Predator 420cc High Torque Engine Build

[@TheLonesometoad]

This is extremely refreshing! I've been a mechanic, engine builder, hot rodder and go cart enthusiast for over 50 years, and I am shocked to see someone on you tube actually build an engine properly. With al the bad/wrong info out there today it is refreshing to watch someone do a build the RIGHT way. Very well done!!!

[@fan1701]

Hey Red, I just wanted to say thanks for the giveaway Tillotson carb. It is going on a new 212 for my son's yellow yerfdog gokart that was at the event. We had a blast meeting yall and riding. You guys were great! I'll have to watch this video tonight with the family but I just had to say thanks right now and a big THANK YOU for being a good sport when the MuchoCabre and Coolranch showed up at your tent. Have a great day!

[@cwthemachinist]

Hey man. You're looking to build a high torque engine. Porting that head, having larger valves cut in and milling it down to raise compression is really the way to do it. The cam will help but airflow and higher compression are what really does it. Also when installing a longer duration cam, you typically need more compression to compensate for the lost cylinder pressure caused by more valve overlap. You can get online and look at automotive valve manufacturers like Manley, Ferrera, Milodin, or especially the import valve manufacturers. You can get really good one piece stainless steel valves relatively inexpensively. Have the machine shop cut your valve seats larger for the new valves and perform a 3 angle valvejob. I think you'll be surprised how little it will cost you to have these things done and the big, low end torque gains will completely be worth it!

[@TheEsseboy]

Or just get a 4 valve OHC engine with EFI and watercooling.

[@charliebellflower2536]

I can't wait to see the build you have for the diesel engine!!! God Bless y'all!!!

[@mtnpeeksgokartfreeks7503]

Thank you red beards garage just got done doing my 420 put in valve springs air intake rejeted it. took out the governor but the one thing I did was I did adjust my valve springs wrong when I watched your video it showed me what I did wrong and I was getting a knocking with my motor so I wanted to thank you very much your video helps me get my problem solved appreciate it

[@RedBeardsGarage]

Thank you for watching man

[@bestusernameevahhh5802]

Just stopping in to say how much I love your channel man, ive watched every vid several times, it even inspired my son and myself to start working on our own buggies. Hes 7 and loving it. Much appreciated.

[@hankjones9212]

You've EARNED 104k subscribers. You deserve more. Thank you for all the videos. Keep up the great work.

[@idk_gfysblitz4255]

Hey you got ties with gopower sports tell them to make a transmission for the those engines

[@willspicer3190]

Would it not be easier to find just the right kind of bike transmission and adapt it to work rather then trying to build a while new transmission from scratch? Just a thought

[@Agavegaming]

@@willspicer3190 maybe, depends on your bike.

[@Agavegaming]

@@willspicer3190 would require a lot of custom fabrication.

[@trevinskiking2165]

IDK.... You'll be lucky.! Trev NZ

[@trevinskiking2165]

Use a bike trans like a Honda C50 scooter 3 or 4 speed box & remove it's crankshaft & replace it with a toothed shaft - connect your engine with a chain Goodluck Trev New Zealand

[@davidmorgan8612]

Well I have been wanting that fab table, You put the link in the description, I clicked, saw the price, now I’m not interested in the table no mo! Lol $7,600 for a fab table. No thanks I’ll build my own. Thanks Red, I love your stuff. I thank your wife as well cause I know she does a lot of behind the scenes stuff.

[@rikkatheconure2395]

That almost makes my head hurt... if you’re in deep enough to need a 7,600$ fab table then it only makes sense to make your own lol

[@crowofjudgement159]

oh yeah a engine build just like the good ole days

[@jamiejames4598]

Another sweet build. Stay awesome RBG.

[@rustybeatty6567]

Every small engine has a counter balance flywheel. Every time the piston or pistons are at full compression right before combustion/ignition the flywheel has counter weights that are closer to other side of the engine and right by the starter on key start single cylinder and on v-twin engine just under or near the opposing cylinder which will help reduce vibration at high engine rpm a billet aluminum flywheel doesn’t have that feature and most if not all motorcycles engines use a similar concept but it’s done internally basically a small counter weight runs of a gear driven unit inside the engine the predator 420 engine has two of these systems only on the flywheel and one inside as well.

[@crowofjudgement159]

you need to upgrade to 35 lb valve springs when you remove the governor on these to prevent this kind of damage.

[@nitroman365]

Remember guys, if you remove the govenor, you need 35lb + valve springs as well.

[@jasbaker13]

I learned this the hard way. First outing I bent a valve, blew a seal and some chunk of casting out of the head. Caused some serious mayhem. I even had the HD springs sitting on my shelf. Expensive lesson.

[@syndeko1632]

35lb springs? cant you just remove the governor and itll be ok?

