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50% scale RC car powered by a KX250 motor?

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50% scale RC car powered by a KX250 motor?

Old 10-27-2010, 01:39 PM
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yamr6rider
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Default 50% scale RC car powered by a KX250 motor?

I do..... well, will. It's a work in progress, but anybody have or seen anything close to this scale? I'm looking for some people to help with ideas.
Old 10-27-2010, 01:41 PM
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Dale Gribble
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Default RE: 50% scale RC car powered by a KX250 motor?

1/4 scale is the largest I have ever seen. Never seen a 1/2 scale before.
Old 10-27-2010, 01:45 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

i have seen somebody convert a real car to rc
Old 10-27-2010, 04:17 PM
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Steve.
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Default RE: 50% scale RC car powered by a KX250 motor?

There is that awesome 70's themed van that is built on a lawn tractor, more like 1/3 size I'd say. Either way it's awesome, you might want to search some threads for it, he used some power window regulators for steering I believe.
Old 10-27-2010, 07:07 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

Sweet, I'll look into that.  I'm looking into using Tone-Seiko PS-050 Servos for brakes, steering, and clutch operation.  A company called Pingel makes a very high powered motorcycle shift solenoid that I plan to use for gear changing.  I've got a club car starter-generator for 12V battery charging ops, and a 5 amp 6 volt car charger to keep the Rx battery full while running.  

Using a JR XF631 radio with the R700 Receiver.  Have everything lined out as of now unless better ideas come up or flaws are brought to my attention.  This will be a slow process as I don't have lots of $ up front, but several of the components are already purchased.  any feedback is appreciated
Old 10-27-2010, 07:15 PM
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Dale Gribble
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Default RE: 50% scale RC car powered by a KX250 motor?

The shifting is going to be very complicated. I would figure out a way to disengage the transmission entirely and run a single speed with a centrifugal clutch off the crankshaft somehow, at least to start. You can always use gearing to get decent ratios for you with a single speed output from the engine.
Old 10-27-2010, 08:53 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

here's the wiring details as things stand... Hope the file uploads, first try on this site.
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Old 10-27-2010, 09:02 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

ORIGINAL: Dale Gribble

The shifting is going to be very complicated. I would figure out a way to disengage the transmission entirely and run a single speed with a centrifugal clutch off the crankshaft somehow, at least to start. You can always use gearing to get decent ratios for you with a single speed output from the engine.
the shifting is part of the grand idea. I've retrofitted the top right aux switch on the transmitter with a micro momentary SPDT switch that feeds channels 5 and 6(refer to diagram). The physical action of shifting would be as follows:
1. let off gas, duh.
2. Right toggle switch up for clutch
3. click up on shift switch to shift, then
4. Ease back on the gas as you let go of clutch....

just like on a motorcycle.

The controls as they stand feel like my PlayStation 3 controller, with the shifter being R1 for up, and R2 for down. You use your thumbs for the joysticks and index finger for the top.

Old 10-27-2010, 09:07 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

By the way, anybody know where I can get a good military discount on some Tone-Seiko PS-050 Servos? It seems I'm in the market for 3 of them.
Old 10-27-2010, 10:03 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

Starting without stalling the engine will be harder than shifting while going.  You don't have to use the clutch to shift while rolling.  They'll usually shift pretty easy as long as the power isn't being applied.  Heck, I've broken my clutch lever in a mx race and still full power shifted without it, although it took some force. 

If you can find a junk golf cart or lawn mower to steal the hydrastatic transmission from or one with the big V belt type clutch mechanism I think you'd be better off than direct drive and trying to shift.  You could use it and keep the kawi in one gear at all times.  It makes more than enough power if the total weight of the car is under 500 lbs.  Even if it weighs 800+ lbs I would imagine just one gear change could give acceptable accelleration and top speed.  Just food for thought.
Old 10-27-2010, 10:27 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

"Starting without stalling the engine will be harder than shifting while going. You don't have to use the clutch to shift while rolling. They'll usually shift pretty easy as long as the power isn't being applied. Heck, I've broken my clutch lever in a mx race and still full power shifted without it, although it took some force.

