Box Stock

Build for torque at stock rpm?

N

Nessmuck

Member
Now I know this is a karting forum, but here is also where the knowledge is, so...
If I want to take a 212 engine and do what I can to get more torque for running a piece of equipment, what can I do?
Stock governor, btw. Better throttle response would be great. It will usually be running at a set rpm via a typical push-pull control.
I'm thinking about it for a rototiller.
 
don't fix what ain't broke .
should be plenty of torque for a roto tiller . unless its 4 ft wide then a bigger engine would be best .
 
Throw in a set of cheap stamped steel ratio rockers, maybe a small Dyno cam, clean the casting marks out of the head and call it the day to stay within governed rpm. Big carbs, high compression, long duration cams, etc just moves the powerband out of range.
 
Simple things.

Get rid of restrictive muffler and air box in favor of free flowing filter and long pipe exhaust.
You will likely need to rejet carb

Set governed rpm a few hundred higher, so when loaded and working you are at the original governed rpm.

Be prepared for the neighbors to complain and to buy hearing aids for yourself when not running the tiller.
 
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I would look into the NR Racing 230-0211 camshaft, maybe a .625 carb (stock is probably fine), mill the head for more compression, advance your ignition timing 8-10 degrees, and I'd try a loop header. If you're really crazy I'd see about getting the block bored a couple millimeters, and run a 72mm piston, (225cc with stock crank), and/or drop in a 58mm crank (223cc with 70mm bore, 236cc with 72mm bore). that would probably be a whole can of worms though... so probably not. Would be wicked tiller though, lol. Oh yeah, and a (light) port job can't hurt. I'd be cautious with the air filter situation if it's going on a tiller.
 
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It's a tow behind tiller for my Snapper 1650. I'm missing a pto pulley, so engine driven is a must.
It's an older, but lightly used model, with a 196cc-ish Briggs. Now they make the same with 8hp.
The engine on it is way over worked. I plowed, then tilled an old corn field and I'm surprised it survived.
Heck, my Troy built has a 7 and is half the width. The 196 engine can go on an old, setup narrow, Gilson / Wards I'm fixing up for flower beds.
I enjoy fixing up old tillers, painting them red, white and blue, and calling then "Victory Garden" tillers.
Mo' pow-eh is the ans-eh.
 
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I forgot to mention the NR Racing 280-0211 in my last post, this cam is probably the best you can do for torque. Just know that you should upgrade your valve train if you want to run something like that. you could also run 1.3 ratio rockers with the NR 230-0211 cam I mentioned before, that should also be a good combo.

Last year I contacted NR to ask about the 230 cam, the following is my question:

Hello, I was wondering how much duration your 230 0611 camshaft has? The description says 30 degrees more than stock, I don’t know what stock duration is. Would this cam, the 230 0611 be a good cam for a mini bike, primarily in the low to mid rpm range?

Their response:
Hi,



I believe it is around 220. The description was written a while ago by the developer of the cam.



The 230-0211 would be better, it pulls hard to 5500rpm, high torque.

The 230-0611 has a wider power band, 6500+rpm. Has some low end, comes on around 4000rpm.



Thank you,

Kenton

Back to me.

By my reasoning the 280 should essentially be an amplified version of the 230, since they share the same duration, centerlines, and LSA, the only difference Is lift.

A lot of people rave about the Isky Black Mamba Jr, though I feel that would be too much cam for what you're looking to do.

Sorry about the long post, I completely forgot to mention this information before, and I like to be thorough with what I post.
 
I'll likely avoid a cam for fear of losing bottom end.
I don't expect extreme airflow.
I'm considering a level 1 kit with resetting the carb, exhaust header, an air cleaner extended up away from the dust and retiming the flywheel with a cheapo degree wheel. Some mild porting also, mostly exhaust.
From what I've found here, if I'm not going for high rpm, airflow and valve train are not the huge issue as in racing.
A heavier flywheel would likely help a working engine to keep plugging through intermittent heavy loads.
I wonder if a flywheel could be added to the crank side as a part of a custom drive pulley?
 
I would implore you to either mill your cylinder head, or buy a 14cc head. The 14cc head flows worse, but will give you huge compression gains, and is one of the easiest ways to pick up power / torque. As for the flywheel / pulley idea, I suppose you could make it work, people have run alternators off the PTO before, so you wouldn’t be breaking new ground… no pun intended. Are you talking about a stock style flywheel, or just a flywheel in general?
 
Well, perhaps if you could get your hands on a large round of metal, you could have the center machined to fit the crank. Otherwise I might look into getting a stock cast iron flywheel machined to fit, they’re pretty heavy, or even better a big block flywheel, or one off a small block v twin like the Vanguard, they’re really heavy. I don’t know for sure if that would work, perhaps the inner flywheel taper is already larger than 3/4”, but it might be worth looking into. Obviously don’t run a stock flywheel that could be compromised though, perhaps this could happen in the matching process if you go this route.
 
Keep in mind, a flywheel only help maintain momentum. No power, or torque is created. 6.5 hp in, nets 6.5 hp out.

For something with a shock load, a flywheel is a good thing to maintain momentum until reduced load allows speed to recover.
A small square baler is a good example of this.

For a tiller, with a steady state load, a flywheel will slow rpm drop, but will also slow rpm recovery. No free lunch.
 
95 shaw said:
Keep in mind, a flywheel only help maintain momentum. No power, or torque is created. 6.5 hp in, nets 6.5 hp out.

For something with a shock load, a flywheel is a good thing to maintain momentum until reduced load allows speed to recover.
A small square baler is a good example of this.

For a tiller, with a steady state load, a flywheel will slow rpm drop, but will also slow rpm recovery. No free lunch.
Click to expand...
Good point, it’s definitely a double edged sword. Hopefully any engine mods will help in the power / torque department.
 
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