, I really amazed If I have a money i buy engine like this , some day🙏

[@CuzznDave]

Great vid even though I know this it was still so good I just kept watching great job. Master Craftsman make it an ART. 👍👍😃😃🥰

[@patherman64]

Love it! I’m working on a 420 now and doing my first pulse pump installation with a top plate. I’d really appreciate some tips for pulse/ venting and throttle hookup. Thanks for all the great content!

[@jondavidmcnabb]

1st. Excellent video and great tutorial. Honestly the best build video on KZbin. Love seeing you make video like this!!! Have you ever considered building an air cooled outboard motor for a boat? Either a mud motor of just a re-power of an old clapped out 2 stroke? I bet you could make a really interesting video about that.

[@mattharvey8712]

Bravo......no turbo.....cheers

[@mphjunkie5457]

These would be sick ass mud motors

[@garyfraser8584]

Awsome motor. I just bought a 420cc predator today. I will be doing some modifications in the future. This is a fantastic build I love all the Billet parts

[@RedBeardsGarage]

Enjoy it

[@garyfraser8584]

@@RedBeardsGarage if I put a flat top pistons in place of the dished piston on a 420 overhead valve non Hemi head how much will it raise the compression

[@fftbrantley]

Rewatching this as I’m building a gx390 stroker and I noticed at 11:28ish, it sounds like someone ripped a big one or your shop has barking spiders 😂😂

[@blainethompson6510]

So informative Question is the coating “polish” to allow flow in porting or is the inherent in the coating?

[@kc37]

Love the vids

[@DIYWilly]

Great video as usual but wish you would have talked about installing the starter ring gear on the flywheel.

[@RedBeardsGarage]

It simply bolts on.

[@DIYWilly]

@@RedBeardsGarage Did you have to drill the flywheel. In your parts line up I saw the ring gear separate from the flywheel.

[@tomcangemi1045]

Big thanks for posting these informative and entertaining videos. I'm still curious about the various breather tubes running from the crankcase cover to the valve covers. I've watched two of these upgrade videos and these tubes suddenly appear without explanation both times. My apologies if I'm showing my ignorance.

[@doitfordale7599]

Hey man really great video!! I’ve watched all your videos and learned so much and I greatly appreciate it man. So question , what is that bigger black hose you have running with your other vacuum hoses coming out of the top of the side cover? Also do you have a fuel pump on there?

[@mphjunkie5457]

My man this on a small to med surface drive would be the baddest thing that side the Mississippi 🤙

[@lizzard7473]

I need a couple thousand dollars to burn. That engine is freaking nice! The white shroud with the gold, and the black block with the billet and gold, man, that is an awsome looking engine!

[@jaicasiltv8374]

Powerful engine..

[@tristanmcnabb2741]

Allsome work that looks really nice 💕🌟👌😁🎉 from cruzermans inventions 😁🎉🌟

[@seansysig]

I like the thump of that cam. I’m 6’1” 280 lbs. curious what a cart like this would cost?

[@theworstgamervr]

Dang dude you've gotten so good at building these engines. I'm guessing the struggles are cut out but you make it look effortless and informative. Not to mention you make it look bad ass, its a beast motor but it ain't meant to be like a pushing all the limits engine, but you got it lookin like that. The Allen bolts with the countersunk spacers look so frickin good. You should do some kinda fast watercraft build this summer some kinda budget friendly tutorial. 212 pedal boat? Built 420 on little fishing boat with some contraption to convert it to a clutched propeller, idk man something crazy get the people in

[@RedBeardsGarage]

I have been wanting to do something for the water for years. I will put it on the project list. Thank you for supporting us!

[@theworstgamervr]

@@RedBeardsGarage yeah, water stuff is a fun build but from what I've seen with cars and cameras is keeping the thing sealed up, and when it ain't it goes south quick lot of back breaking work getting it out. And a jet ski will it run is fun but ain't really a build or much informative past having the same model. A more custom water sport build would be awesome

[@seancervantes1]

@@RedBeardsGarage I'm sure you could hook up a 420 or 670 to a little jet boat

[@dj13yrs1]

They make a mud motor (long shaft with surface drive prop ) for the small singles

[@mikellewis2346]

@The Real Huck Finn breathers I'd think. Lots of air moving in a high rpm motor.

