200+ miles per gallon

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kolbpilot

New Member
I now have 230 miles on my creation. On my first miles per gallon fact finding rides I came to the conclusion I was getting 180 to 200 miles per gallon, based on a 16 ounce tank & getting 25 miles per tank. Never one well leave well enough alone I started with first modifying the airbox on my 25cc Homelite. I really didn't do much at all to it, just making sure the sponge filter is clean at all times & I drilled a 3/8ths in. hole in the air box directly in front of the filter, figuring it would help it breath a little better. That really didn't change anything so I looked at the exhaust, namely the muffler. My muffler is of the kind that had the screen & cover plate over the 4 or 5 factory holes. I had long gotten rid of the cover plate & screen but figured I would open up the smaller screw holes to the size of the rest of the holes (approx. 5/16ths) & drilled 2 more holes. While my top end is no different (27 mph), it accelerates better & runs cooler. Best of all, I'm now getting 30+ miles per tank which equates to over 240 miles per gallon. I would say exhaust noise has gone up a few decibels but well worth the performance improvement. cvlt1
 
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I am still quite ignorant on how to get a video on youTube or any where else. I'm lucky I finally got a couple of static pics of the Homelite Huffy posted on this site. Never say never though, maybe one day. Thanks for the response. cvlt1 .....I should note I'm getting these big numbers by riding at 20 mph or so, meaning approximately 1/3 throttle & keeping the tires pumped up on the high side.
 
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It might well be running too lean, for I've it dialed in for peak performance, with no '4 cycling' in the entire RPM range. It has run fine so far, it doesn't appear to be getting excessively hot after a work out. I have about 400+ miles on it now. The little 25cc is out of its league somewhat, powering a 250 pound device (bike/rider). Not much I can do to the bike to lighten it up but the rider could shed 20 pounds. cvlt1
 
Great testing pilot!

I do OK on my little mab, but never checked results.
maybe I look into installing the bike computer/speedo thing today.

...kinda ticked me off when I had to buy another gallon of gas the other day! lol
I think it's been abt 3 weeks???

hurts to put gas in the truck... we don't put in much at a time... only $40 bucks worth. doesn't last but 1/2 a week. would be much more if I did not use the mab for all the short hops.

Keep up the good work!
rc
 
Be careful when playing around with intake/exhaust as both can alter your air/fuel mix as others have specified before. I suggest you do a plug chop or get your exhaust fumes analysed as you may be running lean (thus getting good MPG). You want your engine to 4-stroke when you apply a given throttle until your speed is constant and then lower the throttle by about 20% of that ammount.

So, let's say I want to check the WOT position tuning:
1. I WOT until my speed is constant.
2. Lower the throttle to 80%. At this point the engine must 4-stroke or else I might be a bit lean.

For the mid-throttle position:
1. Apply 50% throttle until the speed is constant.
2. Lower to 40%. Again, it should 4-stroke.

This method is not the best of all for carb tuning but it is a good general indicatior of the tuning and is readily doable.

For more information on this method, look up "How long till it 4-strokes carburetor tuning" on google.
 
@vachon644, Agree. My bicycle will not probably be rode for the next 3 to 4 months due to Winter time. Will drain the lousy 50 to 1 ethanol blend gas out & try and purge the Chinese Zama carburetor of all fuel as well. I bought that carburetor new off eBay for $15.50, to my door. The carburetor was put on a 5 year old 25cc Homelite with about 14 hours on it after it was relieved of weed wacker duties & its original non adjustable Walbro. Now it became the friction drive workhorse for a 40 pound Huffy & my half century plus self. 25cc's is supposed to get me .8 horsepower. Since I rarely ride full throttle I figure I'm using about .6 or so. Roughly 50% throttle. My semi tuned in ear guesses I'm taching 5000-5200 rpm at 22 mph ($6 cycle computer). Here in flat, sea level Virginia, I can reach 25 mph in optimum (no wind) conditions, 240 pounds of bicycle, 6000 rpm or so. 29 mph is my personal best with a nice tailwind & probably 7000 rpm. But that's an exception & short burst. I'm in the 3500-5000 range that's where the lean tuning helps. Any kind of a headwind or hill slows me down quick & I pedal to help the little piston along. If the engine burns up in time then I'll chalk it up to the grand experiment. But I think it'll be OK. I run the fuel at 50 to 1 as well, somewhat lean, but the modern day standard for a 2 cycle. Supposedly this engine has a design life of 250 hours. I guesstimate I have approximately 55 hours on it now. What this bike needs is a rider weighing in at no more than 150. Then I can see richening up the mixture for the engine will produce higher top end rpm's that will create more heat. cvlt1
 
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The old Velosolex was advertised top produce 200+ mpg. It was/is a 49cc. Its strong point is torque. Doesnt run much over 20mph. It was also said to make .8hp. The little Homeys are used to power certain R/C aircraft and boats. There are some tuned pipes for boats out there but I would think the tuned range to high for a bike. These engines are known for being rugged, if you get the older ones made in the good ole USA. The 25cc are turning in the 7500 rpm range on an aircraft with no problem. Short of a lean run or an oiling issue, should run just about forever in a relative term. If you find a blower most but not all were 30ccs, a little boost in power.
 
I've seen those on youTube, different videos of the r/c model plane & boat crowd. Turns out the old Homelite is the popular choice. Never knew any of that 'til I was researching bicycles. I know the 30cc ones exist, one will turn up sooner or later. I grew up with the old Solex, seeing them everywhere in the '70s Holland. Even rode one once. A front wheel drive moped.
 
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