Honda c70 conversion Gas to Diesel

[papaslides]

Ok so here's the new post for the diesel project. (Here is my original post)

What I would like to do is take my broken down/not running 1982 Honda c70 Passport and get it back on the road with a diesel engine and running on biodiesel. While I'm messing with things I would like to put a slightly more powerful engine on it (right now it runs a 72cc motor, and I'd like to see closer to 125 or so) the reason for this is that I am 6'1" and weight 210lbs, so a 72cc motor will have a hard time pulling me up the hills in Ann Arbor. I realize this would mean possibly upgrading the breaks as well.

What I need help on for this project is...well everything. I know little to nothing about working on engines, cars, bikes etc. I just have what I think is a great idea, and a desire to have a great high MPG commuter for driving around town in the summer (if gas prices hit 5$ next year this project will pay for itself in no time... even with my short commute and hardly any non-work related driving, I'm paying at or above 80$ a month on gas)

So here's my question request list:

1. What kind of engine should I look for (remember I'm trying to stay as close to 100mpg as possible, even though biodiesel is cheap/free and all, the bike still only has a 1 gallon tank, also remember I am a bigger guy with some decent hills to contend with so I need a level surface top speed of at or above 50mph (ideally 60) and the torque necessary to climb those hills)

2. What other parts of the bike need to be replaced in order to make it biodiesel?

3. What kind of sprocket ratio am I going to need to get the kind of performance I want.

4. Since I am replacing the engine, and it has most of its electronics missing, should I replace everything at 12v (factory) or should I switch to a diff. volt battery/electrics (right now the bike has no blinkers, no starter, etc. etc., basically the only electrics on it are the speedometer, the headlight and taillight)

5. Most importantly: does this project seem doable and does it seem worth the time/effort/money?

Thanks again!

p.s. here is a link to an image of the bike
http://www.freewebs.com/papaslides/a...hotoID=6658817

[elhigh]

You're kind of a big guy to go on a c70 in any case, aren't you? I'm 5'10 / 180 and while I grant my little 50cc Express isn't a lot of power under anybody's hiney, 72cc wouldn't be that much more under mine.

Considering everything you want to do, you might consider buying a stripped frame and buildling a bike from the frame up, from scratch.

Take a look at this: http://www.dieselbike.net/video/video.html

You're not the first guy with this idea, also Google Changzuki for a guy who started with a perfectly functional bike, pulled the motor so he could stuff in a Chinese diesel.

I'd like to see one with a small Caterpillar C.7 engine. In Industrial Yellow, of course.

[LostCause]

If saving money is your goal, I'd rebuild the engine with an overbored piston and stroke it to increase its capacity. I bet parts are cheaply available on the internet, since the C70 was so popular.

To get the kind of power you want, you'll need an oversized (i.e. heavy) diesel. On a cc/hp ratio, diesels generally perform worse than the OHC engine on your honda. In any case, a one-off installation is going to be much more difficult than rebuilding an engine that has been rebuilt millions times all over the world.

To save money:
1.) Find a chaincase if your C70 doesn't already have one. There is no reason to expose a chain/sprockets to the elements
2.) Pump up your tires and learn to handle the change in riding quality
3.) Run a smaller rear sprocket to lower engine speed. Without an engine map, this will require testing
4.) Ride tucked as much as possible
5.) Consider building a fairing. You can start slowly at first (windshield) and work your way up (Craig Vetter)
6.) Try to find a manual engine (w/ clutch) so you can EOC
7.) Cut your engine at stoplights
8.) Replace bulbs with LED's
9.) Remove brake drag through adjustment
10.) Lose the Stator and run off of battery power alone (PbA, NiMH, Li-ion, etc.)
11.) Buy slick or low tread tires

Get creative, but try to stay in the realm of practicality. The more outlandish an idea seems, the more expensive, time consuming, an unworthwhile it is likely to be. Stay gas powered and save money.

- LostCause

[bennelson]

Funny how the poll at the top is so split!!

I think this cycle would be great either restored, converted to diesel, or left as gas, but modified (different engine, etc.)

Remember, if you just want it all to work, you don't have to buy parts very specific to it. In general the more generic of something you can find that will still work, the cheaper and easier it will be to find.

The turn signal/horn/highbeam switch on my cycle had to be replaced. The "official" one for my cycle would have been about a hundred bucks. I bought a a new one for a scooter for $38. Maybe I could have found something even cheaper at a salvage yard.

Anyways, use what you got, what you can find cheap or free.
Talk to lots of people. It is amazing how many people can be very helpful and supportive.