If you can find a junk golf cart or lawn mower to steal the hydrastatic transmission fromor one with the big V belt type clutch mechanism I think you'd be better off than direct drive and trying to shift. You could use it and keep the kawi in one gear at all times. It makes more than enough power if the total weight of the car is under 500 lbs. Even if it weighs 800+ lbs I would imagine just one gear change could give acceptable accelleration and top speed. Just food for thought."



total car weight should not exceed 200-250 lbs. I guess I relly don't understand why you guys'd be opposed to manually shifting an RC car other than the fact that you're used to it in the RC world. I've driven many standards and several motorcycles, and it's clear by the sound of the engine when to shift and if your clutch/throttle balance is right. With the range, and the engine/exhaust setup, even at full range. I should be able to hear it n-uff to get going and from there, I'd deff hear when to shift. I think you guys are trying to over-simplify here, naybe I'm wrong. I also understand most of you wouldn't even consider using a dual-joystick 6 channel setup on a car, but it seems to fit pretty easily as I am used to the setup from consolegaming.

I was really looking for guidance on whether everything I have put out to you guys and the diagram I have shown looks like it'd electronically and mechanically work out. I intend to continue anyway, just wanted to work out any kinks that anyone came up with along the way.

BTW, to Start:

(car in neutral)
1. Right toggle down for choke
2. Right toggle left for start switch. Voila, it's started and running.
Old 10-27-2010, 11:12 PM
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willclark77
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Default RE: 50% scale RC car powered by a KX250 motor?

Oh no, I'm not oppossed to it and think hearing it row through 5 gears would be awesome!  It's just that it would be very difficult to get to work dependably.  Not only that, but that engine can propel a 230 lb kx250 with a 160 lb rider from 0 to 80+ mph in a few seconds.  That's impractical and overkill for an rc application.  Just one or two gears could provide that.  That's all.  From a concep standpoint or "just to see if it could be done" point of view it would rock.

I'm no electronics expert at all and am at work right now and haven't had time to study your diagram.  I would imagine the starter will need a relay though and not sure how you'll get reverse.  You'll definately need to read up on how to wire the large servos because I'm not sure how much voltage they draw and if they'll need relays.  I'd love to see you make it work though!
Old 10-28-2010, 06:55 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

anybody have a chance to look at the drawing and see if things are looking right from that standpoint or not?
Old 10-28-2010, 07:18 PM
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Dale Gribble
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Default RE: 50% scale RC car powered by a KX250 motor?

Personally, I think it is far to ambitious, but that is what makes us great as individuals! I see an unwinnable challenge and you see an opportunity. I would personally scrap the reverse idea with the electric motor. That is a nice to have, not a need.

If you are a machinist, mechanic or engineer with access to a CNC machine, a welder and a machine shop, than I say you have a chance. If you aren't any of those things and don't have access to those things, I think it is an uphill battle. Also, I think the cost will be significant.

I have seen overly ambitious projects die, but I have seen projects where folks start with a baseline (e.g. no reverse and no transmission) and build from there as they learn more and more.

I would recommend first building the chassis, building the motor mount, the suspension and the drivetrain out a bit and see how far you get before you decide whether to proceed or not.
Old 10-29-2010, 07:05 AM
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Default RE: 50% scale RC car powered by a KX250 motor?

and coming off drag bikes the pingel shifter will eat air, quickly. you will need an on board air compressor or a very large holding tank. with bikes we used an on board compressor.
Old 10-29-2010, 02:19 PM
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Default RE: 50% scale RC car powered by a KX250 motor?


ORIGINAL: HEMILLER3

and coming off drag bikes the pingel shifter will eat air, quickly. you will need an on board air compressor or a very large holding tank. with bikes we used an on board compressor.