[@mrsideways4574]

Getting my first mini bike tomorrow I’m pumped

[@larrymunday7519]

You need to start measuring your valve clearance to piston interference with dial indicators. You may only need .005 more clearance.

[@RR-dq5dr]

ARC now sells billet flywheels with the electric start ring gear

[@zanecrocker9091]

R R wait what?! Im building a flathead race engine i wanna buy that

[@rustybeatty6567]

But does it have battery charging as well.

[@alphamoto466]

@@rustybeatty6567 no they don't

[@dreamstreetskate5291]

@@alphamoto466 Yes they do! It has a stator that puts out over 12v at idle.

[@darnellperez6103]

Thank you for the parts list, helps a bunch!

[@coolness-ic7xx]

Do a video on how to install a 32mm mikuni carbeutor on a 420cc predator!! Please!!

[@ethanlocke6331]

The new intro is awesome

[@matthewanderson7766]

Super excited to see that build

[@jamesduffy9756]

You said that the can is a "High Torque Marine Cam" does that mean it is from some "Marine" motor or it is for that motor but for Marine applications with a predator motor???

[@willspicer3190]

Im going to assume it's a mod for of yoi was going to run like a mudd skipper prop or something idk. As it brings torque down to a more useable range id say that's why.. So hes not just screaming tje little bitch around LOL

[@trevinskiking2165]

James...good point ,! Trev NZ

[@jamest.5001]

The valve been sneaking around with the piston on the side!!

[@brianevans5994]

I bet the alt kit for the 670 will bolt right up to the 420!

[@jhitt79]

To set valve lash you don't need the engine @TDC. Rotate engine until exhaust is open and set the intake. Rotate until the intake is open and do the exhaust.

[@ryanrohauer5940]

Ya it's just good a practice

[@jhitt79]

Ryan Rohauer I don't see how. If your intake is opening then you know the exhaust is fully seated and vise versa.

[@dillondixon507]

I wish I could afford to build sweet engine, definitely know who’s video I am watching if I ever get the chance too

[@jodyatarcracing9112]

If you want a cheap and easy way to see the true contact area of your valves to seat. Clean the valve and seat very well, then take a Sharpie and color the seat only. Place the suction cup on the valve and carefully place it in the seat. Rotate in one direction for one compete turn. Do Not rotate back and forth like you do when lapping. Remove the valve and see if you have contact all the way around. Clean the seat and valve and color the valve this time. Repeat the process to see contact area. This will show you the actual contact area between the valve and seat. It should be a smaller area than the area the lapping compound left.

[@michaeljbaker3492]

Good video. Itll be very informative for anyone doing a build on one of these for the first time :)

[@nickthecarguy-channel]

That’s a mean motor!

[@dallinbrimhall1033]

Just started the video super excited to watch it!!!

[@mikefader1988]

Thank you so much that answered so much for me

[@AridersLifeYT]

20:30 - Kymco is taiwanese not Chinese lol. thats like saying Americans are British

[@craigchiddo2794]

Lap the 35mm valve really good it will work haha

[@ihus9950]

Another great video, and great build!👍

[@amorykin]

I was hoping to see if you used any sealer on your head gasket, or do you just put it on? Also head bolt torque settings? Perhaps you have a link to another video that you show this process? Awesome videos! Keep up the great work!

[@SIRafiq]

What is the max hp you can get from this engine, after all the necessary mods?

[@trevinskiking2165]

1-1.3hp per c.i. and your doing pretty well....like the 375hp 327ci OEM small block chev.Trev New Zealand 🤗🇳🇿

[@myparadiseonbantayanisland9030]

I have a 420cc sumo rato 15hp engine and it says 3600 rpm is max, can this engine be safely rev'd over 3600 rpm? I see your engines are reving well over 5000 rpm.

[@ruicunha103]

so you set your valve clearence only after the exaust valve makes that small release, when compression stroke ends?

[@Armilite1]

Is there a certain rpm the stock rod & flywheel is good for? Like 5000rpm before they need to use the Billet parts?

[@matthewarnspiger632]

yeah... I dont have a lot of expirence with predator engines but from my little expirence wihtout the govonor valve float accours arfter 500 so need stiffer springs we still maganged to get it up to 6400 RPMs withoout a rod breaking or flywheel exploding. so I would say keep it safe and limit yourself to 6000rpms if you dont have forged rods and flywheels

[@1darrious2tim]

Where do you get a hemi 420cc head

[@zoesdada8923]

I need this for my cycle cart. I knew those valves weren't going to be right.

[@atobspecialists9489]

Is the balance shaft absolutely needed? Can you make more power without it?

[@Bikescameras849]

Can i use 35 pound springs in my 420, if only removing the governor? The only other mods that I've done is the stage one kit. Thanks in advance.

[@RedBeardsGarage]

Yes stock cam and no governor is 35lbs springs.