[Ryland]

It really sounds like you are not much of a mechanical person if you are unsure about your ability to fix this vehicle so because of that I would say that putting a diesel engine on it is going to be way way over your head, besides the diesel engines out there that would fit this start at about $900 and weight over 50 pounds and does not have a transmission on it, your current engine shares a case with the transmission, shares oil, when you split the case open it's hard to tell when the engine stops and the transmission starts, a diesel is also going to vibrate enough that it will rip the frame apart, besides it being to big to fit in the space you have, you basically need a good size motorcycle frame for one of the hatz 7hp diesels to fit from the checking I've done, a Yamaha rd350 would be a better start for a diesel bike as their engines burn up quickly and their tranny has it's own oil.
I also don't see where you are going to have space for batteries if you want more then a 5 mile range as an electric unless you put them on either side of the rack, but at 50+ pounds each you will need a good size rack for the 3-4 batteries.

I voted to restore/fix it, because if you spend $300 on new parts from the dealership and buy a repair book then it is just a matter of fallowing the dirrections in the book, unbolting old parts and bolting on new parts, adjusting things to their specs, then ridding it, at 70cc it should have no problem hitting 45mph, I'm 235lb and if I found one of these I would ride it on roads with a 45mph speed limit, so in short, if you can read and fallow directions, have a 10mm and 12mm wrench and a phillips screw driver you should be able to fix this for $300 or less and will have a 120mpg vehicle, if you can't fix it then sell it, if you are need Wisconsin then sell it to me.

[metroschultz]

I believe you could find one of the small diesels (Kubota?) that would bolt eight up.
your prob would be in finding a way to shift gears, seeing as your gearbox is broken now anyway.
Perhaps find one of the moped style continuously variable clutch setups that would handle the torque.?
just a thought.
I like your website BTW.
S.

[rbhollabaugh]

I voted to restore it as-is. I think you would sink a couple grand at least if you do either the electric or diesel conversion. You'll never make that up in gas savings unless you ride that thing alot. So, I'd just repair it and use it the way it was made to be used.
The comment about a bigger piston is a good one. If these performance items for this bike are available I'd do that.

[papaslides]

After much consideration, and research its seeming more and more like I should just restore the thing. The main problem is that it would cost a lot in parts (even looking for generic stuff the bike is missing most of its electronics, and there is a big crack in the engine casing). I'm not selling it off just yet, but I am looking for less beat up bikes. If I just can't find anything good, I'll fix it up (I may have a friend with work space and interest in helping teach me to do it right). This is such a cool bike I don't really want to look into different body types, I'd rather just mod it to have enough power for my body, (90-100cc motor with better brakes to manage) and use it to commute.

Thoughts?

[COMP]

,,i wish it was mine

[Kismet]

OK.
Park it. Don't put $ into a non-running, case-cracked, gawd-knows-what-else 27 y/o scooter. Hang on to it. Advertise for another passport (C70-C90), running or not, in craig's list. Haggle and buy inexpensively. Figure @ $100 for title search and license from State. Tires and tubes? figure @ $60..get Michelins if you can. Gotta have a battery, even a dead one for scooter to run...it acts as a resister. A good battery will let you look for a working headlight...even if you have to score the back of the old off and put in a 6v bulb. Run without battery?=pops the headlight. Battery...probably under $20.

So...whattaya got? "X" dollars for purchase, $100 for title and license, $60 for tires and tubes, $20 for battery, about 8$w/shipping for new plug. That's @ $200 plus cost of second machine...and you STILL don't know what is wrong with the machine in the first place.

They are simple...mostly. Points, plug, coil...pretty back to basics. You get into the internals, as with your current Passport, and you get more expensive in shop time and parts. But the part's bike may save a bunch of money as you tinker to find out what is wrong with the as-yet unfound new scooter.

I'm 180 pounds and mine goes up to 40 on a flat, 42 on a slight decline, down to 20 on a moderate hill. Windscreen does not make you more aerodynamic. Think 'sail' into the wind.

Big ole refridgerator rack with hose clamps on the back makes it much better for carrying stuff. Get a gym bag and use wire ties or GB ties to hold it on. Works a charm.

I'd stay away from chinese stuff for the time being. Symba? made Honda engines for these for years...may still. Lifan has been given good reports.

But...look at the dollars and the return on investment, before you do anything. If it is a toy you want to screw with and can afford, fine. If it has to be cost effective...consider carefully the time, money and labor, plus frustration you will invest...with uncertain resale value, should that time come.

Good luck.