8 speed 79cc revival

xXNightRiderXx

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Jan 12, 2017
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Your present gear ratio in First gear is. 13.04:1, not 15.48:1.
Small math error. Like you said, you have a 32-11 cassette.
No big deal, if your engine doesn't mind.
So maybe your engine isn't wound up so high.
yep, I was worn out from wrestling this thing around last night. Thanks for that catch.
 

LR Jerry

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Dec 19, 2011
1,160
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Rockwood, TN
The bike weighs, empty, around 85 lbs. With my planned fuel capacity of 6 gallons, it will have an additional 48lbs. This will also give me an estimated range of more than 500 miles. As it is, I need to do a dyno test to really see how much power this engine is putting out with the cylinder head sanded down and the carb I have installed. I removed at least .018", so compression ratio should be closer to 9:1 now, instead of the stock 8.5:1. I have no intention of going any faster than 65 at any time, this is meant to cruise at 50mph on back roads. Right now though, this bike will not go above 5th gear and 45mph. I believe High Desert Harley Davidson would be able to accommodate the dyno test, and confirm the top speed.

Cassette tooth counts:
32-26-21-18-16-14-12-11
I aim to cruise around in 6th gear.

Average hill grade here is 3-4%, but I expect to encounter at least 6-7% on my travels. This thing should putt right along at 30mph on those steeper slopes, but considering the average speed on those back country roads, that's why I'm installing hazards, operated by the kill switch on the right side control.

Here's a basic representation of my wiring:
Control wires:

Turn signal:
green-white = right = green supply to rear = orange
green-black = left = green supply to rear = blue
orange = hot

Headlight switches:
yellow = hot
yellow-red = to high beam switch
red-white = to high beam flasher
light blue = low beam/DRL = yellow to rear = yellow
blue = high beam

Headlight wires:
blue = high beam/DRL on turn signals
red = DRL
green = low beam
yellow = amber DRL - disconnected, unstripped, reserved for hazard lights
black = negative


Brake light switch:
red = hot
bottom red = supply

Tail light wires
orange = right signal
blue = left signal
yellow = running lights
red = brake lights
black = negative

SAE waterproof plug:
black = negative battery terminal
red = positive battery terminal

Hazard lights:
red = power from flasher relay
black-red = supply to rear turn signals and amber DRL on headlight.
Wow 3-7% grade that's like a bump in the road here in the mountains of Tennessee lol. Up to 30% grades are fairly common here. If you're under a 10% grade hills and total weight is under 250 lbs you probably need no lower than a 16:1 Reduction at best.
 

5-7HEAVEN

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Aug 2, 2008
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If you're planning 500- mile travels, ya never know what kind of terrain you'll encounter.
In that case ,I'd suggest to have very stiff gears, to a point where final drive maxes out your dream speed.
I'd also go with that 42-11 cassette. However, I'd reduce the 30t to save weight and have a smaller "chainsaw blade" near my left calf.
To make up the gear reduction, I'd lower my chainring sprocket from a 36t to a 24t.
 

xXNightRiderXx

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Jan 12, 2017
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Wow 3-7% grade that's like a bump in the road here in the mountains of Tennessee lol. Up to 30% grades are fairly common here. If you're under a 10% grade hills and total weight is under 250 lbs you probably need no lower than a 16:1 Reduction at best.
I do plan on using this bike several times to go to las vegas via ID-51 / NV-225. It seems like the grade in several spots exceeds 30%. These are going to really cut down my range, especially considering I intend to tow a very carefully selected trailer, loaded with no more than 20lbs of clothes and 15lbs of extra fuel (about 2.5 gallons). The downhill sides are going to be super fun, but the uphill sides, I will probably have to stop every now and then to let my engine cool off. I do also plan on putting a 42-11 cassette on the bike, with that 28t chainring. I won't have any issues at all climbing any mountain with that. It's a very similar gearing to my mountain bike.

This is the route I plan on taking to vegas.

