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-   -   Predator 420 with 40 series CVT (http://www.diygokarts.com/vb/showthread.php?t=40992)

67StingrayJ 04-04-2019 03:44 PM

Predator 420 with 40 series CVT
 
Ok guys,
I got it all hooked up, the 420cc predator engine with the 40 series CVT on my Carter Bro's buggy. I didn't remove the governor but I did bypass it by removing the tiny spring and connecting the throttle cable directly to the carburetor. What sort of RPMs should I be getting with this set up?

https://www.youtube.com/watch?v=KI_Gq2UlsaU

JTSpeedDemon 04-04-2019 04:23 PM

Uhmm, after you destroy your engine? Or before?
DO NOT BYPASS THE GOVERNOR!!!!!!!!!!!!!!!!!!!!!!!!!
You WILL make the governor pop off and bounce around inside your crankcase, and you will be one UNHAPPY person.
Do NOT rev it up!
Not until you fully REMOVE THE GOVERNOR!
It's not that hard!
Also it's a very good idea to get a billet rod so you don't completely kill your beautiful 420.
Case in point: https://www.youtube.com/watch?v=GCXELPyQKvE

Kartorbust 04-04-2019 05:39 PM

Valves will start floating around 5000 to 5500 rpm. The governor can break apart much above 3600 rpm and the pins that hold it in, can potentially get lodged in the gears for the crank, balance shaft and camshaft, causing a lot of issues (broken engine). If you do remove the governor, the next failure point is the connecting rod snapping.

Valve flutter will limit how fast your engine will spin up, until the springs get replaced. Replace the springs, you'll want to replace the flywheel with a billet aluminum one and connecting rod. Gets a bit expensive to go fast.

JTSpeedDemon 04-04-2019 06:23 PM

And above all:
REMOVE THE GOVERNOR!!!
I think I've made myself clear.

---------- Post added at 07:23 PM ---------- Previous post was at 07:22 PM ----------

None of us on here want to hear about your wrecked 420, please.

67StingrayJ 04-04-2019 09:44 PM

Wait, Wait... Take what out... LOL.

OK, I get it. I'll take out the governor. AFTER I remove it completely, what sort of RPM could I expect? I eventually wanted to pass this kart on to my kids when they got a bit older (and when I can afford a RZR) and kinda liked the idea of keeping a governor on it for them. Options???

txluke 04-04-2019 09:48 PM

Just keep it on. I am sure you have plenty of power. At least give it a month with it before you pull it out.

Dingocat 04-04-2019 10:53 PM

And no bypassing.

landuse 04-04-2019 11:44 PM

After removing the governor, the stock valves will cause valve float at around 5000RPM. You can use any speed calculator with those numbers and your gearing to work out top speed. We cannot help you at all with that because we have no idea what your gearing is, what kart you have, how heavy it it, rear tyre diameter, terrain you are riding on etc etc.

You only have to start replacing internals with billet parts once you get stiffer valve springs. Don't worry about it before then

Quote:

Originally Posted by Kartorbust (Post 519119)
Valves will start floating around 5000 to 5500 rpm. The governor can break apart much above 3600 rpm and the pins that hold it in, can potentially get lodged in the gears for the crank, balance shaft and camshaft, causing a lot of issues (broken engine). If you do remove the governor, the next failure point is the connecting rod snapping.

Valve flutter will limit how fast your engine will spin up, until the springs get replaced. Replace the springs, you'll want to replace the flywheel with a billet aluminum one and connecting rod. Gets a bit expensive to go fast.

Basically this

67StingrayJ 04-05-2019 07:48 AM

You guys are so helpful! OK, I didn't know I could still run the thing with the governor on and still be able to connect the throttle cable to the Carburetor. It seems that now I have no choice but to remove the governor because I used the connecting rod between the carb and the gov. Fast forward to 23:16 in below video to know what I'm talking about.

https://www.youtube.com/watch?time_c...&v=KI_Gq2UlsaU

JTSpeedDemon 04-05-2019 08:43 AM

Yeah, usually governor removal just involves prying it off.
Don't forget to take the washer off behind it!

KartFab 04-05-2019 08:51 AM

to answer your original question: ~4500 rpm.

67StingrayJ 04-05-2019 10:09 AM

Quote:

Originally Posted by JTSpeedDemon (Post 519165)
Yeah, usually governor removal just involves prying it off.
Don't forget to take the washer off behind it!

Wait, I thought you guys said I had to remove the governor, not just bypass it...

I physically disconnected the governor from the top of the engine but did not open the engine case and remove anything internal. Is this good or bad?

JTSpeedDemon 04-05-2019 10:13 AM

1 Attachment(s)
The governor is INSIDE!!!!!
It's a little plastic gear with a doohickey on top. (See picture)
Rookie mistakes. :thumbsup:

JTSpeedDemon 04-05-2019 10:14 AM

And also, if you didn't do the basic performance mods(intake, header, jetting), yes it will rev higher, but it won't reach it's full awesomeness.

67StingrayJ 04-05-2019 10:52 AM

Quote:

Originally Posted by JTSpeedDemon (Post 519179)
The governor is INSIDE!!!!!
It's a little plastic gear with a doohickey on top. (See picture)
Rookie mistakes. :thumbsup:

I know the thing is actually inside the case. How do I just "pry it off" when the thing is inside? Your not making any sense JTSpeedDemon. Please be clear here, for my sake and for future readers! Did you mean you just have to open the case and then "pry it off"?

JTSpeedDemon 04-05-2019 12:35 PM

1 Attachment(s)
Take the sidecover off, pry off the governor, and then cut off the governor arm from the inside.
Other people might be able to help more.

67StingrayJ 04-05-2019 01:27 PM

Quote:

Originally Posted by txluke (Post 519135)
Just keep it on. I am sure you have plenty of power. At least give it a month with it before you pull it out.

txluke,
can you tell me how you recommend I leave the governor without doing any serious damage?

JTSpeedDemon 04-05-2019 01:28 PM

Don't rev it up is my advice! :P

67StingrayJ 04-06-2019 12:33 PM

ok, so how do I use this engine with the governor still on?

JTSpeedDemon 04-06-2019 12:56 PM

I don't know for sure, but don't rev it much past ~4000 RPM is probably a good guideline since you don't want a governor splattered all over the inside of your crankcase. :oops:


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