Low end torque build ideas?
- Thread starter MJL
- Start date
MJL
base on just this.......
my opinion(doesn't mean jack sh..):laugh:
i would use the factory head and keep the small valves in it and do just a lite porting, mill the head,but keep the compression under 11:1
advance the timing,rejet the carb,good air cleaner,header pipe and if you want to keep it a little quieter? run a rvl muffler or baffle the header. set the governor at 4000 rpm's
couple other things that i think may really help your low end performance, install a 7inch rear driven. that part you already ask about in another thread and maybe change the rear sprocket.
i'm assuming this is going on a coleman bike? or something like it...
my opinion(doesn't mean jack sh..):laugh:
i would use the factory head and keep the small valves in it and do just a lite porting, mill the head,but keep the compression under 11:1
advance the timing,rejet the carb,good air cleaner,header pipe and if you want to keep it a little quieter? run a rvl muffler or baffle the header. set the governor at 4000 rpm's
couple other things that i think may really help your low end performance, install a 7inch rear driven. that part you already ask about in another thread and maybe change the rear sprocket.
i'm assuming this is going on a coleman bike? or something like it...
Thanks, Delray. This would be for the Baja. My longest run on the property I ride on is 200 yards, so no need for high top speed, acceleration is the goal. I've got a 70 tooth rear sprocket on it and a 7" pulley in the mail. Keeping the neighbors from calling the cops is high priority. From my reading, a hotdog muffler is much quieter than the RLV, so I might try that. Can I get by with a thinner head gasket rather than shaving the head to boost compression?
Depends on which Predator you have. The non Hemi already has the paper thin metal head gasket. The Hemi has the thicker fiber head gasket.
I have the non Hemi on my CT200U, with the billet rod/flywheel, some porting, 22 pound springs, jets/e tube, air filter and header, and a Chinese TAV. I'm 6' and around 220 pounds, and that thing with the stock rear sprocket will pull stumps, and fly.
I have the non Hemi on my CT200U, with the billet rod/flywheel, some porting, 22 pound springs, jets/e tube, air filter and header, and a Chinese TAV. I'm 6' and around 220 pounds, and that thing with the stock rear sprocket will pull stumps, and fly.
Get a 420. It has a stock rod and flywheel, has quietish exhaust and happily runs on corn liquor gas. It also has an order of magnitude more torque than the 212. The way you get more low-end torque is more displacement.
(Here comes the part where everyone feelings are hurt because their 212 builds are totally unsuitable for the parameters given but can't give up the idea that their beloved 200cc motors simply aren't suitable for every application on planet earth.)
(Here comes the part where everyone feelings are hurt because their 212 builds are totally unsuitable for the parameters given but can't give up the idea that their beloved 200cc motors simply aren't suitable for every application on planet earth.)
Last edited:
MJL
not below 4000 rpm. bigger carb may just kill the lowend response and same with the cam.
i think the big thing would be to tune that motor like i said earlier and install a 7inch and a bigger rear sprocket.
thats a heavy bike. so all thoses up grades will make a big difference. but you need to do all off it not just one thing.
i also have a large baja bike and it has a stock 5hp big block briggs with just a billet rod,small mikuni/clone mmcarb, stock 6inch rear driven,stock rear sprocket still and and it just won't rev over 3600 rpm's still.
i need to advance the timing little and change the driven and rear sprocket to help it get out of it's way...:laugh:
i kind of like it being the way. use it for for cruising on road trips...... last ride i did on it we put 37 miles on it in one day..:thumbsup:
i think the big thing would be to tune that motor like i said earlier and install a 7inch and a bigger rear sprocket.
thats a heavy bike. so all thoses up grades will make a big difference. but you need to do all off it not just one thing.
i also have a large baja bike and it has a stock 5hp big block briggs with just a billet rod,small mikuni/clone mmcarb, stock 6inch rear driven,stock rear sprocket still and and it just won't rev over 3600 rpm's still.
i need to advance the timing little and change the driven and rear sprocket to help it get out of it's way...:laugh:
i kind of like it being the way. use it for for cruising on road trips......
last ride i did on it we put 37 miles on it in one day..:thumbsup:
Last edited:
MJL, rvl muffler will help keep the noise down. i don't think the neighbors would call the cops on you? not a real big fan on the hotdog muffler.
if your preferring to the briggs style muffler. i personally think thats kind of a restricted muffler and you could kill little power with that. but i understand with the neighbor thing too........
if your preferring to the briggs style muffler. i personally think thats kind of a restricted muffler and you could kill little power with that. but i understand with the neighbor thing too........
Well, if you're not wanting to spin higher rpm (billet rod and flywheel), and you wan't quietish exhaust, then your only option is to run a bone stock motor with a good intake and carburetor rejet. You could increase the compression, but you're making a bigger bang in the combustion chamber, and you'll need a good rod to take the abuse.
With the parameters you've set, you're not going to get most of the way to a 301, not even close. Even if you make more power, and you will, it won't have the torque of a 301, which what you're really after.
It's like you're asking how to fly without wings. Well, it isn't flying, you're just going ballistic. Good luck with landing safely. The universe doesn't bend around us.