[@Bikescameras849]

@@RedBeardsGarage Ty

[@charlienorton2337]

Woah 105k! Seems like just the other day that you were on 10k!

[@bamamowersgarage8937]

Craig I hand fun meet y'all and your family love to y'all next time thanks &God bless

[@charlesrose3303]

Love the new intro

[@Gräsklipparmarodören]

sweet man, Have you ever grenaded a stock Rod on one of those things? it looks pretty well designed tbh. also how many Hp do the red washers give you?

[@hunterpoucher3938]

Random Engine Stuff roughly 100 buff horses #donutmadia #mopowababy

[@willspicer3190]

It is a clone of a Honda basicly...so ya it should work great lol

[@fredstarrett5058]

Love your videos, keep up the good work.

[@michaelcody3356]

If you are looking for a good motor with a transmission a lifan 200cc 5 speed that will run 75 is bout 600 or a lifan 125cc for bout 400 their 4 speeds go bout 45

[@kartnerds]

What were the specs on this camshaft? Did they ever offer it for sale?

[@tuyo_adventures.2185]

What stroke should the exhaust valve be for the .005 adjustment?

[@swrvtech]

What valves did you use I need new valves

[@anthonyhamel3148]

Stock push rods with 50 pound valve springs on 440cc duromax 18 hp?

[@trevinskiking2165]

Anthony = OK @ that spring #...Trev New Zealand

[@rollfablife3363]

I have a question about this duromax 440 engine. Would the engine run correctly if I put the Go Power Sports Predator 420 jet and air filter kit on the Doro Max 440 engine? I would take the governor out and have a header would everything work correctly? Would I need to take out the bouncing gear or need valve springs or anything else?

[@tscustoms721]

Hey red beard can you put the link to the 420 hemi valves you put the wrong link in. My 420 valves are have the same problem and i have been looking for valves all summer so if you can put a link some where that would be awesome thank you sir .

[@daywalker121800]

Love the channel. I’ve been going back and watching all your videos. I built my motor with this video as the source but I keep blowing side cover gaskets on it. Any insight as to how I can get the bolts to stop coming loose and not blow the gasket?

[@trevinskiking2165]

Vent the Crankcase to the atmosphere through a spiggot attached to a threaded hole in the top of your crankcase & feed it into the air filter box so the engine sucks back in its own fumes/crankcase pressure & put some superglue on the bolt threads... it's just uncoloured Loctite at about 1/10 th the price & glue the side Cover gasket with some RTV but you shouldn't need it with those mods.Trev New Zealand 🤗🇳🇿

[@brody2927]

Hey RBG, I have a predator 420 with a surface drive mud motor on my boat. Would a build like this be good to get some extra power out of mine. And how reliable would it be?

[@trevinskiking2165]

Brody....too unimportant to answer but yes it would,but keep your Cam Duration mild but the lift high & Clearances wide.Goodluck but a must is change out those Valvesprings.Trev New Zealand (south pacific)

[@scottykify]

Im curious how the driveability is with the knock off carb? I am building a similar engine for a golf cart and thinking of using this carb on it, thanks for the videos RB

[@trevinskiking2165]

Scott: like night & day over the butterfly carbs, you'll never look back once a slider is fitted...about a 26mm Should see you about carbed right for good throttle response & economy Cheers Trev New Zealand 😇🇳🇿

[@MrRokusek]

Did you change the head gasket?

[@jeffwright6685]

Question on the 6° key is there a shim placed in the spot removed on the key so it has no chance of moving and changing the timing ?

[@juicebox2260]

How are you setting up throttle linkages?!?

[@GoKartsorGoneFishin]

Rasta B TV put a 420 in a 4 wheeler..stock tho..good show Greg!

[@dana7413]

Do you really need to put the balance shaft back in when you build the motor

[@donaldfuller5041]

Spring compressor with the vice grip type clamp are so much better.

[@seanbinyamin]

hey , link for the Header Cup Washers ?

[@danny-1424]

Have a question ordered 34 mm carb off Amazon nockoff mikini when floored it wants to die after 25-30% throttle do I need bigger main jet tried 125-130 didn't make a difference idk size in it isn't labeled

[@JohnGabby-q9n]

hey there! what size main jet are you using?

[@benjamintaylor3962]

What's the torque needed for the side cover gasket and everything else? Any help would be great! Thank you

[@NotMeeither]

You should consider putting a new piston in that engine , with it hitting the valve that much the piston could have stress cracks in it !

[@ksedgewick]

HELP! I'm in the process of building up a GX390 with governor delete and everything I read is to ditch the stock flywheel so it doesn't grenade. But I want to run lights, etc and no billet flywheel appears to be able to support charging. Any ideas? Keep the stock flywheel and just don't push redline?

