86 Elite 150 quest for 70mpg

I've almost got this scooter sorted out. Now I'm on the quest for the MPG that it should have. Somehow I'm wasting fuel somewhere.
I'm on my fourth tank, and averaging 51.7mpg.
51.0
50.3
53.9 (this one I tried to ease up on the throttle as much as possible and drive for economy, and had a couple oz of Seafoam)

Not sure where to turn next, but I've got these ideas in mind:
1. Rebuild carb or just buy a new $37 eBay/Chinese unit.
2. Buy new vacuum petcock.
3. Adjust valves.
4. Buy new variator belt.
5. Buy new CDI and spark wire.

I'm going to focus first on the fuel delivery. I can faintly smell gas on the engine if I get my nose down there on the vents.
It starts well, idles down 15 seconds after start, runs great, idles hot no problem, takes off great, I can hit 60+ with out too much trouble or hesitation. Which to me, all indicates that the carb is functioning well. But there's so much other stuff going on with this carb that I would guess 20yrs of sitting around would have ruined something.

I read on another thread about cheap eBay GY6 150 carb rebuild kits that work great, but the link was old, and didn't work, and I can't find it anywhere else. I'm leaning toward a whole new carb because the NOS Honda float valve alone is almost the same cost as a whole Chinese replica carb?

Thanks,
Kevin

Look up vetter freedom scooter and you see that slip streaming is about the only way to go. The other thing mr vetter did was get some custom trans gearing cut . Up the mileage. I don't know if you can get much beyond 60 mpg but then again I been known to be wrong about , at least when it comes to woman.

Mine got around 87mpg if I recall... my 250 Helix is good for roughly 75. Avoid the Chinese carb... seriously, they're total crap. I feel you're headed in the right direction with rebuilding your old one; replace the petcock only if it leaks (should start pouring with light suction on the vac line, and stop immediately when vacuum is lost). The float and needle valve should be replaced with genuine Honda parts; the CV piston, needle valve, and diaphragm are the most expensive parts on that carb; luckily, a visual inspection can determine if they're bad; check the diaphragm for cracks or swelling, and the needle should be straight and free of rust and pitting.

Check the jets for cleanliness; they should be shiny brass. If they're dull, or show any signs of corrosion, replace with genuine parts.

Valve adjustment procedure is very simple, if you need help, i can give you the entire procedure from memory.

The CDI should only be replaced if you're having running issues; it sounds like yours is fine (and a proper test can be carried out with a multimeter).

Honestly, here's what's going to kill your mileage;

-Compression loss (have you checked it?)
-Worn belt, and worn variator rollers
-Low tire pressure
-Wrong fuel (these are designed to run premium, if I recall)
-Bad (or leaking, or Chinese) bystarter. Actually, this might be it altogether... have you tested your bystarter?
-Strapping a billboard to your back (why anyone would do this is beyond me...)

Honestly, those Chinese carbs are junk... I bought one, and most of the parts didn't even fit right; poor machining, leaky cutoff valve due to a warped cover plate, rubber parts that were already disintegrating... ugh.

Hey, I have a stupid question... with the gas mileage you are getting, what speeds are you driving? I ask because my wife and I went on camping trip on our scooters... me on my 400cc Majesty and her on her 250cc Reflex. We did around 500 miles, on Freeway, and other roads.

On our first gas stop, I was surprised to find out my Majesty got better gas mileage than my wife's Reflex. The Reflex is said to get around 70 mpg or more, so I was expecting to be blown away by the gas mileage. I wasn't. Her bike got something like 52 mpg at 70 mph.

I wonder if the high gas mileages that are posted are due to driving less than 55 mph? After 50 or 55 mph it gets very hard to push through air. This is true for cars, motorcycles, etc. Remember how hard it was to wade upstream in a fast moving stream?

Something is not right. My wife's Flex gets 65-70 mpg regardless.

Lose lbs and gain mpg.

I spent hours and days reading about Vetter's stuff last summer. Love it. If I remember right, his conclusions were that the CVT was holding him back from going to the next level. I also read the full 20 pages of this build that is pretty summed up here on Ecomodder.com Before I go for aerodynamic improvement, I think there's some mechanical/carb problem(s) that need to be addressed first. Seems like reports of 70 to even 90mph are possible.