They also make an electric one that's a double-action linear solenoid.
Old 11-03-2010, 07:37 AM
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Default RE: 50% scale RC car powered by a KX250 motor?


ORIGINAL: wolfie1

i have seen somebody convert a real car to rc
They do it on Mythbusters so they don't get killed doing their crazy stunts.
Old 11-05-2010, 12:49 AM
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Default RE: 50% scale RC car powered by a KX250 motor?


ORIGINAL: yamr6rider


ORIGINAL: HEMILLER3

and coming off drag bikes the pingel shifter will eat air, quickly. you will need an on board air compressor or a very large holding tank. with bikes we used an on board compressor.

They also make an electric one that's a double-action linear solenoid.
I run a Sam Biondo electric shifter for the drag car. It's only a two speed powerglide though.

Yam, when I said starting I meant getting her rolling, not the cranking part. Best of luck with the project and I would take Dale's approach: Build the chassis, suspension, mounts, etc then the driveline since it'll be the most difficult. Sorry you haven't gotten the best help on your specific questions. Keep us updated if you pursue this project!
Old 11-05-2010, 03:12 AM
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Default RE: 50% scale RC car powered by a KX250 motor?

Hey I like the sound of this!
I'm all for starting crazy projects (fininshing them is the hard part)

I can't help you with the electrickery, as I know next to nothing about that stuff, but I agree with the others, start simple with 4 wheels and a frame.
Get your suspension and steering sorted first.
That will take a while to figure out and get right.


Here's a couple of things you might be interested in for inspiration/ideas.

[link=http://www.fieroaddiction.com/buggy.html]BIG RC CAR 1[/link]

[link=http://www.rcgroups.com/forums/showthread.php?t=1277863]BIG RC CAR 2[/link]

[link=http://www.rcuniverse.com/forum/m_9408228/tm.htm]BIG RC CAR 3[/link]




http://www.youtube.com/watch?NR=1&gl...&v=6bLp0sQgmas
Link to webpage in description.
I think that guy is pretty clued up on electronics too so might be an idea contacting him if you need some advice.
















Old 11-05-2010, 10:05 AM
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Default RE: 50% scale RC car powered by a KX250 motor?

personally i can't see a problem with the shifting, power shifters have been around for years, air and electric, the motogp boys have been using electric solenoid power shifters for a few years now also, you just have to make sure you have an ignition cut off wire that acts a fraction of a second before the shift to take the torque off the trannie while it's shifting..that way you can keep the th wide open, shift and forget about the clutch...you just hit a button..a bit of clutch is nice for the downshifts to smooth the shift but not totally necessary until you get to the lower gears , being a sequential box clutchless up and down shifts only really reguire that momentary torque release so the shifting can be done easily with just a bit of set up. You might want to contact someone like this for more advice and parts [link]http://www.holeshot.com/shifters/ps2.html[/link]

As for the clutch itself it'll be a bit snappy but you could use something like a wiper motor to make it more progressive on start off and have it on a dial switch on the handset(if yours has one) and not a linear switch...that or you'll just have to give it plenty of juice off the line...F1 cars have a button on the steering wheel for a clutch as it's only used to start and stop so the principle is not new.

don't think you need 2 servos for shifting either just put the switches round the opposite way and on the outside arc of the horn, you've got 2 doing the work 1 can do.

as mentioned get your chassis done and then go from there...everything you mention is feasible, finding the correct parts and getting everything working together may try your patience a tad though.
Old 11-05-2010, 11:15 AM
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Default RE: 50% scale RC car powered by a KX250 motor?




ORIGINAL: mooman007uk
you just have to make sure you have an ignition cut off wire that acts a fraction of a second before the shift to take the torque off the trannie while it's shifting..that way you can keep the th wide open, shift and forget about the clutch...you just hit a button..
I'm not gonna have the $ off the bat to have a full shift system that does that, so it's gonna have to start off manual clutch. That was a serious consideration though.

