New guy - advice needed

[Htx86chevy]

So I got a great deal on this chinese off road frame on CL.
I would like to build my kids (15 & 13) a powerful off road buggy.

I'm thinking of picking up the HF 22HP (670cc) vtwin and slapping that in. Would this be a good start? What torque converter would be needed?
My tires are AT 21x7-10 28F
I have a sproket but cant remember the size. Im willing to buy a diff size if need be.

Its definetly not my first gokart but my previous 2 karts were yerfdog CL finds that I slapped 6.5 clones in and ran em as is.

Any advice would be greatly apprectiated.

 

[MiniMudder12]

In my opinion this would be a good way to get your kids killed (670cc for gods sake) I have a mini bike with a predator 212cc with a 30 series torque converter it tops at 40-45 mph and can climb upwards of a 60 degree angle. (My mini bike https://prnt.sc/fmhupw) if it where me i would spend the money on a 420cc engine and do some mods (I don't know how much you know about engines so ill list a few mods) you could run bigger jets and air filter and a pipe if hate your neighbors. But a 420cc with a torque converter and some mods would have enough power to sling your kids around. But if you want to get them out of your hair sure get a 670cc.

 

[KartFab]

good engine, but almost too powerful for any sort of transmission you would put on it. However the "22 hp" engine is severely overrated and has 45 nm of peak torque vs a honda that is rated at 20 hp that has 48 nm of peak torque. So.... id say the predator is more around 19 hp...

Comet 40 series are rated up to 18 hp, and a lot of people use the 40 series with no problems on these engines.

Another option is the predator 420cc engine, or even those vegas karts engines which are similiar to the honda gx390/predator420, but with a lot of performance modifications to rev higher. Soo... if i were going to spend about $600 on an engine id choose between

predator 420 - solid choice, inexpensive, can do performance mods later, save money.
vegascarts 440/460 etc solid choice as well, comes with performance parts already.
predator 670 - may be too much torque, and with limited/almost no performance modifications.
motorcycle/large dirt bike engine spending that much money, you might as well look into these, esp for a mini buggy. More than enough power and speed and dont need 'performance mods'. Will require a lot more fab skills and gearing math. End result will likely end up extremely dangerous and too fast.

Also, if you are sticking with the standard larger industrial 4 stroke engines, regardless of how its geared, you are shooting for a speed of 36-40 mph at 3600 rpm. This usually translates into a 6:1 gear ratio. There are some of us on the board here that would disagree with me because of the weight and size of the kart, and suggest a ratio other than that. This ratio is fine for the larger engines and the 40 series torque converters (because of the massive amount of torque they have at engagement rpm, multiplied by about 3 with the torque converter) and manco has used this on all their larger 2 seat mini buggies/go karts with 8-13hp engines, so it is a good place to be geared unless you plan on running a centrifugal clutch (bleh).

 

[MTNSleder]

Model 44 CV "Magnum" Series (Symmetrical) is the torque converter you need for your engine "I think". http://www.hoffcocomet.com/EpiphanyWeb/flexpage.aspx?ID=75
As for 670 v-twin Engine your kids will be fine (Post #2 that is), I've been riding 800cc 180 Hp sleds since I was 10 and I'm not dead yet, weird

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