[@z1berzerker]

3rd time watching this video 📹 👌 Great content

[@IanStClair-dy1eu]

I took my 420 to a dyno shop, same build as this. It made 33hp and 46 ft lbs.

[@CantoniaCustoms]

How much did you spend on parts? Trying to see if building would be more cost effective than just buying a 670cc engine.

[@IanStClair-dy1eu]

@@CantoniaCustoms honestly, it depends what you are trying to do, I have my 420 on a doodlebug. I spent about 2200$.

[@CantoniaCustoms]

@@IanStClair-dy1eu Ah, I'm just trying to get 22-25 hp. Planning on shoving it into a Kubelwagen or Jeep lookalike.

[@NCMATT]

I need that on my 4wheeler

[@BigHeartedMan65]

What I would LOVE to see is a V Twin motor set up with a Miniature 671 Style Blower . Then run it on Nitro Methane . Then Build a JR type of Dragster and see what that baby would do in the 8th mile .

[@chandlerknight8623]

What are you using for a fuel pump? Did you go electric or are you running a pulse pump? Also are the hoses from the valve cover to the motor to equalize pressure?

[@Ma007rk]

This brings back so many memories. Except back whenever. I was into Go Karts and Mini Bikes we're talking 50 plus years ago. Back then, as kids, we were so poor that we used to take the cardboard off the backs of the paper we used to get at school And use them for head gaskets. I remember one of the engines that we had was an old Tecumseh (I think that's how you spell it) Engine. (Such as were the memories back then) We rebuilt that engine and it ran like a raped ape.

[@letrasmais4215]

in Brazil we do this type of preparation in a motorcycle engine like the Honda cg originally 150cc and with adaptations it reaches 500cc but the most common is with 270cc, also very common with Honda CBX 250cc Twister engine is the most common with 450cc.

[@BuildBreakFix]

Question why exactly did you cerakote the piston?????? Never heard of that before ! Would this help stop cold seize in cast iron jug /aluminum piston build to some extent?

[@justintroy9827]

Would you recommend an engine swap like this 420 over the 459 in a ezgo golf cart? Seems like I’ve been seeing a lot of small issues popping up in the 459.

[@barrettjg2]

How much piston to valve clearance are you running on this build?

[@TurboMio]

That is amazing 🦾🚀

[@MrCarmelo1959]

Hi Red me again forgot to mention I’ve been rebuilding my Kawasaki mule like the one you did putting in a DuraMax 715cc?? Man I just got a deal on a DuraMax 16hp 420cc and I’m dropping in my mule never never have I done this before but I’m going to try it myself watching your videos have inspired me in growing a set and getting it done there’s too many people out there who charge too much for doing this work my mules been sitting for more than 2 years bought it with a bad motor but you confused me talking about the dif going in reverse changing it around replacing it with a golf cart dif….got to go back and watch that video several times to understand what you were saying anyways wish me luck later brother Red😊😊😊

[@mikesbarn1858]

Beautiful build. One other thing. Gapless compression rings.

[@contraband1543]

That would mean a broken ring once the engine gets hot.

[@mikesbarn1858]

No it’s a twin ring for the top compression ring. Gaps are offset and compression forces them together sealing piston tighter.

[@garyfraser8584]

What kind of compression ratio did you end up with on this motor with the flat top piston? Also was the head milled at all?

[@zadgill]

Love the videos. Very informative. I have a question for you. I’d like to put a modified predator 420cc engine into a Honda Navi. Is this doable?

[@fishsticks88]

Basically a $2500 motor I like it

[@mikerammelt2420]

Hi whouldn it be a good idea to balance everything.

[@lomsomesGarage]

How much increase of voltage and amplitude increase do you get by running the ground strap

[@donaldrush5760]

How do you change the battery, with. out the charging. coils???

[@tjtj3027]

I'd like to know what clearance work was needed for the cam.

[@MrCarmelo1959]

Hi Red you always amaze me how talented you are and knowledgeable you are you’re a beast builder. Can you tell me if you can rebuild one and ship it out to me is that at all possible..just asking because I know it would be great if you can thanks always appreciated your videos brother Red👋👋👋

[@hacxer8424]

Build one for a mini bike

[@twitchsoft5]

Doesn't Yamaha and the likes get 50+ hp out of their 400's? Lol, keep polishing that turd!!! Honestly, I love doing this shit! Nice work bud!

