[Joe Nichols]

I talked to a guy that has these little hot rod go karts (pretty bad ass) and he told me about how he takes and machines the weight out of fly wheels and timing and polishing and porting. I told him I have a good friend who works at a machine shop that could take some weight off the flywheel. He told me its important to take the same amount out. What about the port and polishing? He told me I could do it with a dremmil tool. What do you all think about this stuff. My fan does good but if I could get more or make it more responsive (which the guy told me it would with the flywheel deal) it would be cool.

 

[Throughthegills]

That's pretty wild.The man and his son that helped me change the crank in mine last year was telling me the same thing.They use to race go carts and both are some sort of bad ass machinists.They definitely knew what they was talking about but it was all way too deep for my shallow mind to fully comprehend.

 

[kythumper]

joe it sounds gd but i don't think you really want to fool with it. yea porting it will help if its done right, but you can make one run like crap real quick if you don't. plus if you port it much you'll have to do carb work. for the gain you'll get i just don't see it being worth the time and money

 

[Adam Harper]

joe i raced karts for several years and yes theres all kinds stuff u can do to make more horsepower but its harder on motor and u have to rebuild them very often.
for example we ran 5hp briggs totally blueprinted on alky and we had to have rebuilt every 8 race weekends.( pushing 8000 rpms) my brother works at http://sbrpower.com/powerplants.html and brian the owner said be cheaper and alot more durable to buy bigger motor.

 

[Joe Nichols]

Im just thinking about advancieng the timing with an offset key, lighter flywheel, and maybe remove the govener.

 

[Adam Harper]

Im just thinking about advancieng the timing with an offset key, lighter flywheel, and maybe remove the govener.

oh lol ya getter done

 

[Joe Nichols]

oh lol ya getter done

Do you think that would be ok to do Adam? I been looking at these tractor pulling forums the past few weeks and thats about all I want to do with out rebuilding every year. A few has told me that just those things alone will make a major change in my application.

 

[Joe Nichols]

ttt

 

[JpEater]

ttt

What brand and what size is your motor? Also, what is your budget?

 

[Gbollom]

Polishing the exhaust runners can help a little but like said above you have to do more than just one thing at a time to really see an improvement. Depending on what your starting with it may not even be worth it.

 

[Joe Nichols]

What brand and what size is your motor? Also, what is your budget?

A rebuilt Briggs iron sleeve opposed cylinder 20 horse. Not much of a budget. Like I said above Im not looking at the whole polish and port deal unless I was gonna build this engine. The thing Im looking at is if they are getting 20 horses out of these 5-6 horse motors with the few things they do thats pretty dang good. If I can get 5-10 horses out of a fewhundred bucks its worht it to me.

 

[VinnieG]

Be carefull takin the governer off, your gonna shuck its cookies.

 

[Guest]

Joe, what kind of prop set up are you using?

Honestly, if you increase your power, your going to have to change your prop. It would be kinda like lifting a 4x4 but keeping the factory slicks on it... Pointless.


A reduction and larger diameter prop would be the way to go. You keep your engine just the way it is so that you dont sacrafice reliability.

as far as your govenor goes, that should be bypassed already if you havent done so. You get a much wider range of usable RPM by bypassing the governor, however, you do not want to spin the engine faster than its rated rpm, nor the prop for that matter.

 

[VinnieG]

Joe, what kind of prop set up are you using?

Honestly, if you increase your power, your going to have to change your prop. It would be kinda like lifting a 4x4 but keeping the factory slicks on it... Pointless.


A reduction and larger diameter prop would be the way to go. You keep your engine just the way it is so that you dont sacrafice reliability.

as far as your govenor goes, that should be bypassed already if you havent done so. You get a much wider range of usable RPM by bypassing the governor, however, you do not want to spin the engine faster than its rated rpm, nor the prop for that matter.

Ok I retract my statement and agree with impaled. If you take the governor off and prop it so that you dont crank it too hard you will be fine.

 

[Guest]

Honestly, the only reason we bypassed the gov. was to get the motor to Idle slower than what the gov. would allow. You get a much more crisp throttle response as well. the 20 honda we use will not go over 2950 rpm at WOT. That engine meets its peak torque between 2800 and 2900 rpm, so there is no reason to go much over that. Its set up with a 1.65:1 arrowprop reduction and a 52'' B-Series Powerfin that is pitched all the way out.

You want some pushing power, try something similar to this Joe, you would think you gained another 20 or so ponies, but the motor stays exactly the same...

It will cost more than a do it yourself port and polish job, but thats what its gonna take to get the results your looking for. All that little piddly stuff will go unnoticed, or end up causing more harm than good to your engine...

 

[JpEater]

If you really wanna get more power it will probably be cheaper and more effective in the long run to buy a bigger motor. If you have your heart set on modding what you have..... I would have a reputable person clean your heads up. Remember there is a fine line. If you go too crazy, your going to kill your low end torque. Those go karts are running crazy RPM's. They don't need low end torque. But a mild port/gasket match head job, shave a little off your heads to bump your compression a little, and put a Mikuni carb on it. If you do the heads and no carb, you may as well flush your money down the toilette. Heads and carb go hand in hand as well as a good exhaust. But if you do an aftermarked carb, you will have to eliminate your governor. You could spend the money on a cam too. But keep in mind, the general rule of thumb is that once you crack the crank case for mods, you will constantly be cracking it open to keep it running. Its going to get real expensive real quick to get any noticeable power out of it. Then you have to ask yourself, is it just cheaper to buy a 35 Briggs and have a warranty?? Probably is IMO.

 

[markland]

Porting and polishing and shaving the heads down will increase horsepower and is not very difficult to do, but any change to the amount of air flow in the engine can result in changing jetting on the carb as well, so that could cause a slight problem for you as I am not familiar with what adjustments are on the carb itself. Lightening the flywheel is pretty common with alot of small engines and just basically takes a slight load off the engine, but mostly is done so higher rpm's can be run on the motor, and that usually will lead to excessive wear and tear on the engine.
Mild porting and polishing with some slight head deck work would probably be as far as I would want to go with it, but since you are doing that look at a big bore kit and put in a larger piston with cylinder boring then figure out what changes need to be made to your carb and you could bump up performance alot and have a safe, reliable engine with not too much invested.

 

[WBG444]

http://www.setxperformance.com/PERFORMANCE-PARTS_c11.htm

 

[WBG444]

http://www.setxperformance.com/Mikuni-Single-and-Dual-Carburetor-Kits_c2.htm

 

[WBG444]

http://www.setxperformance.com/Rev-Limiter-007.htm