I applaud your efforts Strantor and was hoping your idea would play out. I know you don't want to make a bunch of extra linkage and such, but take another look at #21. I'm not saying follow it to the T, but maybe move your heavy spring to the linkage from the pedal and the rest of the way could be weaker springs since your pedal will have the spring rate needed to make it all happy. I didn't consider the spring rate of a pedal versus a typical small engine throttle in the beginning. With the heavy springs before the actuator you could get by with a smaller actuator since you really won't need any springs afterwords other than the governor spring (for now at least until the upgrades), and the spring connecting the linkage sections.

The butterfly between the carb an intake almost sound workable in my mind, except it kind of doesn't also. As you may have gathered from your research you don't really want to mess with your mixture too much. Lean will burn holes in pistons, and rich will thin out the oil and scar your cylinder walls eventually. Killing the spark for extended periods of time and turning it back on will lead to blown apart exhaust. Once you add the blower (if you go that route) it will even be more critical than now.

Keep thinking... you will make it happen I'm sure.

... just noticed shortbus mentioned the mixture issues back in #70... kind of glanced over things at first since it seemed it was more to do with the CVT than the governor idea.

 

Nice work on the screw and motor setup in your picture also!! Surely there is a way to make it work.

 

Part of my concern about the butterfly between carb and intake has to do with which jet the fuel will be pulling from. I've never studied the small engine carbs enough to know the exact science, but I do know in some automotive ones the throttle plates would block passages as they close to eliminate vacuum in that particular circuit.

 

I've never studied the small engine carbs enough to know the exact science, but I do know in some automotive ones the throttle plates would block passages as they close to eliminate vacuum in that particular circuit.

Small engine carbs also have the "transition holes/jets" just like a Holley or any full size carb.

 

It would be in a PID loop, reacting to changes in vehicle speed.

I maybe wrong, but haven't you in the past complained about computer controls on full size vehicles? But now you want to add them to a toy.

Letting them operate a vehicle capable of 60mph unsupervised is in the same category in my mind.

There's your chance! Tell the wife you need another of these things, one slow for the kids and one fast for you.

 

You haven't said it yet, but the CVT on small vehicles like this is really to keep the engine in it's best power band/range, no matter what engine speed is being used.

And not to beat a dead horse, restraining either pulley is the easiest way to limit speed. We did it back in the day for people that had kids to limit the speed on a snowbuggy. It isn't that hard or complicated, a couple of skate board wheels and a frame work to hold them. When YOU want to go fast you pull a clevis pin and the frame moves out of the way. But I know that isn't want you want but it works.

 

I maybe wrong, but haven't you in the past complained about computer controls on full size vehicles? But now you want to add them to a toy.

I don't know what you might be remembering, and I don't remember what I might have said. My opinions are pliable and maybe different now than they once were. Regarding automotive electronics, for several years now, I have had specific beef with proprietary programmable electronics. If I buy something I want to own it and have the freedom to modify it to whatever my whim. When I find that a manufacturer has gone out of their way to stop me doing what I want with what I paid for, I take that personally.

There's your chance! Tell the wife you need another of these things, one slow for the kids and one fast for you.

Maybe the best idea yet!

 

When I find that a manufacturer has gone out of their way to stop me doing what I want with what I paid for, I take that personally.

So do I... but sometimes I also see it as a business opportunity

 

So do I... but sometimes I also see it as a business opportunity

Me too. Not that what this thread is narrowly focused on is itself very marketable, but it's only part of a larger project from which hopefully something marketable will be born. I was discussing it with a coworker who builds ATVs and when I showed him the pictures of machining my clutch, he got bug eyed. He asked if I could machine his clutch. He said there would be a big market for that around here, as there's only one guy anywhere around who knows how. I confessed I don't exactly "know how" assuming there's probably something special to it that I don't know, and I'm just some dude with a lathe who doesn't know any better and isn't afraid to break things. I told him if he has a clutch far gone and isn't afraid to see it too far gone, I would be happy to give it a shot. He is supposed to be bringing it to me next time we are together at the same facility. If I do well, he says he has plenty of business for me between his own operations and his circle of friends. Funny, I thought the control system or some element thereof would be the marketable thing; turns out to be something else. Things often work that way.

 

An idea to try, but have never done myself. Instead of restricting the intake to cut power, you could try restricting the exhaust. Using bigger pipes increases breathing, what I and most people do, so maybe adding a restriction to the exhaust pipe would do the opposite. Just think of what the old trick of a potato in the end of an exhaust did, but you don't want to completely block it off.

 

An idea to try, but have never done myself. Instead of restricting the intake to cut power, you could try restricting the exhaust. Using bigger pipes increases breathing, what I and most people do, so maybe adding a restriction to the exhaust pipe would do the opposite. Just think of what the old trick of a potato in the end of an exhaust did, but you don't want to completely block it off.

That would need to be a valve with pretty high heat tolerance. I know my exhaust gets at least 400degF. It baked all the zinc off the galvanized piping I used almost immediately. Any ideas what would work off the shelf?

 

Blocking exhaust sounds good except it would be a good idea to monitor temperatures until it proves itself. It seems to me it would lead to higher temperatures than an air cooled engine can deal with.

I don't know how hard it would be to find or how expensive, but I once drove a small Mitsubishi diesel that had a butterfly valve in the exhaust. Part of it's purpose was to help the engine warm up on a cold day and the other part was a pseudo engine brake. It kind of worked for the engine brake, but I'm guessing it never fully closed. It made it warm up a lot quicker though. I think they are kind of common among small box trucks of all makes. I also remember a Ford / Nissan (UD) creation that had one too.

 

Not knowing enough about engines and valves, etc. I defaulted back to the cable sheath linear actuator. I got rid of the reduction gears and direct coupled the motor to the leadscrew as I found that I get more leadscrew force direct coupled at low RPM, than I do with 3.5:1 reduction with midrange RPM. Also I ditched that silly UHMW nonsense.