I spent an hour last night looking for your full review of a Honda carb vs a china replica, but couldn't find it. You pretty much summed up the results here, so I'll look no longer. I'm just bummed about the genuine Honda parts cost. I could spend a couple hundred bucks replacing everything that was suspect. I saw a post from a year ago about replica Honda rebuild kits that work really well, but the eBay link is old, and I don't see them anymore. I would love to find a quality replica kit for $9! Any ideas on alternative full kits?
1. New vacuum petcock is on it's way. The original in-tank screen massively failed, and it's the same cost to buy a whole new petcock as it is for the screen only. petcock seems to work fine in the garage, but my theory is that residual rust from the tank will get caught in the diaphragm and cause a leak. I did put an in-line fuel filter, and it's doing it job catching fine rust particles.
2. Next time I'm in there, I'm going to polish the float valve seat with a Q-tip and fully test the valve.
3. my jets are brown and ugly. all I did was soak them in carb cleaner when I went through the carb.
4. I never even opened the top of the carb. Hopefully all those expensive parts are fine.
5. I should be able to check the valves, but I'll call on you if I have questions.
6. No apparent problems with the CDI, but I do now know what to look for thanks to other posts here.
7. I have not checked the compression. D'oh! I will. I have that technology. I only assumed it's good with 3700 miles and apparent full power.
8. Belt looks brand new. Measures full size. I think I put it on backwards when I inspected the variator/belt/clutch because now it squeaks just off idle.
9. Bystarter. Haven't done squat to it. I'll check that too.
10. Besides my 5'10" 203lb frame and a full face helmet, aerodynamics are normal.

Q: I'm trying to wrap my head around this theory: If my jets are ugly (assuming some sort of restriction) wouldn't that lean out my carb? = less gas? or does that lean situation just beg for more throttle -> inefficient burn?

I'm mostly commuting 6-7 miles each way on 25-35-45 mph roads from the suburbs to downtown and back. I do go over a sizable urban range that's a 600-800' elevation change, but it's pretty hard to avoid hills in SW Portland. There's virtually no flat roads at all. I'd like to do a flat, steady, economy test, but it ain't gonna happen anytime soon.

There is a faint gas smell coming from the engine compartment. I've had to ask my daughter and friends to smell it for me to get a second opinion. After cleaning out the tank and pulling the carb off 3-4 times in the last couple weeks, I think the combination of carb cleaner, solvents, and gasoline has made me immune to the smell.

I'd really like to do this scientifically and change one thing, ride a whole tank for a test, then repeat. But that's going to take weeks, as I fill it only every 3-4 days. I'll probably do everything in one sitting and unless there's an "a-ha!" moment, I'll assume it's a little of everything that's going to help.

Thanks so much for all the ideas. Exactly what I was looking for. Sorry if I'm so damn wordy. I will sprinkle this with pictures as I go forward.

-Kevin

I know. Right? As a matter of fact I'm going to work out right now. 2nd day after...12 months off?

In road racing we would assume losing 7 pounds was the equivalent of gaining 1hp. But that's a 380lb bike and 190hp. Not sure if it translates to a 236lb scooter and 10hp. Also not sure how it translates to MPG. Racing has now taken a back seat to parenting.

My fighting weight is around 185. I'm not fat, but I could lose a few. Either way, I don't think chopping my arm off alone is going to get me 20+ mpg.

But, it could be a start. Just kidding .

3700 miles? Garsh... really? Yes, clogged jets would cause a lean condition, but I only mentioned it as a matter-of-course considering the age. At this point, I'm leaning toward a leaking float valve (since this is a gravity-fed unit, a worn float valve would cause it to run rich), and a possible failure in the bystarter causing it not to seal the cold-start circuit properly.

I was able to find the two-part series on chinese carbs by googling "bbishoppcm chinese carburetor"

Well, I just turned 4,000mi, but when I bought it, 3700. Sweet eh? Sat in a garage from about 1990 to 2011. Then the guy's son got it going well enough for me to buy. Not before putting a crappy loud straight pipe on it. That was my first job. Then the rusty tank, now fine tuning. He also put sweet brand new Michelins on it, and I put the proper 90 deg valve stems. He painted the wheels black, and I finally figured out that the wheel bolts were loose.

I did notice on the 3" tailpipe that there was a lot of soot. Leads me to believe it's running rich. Really rich.

I found the right valves on cheapcycleparts.com for $17 vs the $34 the dealer wanted. I watched part 1&2 and I'm convinced to refurb my carb and not buy the replica part(s).

Thanks for talking me through this. Hopefully its easy.

-Kevin

Got all the little parts in the mail yesterday and dove in. I stripped down the carb to just the body and used an old timer trick of boiling the carb for an hour in water. Just to make sure all passages are clear. Then reassembled.

Polished float valve seat.
New float and float needle.
New petcock and screen.
Tested bystarter, and it's in spec, and extends after about 70 seconds. Cleaned the dirty tip.
Opened air mixture screw cap. Tip was dirty with crud, cleaned and set.
Lubed all the squeaky suspension points while the carb was boiling.
Forgot to check compression. It was 1:30am when I quit.