[@frankjames4439]

What size bolt do you use for 420cc predator and 40 series comet for crankshaft

[@littlek0690]

I have a built 196 I have everything done to it except for the stock piston. I’ve been using it for a while now and now when I started up some smoke comes out of the exhaust but then it clears up. Is this something to be concerned about?

[@S.P.O.C]

You think you could build a 420 like today and make it compete with ex 400 honda 4 wheeler if in same frame and equal weight?

[@christophermcmahon7920]

What is the valve to piston clearence? I am doing g the exact build and only have .025 intake valve to piston. Maybe want to check that before people build a motor that gets destroyed right away

[@bryanmorgan8501]

I want to build a 212 like this for my dirt bug mini bike

[@ridingdirty8897]

You can also put more timing in that buy using a off set fly wheel key. But I'm sure you know that. Most people dont

[@christophermorin9036]

Hey Redbeard, how come you don't put the piston rings on from the bottom, then put the wrist pin in? I noticed that you scuffed up the ceramic coating quite a bit pushing the piston rings on from the top.

[@Popcultpistons]

SWEET! Was this ever put on anything?? Cant find other videos with it!

[@alekshaw2467]

Is there any other way to remove the bearings in the crank case?

[@jsmalone]

Can the 420 motor charge the battery while its running?

[@ecord87]

Your video's are awesome! If you had to choose between the Duromax and the Predator what would be your choice? Which one do you think is better built?

[@Jalen_Knight8526]

He has already said he likes Duromax because it is around the same price and way higher quality.

[@uriahgiroux9694]

Wish they made a Ghost version of this to be modified!

[@GREGDICKINS]

Can I ask why the four clear tubes from crank case to rocker cover?

[@ianellithorpe5918]

Soooooo dope

[@williamworth2746]

From one bald red beard to another nice build

[@normanc5700]

I need that old side cover

[@justiningram2380]

How much issues do you have with the valve seats I run these motors on my generator and I have hell with the valves always have to readjust the valves

[@ramseysteinkamp9391]

How do you tell the difference between the hemi and non hemi 420? I've seen people say it's the torque rating on the box, the part number, and the valve cover.

[@chandlerknight8623]

The part numbers are different on the box. As for the motor the hemi has a rectangular valve cover and internally the motor head is hemispherical (round).

[@Brickedaboss07]

So I got a Briggs and want to put a big filtered carb on it but it will fit with a gasket so should I do it

[@SuperBigdanno]

Please explain how the extra ground strap from the coil to the head helps spark.

[@RedBeardsGarage]

Normally the spark plug gets ground through the head and on through the block to the coil. Grounding the coil to the head instead of the block helps a better transfer of power.

[@SuperBigdanno]

@@RedBeardsGarage thank you

[@garyfraser8584]

S0 how much hp did it end up making? Im doing a similiar build with a440 stroked 420 non hemi with ported head 40mm and 34mm valves 306-0411 cam flat top piston .027 head gasket billet everything arp studs for everything.34mm mikuni flat slide carb and custom header.

[@brandonhewitt2386]

I was wondering if using that coating on the block would cause it to have less heat transfer. Being that it is air cooled you want to get the heat out of the engine quickly as possible. I love the build & as usual you've shown me some things I didn't know.

[@duanehenicke6602]

I was thinking the same.

[@johnmcclain3887]

The best way to get heat out of an engine is to minimize heat transfer into the head and block, and ensure the highest exhaust temperature. Free flowing exhaust carries the most heat, allow it be cooled by contact with the block/head area, lowers the heat, lowers the thermal expansion of the exhaust gases, slows the movement of gas volume, so it more time/contact with the block and head port. Porting is mainly about keeping an even cross-section to minimize "volume change" in the intake charge, to keep low velocity flow smooth, constant going in, and keeping the exhaust cross-section change minimum, to minimize heat transfer as the rate of flow changes. Slight change in port volume changes velocity of flow, allowing more energy transfer equally more heat transfer from the exhaust into the block.

[@carsonhendee919]

He said on a livestream a few weeks ago that the type of coat got he used is supposed to help expel heat

[@andrewbodine5663]

What would cost be to buy the stock engine and all the upgrade parts?

[@matthewsmith6343]

Can you rebuild the saki motor on my zero turn? It won't be fast like a go kart, but the 23.5 V-Twin just ain't cutting it anymore, no pun intended