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clif · #41 06-02-2010, 05:38 PM

OK I have installed this throttle shaft, now my engine idles at 3550 rpm, pretty much wide open. How do I get it to go back to 1550 rpm, like it was before swapping throttle shafts? The idle adjustment screw on the carburetor (the one right next to the throttle linkage cable and throttle shaft) does nothing, since this is only a stop for the throttle shaft and the throttle shaft won't close very much even when throttle lever is set to slow idle.
There is that screw that's mounted on one end of that throttle cable/ choke cable control plate, it is very difficult to access, nearly impossible short of removing the entire engine. I guess it has something to do with that governor shaft. If this isn't it, does anyone know other ways to lower my idle speed?

For people that have done this upgrade already, have you had to make adjustments to lower the idle speed after installing the new throttle shaft, if so what did you do?

underPSI · #42 06-02-2010, 08:46 PM

You put something back together wrong or something's reversed. There is no way you'd have to adjust anything after a throttle shaft swap. Besides, the difference between the two shafts is so minuscule that if any adjustment were required it would be a small one. The only obvious answer is something is backwards. Remove the air cleaner and look at the throttle plate when the throttle control is set to idle. Now move the throttle control to WOT and look at the throttle plate. What are the differences? Any? I'm guessing the throttle plate is fully open regardless of throttle control setting. If this is the case I'd check the linkage for binding somewhere near the governor. Did you use the correct linkage or are the two reversed (choke and throttle)?
Just trying to throw some ideas out there for you. My parts arrived today. Hopefully I'll get it on this weekend.

Quote:

and the throttle shaft won't close very much even when throttle lever is set to slow idle.

sorry, I just re-read your post and this popped out at me. I am inclined to believe a linkage is binding somewhere not allowing the throttle plate to close. I'd look closely at the governor.

matt250r21 · #43 06-02-2010, 10:48 PM

After reading this post I decided to dig into the FH601V on my old Turf Tracer 60. I pulled the carb off and noted that the butterfly valve in the carb only opened maybe 3/4 of the way. I thought no problem, I'll grind down the stop on the throttle shaft so the valve will open fully and that will be it. Yep it worked the valve opens fully, but not after I hooked all the linkage rod parts back up. I can get the engine to idle as it should and throttle up to where it was before the mod but cannot get any extra throw out of the linkage to move throttle shaft fully open. I can force the extra movement with my finger on the throttle shaft and note that there is a big difference in engine performance. I'm thinking the linkage rods may be different on these engines and plan on comparing part #s when I get a chance. As a side thought anyone who has played with those throttle plates and that spring that conects from the govener arm to the throttle plate know how big a pain in the a** they can be.

clif · #44 06-02-2010, 11:13 PM

Quote:

Originally Posted by underPSI

You put something back together wrong or something's reversed. There is no way you'd have to adjust anything after a throttle shaft swap. Besides, the difference between the two shafts is so minuscule that if any adjustment were required it would be a small one. The only obvious answer is something is backwards. Remove the air cleaner and look at the throttle plate when the throttle control is set to idle. Now move the throttle control to WOT and look at the throttle plate. What are the differences? Any? I'm guessing the throttle plate is fully open regardless of throttle control setting. If this is the case I'd check the linkage for binding somewhere near the governor. Did you use the correct linkage or are the two reversed (choke and throttle)?
Just trying to throw some ideas out there for you. My parts arrived today. Hopefully I'll get it on this weekend.

sorry, I just re-read your post and this popped out at me. I am inclined to believe a linkage is binding somewhere not allowing the throttle plate to close. I'd look closely at the governor.

I'll recheck the governor and cable for binding tomorrow.... Damn thing has a ton of power now though. Cut my back yard (wet grass) full speed as short as I could, didn't bog down any. I can tell from the way the blades spin up much faster that it's more powerful. Plus, if I push the levers full speed ahead too quickly when mowing, it will pop a wheelie now. I guess before, the blades tapped a little power from the hyrdos so that didn't used to happen, now they have more reserve power>?? lol More fun this way to drive now, can't wait till Monday when I go cut a bunch of different yards and vacant lots to see the difference. Once I figure out why my idle is so high, I'll post pictures and explain step by step what I did for others interested.

Chris "Greenville" · #45 06-02-2010, 11:17 PM

Effectively is your MINI Z now a Super MINI Z? I know those were sold with the 25hp Kaw. Do you know if the extra power will have any effect on the Hydro's. Still strongly considering this upgrade myself. Thanks.

clif · #46 06-02-2010, 11:18 PM

Quote:

Originally Posted by clif

I'll recheck the governor and cable for binding tomorrow.... Damn thing has a ton of power now though. Cut my back yard (wet grass) full speed as short as I could, didn't bog down any. I can tell from the way the blades spin up much faster that it's more powerful. Plus, if I push the levers full speed ahead too quickly when mowing, it will pop a wheelie now. I guess before, the blades tapped a little power from the hyrdos so that didn't used to happen, now they have more reserve power>?? lol More fun this way to drive now, can't wait till Monday when I go cut a bunch of different yards and vacant lots to see the difference. Once I figure out why my idle is so high, I'll post pictures and explain step by step what I did for others interested.

The throttle shaft barely moves when adjusting the throttle lever. Come to think of it, the cable didn't seem to be binding, because it moved the little thing on the control plate, which is tied in to that governor arm with the spring. It's like the governor arm isn't pulling the throttle shaft closed enough when I back off from the throttle. I can force it, but it doesn't stay. I can't find the throttle cable part on any of the sites I looked up all my parts on either. Maybe this is a hustler part though. I think the "super" mini z used to offer the 25hp kawasaki when I bought my mini z.

clif · #47 06-02-2010, 11:25 PM

Quote:

Originally Posted by Chris "Greenville"

Effectively is your MINI Z now a Super MINI Z? I know those were sold with the 25hp Kaw. Do you know if the extra power will have any effect on the Hydro's. Still strongly considering this upgrade myself. Thanks.

The hydros on the mini z are the HYDRO-GEAR BDP-10A, whereas the "super" mini z hyrdros are the HYDRO-GEAR BDP-16A, bigger size pumps by 6cc's. Plus, the super mini z has a hydraulic oil cooler system added. But it will have an effect on the hydros in that when you hit tall grass that usually bogs down your engine, you may not bog down anymore or as much, which means your pumps operate more near their maximum output, which means you stay cutting faster -- longer....

I really wanted to upgrade my mini z to the old super mini z 13mph beast once I did the horsepower upgrade, but after pricing pumps, at $400 EACH I decided 9mph will have to do until it craps out then I will buy the 15mph super z. Now I suppose if you know of someone selling some used pumps like that for cheap it might be worth looking into...

Chris "Greenville" · #48 06-02-2010, 11:32 PM

So the larger pumps are only to increase ground speed and have nothing to do with the increase in HP right? I would hate to blow out my pumps due to the power upgrade.