Smily Can't make it up hills...

Pea-Jae Stasuk /

Hello, MA-troops!

My '76 DEMM Smily is running and rolling! I can zoom along at 25 mph on flat, but slow to a dead stop on long/steep hills. Engine still runs well (no bogging or backfire), but there's no power to get moving on the hill. I have to pedal a bit and then walk it up the rest of the way.

Details...

NOS OEM muffler just put on (only 15-20 miles on it)

14.12 SHA sparkling with no blockages

Stock no-angle/cutaway slide

Stock Smily 53 jet

New float needle

New Banjo filter

Very tiny air leak at carb to intake pipe (waiting on an O-ring to seal that up today)

No other air leaks (new base, head, exhaust gaskets)

Cylinder and piston are quite shiny

RIngs ok (small sign of blowback at first ring, but is mostly stopped by ring two

Fuel is good and flowing well

Smily asks for 20:1 ratio

Timing and point gap darn close to stock

Plug gap in spec

Brakes don't seem to drag, but I am replacing pads this week.

What am I missing?

Thanks for any advice and help!

Be safe and be kind.

Peace,

Pea-Jae

moped-army-e1be489bd59952835412a667eea8733c.jpg

Re: Smily Can't make it up hills...

You have not tuned the carb. With the stock jet, larger carb, and no air box you are running too lean. Too much air, not enough gas. Get some larger jet sizes, and an airbox.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Hi, Cap!

Larger carb?

It's the stock 14.12 carb, and I forgot to say I added the Minarelli air box.

malossi-sha-filter-040843-2T.jpg
malossi-sha-filter-040843-3T.jpg

Jets are on my list to try, but it should be able to move up a hill without coming to a dead stop in a stock state, no?

Other thoughts?

Peace.

Re: Smily Can't make it up hills...

Pushrod Fifty /

An air leak will make it run like a dog. A bad condenser will hurt even more.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Hi, PF!

I'm a total noob, so "like a total dog" is a bit vague for me.

Smily runs smoothly and responsively above 10 mph on flat. Slow off the mark and unable to go up hill without a long speed up to it.

Dog?

The air leak is very slight. Can I do anything temporary at the carb out to seal it up for a test? The damned o-ring isn't here today .

What does the condenser do in the process? Would a bad one cause a problem at low revs vs high?

Thanks a ton!!

Peace.

Re: Smily Can't make it up hills...

Don't think this would slow you down, but 20:1 is crazy oil rich, and will carbon up your exhaust port and pipe quick. Anywhere from 32:1 to 50:1 is fine. If I remember right this is a single speed moped, and they just don't have the power for hills, especially if you are on the heavier side. Repack wheel bearings, and be sure tires are properly inflated. Remember, this is a comfortable bicycle, NOT a slow motorcycle. Fix your air leak before messing with jetting.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Hi, Steve!

Thanks for the insights! Would changing the oil ratio from the OEM spec be risky? What would the benefits be? What should I watch out for?

Peace.

Re: Smily Can't make it up hills...

Jeremy Homser /

Oil is alot better now days. You can run 50:1 with no problems

Re: Smily Can't make it up hills...

Pushrod Fifty /

Two stroke oil is alot better than it was, alot of old bikes were calling for high oil mixes but 32:1 for a cast iron cylinder or 50:1 for an aluminum cylinder is about right using conventional nonsynthetic. There are many posts on the subject.

If the condenser is original, it must be bad. You can search for how to mount an external condenser. Replacing the spark plug is the first thing to do because its the cheapest and easiest maintenance item to take care of.

You can use a little bit of Hondabond sealant to seal the carb flange if it is the round vlamping type but you would want to do a leak down test first to find any possible engine air leaks. You can search here how to do it but basically you plug the exhaust port and pressurize the carb port with about 5 psi and look for a pressure drop on the gauge. Brushing on some soapy water will reveal the leaks on tne outside of the engine, but if not found, the crank seals are the usual leak source.

Re: Smily Can't make it up hills...

Dan (high idle) Conway /

actually if you are underjetted on certain single speed bikes you just cant make it up hills. I would try a larger jet. if you have mopeds you should have an assortment of jets too, they need to be changed sometimes even if a temperature change is drastic enough

Re: Smily Can't make it up hills...

fix your airleak first. Then upjet.

53 jet is smallest Dellorto jet I own. Nothing can run well on that. Go up in jets, then test taking the plugs out of your airbox, if applicable. Check point gap and timing.

I had a stock Demm like yours that went 35. It wasn't too sluggish and could slowly climb a hill.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Well, my intake o-ring arrived today, so I’ll see what sealing that leak up does!

I do have a small pile of jets coming from Treats, so I can see what that does soon.

Is the crankcase an airtight environment? Does a lack of seal there create a loss of power?

If I’m able to run well on flat and high revs, but slow off the mark and low power in low revs, would that indicate too much air?

Thanks for everything, folks! You are all so knowledgeable and helpful! I am very grateful!

Peace,

Pea-Jae

Re: Smily Can't make it up hills...

Change the title of thread to : "Smily Can't Make Demm Hills". Sorry P J- couldn't resist it. I hope you get it fixed. Keep working on it.

Re: Smily Can't make it up hills...

Pushrod Fifty /

It is a cool looking Italian moped. Did someone lower the forks or are they stock?

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Oh, Bob!! Hahahaha!

That nails it! Perfecto!

How about....

Smily can’t make it up a DEMM hill!!

Peace.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

PF,

Nope, that’s stock.

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It’s a lovely little bike! I’m very lucky to have it as my first!

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Peace.

Re: Smily Can't make it up hills...

Did you check the compression? Very important ,should be the first check done, it will either eliminate or answer a lot of problems

Re: Smily Can't make it up hills...

Is the throttle slide coming up all the way when the throttle handle is twisted to full throttle ?

Re: Smily Can't make it up hills...

I had a Malaguti that would only do 25 mph no matter what I did.... then one day I pulled the wheels off and carefully took the axels and bearings out cleaned them all up and put new grease put it all back together and the thing did 33 mph

Then I got a tiny rear sprocket and did 35

For hills you’ll want a big rear sprocket but it will keep your top speed low

But make wheelies easier

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Hi, Bob!!

Yes throttle slide is free-moving and gets out of the way.

Peace.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Hi, Rich!

Yeah, I am going to clean out the wheels soon. Just got new tires and brakes from our Treatland friends!

I’m sure that will help a bit!

Peace.

Re: Smily Can't make it up hills...

Pea-Jae Stasuk /

Tim,

I just got a compression gauge, so I have to figure out how to use it now. :/

Learning is fun!!

Peace.

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