Annotation 2020-05-28 103659.png
Annotation 2020-05-28 103730.png


Yeah, that 30t is pretty heavy, an easy 5lbs. I'm going to look at SBP for options. I have both #420 and #40 power transfer chains available for use, so I don't have to worry quite as much about what the sprocket needs, so long as it's not #35. I'm not too worried about that 30t being a chainsaw, if that #40 chain breaks, that gear is going to simply stop turning, and it's actually closer to my ankle than anything else. I can use my shoe to stop that gear if the chain breaks, and then the freehub takes over. I'm literally far more worried about throwing a rod or breaking my flywheel than I am about being shredded by gears. I've also got those teeth tapered to the inside (god bless bench grinders), so even IF that gear keeps turning after being disconnected, I won't suffer serious injury from it.

I have also requested a quote for having a flywheel and rod machined at a precision CNC company here in Boise, but they have not responded yet. I'm going to message a few more precision CNC companies.
 
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5-7HEAVEN

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Aug 2, 2008
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It's not if the chain breaks.
It's if the chain DOESN'T break at 6,000rpm. Your 30t sprocket will be spinning like a 2,000 rpm chainsaw blade, if you have an accident.
You should think about making chainguards.
What exactly are you gonna have the machinist do to the flywheel and crank?
 
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5-7HEAVEN

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Are you riding alone to Vegas? If so, maybe you need a friend/relative following you in a vehicle.
It's safer, also less chance of getting sideswiped/run off the road.
 

xXNightRiderXx

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Jan 12, 2017
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I've been riding bikes my entire life, and I rode in heavy vegas traffic for two years. If I can survive vegas halfbrains who don't even look before they turn less than 20ft in front of me while I'm goin 30mph, I'm pretty sure I can survive some ******* trying to run me off the road in a straight line at 50, or a moron who merges into my lane without looking. The majority of roads I'm going to be traveling on, however, are going to be 2 or 4 lane with a maximum speed limit of 65mph. There is no way in **** I'm going to be using the interstates with this bike, because that would increase my chances of running into one of those people. I'm confident enough in my awareness to know that I have a higher chance of going down from a blown tire than from an idiot in a cage on wheels. To increase my chances of surviving those idiots, I'm going to install the loudest, most annoying horn I can find. I'm thinking this one.

I planned on having them scan the stock flywheel and rod and machine lighter duplicates out of billet aluminum. I even offered to disassemble the engine and directly deliver the parts myself.

Even if the sprocket remains connected, those teeth aren't in a position to do damage. They're 3 inches away from my pants leg, and anywhere my foot or leg would come close to taking damage is covered by the chain. Being a mountain biker as well, I've conditioned myself to drop the pedal on the outside of the lean, which means that the raised pedal will act as a crashguard. I also extend my inside leg so it doesn't get trapped.
IMG_20200528_135837[1].jpg
 

xXNightRiderXx

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Jan 12, 2017
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Are you riding alone to Vegas? If so, maybe you need a friend/relative following you in a vehicle.
It's safer, also less chance of getting sideswiped/run off the road.
One more thing, I don't have anyone who could afford to, or would even be willing to, follow me into vegas. Everyone in my circle wants me to not ride motorbikes at all. Literally everyone except my dad, but HE wants me to get a retail motorcycle. I'm completely alone in this endeavor, and to be honest, I prefer it that way. I have more freedom to go where I want to, stop where I want to, take detours if I want to (and have the gas to).
 

xXNightRiderXx

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Ok. Stay safe.
Maybe one of the forum members could ride or follow.
If I lived by you, I'd follow you in my car.
I appreciate that. Believe me, safety is my first concern. It's why I got the headlight and turn signals I did, mounted my taillights where I did, and then took 3 days with more than 8 hours each getting this thing wired up just right.

