Gas tank placement advice?

bluegoatwoods

bluegoatwoods

Active Member
Given my choice, I'd really rather put my tank on the downtube. Mostly because I just don't want a gas tank, or anything else, in my face while riding.

I can get it in the spot I want. And it looks okay. It needs to be tilted toward the right to clear the top tube. Tilted left is not good. Gets awfully close to the exhaust.

I'll lose a bit of tank capacity because of the angle involved. Looking at it I'm guessing it'll hold about 3/4 what it would on the top tube. I can live with that. The outlet is just about perfectly level with the fuel intake inlet port. So there'll be just a little bit of the bottom of the tank that will be too low for fuel to flow out. Very little. And that's okay, too. It'll make a sediment trap, if nothing else.

But now I've got to figure out what to do with my CDI. The first thing I tried was moving it down to where it's just in front of the cylinder. Not too bad, maybe. It'll be fairly well protected from weather and road splash. But it's pretty close to the cylinder and the exhaust. I'm wondering if heat could be a problem?

CDI near engine.jpg

Or I could mount it directly underneath the gas tank. It'll be more or less in the standard spot. It'll have its 'head' pointed downward, though. Definitely exposed to the elements. But I guess I could come up with a cover of some sort.

CDI under tank.jpg

The simplest thing would be to mount the tank over the rear wheel. But I just don't really like the look of that.

rack mount.jpg

So I'm inclined to go with the CDI under the gas tank. But I'm wondering if anyone has any other ideas. Also, am I missing something? Are there any dangers to the equipment here that I'm not taking into account?

Thanks.
 
you might look into pressurizing the tank like an outboard or camp stove - that way you can flow uphill
 
Well, that's actually an interesting idea. But the placement is such that I don't think that would gain me more than a few ounces of usable fuel in that tank. I don't think any more than that will end up in the downhill direction.

Where I'll actually lose some capacity is in the top of the tank. It'll be tilted to the point that I won't be able to actually fill it. There'll be some dead space at the top.

But that won't be a major problem. It won't amount to all that much.

In the end I suppose I'm likely to go with top tube mount. But I sure would like to eliminate some of the gooseneck clutter.
 
Yes, I guess I see what you're getting at.

If it were mounted someplace down there where it wouldn't interfere with crank or pedal movement it could be workable.

And it would be kinda stealthy, too.
 
am also thinking of friction wheel hooked to rear tire for oil injector since these are one-speed drives that match tire speed to motor speed
 
racie35 said:
No gravity feed if you go low....just a reminder
Click to expand...

Yup! Thanks.

But that actually won't be a problem. Most of that fuel will be above the intake port. The tank outlet will be just about level with the carburetor intake.

Which does bring up another problem. A direct line from the tank outlet to the carburetor inlet goes right past the cylinder jug. Obviously I can't afford to let my fuel line pass right alongside of that. (I'm actually finding myself giggling a bit over the results of doing such a dumb thing. There's something wrong with me. It's not funny. But I do have an absurd sense of humor. I have to be careful with that.)

So my choices, it would seem, are a long fuel line loop down low, up high or outward. Where it could certainly interfere with pedaling. Not that I'd swing it way, way out there. But a little bit could be enough for trouble.

I guess I'll probably end up putting it on the top tube. I'd like to avoid that. But this is a matter that needs to be done right.
 
crassius said:
am also thinking of friction wheel hooked to rear tire for oil injector since these are one-speed drives that match tire speed to motor speed
Click to expand...

yessss.......I can see that, too. Interesting idea.

But I don't think I'll try to engineer something like that. I've already got my hands full enough.

I think I'll leave that to the guys who are more 'motor-heads' than I am.
 
a small hook on a piece of stiff wire (coat hanger maybe?) attached to a head stud will route fuel past the head without heating
 
Ok, Tried to get a second picture of a 4 liter tank won't go but the price is fair for the extra liter or so of fuel can't fill these to the top but it will likely go 3/4 of full tank or until I get a good breather cap. Anyway typical placement old bike nearly completed. Nexus 3 speed sick bike shift kit and a few bolt on enhancements.Looking to get it to go in a few days trying to find a roller brake conversion for the coaster brake on it currently should idle about 30 mph in 3 rd unsure yet but runs a wet clutch with Lucas #2 in the clutch /pressure plate side of the engine have diamond epoxied to the pressure plate unsure how that will preform hoping for some luck and less noise on that idea.
 

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BOYGOFAST said:
Ok, Tried to get a second picture of a 4 liter tank won't go but the price is fair for the extra liter or so of fuel can't fill these to the top but it will likely go 3/4 of full tank or until I get a good breather cap. Anyway typical placement old bike nearly completed. Nexus 3 speed sick bike shift kit and a few bolt on enhancements.Looking to get it to go in a few days trying to find a roller brake conversion for the coaster brake on it currently should idle about 30 mph in 3 rd unsure yet but runs a wet clutch with Lucas #2 in the clutch /pressure plate side of the engine have diamond epoxied to the pressure plate unsure how that will preform hoping for some luck and less noise on that idea.
Click to expand...

Where's the front brakes? You gonna need 'em.
 
BOYGOFAST said:
Ok, Tried to get a second picture of a 4 liter tank won't go but the price is fair for the extra liter or so of fuel can't fill these to the top but it will likely go 3/4 of full tank or until I get a good breather cap. Anyway typical placement old bike nearly completed. Nexus 3 speed sick bike shift kit and a few bolt on enhancements.Looking to get it to go in a few days trying to find a roller brake conversion for the coaster brake on it currently should idle about 30 mph in 3 rd unsure yet but runs a wet clutch with Lucas #2 in the clutch /pressure plate side of the engine have diamond epoxied to the pressure plate unsure how that will preform hoping for some luck and less noise on that idea.
Click to expand...

HERE it is Rick. If this IS rick of BGF.
http://www.ebay.com/itm/80cc-Motori..._Accessories&hash=item258645a0b5#ht_671wt_914
 
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