Horsepower is made in only three ways: Make a bigger explosion, turn higher RPM, or make the engine more efficient.
1. Bigger Explosion: This can be done with higher compression, literally squeeze fuel mixture into a tighter space. This is how atom bombs can blow up whole cities. You can increase the amount of fuel mixture going into the engine with intake and exhaust: More air and gas sucked in means a bigger explosion. The more exhaust gases you push out means more room for air and fuel to get sucked in. You'll need a good rod for the compression. You'll need a good exhaust pipe as mention. Both of which you have eliminated given the parameters.
2. Turn Higher RPM: HP = (Torque * RPM) / 5252. Double the RPM, double the horsepower. Simple. Don't go over stock RPM with a stock rod and flywheel--things you have eliminated given the parameters outlined in your original post. You can adjust the governor with the throttle stop screw, but still you're limited.
3. Make the engine more efficient. Higher compression makes an engine more efficient. A lighter rod will make a more efficient engine because the engine will spend less energy keeping itself running. Again billet rods are great for increasing efficiency, but again that isn't a part of your parameters.
Your only option given these parameters would be to install a good intake, rejet the carburetor, and turn out the throttle/governor stop screw, keep the stock exhaust. That might get you an extra 0.5 hp maybe and 0.75 extra horsepower. You won't see much better performance over the bone stock engine.
With the parameters you've set, you're not going to get most of the way to a 301, not even close. Even if you make more power, and you will, it won't have the torque of a 301, which what you're really after.
It's like you're asking how to fly without wings. Well, it isn't flying, you're just going ballistic. Good luck with landing safely. The universe doesn't bend around us.
Horsepower is made in only three ways: Make a bigger explosion, turn higher RPM, or make the engine more efficient.
1. Bigger Explosion: This can be done with higher compression, literally squeeze fuel mixture into a tighter space. This is how atom bombs can blow up whole cities. You can increase the amount of fuel mixture going into the engine with intake and exhaust: More air and gas sucked in means a bigger explosion. The more exhaust gases you push out means more room for air and fuel to get sucked in. You'll need a good rod for the compression. You'll need a good exhaust pipe as mention. Both of which you have eliminated given the parameters.
2. Turn Higher RPM: HP = (Torque * RPM) / 5252. Double the RPM, double the horsepower. Simple. Don't go over stock RPM with a stock rod and flywheel--things you have eliminated given the parameters outlined in your original post. You can adjust the governor with the throttle stop screw, but still you're limited.
3. Make the engine more efficient. Higher compression makes an engine more efficient. A lighter rod will make a more efficient engine because the engine will spend less energy keeping itself running. Again billet rods are great for increasing efficiency, but again that isn't a part of your parameters.
Your only option given these parameters would be to install a good intake, rejet the carburetor, and turn out the throttle/governor stop screw, keep the stock exhaust. That might get you an extra 0.5 hp maybe and 0.75 extra horsepower. You won't see much better performance over the bone stock engine.
Last edited:
Put a flat top piston in it. I agree with delray set your governor to 4K. I have mine there now. I would advance the flywheel a few degrees. Pull the flywheel and file the back side so you can advance the flywheel. My flat top made a very small difference in power. If your looking for torque the best way to get it is with gearing. A high torque cam might be a good swap as well. Although they say max RPM of 5,500 RPM they peak torque much lower. I have not tried a cam with the governor in but would swap cams. I would expect a small cam to make more power every were in the power band.
I do wish some one made a cam specific for a stock motor. Not the stock cam but something with about 210-215 Duration @0.050, .275 lift and around 100 ICL/104 LSA. A stump puller cam...
I do wish some one made a cam specific for a stock motor. Not the stock cam but something with about 210-215 Duration @0.050, .275 lift and around 100 ICL/104 LSA. A stump puller cam...
They do. Probably not exactly what you're talking about, but I imagine you can get them to make you just about anything.
Camshaft, Custom Grind, Honda GX Engines
https://www.smallenginecams.com/grinding
What about a good old CL1 camshaft. the original design with the torque?
Camshaft, Custom Grind, Honda GX Engines
https://www.smallenginecams.com/grinding
What about a good old CL1 camshaft. the original design with the torque?
Last edited:
Went and picked up a muffler a washer and some pipe fittings to give it a try before I committed to a full header, just to take it off because it's too loud. I know the 90 isn't the best, but I didn't have any luck bending conduit (packed it with sand, but no dice). I did pick up 2-3 mph on my nearly flat 200 yard sprint and stop run (up to 32 mph now) My wife said she didn't notice any difference n tha ound (they are all loud to her!), but said my son sure did. It also got the heat further away from my leg and the seat, both of which were starting to melt! I've got some fiberglass cloth around somewhere, I might give the muffler a couple wraps when I get around to it (after I burn myself!).
Last edited:
I have the CL1 high torque just have yet to install. I thought about getting the custom grind but at $100+ I just have not done it yet. I guess when I paid that much for my Mikuni knock off kit it's no different. Was thinking of grinding something close using the 280 lobes with the 220 duration. I don't know the timing of the NR 280 grind so should probably look at that before paying to have one ground. One day just not soon.