By the way, I recommend this brake light switch for anyone installing brake lights. It is very sensitive, and if set up right, you barely need to pull on the lever to activate the brake lights. Makes it very easy to flash your brake lights before you hit your brakes.
 

xXNightRiderXx

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Jan 12, 2017
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Alright, I used some realistically estimated values in a compression ratio calculator, and I'll confirm once I have a cc'ing kit and a digital micrometer, but it says I have a 9.92:1 ratio. That is close enough to my targeted 10:1, and in 5th gear, I managed to get to 38 mph measured by gps, going slightly uphill, maybe .2% grade. I really need a dyno test to see where in the RPM range my power band is, and I definitely need to get a billet flywheel and rod made so I'm on the safe side, and don't have to worry about keeping it under 6200 (i'm hitting about 5800 if my ears don't deceive me). As far as acceleration goes, I'm doin 0-20 in about 6 seconds. I blame it on my rims.
 

xXNightRiderXx

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Ok, now I have a mechanical speedometer goin up to 50mph. I'm going to swap out these mag rims and build my own wheels with 12g spokes. I'm installing the driver so it's driven by the brake rotor, so it doesn't really matter a whole lot, but I want those wheels to be lighter. I'm losing a lot of acceleration from that weight. I will also be modifying my exhaust pipe, cutting off the muffler and expansion chamber and installing an open flow muffler. This will let me optimize the routing and length of that pipe so it's not so damn close to my leg. Oh, i also decided that I am indeed going to install an alternator, and I'll just make my own bracket for it. I need something to run my lights and charge my battery. Just running that battery is going to kill it. Oh, and just one more order of business: anyone got a spare suspension fork layin around with a 1" steerer tube? I don't care if I need to use an adapter to make it work with my brakes, I just need a telescoping fork. I keep riding my bike like it is, and that steerer is going to shear.
 

5-7HEAVEN

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Aug 2, 2008
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Ok, now I have a mechanical speedometer goin up to 50mph. I'm going to swap out these mag rims and build my own wheels with 12g spokes. I'm installing the driver so it's driven by the brake rotor, so it doesn't really matter a whole lot, but I want those wheels to be lighter. I'm losing a lot of acceleration from that weight. I will also be modifying my exhaust pipe, cutting off the muffler and expansion chamber and installing an open flow muffler. This will let me optimize the routing and length of that pipe so it's not so damn close to my leg. Oh, i also decided that I am indeed going to install an alternator, and I'll just make my own bracket for it. I need something to run my lights and charge my battery. Just running that battery is going to kill it. Oh, and just one more order of business: anyone got a spare suspension fork layin around with a 1" steerer tube? I don't care if I need to use an adapter to make it work with my brakes, I just need a telescoping fork. I keep riding my bike like it is, and that steerer is going to shear.
Ebay has Suntour 1"suspension forks under $100. I bought one.
 

xXNightRiderXx

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Ebay has Suntour 1"suspension forks under $100. I bought one.
They don't anymore. They discontinued production and sold out. Same with RST. ZOOM is the only one making 1 inch steerers anymore, and those are threadless. Right now, my options are pay more to go threadless, buy used, or stay springer. I want a fender up front, so that knocks out springers.

I know how many people actually have no clue about bike maintenance, let alone repair, so I can't trust most used forks, and mountain bikes back in the time of 1 inch steerers were run to the point of failure most of the time, so I can't trust THOSE used forks on such a high stress machine.

That's why I asked here. You guys know just how much you put on your forks, so I could be informed of the risk. You just don't really get that on ebay. I don't care how much I'm paying, so long as what I'm paying for is reliable and fits my needs.
 

curtisfox

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Dec 29, 2008
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Try Moped forks, some Whizzer guys use them. Think the site is called treadland or something like that...........Curt
 

5-7HEAVEN

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Aug 2, 2008
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Wow, you're right!

Suntour forks were cheap; I bought mine for $70 delivered. Now they're gone or being scalped for $200.

You just need to keep looking; all you need is one.
 

xXNightRiderXx

Active Member
Jan 12, 2017
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Wow, you're right!

