Predator 212 "The Hemi Head Swap"
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- เผยแพร่เมื่อ 27 ธ.ค. 2021
- Hey guys FatBuddyCat here! As per viewer request I take you through a slightly untraditional yet effective head swap that you can perform to bump your stock Predator 212 Hemi up to one full horsepower! This is a cost effective approach at using the engines displacement to efficiently create useable torque and mid range grunt from a substantial increase in compression rather than relying on maximizing the flow. We achieve this through utilizing a simple 14cc small valve clone head. Though we may be moving less fuel and air, we are reducing the volume of the combustion chamber which produces greater compression resulting in a boost in overall power.
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I did just about the same thing ,
it was the fastest,smoothest & had the best idle out of all the engines.
I also spent many hours porting & polishing the ports, combustion chamber & the top of the piston. I didn’t notice any loss of top end , thought it was faster all the way around …. It’s mounting holes in the coil were dremeled out to adjust timing & I think it had stock ducar springs with homemade shims made out of keepers
Wow! Great information!! I think I can play with this for a great budget build that is actually a performer. I'm really glad I did this. I'm learning a lot.
Two words for a future project. Drag bike
Lol I know. I have soooo many projects I can try! I'm having way more fun doing custom stuff and cool engine mods. I really do listen to pros so hopefully people take advantage of some of the cool stuff and try it themselves too. I have a picture in my head of something set up for drags I just have to find the right parts.
i heard about racing gokart guys doing this. good stuff FBC.
Right on! Those guys know a lot of tuning tricks that they can do in a hurry and without too much attention for some reason....🤔
I just bought a 225 rs tillotson head from go power sports, it's an 18cc non hemi head with larger valves. I think it's a good value for the money, under $100.
@Skott LeFever ct200 u-ex engine. I'm putting longer stroke crank, super x (265 cm)cam and a couple other things in it in the next couple of weeks.
The RS head can be shaved to I think. If you shave the 18 to 14/16cc and run a slightly shorter push rod you can really make some progress too. There is a 14cc big valve head that is pretty boss too. I can get a good deal on one with stainless big valves installed. Just port and polish. There's a few tricks we can try first though. I'm learning to build off efficiency and controlling the flow. Bigger valves sometimes warrant a larger carburetor. A large carburetor is down tuned which will not run at optimal performance compared to a carburetor that is flowing exactly as it should. This is all for basic riding conditions and so forth..... on a drag bike you can run small chambers and big valves because your not worried about the idle rather than busting out crazy rpm to control the feed at full throttle.
Sounds real good.
You mention a 1 HP gain. I would have went with a 2 HP gain or more with the head and Champion rockers. In my opinion EVERY straight valve legacy head should have Champion rockers for a go kart or minibike application, governed or not.
I'm totally coming back to this but you are absolutely correct. We can get 2 or more from this with a little more effort. I'm going to order a few things to start working it over....😏 We're going in on this one Deuce it's worth further investigation.
If you replace the "thick" stock head gasket with the "thin" type metal head gasket, there's also a gain in compression ratio. If the hemi head's flow is a lot better as the 14cc head (I can not imagine it is a LOT better), perhaps the thin gasket trick is a good solution with the hemi head.
I'm definitely coming back to this with some port/polish and a tighter gasket. This is a very smooth configuration that really surprised me.
Your 100% correct. I think I can use one of those thin metal gaskets next time.
@@fatbuddycat If I remember correct, going from thick gasket to the thin one, is the same compression gain as going from 18cc head to 14cc head. Again: if I remember correct... It's been a while since I wrenched on those engines, the build of the new shop is taking a lot of time and weather is not cooperating.
@@LilPopeye it does make a good bit of difference because of the amount of surface area reduced by the gasket and not just the thickness itself. I'm going to take it off, port it and try the thin gasket. Your new shop will be amazing!!
@@fatbuddycat I ordered two for the bikes I'm working on a day and a half ago lol.
Thank You I really appreciate it!
Your welcome! If you have any questions let me know and I will do my best to help. IF you go over to OMBWAREHOUSE.COM you can save 5% with the FBC5OFF code!
Definitely thought your gas tank was a take out box at first😂😂😂
Lol I'd have to check but I've had some strange ones!
Just the 4 bolts also what size ?
The head bolts? I just used the stock hemi bolts since the threads definitely mate up.
fatbuddycat Sounds Good. What's That Engine Going On?
93 octane.
The pk3a carburetor is much better than the stock SP unit and doesn't run as rich as the pk1b.
Lol you meant mini bike! WHAT mini bike 😆..... not sure yet but I have an idea!!
Excellent video. I heard the Predator non hemi head is better than the hemi head. What do you think?
The hemi head is said to have thinner walls due to the extra material that has been removed to stay within the parameters and scale of a gx200/clone motor. It makes sense if you think about that way. I wouldn't spend much time porting a hemi head when you can achieve better results with a properly worked non-hemi head. Hemi heads for stock class motors typically have better flow and yield better results. The 212r is cray cray but that's because it's got the EC treatment. I might be revisiting one of those again soon too!
@@fatbuddycat Exactly what I needed to know, might throw a non Hemi head on the hemi later on down the line then. That 212r looks amazing.
@@xaviermccloud4586 my Custom Doodlebug boots on a completely stock 212r and Torkzilla. 5800 rpm no surge right out of the box.
@@fatbuddycat Zaaaam. Hey question... If I am going to build a mild motor, stage 1, 18lb valve, 28mm carb, no Gov, pipe etc. What will my highest rpm be on a 212? It's actually a 208cc DurOmax (clone).
@@xaviermccloud4586 I'm pretty sure the stock cam stop producing useable power around 5500 on 10.8s so with 18s you will go higher but not really sure maybe 6500-7500.
Thinking about getting one, wondering how many horses on it.
I'm thinking it might actually ramp it up a couple with a full governor removal. It's very smooth and starts very easy for having such an increase in compression.
Even stock with the governor it picked up noticeably.
Thank you guys. Considering one.
@@leonardarola if you have any questions feel free! I would absolutely recommend this for new builders and those trying to learn about building efficient performance gains.
@@fatbuddycat Appreciate that.
But why Gx200 push rods?
If the pushrods are too long than they will open the valve too much and contact the piston. Non-hemi heads have longer valve stems (that's why the hemi valve springs are shorter). Longer stems need less throw from the pushrods to achieve the appropriate distance for the valve to travel during combustion.
The 5.260 length gx200/clone stock pushrods are shorter but the valves are longer. The hemi has shorter valves but longer pushrods.