Do I drill the tank?

Hi. I'm adding a teardrop Happy Time fuel tank to "Mr. Hyde" my dual-engined bike as an auxiliary tank to feed the 43cc Mitsubishi engines' fuel tanks. I will install a T-fitting under the tank near the tank's shutoff valve, then steel lines towards frame stem(front) and seatpost(rear). Foot-long fuel hoses will feed into the top of the tanks, so I can fill both tanks by gassing up the teardrop tank.

Having a hard time finding fuel line grommets so the new rubber lines can enter the tank.

Should I just force the new line into the existing fuel grommet that feeds the carb lines?

Or drill through the gas caps? But then the hoses are further away/exposed from the engine than I'd like them to be.

Or should I just drill through the tops of the tanks so that the fuel lines will squeeze tightly thru the new hole I just drill?

The only grommet I can find is barely larger than the fuel hose, more like a thick o-ring with a groove in it. Should I use this one?

Thanks for help.

Thanks for the reminder, mechanickid. I forgot about that. Maybe I'll just ream the hole, for starters.

Dan, I think using the HT as an auxiliary tank is an EXCELLENT idea. I won't have to literally prop my bike up into a tree fork trying to fill the fuel tanks, which I have to do every 20 miles or so. Having this option means being able to pull into ANY gas station, shut the petcock, add oil then gas, open the petcock and drive away.

I will have increased my driving range from a mere 20 miles to infinity. And no chance of running outa gas, no more propping up the tree fork, which is a difficult manuever for this senior citizen.

There were only a few grommets at the local Home Depot, none of them fuel-resistant. None were available at Checkers Auto or Napa; the closest grommets were for larger PCV valves for cars. Today I'll try the marine supply store.

No brass lines for me. The fuel line I bought from Checkers was dark-colored and matched the bike frame perfectly.

Everything's installed. Just waiting to determine how to plumb into the tanks.

Dan, it's simpler Teeing off the bottom than drilling/welding into the metal teardrop tank for the second fuel outlet. Then that extra fuel grommet would be another potential leak. I was lucky to find a 1/4" brass fitting with three barbed fittings cast into it, so three less clamps and potential leaks to worry about. Compared to the engines' tiny fuel hoses, the steel lines and 1/4" hoses are overkill.

Since the fuel system has no pressure, leaks should not be a problem.

I'm glad I won't be propping up the bike into the tree anymore. This dual-engined monster must weigh at least 75 lbs.

I bought a used Polini engine years ago. Its fuel tank had a brass fitting screwed in as a fuel outlet. Since the older Mitsubishi tank hasn't much space on top for a sizable fuel grommet, I'm gonna try screwing a 90-degree brass fitting into the tanks.

2fast, if you mean to place tees on the stock engines' fuel lines, I don't think they make fittings small enough to fit those cheap tiny lines. Then I'd have to find an adaptor to step down the tank's 1/4" fitting.

Anyway, I drilled the plastic tanks, screwed on brass barb fittings with liquid teflon and attached the 1/4" ID hoses. I also removed the Happy Time tank's filter screen, replacing it with a Fram inline car filter.

Time will tell if the fuel system stays intact.