Suntour forks were cheap; I bought mine for $70 delivered. Now they're gone or being scalped for $200.

You just need to keep looking; all you need is one.
Yeah, I was actually keeping my eye on them for a while, but until now, i just didn't have what I needed to make the switch.

HOLY ****, RST RESTOCKED WITH A FEW! Just under $80, I'm gonna grab 3 in case I ever need another one, or a replacement.

I've decided to also add an oil pump and run a filter. I'm wondering if anyone's done anything similar? I'm thinking of doing 2 things to accomplish this: First, using the oil sensor hole as the inlet for the pump. Second, running a line from the filter through the governor arm hole. This pump will only run for 2 minutes at a time, intermittently through the ride. This should help pull most of those metal flakes out of the oil, and keep the engine clean and running well. Obviously the dry start elimination is moot, because engines without oil channels don't have dry starts. My only problem is this: where do I mount the filter? It has to be in a place close to the engine to minimize the amount of oil in the lines, but it also has to be far enough away for easy access. I've been thinking of drilling into the case to mount it, but then there's the problem of no space once the alternator is installed. Another option is mounting a plate to the frame above the truss rod, and then mounting the filter mount to that plate. The pump itself will mount under the engine, with the U bolt holding the shaft plate to the frame. This pump moves 3gpm, so it should provide enough pressure to run the oil through the filter.

Case breather will be installed through the valve cover. My friend has a drill press that I should be able to use to drill through that CNC'd valve cover, but I'm using my own bits.
 
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5-7HEAVEN

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You could Google. Someone probably did it before.
You do know not to run the pump while the engine is running. If you removed your oil sensor and your pump is powerful enough, your engine will starve and self-destruct.
 

xXNightRiderXx

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You could Google. Someone probably did it before.
You do know not to run the pump while the engine is running. If you removed your oil sensor and your pump is powerful enough, your engine will starve and self-destruct.
Google it was the first thing I did, hoping there would be a kit for these engines. Sadly, all I got were people doing filter stuff for things like 350 v8s and such.

It's not so much a matter of not using the pump while the engine is running, but maintaining the oil level as the lines and filter fill with oil, and then pressurize. This means that when the pump is off, the engine will be in a slightly overfilled state. I'm not going to run this pump if there is any risk at all of running the engine dry. This is also another reason for having the filter outlet running straight into the top of the case, if the oil does get low while the engine is running, it will still be dumping that oil right over the crankshaft counterweight, so that bushing still gets lubrication. However, with the forward angle of my engine, this means that i need to be overfilled anyways, and I'm not getting quite as much oil dumped on that counterweight. Maybe I'll just drill a new hole for the inlet, so the oil dumps right onto the crankshaft. After all, most modern cars also have oil being directly pumped onto the crank and cam after being run through the filter.

All this being said, I know it won't be simple, and I know I run risks, but the benefits of having that oil cleaned means I can go longer without changing my oil, I can run the engine harder, and if I need to, I can add a cooler to the mix. It's worth the risks. I really have no clue why these little engines don't have any kind of stator to run a small electric pump for an oil filter. People would pay that extra cost for a more reliable generator engine, I'm sure. I certainly would.

I just had an "ah hah" moment: I could use the stock chain guard to mount both the pump and filter, especially if mounted with brackets to the front of the engine. This would let me run the alternator as well. Small bits of angle iron should work well as adapter brackets.
 

5-7HEAVEN

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All modern day vehicle engines pressure-feed their cranks, cams and rod bearings. Absolutely no manufacturer dumps oil on cranks and cams. More expensive engines run dry sumps (zero oil in their crankcases to prevent oil slosh and drag).
Profit margin and consumer demand are the reasons that these utility engines don't have what you're building. YOU might want to pay more for alternators and oil filtration. Im guessing 99% don't want to pay extra for alyernators and oil filtration for their lawnmower, tiller, snowblower, pressure washer utility engines.