ANYone 'know' the govenor set RPM for a 'Predator' 212?

[Half-breeder]

In the past I have seen/heard that the governor set RPM is 'around' 3600rpm... I've 'also' read/heard ppl spending to beef their clones to 5800-6krpm...

Now... my question... I have been 'officially' clock by a NCSHP(North Carolina State Highway Patrol). Knowing how fast I travel, and knowing 'what' Im running (12clutch,60axle,10"wheels=33mhp (for me))... theoretically I'd have to be doing 5500rpm to get that speed(that's when governor kicks in)... according to http://www.diygokarts.com/speed-calculator.html. So what IS the governor set for on our 'Predators'... or atleast mine.

Ive done NOTHING to my motor cept regular gas and synthetic oil(not racing). Governor, evidently still attached and working...intake/exhaust straight factory(bought motor NEW)... so why am I calculating slower than 'actual' by such a drastic amount(unless its rpms)?

(For those that Lo-T is 'nolonger' the above configuration... Im working on 'Priceline' another dead wheeler that is getting all of Lo-T's stuff... so... still gonna need to know either way the governor RPM's)

 

[Doc Sprocket]

I do believe it comes out of the box +/- 3600RPM. Either there's a flaw in your calcs, or something else isn't right. I don't think you could be turning 5500 with the governor even tweaked some.

Are you 100% sure of that rear tire diameter? I would encourage you to take a static measurement from the ground to the dead center of the axle, and multiply by 2 to get the most accurate diameter for calculation.

I don't understand the following statement:

I'd have to be doing 5500rpm to get that speed(that's when governor kicks in)

Sure- the math says you'd have to be doing 5500+ according to the current numbers- but what do you mean by "that's when the governor kicks in"?

 

[Cole Tallerman]

Something doesn't add up. A predator with no upgrades should be doing no more then 3600 rpm's. are you sure that the speed reading was correct? Time how long it takes you to drive a mile and calculate your speed that way.

 

[ML-TOYS]

going downhill does not count for added speed

 

[philip metzner]

Are you calculating based on wheel diameter instead of tire diameter?
Also I have seen many times that radar checks of karts and mini's be way off.

 

[Half-breeder]

I do believe it comes out of the box +/- 3600RPM. Either there's a flaw in your calcs, or something else isn't right. I don't think you could be turning 5500 with the governor even tweaked some.

Are you 100% sure of that rear tire diameter? I would encourage you to take a static measurement from the ground to the dead center of the axle, and multiply by 2 to get the most accurate diameter for calculation.

I don't understand the following statement:


Sure- the math says you'd have to be doing 5500+ according to the current numbers- but what do you mean by "that's when the governor kicks in"?

When the govenor kicked in(at top speed, on flat ground) is when i got clocked. I ran next to an atv w/ a speedometer too, same reading, but didnt find that to be as accurate as SHP radar...n yes im sure on tire size(bought enough rear tires). So... Yea im 100% sure on wut im runnin, n bout 95% on the speed... Just mathimatically at 3600ish rpms its impossible... I know iknow ... I must be puttin the #'s in wrong or im illiterate... Im just confused... Heck you can watch my vids n see im goin faster than 21 mph 'after' I opened the thrttle all the way...so yea im confused! http://youtu.be/ys_-qd89Ip8

 

[DaiSan76]

You could use a GPS app if you have a smartphone. That is how I check my speeds. When I enter your numbers I come up with 21.42 MPH. That is approximately the speed of my mini-quad clocked by GPS.

 

[itsid]

Hm, have you rode that kart downhill at full throttle (no not when you clocked the speed, before that) ?

Although it's very unlikely, that might broke the governour (that is one of the two flyweights came off) thus it needs way more rpm to let it kick in.
(the engine is forced to go faster than the governed speed by gravity, the governor arm pushes against the governor and it couldn't stand the abuse)

Also, the governor arm can be twisted adjusting the regulated rpm a little,
maybe the bolt rattled loose and that happened maybe enough to completely disable the governor... and what you think is the governor kicking in is actually the valve flutter adjusting the speed

So if you want to make sure, first check the governor arm, if that's all right I'm afraid you should open the engine and take a look,
if one of the flyweights actually came loose it's in your engine tumbling around which is NOT a good thing to have it should be removed before worse things happen


[EDIT]

Sorry, but again on the wheel thing..
According to your pictures
View attachment 40444 (that's LO-T right?)
the 60T sprocket (7.25") is only slightly larger than your rims, thus your rims look like to be 6" (the red narrow ones) the tires look like to be 4.10/3.5 -6 sawtooth thus have a OD of 13 inches, the wider ones you recently mounted (to the other one?) look like to be 15x6.0 -6 with of course 15" diameter
Are you sure about 10" OD of your tires? since the small slicks are 11" I'm pretty baffled

'sid

 

[Half-breeder]

Yep ive driven it down hill n had the govenor kickin(kinda annoying...sudden loss off power... then shortly followed by the neck snap back of full thottle... then back off) so I 'know' the governor 'is' working. Ive never heard any 'odd' scratching or clang or banging commin from the motor, so 'pretty' sure all is still intact.

Ill check the arm in the mornin(seems 'logical').

 

[OzFab]

Ok, the governor is working but, not correctly; it shouldn't fluctuate, it should be constant...

I can see why you're confused, something just doesn't add up. Theoretically, it's not possible to do that speed, Absolute worst case scenario, you should be getting valve bounce at around 5krpm

 

[Half-breeder]

Recently I changed out my fuel tank to a smaller one(also to remove the stock tank to make the motor look alil less like something I pulled off a lawn mower). As I reinstalled the location of the spring...I came across the 'reason' I was going faster than what 3600 rpms would do, and why my governor was reacting so 'violently' to working(whiplashing forward and headslamming engagement)... it was the throttle-spring's location!

At idle the spring cleared the governor throw arm...at FULL throttle, the spring lightly pushed on the arm enough to cause it to go faster. The spring pressing on the arm caused 'more' tension for the arm to withdrawl back which caused the sudden drop in rpms at top speed and the 'sudden' reengagment after rpms slowed enough to release the governor, all awhile the spring pressed on the arm.

Also noticed as I figured this out... the governor arm that the wire-rod and springs that are joined to the carb. The location of the thicker spring, connecting to the arm, has 3 'other' holes(in pic theres only 2 'other' holes), that appear to be a form of 'adjusting'.... maybe?

This is NOT my motor... but the holes are in the same place(right side of pic... where the long spring is connected)...what are the holes 'actually' for?

 

[Doc Sprocket]

Placing the thicker (black spring shown) in the other holes will alter the governed top speed of the engine.

Just for clarity to all readers, I'd like to point out that the governor does not, and should not "kick in", per se. The governor (when properly functioning, obviously) is ALWAYS in effect, always working- not kicking in or out. Close study of the linkages will reveal that there is NO direct mechanical connection between the engine's hand throttle lever (OR your foot for that matter) and the actual throttle shaft on the carb. The hand throttle merely alters governor spring tension to the carb.

It's a long read, but a full explanation can be found here- http://www.diygokarts.com/vb/showthread.php?t=16518

Back to the point- the spring in question is the link between the hand throttle and the governor arm, and is what balances the governor operation and ultimately affects the RPM range. Putting that spring in a different hole alters the spring tension and therefore the RPM range.

Since the actual governor mechanism (by design) "wants" to hold a fixed speed under varying loads, that spring is used in conjunction with a user-controlled varying tension adjust (the hand lever) to turn that fixed RPM into an entire range of speed.