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jonathan150cc 07-20-2009 04:17 PM

17 MPG increase on the cheap!!!
If the title sucked you in looking for a way to increase the FE of your automobile, you might be a little disappointed. However, this is a success story involving a 17 MPG increase on my 150cc Chinese scoot.

First, a little back story. I bought this scoot for $900 off of Craigslist. I got a great deal from a guy who had already dropped approximately $500 in performance upgrades and was giving me a spare motor and all of his good OEM parts for the price of a pool table that he wanted. I've had several other motorcycles in the past, all 250cc, and my lowest FE came from a 2003 Ninja 250. I consistently got MPG #s in the high 50s with that bike. I also had a 2006 Suzuki GZ250 that averaged in the high 60s. When my first couple of tanks on the scoot revealed an average of 55 MPg, I was a little disappointed.

Now, I knew that the performance upgrades were hurting me a little but I didn't know by how much. Not too impressed with the sound of the performance exhaust system that came with the bike. That was the first thing to go. I noticed no noticeable change in FE.

Next, after trying to decide how to route this little pod air filter for stability, I just pulled it and reinstalled the stock air box and air filter, although I did swiss-cheese the air box because I couldn't see how else any respectable amount of air could get it. At the same time, I removed the Dr. Pulley performance clutch and replaced it with the OEM clutch.

By now, as you can probably already correctly assume, the bike was running just a little rich. I first pulled the needle holder and lowered the needle one slot. These needles have grooved slots that allow for easy adjustment of the washer up or down. This mod was free. I then set my low speed idle around 1900 rpms and adjusted the idle mixture.

For $8 I picked up a 115 main jet from a local independent motorcycle shop and swapped it in place of the 120 (or 125) that was in there.

On 6-27-09, with no changes, I got 55.55MPG.
On 7-6-09, with half the tank seeing the new smaller main jet, 60.18MPG
On 7-20-09, I filled u ptoday and was very pleasantly surprised to see 75 miles on the odometer and 1.028 gallons to fill-up. That's 72.95MPG


THAT'S WHAT I'M TALKING ABOUT!! Now when people ask what FE I get, I don't have to use qualifiers and hang my head in shame. 72 MPG is pretty respecatable.

I'm hoping to baby it this next tank and see if I can coax 75MPG out of her. My gail is a legimate 80MPG. We'll see how she goes. With proper inflation and some non-ethanol gasoline I might just get there.


bgd73 07-20-2009 04:31 PM

I'd go for 100mpg if cooling and materials are strong enough.

I think 72mpg on 1 cylinder, 1 passenger...and drop this thought to 40mpg, not even 50% less, and think, 10 gears, AWD, 3000 pounds and 5 passengers and a spare 1781cc in the back towing a trailer up to 100 scooters heavy...

See? I am not scooter worthy. It is still a selfish machine.

That is decent to have a machine that can do the 70mpg however. :)

beatr911 07-20-2009 06:31 PM

Nice goin on the tune up. You've hit on a large part of the reason why bikes don't get very good mileage, they seem to be factory set-up to just work OK.

Optimization efforts can reap some pretty significant gains. It's like the dark ages of the automobile (the 1970's) where the manufacturers were struggling in dealing with emissions, gas mileage, unrefined manufacturing methods and just plain cheapness.

Even then, when good mechanics got ahold of a vehicle with free reign, good things could happen. I'd gain some MPG and gas mileage in my 70's and 80's vehicles by just advancing the timing some and using a good strong ignition system.

Just by leaning out the factory overly rich jetting on my Kawasaki I gained about 5 mpg. Others have done some reenginerring on the shaft drive to gear-up the engine, seeing from 2-5mpg increases and less frenetic engine speeds. The good aftermarket "shouldabeen" engineers can make a good difference if done correctly.

Keep it up, you'll probably find even more opportunities to make your bike run like it "shouldabeen" from the factory.

Frank Lee 07-20-2009 07:06 PM

...from the factory? I'd place most of the blame on the aftermarket junk.

The Atomic Ass 07-20-2009 10:55 PM


Originally Posted by Frank Lee (Post 116775)
...from the factory? I'd place most of the blame on the aftermarket junk.

I would as well. I went down that path with my Ninja 250, from solid 60's stock, to a road trip on the highway that had me at 50 MPG FLAT.

