Double 212 predator engines on go kart

[Shifter8921]

I would like to put two hf predators on the arachnid go kart im making. What are the pros and cons. What should the gearing be?
Please dont tell me one is better because that is not what im looking for.

 

[DaiSan76]

Cool idea, only con I can think of is that it will be hard to hook up the throttles and get the carbs in sync.

Looking forward to reading the build thread.

 

[Shifter8921]

What about using a single 400cc carb with a some sort of double valve mod for both engines

 

[GreyW00lf]

you could use some sort of steel rod between the two throttles and just hook up your Cable to one throttle on one side of the Rod?

 

[landuse]

What about using a single 400cc carb with a some sort of double valve mod for both engines

I don't think a single carb will work, and if it would it would be too much of a hasstle.

If both predators are out of the box, you shouldn't have a problem with one being stronger than the other. The only trick will be to get the throttles properly in sync. There are a few duel engine projects on the forum. Do a search for some more info

 

[DaiSan76]

you could use some sort of steel rod between the two throttles and just hook up your Cable to one throttle on one side of the Rod?

You would use something like this.

 

[jamyers]

Hmm...is this with or without a governor? Direct drive (cent clutch) or CVT?

Using one carb would simplify the throttle control (and mean no governor), but you'd need an intake manifold to split and feed both engines - which is doable using radiator hose and some sort of fabbed "splitter", but you'd have some pretty long intake runners, which may or may not be good (I'm betting not).

The split cable above is nice. If you didn't want to buy that you could fab up one with 3 cables, a cable clamp and a mounting plate.

Syncing them just means that both engines are idling the same, both throttle cables have the same amount of slack in them, and both throttles will go to WOT at full pedal travel. With a governor you won't care about the WOT part as the governors control that.

 

[Shifter8921]

Both engines will still have the governor.
Ive heard something about self synchronization by being forced to drive the same axle.
What your guys thoughts on this?

 

[jamyers]

Once both engine's clutches are engaged, the axle will make them both turn the same rpm regardless of their relative throttle positions. Their RPM's will be synchronized, but that's not the same as syncing the throttles.

All syncing does is make sure they both idle and come off idle (start to pull) at reasonably the same time, and that the loads on both engines once running are reasonably the same, that's all. Some folks overthink it and get wrapped around the axle thinking one engine is going to be a drag on the other one, but unless it's off or it's throttle is SO far off it's trying to decellerate, that's not going to happen.

I'm halfway toying with the idea of adding a 6hp engine to my 8hp kart. Somebody argued that the 6hp engine would drag the 8hp down to a 6hp level and I'd only have 12hp at best, which is silly - unless one is an actual DRAG on the system, 8+6=14 hp.

 

[Doc Sprocket]

Yep- no issues with the dual engines as stated above. When you set up the throttle cables, make sure you have lots of room for adjustment. Be very careful when setting them up, and you'll be fine.

 

[bshinn]

Done all the time back in the day with Mac's Clinton's WB's & the like. Plenty of C-Open karts still running twins today. Any good Kart Shop should have the throttle hardware you need.

If you do this I would recommend ditching the stock fuel tanks replace them with ARC top plates & fuel pumps which would just about mean getting rid of the governor.

This will make working out the throttle cable arrangement much easier.

As toystory stated, just make sure you have plenty of adjustment in the throttle cable & you'll be fine.

 

[Arrowking]

I'm just tossing out an idea here, but what if you put an engine on each rear wheel? You would have sort of a dual dead axle or a live axle if sorts. The engines couldn't regulate each others speed though like they could being on one axle.

 

[Shifter8921]

i know what you mean. that is something i was thinking about earlier, arrowking, it doesnt sound like a bad idea at all.

 

[Arrowking]

I was thinking it could be an alternative way to get a live axle setup(albeit more expensive and complicated) for those who can't weld.

 

[voided]

Try looking into a gyro brake line for a bmx bike... 2 into 1 and 1 into 2... Use the rear section where its 2 into one and simply spin it around as 1 into 2 and the rear is longer..

 

[Doc Sprocket]

I'm just tossing out an idea here, but what if you put an engine on each rear wheel? You would have sort of a dual dead axle or a live axle if sorts. The engines couldn't regulate each others speed though like they could being on one axle.

This really is overcomplicating things. Not only do you need the special double-flange hubs, BUT---

Think about how you'd mount a standard rotation engine on the right-hand-side of the kart with a dead axle. Good luck.

And the engines WOULD "self-regulate" any time you had good traction at both wheels.

 

[Shifter8921]

okay. does can somebody tell me what ratio the gearing needs to be or how many teeth.
i need a ratio that will give me the most overall power out of the twin engines

 

[Doc Sprocket]

Tire size, riding conditions, and total weight including driver please.

 

[Arrowking]

This really is overcomplicating things. Not only do you need the special double-flange hubs, BUT---

Think about how you'd mount a standard rotation engine on the right-hand-side of the kart with a dead axle. Good luck.

And the engines WOULD "self-regulate" any time you had good traction at both wheels.

I knew there were some holes in my little idea, but wow I didn't even think of how you would mount the engines.

Well, my idea is out(unless the engine mounting down)

 

[Doc Sprocket]

Back in the old days, this was done much more easily with 2-cycle engines. The one on the right side of the kart was a reverse-rotation engine.