Hi Seandonato,
The engine came from a McCulloch 710. I got a couple of good saw engines, a 610 and 710, and chose the bigger one for this build. I'm using some of the components from the 610. I like to collect and build things out of small engines, primarily two strokes.
As for the brakes, my current thought and design process is for the rear disk brake. I got my inspiration from bicycles/gopeds, and the parts are readily available and often times much cheaper than RC specific stuff. For some reason I feel like RC parts are just anodized and slapped with a huge markup! I haven't chosen either cable or hydraulic yet, because it partly will depend on what I can source for a decent price. I'm not cheap, but I've got my hands dipped into tons of project so if I were to just bug out on everything, I'd be broke. If that makes sense.
As for the throttle servo, I really need to mount it first and then work on the linkage, sort of playing with the design as I go. I'm not too worried about it though, I expect it will be a simple aspect. I already have a 25kg small case servo dedicated for this. Actually, I've got a couple of those servos on hand, I wonder if a 25kg one would be brute enough for the brake system too....
I'd love to hear your idea though for a single servo setup. Ideally, fabrication is preferred, rather than buying parts. The more this is custom, the cooler I'll feel.
Regards,
Erik
Cheers, my name is sean btw. No need to spell out my entire name.
Heres the mix page of the instructions for the
3pv. It's very very basic and featureless imo, as you have to use channel 2 and 4 under the brake mix, the 4ws is useless in this application as it will only mirror the other servo.
You need to remember channel 4 is only a slave channel and not programmable to do much, hence why I suggested a 4pv or 7px. Then you have normal servo mix capabilities.
Second I think your 25kg servos are going to be woefully inadequate for your braking needs, 25kg roughs out to 350oz in. Where as most of us run a
d845wp hitec which is 50kg as brake and throttle servo, your rig is going to be pig heavy, of this I assure you. It will need all the help it can to stop effectively.
Any examples of what bicycle specific parts your looking at? And yes rc stuff is expensive, kinda the name of the game. Take for instance imported your pm710 is a 70.5cc engine netting around 5.6hp, a modded zenoah g340 will get you up closer to 9hp and weigh half as much, it will also set you back $600.00 give or take. I'm not knocking the want to build and use your own stuff, just let you know where the cost comes from. Light weight power dense engines, and parts specifically made to keep up with that power. A 70cc rc max engine is more along the lines of 15 ish hp. I'm a big saw nerd and that's just not obtainable from an old 710. Anyway. Some more for you to think about.
Back to the single servo set up. I would advise a hilatronics 8000, 1000+ oz in of torque, will stop that beast with ease. The key to using it as a single servo is getting your linkage set up properly I would advise a push pull system, that way you can have a double slider with easy adjustments like a normal rc. I would set it up exactly like this.
When the throttle is applied the brakes simply relax
When the brakes are applied the throttle is returned to closed and the brakes are pulled on in this set up (for push just reverse the rod direction from what is shown if pushing a master cylinder. Brake movement doesn't matter as there is a small weak spring to keep the throttle pushed closed
In your application you have a ton of real estate to use. Situating the servo intron and off to the side you should easily be able to fabricate linkage to get to the carb, and have a master cylinder/ cable termination block next to the engine. Thus fully integrating the kiss method and eliminating the need for another servo in the mix. Then you can get away with a 3 channel radio. Throttle and brakes on 1 channel, steering on another, and kill switch on the third channel.
I can understand the multiple hobby thing and wanting to piss a bit of money on each of them, lord knows I have too many hobbies and projects. But i find I'm much happier when i finish one and then move on to the next project.
Cheers