Also, there's room for even greater improvement, so why settle for 75? I'm doing 81.5, and I've got a 385cc. I've yet to do any serious modifications, most I've done so far is over-weighting the CVT rollers for quicker shifting.

janvos39 07-21-2009 05:19 AM

Nice step forward Jonathan. Up to the next improvement. Can you supply data of your scoot for doing some calculations? Bore stroke, weight dimensions, geart ratio etc.
I am considering for my Burgman to reduce engine capacity to 300 cc, should come out better in FE . What rpm you have running 60 MPH? What hypermiling trics do you use already? Is it comparable with the way Atomic is riding his Burgman ?

The Atomic Ass 07-21-2009 06:02 AM


Originally Posted by janvos39 (Post 116842)
Is it comparable with the way Atomic is riding his Burgman ?

Given his engine is less than half the size of mine and he's struggling around 10 MPG less than me? Doubtful. Technique is a major portion of my gains, I used to get 64 MPG consistently before I began hypermiling. Now I'm on an upward trend that's at 81.5, and still rising. :D

Although he probably won't be able to use some of my techniques, as I do a fair amount of Killed Engine Braking (I hereby lay claim to the acronym KEB), which can't save gas when applied to a carb'd engine.

jonathan150cc 07-21-2009 08:02 AM

I think one of things that is holding me back and keeping me from utilitzing more hypermiling techniques is the fact that I have no way to control the release of the clutch. It drags quite a bit while coasting and doesn't allow me to maintain speed without applying throttle. I have to be a "hard-to-walk-up-hill" in order to gain any kind of speed on the decent without using the gas. I wish there was someway to solve this issue.

As far as EOC, I can't do that either. I tried it the other day, just to see how the bike would respond. Since the clutch won't disengage unless the engine speed is very low turning the bike off while at speed simply left ti trying to turn the engine without any spark... It was chugging until I came to a stop at a redlight and then gave me a return "POP". I don't think I'll be doing that again. These Chineseum engines are tough but not bullet proof.

To answer some question:

At 60mph I'm hitting 7500-7600 rpm.
The only "real" hypermiling I do is that I coast as much as possible. I keep the bike in the "butter zone" which around 6300 RPM and 45 MPH. She is very responsive and not overworked in this zone. The one time that I broke 60MPG without and modifications was when I went for a long ride one evening and didn't get above this 45 mph zone at all.

In response to BDG73, There is a lot to be said for Per Passenger Miles Per Gallon (PPMPG). I mean, anyone can argue that a Prius with 4 people is more efficient than 4 separate motorcycles. (The Prius would get ~160PPMPG while the motos still only gets ~60PPMPG) But, the fact of the matter remains that people in the US still favor the individual commute to work.

It's very rare to see more than one person in a car on any given day...except maybe Sunday. Ever notice how many fewer cars are on the road on Sunday mornings. You can blame poor attendance or lack of faith but some of it has to do with what happens to congestion if people would just carpool.

Kind of getting off topic....

I can't give you an specific engine specs off the top of my head, but it's just a plain jane GY6 157QMJ engine. That info alone should net you some worthwhile results on Google. :)

janvos39 07-21-2009 10:48 AM

Your describtion of the problem to do hypermiling is identical for all scooters with vario drive. In the past there where scooters with 4 speed gearbox like Vespa. The only way to do EOC is in my view to build in an overrunning clutch ( see the thread manual disengage for a centrifugal clutch of Atomic). By doing that the only way to reduce speed is by braking, no engine braking possible. In a number of weeks from now I will be able to give results. Short term I have to recover from a surgery I had to undergo.
I checked the engine type on Google. With a stroke of 57.8 mm for your engine the revs your making at 60 MPH do give a piston speed of 14.4 m/s . A lower value should help to reduce engine losses, but that is not easy to make.

The Atomic Ass 07-21-2009 01:35 PM


Originally Posted by janvos39 (Post 116857)
The only way to do EOC is in my view to build in an overrunning clutch ( see the thread manual disengage for a centrifugal clutch of Atomic).

I've been doing some thinking, and I took a good hard long look at the clutch the last time I had the whole mess open, and I'm thinking a manual release might be possible, and the best way to go. If my idea works, it would actually work in both directions, both manual release AND manual engagement. Which would be awesome for that ~5mph traffic I occasionally encounter, or for bump starting during P&G events.

Actually, if I did away with electric starter events, I could probably justify disconnecting the alternator, as the battery holds a high voltage for quite a while, and the static drain is fairly low with the headlights off. :D

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