Garage smells like gas and carb cleaner, and I think my nose is immune to the smell now. It's going to take me a week of driving to see if this 4hrs of work will make a difference.

If you do this, don't let your wife see (she was asleep). Use a crappy camping pot, and keep the fan on high the whole time. Remove all rubber/plastic parts and boil for 1 hour. It's the cheap, effective, and environmentally friendly alternative to a chem dip. I learned this trick when I was fighting a GL1200 with 4 gigantic carbs, That time I used the BBQ and a big ass 3-4 gallon pot. This was the final solution that brought success on that project.

-Kevin

That's just awesome! I believe you have me beat... during the Winter of 2009, I was using my condo as a restoration shop for my '86 Elite. I was baking freshly painted parts in my oven at low temps while tearing the motor apart on my (then brand-new) coffee table, while the stripped carcass stood proudly next to my recliner in the living room. Body parts were mostly stored in my bedroom, and on the deck. High-temp parts were baked on my Weber gas grill. I rebuilt the carburetor on my kitchen table. When I needed to rebuild the clutch on my Helix, I dragged a small air compressor home and zapped it apart on the kitchen floor. The funny thing? I didn't spill a drop of grease ANYWHERE. My carpets were spared numerous close-calls, but that's about it. Hey, it's a labor of love at any cost.

...but I've never boiled a carb! I'll have to give that one a try.

I saw a picture of your scoot in the living room in some old post. I was going to say something, but since you brought it up...
I do have a garage now, but there was a time when I might have kept a brand new supermoto bike in my house....

My wife would freakin' kill me now. She was bitching that I smelled like gas in bed, even after a shower.

Hi duke, it looks yummy...
but all I suggest is trying "Gunk" or equivalent product spraying it through your carburetor, it'll be better boiling it in water. Good luck.

Actually, Gunk was the brand of carb cleaner I was using. I decided to boil it when I couldn't get a good stream of carb cleaner to come out the pilot jet passage way in the venturi. It was bleeding out, but not streaming. After the boiling, it shot out.

Rode to work today. I had to adjust the idle down, and it's much smoother. I'm assuming my complete cleaning and boiling had something to do with that.

I can't tell if there's a faint smell of gas or not. I think my nose is still ineffective from the cleaning session. Or there's some leftover cleaner/gas that still hasn't evaporated.

No results on mpg yet.

-Kevin

I think the answer to your problem is likely to be that exhaust system. These things love the stock exhaust pipes for over all performance. I tinkered with different exhausts on mine with mostly negative results and all of them greatly reduced mileage. Even so, mine only gets around 60mpg. My 250 Elite does better.

You must have seen the other thread I had about the exhaust. I ended up finding a stock exhaust for $40 on craigslist. And as a matter of fact, I just sold that straight pipe on eBay for $70. (I was going to throw it away). I never even rode it with that nasty straight pipe except for a pre-purchase test ride, no offense to the battle scooter crowd.

I had a co-worker smell my bike at lunch to see if he could smell gas and he smelled nothing.

So three tests after doing carb work:
1. It runs.
2. it doesn't leak fuel (no smell)
3. TBD- 70+mpg

I wish I had time to just take her for a 100 mile ride, but I want to keep the testing mode the same; Commuting.

The power that goes to the bystarter comes directly from the stator. Check all the connections, clean everything. You can check for current when the engine is running, but not with just the key on.

The connections at the starter solenoid are also crucial to happy motoring, and if they are dirty the charging circuit won't function right, leading to dying batteries and some engine misses. Finally, multiple ground lines come together to a common stud on the frame below the nose of the seat, down low. If you find it, clean those contacts, too.

I like 32 pounds in the rear tire, 26-28 in front.

Enjoy!

Good stuff! Thanks.

Bystarter works.

Not only did I clean the connections, but I slathered dialectic grease on them for the future. Charging system works well. I didn't check any body grounds, that's a great idea, and a common simple failure missed all the time.

34 rear, 24 front (by memory) Brand new Michelins, but I replaced the valves with 90 deg ones and set the pressure.

While I was in there this last time I also greased all the squeaky suspension joints. Now that the bike is so so quiet, I feel this very slight vibration when I'm off the gas. Feels like it's coming from the CVT, but it's not a familiar feeling to me. (this is my first CVT bike).

My idle is still too high after riding around today. I think I had some pilot jet issues and it was masked by too high of a idle setting and running off other circuits.

Thanks for the ideas!!!

-Kevin