Governor Screw on HF 6.5

[rob328]

Hey, I'm pretty new here, but I've noticed there is a TON of great information on this forum and website!

I have a go-kart my friend gave me earlier in the year but the engine was siezed (he said his neighbor gave it to him for free before they moved).. Rather than messing with the 5hp engine on it, I just went to Harbor Freight and picked up a 6.5HP clone engine which was on sale for like $119!

Anyway, the thing runs great, and it's a blast, but I couldn't help noticing that with the 3600rpm governor, my cart can only go 27mph (with the 13" tires, 10tooth sprocket on the clutch, 51tooth sprocket on the axel).. I've read a lot about removing the governor on here, but it seems this 6.5 engine has a little screw that limits the throttle lever from going further at full throttle.. If I removed this screw, what would the engine's RPM reach? It seems like it might allow it an extra 500 or so rpm(does this seem accurate?).. Which would allow 30-32mph, pretty nice gain in my opinion. I'm worried about removing this screw though as I don't know how much that will effect the reliability of the engine! I do want to keep it for a couple of years...

Any help is appreciated, thanks!

Here are some pictures for reference:
Throttle at Idle:

Throttle at Full:

 

[jr dragster T]

Thats not the governer ajustment? It already goes full throttle on the carb untill it hits 3600 RPM. I would think if you loostened the screw all it would do is pull on the carb harder and possibly cause damage.

 

[Jerryburger]

Hey Rob328!
It IS a governed speed adjustment, and on my motors I tached them at 4300 rpm with the screw backed all the way out. The governor still functions, but it just maintains a higher rpm. It's probably pretty safe, (no problems with my motors yet) and of course, it's ultimately your call. If you look on this and other forums on the net, most people are getting satisfactory results (no harm or ill effects to their stock motors) all the way up to 4500 rpm. Just keep your oil changed and the motor maintained, and you should be good.

 

[killawatt]

well what if you bypass that screw all together will that cause the governer wheel to fall apart

 

[jr dragster T]

If you want to remove the governer FULLY remove it, This envolves pulling the sidecover off and pressing out the governer gear shaft and tap the hole for a 1/4" bolt. But you can leave that shaft pressed in but I dont.

 

[killawatt]

I understand that but at what speed will that governer wheel start to...... fall apart i guess if how many rpms can i force out of my motor before i need to worry about the governer being over worked and falling apart basically because that could bot be good for a motor

 

[Jerryburger]

I have a hard time believing that they (the designers) would have an adjustment that allows the gov to work all the way to 4300 rpm with potential pitfalls in the process. (Gov weight thingy flying apart inside crankacase.) Like Tyler says, though- if you disconnect or bypass the gov, get the assembly OUT of the crankcase. I think when the gov is disconnected, it allows the weights to extend past their design limit, and that causes the resulting failure. If my motors (completely stock) fail or act up, I'll post an alert in the forum right away. So far all all has been well at a governed 4300 rpm, though.

With proper gearing 4300 rpm is plenty, and if you look at BradenM's "Clone Build Up" article he posted, a stock clone kinda runs outta steam past 4500 rpm anyway. You'll have to go internal to get more from it.

 

[GXMATT]

i hve bypassed my govenor, used the rod direct to my throttle lever. i have to fully remove the govenor then? in simple terms how do i do it? i will limit it with the throttle screw. i just want my engine to be safe. so much work to mess up now.

 

[Kenny_McCormic]

http://www.youtube.com/watch?v=FTNbDvfIHoo

Click on it and watch all 4 parts

 

[GXMATT]

I understand that but at what speed will that governer wheel start to...... fall apart i guess if how many rpms can i force out of my motor before i need to worry about the governer being over worked and falling apart basically because that could bot be good for a motor

watch the videos, remove it. its a piece of cake! and if your worried about rev's restrict it via the throttle screw. trust me gov removal is very easy!

 

[rob328]

Hey Rob328!
It IS a governed speed adjustment, and on my motors I tached them at 4300 rpm with the screw backed all the way out. The governor still functions, but it just maintains a higher rpm. It's probably pretty safe, (no problems with my motors yet) and of course, it's ultimately your call. If you look on this and other forums on the net, most people are getting satisfactory results (no harm or ill effects to their stock motors) all the way up to 4500 rpm. Just keep your oil changed and the motor maintained, and you should be good.

Awesome, thanks for the insight!! Just to follow up (been a while since I posted this thread), I backed the screw out a little bit, to allow me to reach 4000rpm, and I can now go 30mph with my kart! That was my only real initiative for doing this, so now I'm happy I might back it out all the way like you did later just to see how much faster I could go...

 

[ZnsaneRyder]

That screw is just a throttle limit screw. I removed my limit screw ages ago. It has NOTHING AT ALL to do with the governor! Use that screw only on a go-kart with a small child, if you want to limit the speed to LESS than the 3600RPM governed speed. The purpose of that screw originally was to limit the speed at your choice for the power equipment it's mounted on, since not every application wants an engine screaming at 3600RPM at full HP.

I know they say 3600RPM, bla bla bla, but I have got ~4000 by completely removing that screw, but it bucks horribly, when the governor is still active. Governor sucks hardcore.

You can get 5000+ if you remove/bypass that governor, and SMOOTH revving. Don't worry about blowing up your stock engine, it's ALL hearsay. Just don't keep it at 5000+ for extended periods of time because it will put stress on the valves.

Just remove that lever going to the governor, and run your throttle straight to the carburetor. I've been doing that on my engine for months, and with zero issues. I use mine on a bicycle almost daily, and have done over 6000+miles, and 50+mph peaks, which means it's under MUCH MUCH more stress than a go kart would endure, so I know it's not going to blow up my engine.

* I removed ALL the outside governor lever parts, removed all springs, and use my own throttle return springs and throttle cable and a piece of solid wire to go from the lever to the carburetor. It works great. I didn't even remove the pieces on the inside, and I've been inside the engine, and it still looks new inside.

 

[Jerryburger]

Just backing the screw all the way out got me 4300 rpm, and it was smooth too. That's weird that yours was bucking, etc. I stuck with the governor because it automatically limits it to an rpm I'm happy with, and I'm too lazy to try and re-do the throttle linkage. Plus- it kinda acts like a cruise control when you pin it with the governor!

 

[ZnsaneRyder]

So far, I've dealt with two engines that buck when gov is removed, and screw is backed-out or removed to allow full throttle travel. One 6.5 engine was on my bike-trailer, and the other 6.5 was on a tricycle I built for a friend.


The bucking may be because a bicycle or tricycle is much lighter than a go-kart, so the speed doesn't stay constant at governor RPM. If you ever rev a new 6.5 fresh out of the box with NO load or anything even attached to it, then you will hear the RPM's flutter when the gov is working.