[@samsgarage1716]

What’s up with the 301cc Predator engine? I never see you work with those engines.

[@corbinboltz3666]

Ive never seen one in the hf near me arnt they a california special or something

[@wafercopenhafer8536]

@@corbinboltz3666 i have them at my hf

[@nickthecarguy-channel]

He did a 301 mini bike

[@brianboyee8972]

No one builds them because they are like an older 305 Chevy~ WHY?,.. Why would anyone choose to build a 305 when you could build a 383 stroked 350?

[@joeyclark789]

Anybody know what cam to buy for a hemi 420.... which ones best and where from...also where to get chromoly push rods

[@trevinskiking2165]

Joey... don't know if it applies now but try Isky 404 Flathead V8 grind : about 265' Duration on 108 LCA lobe centre angle, you could tighten that up to 106' degrees overlap for more Lope & torque.Pushrods should be ok but they might have pair of junior dragster. Cut to length set.Goodluck.Trev New Zealand

[@prestonmarcotte5803]

Si like this channel but he should start getting some Honda motors

[@a.j.sgarage9637]

where did you get the motor stand?

[@Johnclark300]

How much power has it been increased to ?

[@redneckboysgarage5772]

Is that cam available yet?

[@noahhowes2174]

I have a 440cc duromax on my 250 Chinese atv. It pulls hard

[@hectarpanghi8495]

I like this engine.

[@jarekmace1536]

Might consider tacking a short sleeve to the spring compressor to keep it from walking

[@adamgarlington2190]

Probably not checking comments anymore but I thought grenading factory flywheel was almost a given when deleting the governor and adding more power? I would like to add electric start to my Honda GX270 but ARC doesn’t make an electric start version.

[@pj2418]

Can anyone explain how to wire up that second coil, and are there bigger & betters ones available for a more powerful setup? My 420 Predator Hemi from Harbor Freight comes with one coil (just like in this video) and so many of us want to add the second coil but don't know exactly what wire goes where. In the mean time I am lovin' this motor! I don't know how unrealistic this is but my goal is to be able to have my battery charge while running the motor and also be able to occasionally run my 36 watt LED headlights. Is there an even better way to generate more watts for heated gloves and stuff like that? I am having trouble finding tips on this sort of thing. Keep up the great work Red Beard!

[@bristol831]

Nice intro!

[@iusdotis]

Sweet build, Red Beard! Is there a reason you don't upgrade the pushrods to chromoly rods when you upgrade the valve train? Are rods available from GPS for the hemi in stock length?

[@robertweeks2039]

How many degrees did you set the timing at?

[@connorw1193]

Will these parts fit on a Honda gx340? Some say they do but I would like to know more awnser

[@geraldsaliva5559]

What type of carb is that a knock off of ? I'm looking to upgrade to a similar one but not sure what's rated for 420cc 15hp

[@christophermcmahon7920]

Where can I get that piston? I am doing gthe exact same build but valves hitting piston.

[@terratrekker2]

After you installed the billet rod, what is the maximum rpm with that engine?

[@ricardomelo4097]

Hello. If you put the key to the south contrary to this one, will it speed up? thanks

[@mackelby1]

Will these parts fit in the 459

[@Ratkill9000]

What's the part number for the hemi head 420?

[@demboycrazy7221]

Ratkill9000 38476482927637394749 yourwelcome

[@rustybeatty6567]

No way in hell I would ever use that billet aluminum flywheel no matter what until they figure out a way to add key start and charging maybe a hybrid flywheel.

[@wesleyseay8901]

Where can I find valve seals at for these 420s

[@peterpalma9293]

Greg, I built two of these inspired by your build (also got a Deuce & 670). Quick question. When connecting the two wires from the charging coils are they connected separately to the pink and yellow wires? Or are they all connected together, or something else? Thank you for your help & keep up the good work!

[@matthewtruelove9298]

Let me tell yuh something guy, you about cause me to bend a rod on my hemi. You said 5 thousandths and seven thousandths on the 18 pound springs, the pull start about ripped my hand off-! I had to set them both to .015

[@gurnblanstein9816]

In stock form is this enough engine for a Honda Odyssey?

[@jamest.5001]

Why not cut the seat for the valve, or re grind the valve for the exhaust seat angle, then it should fit, if the length and diameter is the same, it's a lot easier to grind a valve than the seat,

[@jeremyb7940]

Can you take out the counterbalance shaft out of a 420

[@RedBeardsGarage]

Yeah it will make the engine vibrate a little more. You can send the rotating assembly off and get it balanced to get rid of it.

[@schaeferbrown2527]

Wish the link for the carb still worked

[@tomgoodwin6275]

Link to the valve spring compressor isnt down in the decription can you add it thanks

[@RedBeardsGarage]

amzn.to/374Mqbe I'll add it. Thanks for pointing that out!