Trying to build a modified Predator 212 that stays below 5,200 RPM. Need advice. (2024)

vpd66 said:

Once again measure your engine and don't take for granted what you read on the internet. Once you know what you have then you can determine what course to take to raise your compression. By checking what your engine has is called blueprinting. checking your engine clearance, calculating your compression ratio, checking your timing, measuring your cubic inches, and etc is all blueprinting and is basically free and just costs you time. I really hate how people just buy performance parts or these "stage" kits and just slap the parts in there engine then come here to try to find out why there engine don't run right of have anymore power! Sorry for the rant!
Porting does not alway decrease lower rpm performance. If you go in and hog the ports out to has big has they will go then yes it will kill low end power and more then likely won't help top end either. What your going after is any restrictions, small steps, sharp turns, and rounding some areas. Paul (the guy mentioned in my other post) has some good videos of obvious restrictions in the ports and combustion chamber.

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I 100% agree with what you said about blueprinting. That's why I came here to ask questions and plan ahead before I started slapping on performance parts and messing with the engine. There are several websites and YouTubers who will sell/promote "Stage 4" kits or whatever "Stage" BS and claim you can make 20+ horsepower with their stuff just by bolting everything on, no planning/measuring/testing/tuning required. Two examples are Red Beard's Garage and CarsandCameras. I honestly despise both of them for lying so much about HP numbers and trying to scam people with their "Stage" kits. Both are heavily sponsored by GoPowerSports (not even a dedicated engine performance website, they sell parts for cheap Chinese dirt bikes and ATVs!) and make wild claims of 22+ or 15+ HP by buying their Stage 2, 3, or 4 kits. Never ONCE have they tested their engines on a dyno, I wonder why. It's an amazing marketing gimmick. Their videos are actually very useful if you're a newbie (like I was) and want to learn about how to pull apart and modify an engine. They are relatively short and make the process seem incredibly easy when, in reality, it's much more difficult and complex. Of course they always begin the videos by saying "I got this Stage 3 kit from GoPowerSports to make 15 HP". So, someone who has no clue how an engine even works goes and spends $600 or more on one of their kits after watching the video to get "15 HP" then ends up with the engine probably making less power than stock since nothing is set up or tuned properly.

Here is a perfect example that proves they are BS.

This is a chart of their drag race and lap times with a Predator 212 at different "stages". Notice the stage number on the far left column and the CLAIMED power on the 3rd column from the left. I believe that the only "stage" which actually increased HP was Stage 2. The predator will respond well to removing the governor, re-jetting the carburetor, using a higher flow air filter, and opening up the exhaust. The power claims for the rest of the stages (3-5) are complete and utter BS.

How are you only shaving off 0.19s on your lap times when you increased HP by 6 (Stage 4 vs Stage 2), while you reduced your lap time by 6.47s with a 2.5 HP increase (Stage 1 vs Stock)???

The drag race times provide even stronger evidence. Somehow, increasing HP by 2.5 in produces a 1.17 decrease in drag time (Stage 1 vs Stock) but raising HP by 11 only results in a 0.52 decrease in drag time (Stage 1 vs Stage 4)??? This is some serious BS here. Even if the gearing wasn't correct, it wouldn't explain anything considering that the Stage 1 engine cannot rev beyond 5,200 RPM while the Stage 2+ engines should be capable of at least 7,000 RPM. More RPM = More Wheel Speed regardless of what size sprocket was used.

The people who get these sponsorships from GoPowerSports (who also put their name on everything imaginable) are some of the dumbest people I've ever seen. If you're going to lie about HP numbers than at LEAST make your lap times/drag times reasonable. The two nitwits in the video couldn't figure this out . (

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I did go with the ratio rockers by the way. 1.3 intake, 1.1 exhaust. I will absolutely check valve train geometry and valve clearance before running the engine. The stock ports on the Predator 212 Non-Hemi (at least mine) are surprisingly clean and I'll only do a bit of very mild porting. Thanks for the recommending the videos, I'll be sure to watch them. OHV 4-stroke valve porting is a lot different from the 2-stroke jug porting I come from, lol.

On a side note, I pulled apart a old Predator 212 I got from a friend that had sucked metal bits into the intake and seized up the engine completely. Out of curiosity, I measured the deck clearance and head gasket thickness with a high-quality digital caliper. The piston was .025 in the hole (not surprising) but I measured the head gasket at 0.010. I measured it again and again, and even checked the bore of the cylinder with the caliper to be sure that it wasn't giving me false readings. Is this because it was already compressed? I thought the stock head gaskets were .040, not 0.010. I am sure that it wasn't ever modified in any way. This worries me because if the stock head gasket on the Non-Hemi Predator 212 I bought (still in box) is actually 0.010 then using a .016 copper head gasket would actually decrease compression ratio, right? Thanks!

Seems like the STOCK head gasket on a Non-Hemi Predator 212 is actually 0.010"? That's strange considering the thinnest copper high performance head gaskets are .016" or greater...