ORIGINAL: mooman007uk
As for the clutch itself it'll be a bit snappy but you could use something like a wiper motor to make it more progressive on start off and have it on a dial switch on the handset(if yours has one) and not a linear switch...that or you'll just have to give it plenty of juice off the line...F1 cars have a button on the steering wheel for a clutch as it's only used to start and stop so the principle is not new.
The clutch is heavy, but I'm gonna have one of the Tone Servos witha spring assist to work the clutch, should be real precise and touchy!

ORIGINAL: mooman007uk
don't think you need 2 servos for shifting either just put the switches round the opposite way and on the outside arc of the horn, you've got 2 doing the work 1 can do.
Good point! I can use a SPDT switch, and stack it on top of the servo to have the horn rock the toggle either way. Great input, thank you.

ORIGINAL: mooman007uk
as mentioned get your chassis done and then go from there...everything you mention is feasible, finding the correct parts and getting everything working together may try your patience a tad though.
Starting off with, it's gonna be real simple: prob no shifting(only 1 gear and a clutch), no reverse, and without the body for now.

Chassis is the most important thing for me right now, so... If I could quit getting speeding tickets, and my job'd quit taking money they overpaid me back. I'd be a lot further along on this already. Once I start posting pics though, it'll come right along.


ORIGINAL: Dirty_Vinylpusher
Hey I like the sound of this!
I'm all for starting crazy projects (fininshing them is the hard part )

I can't help you with the electrickery, as I know next to nothing about that stuff, but I agree with the others, start simple with 4 wheels and a frame.
Get your suspension and steering sorted first.
That will take a while to figure out and get right.

Here's a couple of things you might be interested in for inspiration/ideas.

BIG RC CAR 1

BIG RC CAR 2

BIG RC CAR 3
Awesome links, I knew I couldn't be the only one looking into things this big. Seems my motor is a bit over the top, but hey, if ya got it..... That first one provides some great ideas. Thank you too!




Old 11-05-2010, 11:38 AM
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Default RE: 50% scale RC car powered by a KX250 motor?


ORIGINAL: Dirty_Vinylpusher

[link=http://www.fieroaddiction.com/buggy.html]BIG RC CAR 1[/link]

you have any idea who this is or how to get ahold of him?
Old 11-05-2010, 11:59 AM
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Default RE: 50% scale RC car powered by a KX250 motor?

Have you seen [link=http://www.rcuniverse.com/forum/m_8654960/tm.htm]this thread[/link]? This car is freakin cool, but maybe it is not big enough for you, hehe! But i guess it will give you some ideas anyway
Old 11-05-2010, 08:17 PM
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Default RE: 50% scale RC car powered by a KX250 motor?

ORIGINAL: yamr6rider


ORIGINAL: Dirty_Vinylpusher

[link=http://www.fieroaddiction.com/buggy.html]BIG RC CAR 1[/link]

you have any idea who this is or how to get ahold of him?

Don't know him personally but there's an email address link on his site here -> [link=http://www.fieroaddiction.com/index2.html]CLICK[/link]
I mailed him once to ask if he had any more pictures of the buggy, and he did reply to it, but told me he sold it long ago and doesn't have any more pictures or video of it.
I'm sure he'll help you out if you have any questions though.













Old 11-10-2010, 04:57 PM
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yamr6rider
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Default RE: 50% scale RC car powered by a KX250 motor?

Ok, so..... Still have plans for everything, but until I get the KX motor up and running, I scored a 5.5hp B&S OHV horizontal shaft motor. I'm gonna make a large sub frame-type mount to hold it in place of the KX motor. Once the big engine is all together, I'll make a subframe for it to fit the same mounting locations as my B&S subframe. The output is on the same side and spins the same way, so score there! I'll have to significantly change the gearing, but I can make that change at the crankshaft so the jack-shaft and everything else can remain the same.

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