carb options for engine with govenor

baja warrior, predator 212 hemi, tav2 clone.

bike is a trail bike so i won't be making speed runs. i've already hit 40mph and that's fine. planning on leaving the govenor in tact. i want to have an open exhaust and a high flow air filter. i know i will at least need to jet my carb, but should i look into getting a bigger carb? i've noticed the mikuni 22mm and the BSP/Clone RuiXing Carburetor. i don't know much about either or if i need either. i don't want to get more carb than i can use. should i look into either of these carbs or just get a jet kit?

if i do what's basically a stage one upgrade, will i need to change anything else? springs or timing or anything?

all i've done so far is remove the filter from the stock exhaust box and put in an autolite racing plug.
Go with a Stage 1 Kit, which will give you the right jets & filter for your stock carb, along with an exhaust pipe & timing key. Since you're not revving the engine, you really don't need the bigger 22mm Mikuni for better breathing at higher revs since you're keeping the governor.

The Stage 2 Kit adds a bored carb, but you probably won't need it for just trail riding. However, the cost is relatively minimal if you want that little extra oomph.
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Swapping to a Mikuni will bypass your governor as it will not longer be able to be attached to the carb. I would just re jet for the air filter and exhaust.


Active Member
These big carburetors don't make power until you start running up the RPM. Just rejet, run an open element air filter, install a good pipe, and call it a day. Want more power with these motors? Yank the governor or just buy a Box Stock motor that doesn't have a governor.
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Well-Known Member
A governor with hi performance parts make no sense. If you're scared of the top end, put a throttle stop on it.
Is a billet rod a high performance part? If I set my governor at 4700 RPM should I have a billet rod in the engine? Probably. Or what about a performance cam that is designed for power under 5500 RPM's? There would be a benefit with that type of cam governed or not.

Same for cars. A street rod may not see 6500 RPM's very much at all. But don't you think roller tip (high performance) rocker arms would be beneficial to the engine in all power ranges?

Some high performance mods/parts are not necessarily always just for high RPM.
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Active Member
It seems ungoverned the small engines can tear themselves apart is why it seems they recommend an aftermarket/performance rod and flywheel as well as other mods to support the higher RPMs. You don't want things like a rod or wheel coming loose and turning into shrapnel while riding a mini bike.

For drag racing, we run special blankets and shields over the transmission and flywheel housing to protect the driver of the manual and trans-brake transmissions.


Active Member
If it's like you have said in the 1st post, a simple jet will fix it for you. New carb comes into its own when higher revs & more flow are in the picture. Otherwise you'll be fine with the factory carb & a new main jet.
Turning an EPA-choked fixed-speed ditch pump mill in to a mild performance piece with governor intact (OK, maybe tweaked a few revs) isn't impossible. Area under the curve is more critical than peak power, on a single-speed bike. Breathing, jetting and timing can all add plenty of sub-gov torque. IMSLTHO, at least.
I hope I get time this weekend as I just got my gaskets today. I am planning on doing mods with governor still in so I can squash this argument. I plan on putting a flat top piston in and I will try to put my CL1 high torque cam in as well if I have time. I will do one mod at a time and let you all know. I have my mini stored about 100 miles from my home as that is were I ride so don't have a lot of time to work on it. Been waiting on gaskets so I can work on motor.
thanks for the replies guys. looks like the rejet kit will be all i need for what i'm doing. and like i said there's no point in me taking off the govenor. it's a trail bike and i will rarely be getting anywhere close to the govenor. i also don't want to spend the extra money to keep the engine from exploding if i do take it off. i can't justify putting that much money into the build, aka:not in the budget. i've still got fenders to cut, parts to trim, rust to sand, and almost everything to paint. updates to follow. thanks guys

quick edit: can anyone explain why i would need an offset timing key?
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Active Member
The stock key will let the motor run well for emissions like the rest of the factory tune, but isn't best for better pulling in general. If you're tweaking the airflow, it's a cheap way to get a bit more performance for very little money. I just went with a 0.040" advance key (about 6 degrees) for the mods I did & it helps with mid range & revs a bit better. You can go more (better top end) or less (lower rpm torque), bit it seems to be a happy medium between top end & low end pulling. A lot of folks run 8 degrees & are happy with that.
okay, so i got my jet kit, e-tube, HF filter combo installed. can't keep the front wheel down. theoretically, advancing by 6-8 degrees would give me less low end grunt and more power at the top. am i understanding this correctly?

*just to follow up with my original question, no need for bigger carb. jet kit/ emulsion tube combo was a perfect fit for my application.


Active Member
I don't think you would notice much difference with the different timing, just figure out how much throttle you need & use it.

After you run it for a while (to get a new plug showing some color), do a good, hard WOT pull, then shut it down immediately & pull the plug to look at the color. You want to look at it after running it hard & wide open for a little time. What you're looking for is a nice tan-brown color from the residue in combustion on the porcelain insulator. Too black & sooty & running rich, too whiteish or gray & it's too lean. A change in one jet size (that's just 1/1000") will show a difference in color when you're close. Once it's there, you will be making the best power from your setup.