What RPM Range are You Running?

[Timbo]

Just curious what Max RPM range people are running to get to top speed and how much of a difference does an RPM range of 3500 vs 4000 have on top speed? My Max IV with a 20hp Kohler tops out at around 12mph at 3550 RPMs. I am working to increase the RPMs through governor adjustment but wasn't sure how much that would impact the top speed if I was able to get to 4000 or more. I guess I need some insight on what RPM I should be shooting for?

Also, My clutch doesn't appear to be fully engaged at my highest RPMs, not sure if it is that my RPMs aren't running high enough or something else. I have a new belt installed and got similar speeds with the prior overstretched belt.

[garrett1308]

Can you post a video of it running and revving in neutral? Could just be a slacked belt. What width belt did you get? I wouldn't play with your governor yet, you should run 25mph or somewhere in there at 3550 rpm. Wd40 the primary clutch's insides through the circular ports, and through the side when it's running and open, (just be careful to not let it eat anything like your hand). WD 40 the spring area on the secondary clutch too, as well as the slide wedges. You should see a slight change, but if still no, use some screw drivers to pry open the primary, and inspect it for excessive rust. Don't stick your fingners in there, it's hard to open the clutch with both hands, even harder with a hand and a half.if it looks like it could use freshening up, take the clutch off the motor, apart, and clean it up, rebuild if necessary.

I main Max 2 right now. No tach, but stock governor linkage. Guessing i hit the 3600 max set point and it sure feels like 25-30 mph with 22" tires.

[Canadian_Zuk]

mine is set at 4200 RPM with my 25HP Kohler. When I was setting mine up I found my clutches would not fully shift out until it hit over 3600 RPM so you may not be seeing your full top speed at 3500 RPM.

[Toys4Me]

My Max IV with 22hp Predator floats the valves at about 4400 and that gets me to 32mph.

[garrett1308]

Also, if you decide you want to take a peak inside your primary, take the belt off, start the motor, and rev it. Primary should open up and stay open after you shut it off. Just learned that earlier today on accident. Used two big screwdrivers to pop it back closed.

[reneeandjustin67]

never knew dat one now I got to take off belt and see

[Reconrokon]

I have been messing around with my MaxII (14hp Vanguard) for a while and still cannot get beyond 15mph. I installed a tach, but can only get 3570 rpm's wide open. I have a new (correct) belt and it is tensioned properly, but the motor wide open will not make the belt go all the way to the top of the primary clutch. If I manually press the governor arm after the throttle is maxed out, it will rev close to 3950 and the belt goes all the way to the top of the driver. I have been warned by several people not to mess with the governor, but I am tempted to modify it to get the full potential. I am convinced the 3570 rpm limit is causing the 15mph top speed. Just my .02- RR

[Toys4Me]

I have removed or bypassed the governor on all my machines. It is like a whole new engine.

[ARGOJIM]

I have been messing around with my MaxII (14hp Vanguard) for a while and still cannot get beyond 15mph. I installed a tach, but can only get 3570 rpm's wide open. I have a new (correct) belt and it is tensioned properly, but the motor wide open will not make the belt go all the way to the top of the driven clutch. If I manually press the governor arm after the throttle is maxed out, it will rev close to 3950 and the belt goes all the way to the top of the driver. I have been warned by several people not to mess with the governor, but I am tempted to modify it to get the full potential. I am convinced the 3570 rpm limit is causing the 15mph top speed. Just my .02- RR

I'm currently having the same issue, have not returned to it yet.

[Timbo]

Sorry for the delay on getting this video posted. Please confirm if my clutch is engaging high enough when I push it to the max RPMs as detailed in the video. I also confirmed that my belt deflection is currently at around 2" so I will need to shim the engine this weekend to reduce the belt deflection some.

[Reconrokon]

I am not an expert by any means, but I have quite a bit of experience with this type of clutch system (CVT). The clutch in your video that is bolted directly to the crankshaft is called the "driver" also known as the primary. The clutch on the T-20 is called the "driven clutch" or the secondary. As the RPM's increase, the belt goes up the driver and down the driven and this allows the gear ratio to change. Your belt is only climbing halfway up the driver so you are not getting the full range. Shimming the motor will probably correct this as 2" of deflection is too much. Rule of thumb is 1" of deflection. My machine gets the belt about 3/4 of the way up the driver, but if I manually override the governor, it goes all the way to the top. I just need to find a way to modify the governor on mine. Your problem could be solved by simply shimming the motor. Best of luck with it and let us know how it works out. I'm sure others will chime in with their .02. RR

[Reconrokon]

I just looked at your video again. You can actually see the shiny area where the belt once went to almost the top of the sheaves. I bet you will almost double your top end speed when you get this corrected. If you look at your driven clutch attached to the T-20, I bet it is only going half down the clutch. Best of luck with it. RR

[dirtdobber]

Timbo, this is a video of my machine with the Comet 780 clutch set up. Yours should function like this (if this link works)

https://youtu.be/dmkUjcR-opE

Question -Since you owned the machine, has it ever gotten above the 15 mph top speed? I wonder if it had a problem when you bought it. Some things that could be going wrong include resistance in either the driven or drive clutch. If there is rust build up on the sliding parts of the clutches could mechanically limit their travel (it either one is limited it will necessarily limit the other also).

[Timbo]

Thank you for the replies and the video. I purchased this machine two months ago. The previous owner only owned it for a few years and was getting the same speeds as me. Apparently it sat outside for a number of years before he purchased it and he had to replace all bearings, chains, and two axles. Rust could definitely be a factor. I sprayed WD-40 into the clutch last night with not much noticeable results. I will correct the belt deflection this weekend and will post back the progress if any. Thanks!

[Canadian_Zuk]

It's hard to tell but in that video it looks to me like your primary is working but your secondary appears to be stuck shut. The belt is able to climb half way up the primary sheaves because you have a good 2" of deflection, maybe more. I would soak the back of the secondary with a creeping lube, make sure it can travel the full ramp.