Hit or miss starting problem By raford3 (Read 1,828 times)

[raford3]

A lot of times my Dash 50cc scoot fails to start with the electric starter. I give it either full throttle,1/2,1/4 or no throttle and it's a no go. I smell fuel in the exhaust. I go around and kick it with no throttle, sometimes only once and it starts right up. It typically has some light colored smoke. Oil? It clears up when it's warm though.
I guess I need to go up to Honda House and kick start one of their new ones to feel the compression. The scoot doesn't have 3000 miles and has had the oil changed every 650 miles since new. Anybody got any ideas? I don't like looking like my stuff is junk.

[Alleyoop]

what kind of carb is on there? Does it have a Enricher(CHOKE) and or a Fuel Primer on the Throttle side. Is it a CVK Carb or SLIDER type.
Alleyoop

[raford3]

It's got a after market Keihin carb w/ a #45 pilot and a #90 main. It has a stock air filter which was replaced due to mishandling (cracked housing). It has the black solenoid coil on the side with the 2 wires which I thought was a choke, but maybe it's something else. The carb has a black diaphram with a needle. I think it's called a CVT. I thought if it was a fuel issue the smoke would be black or it'd be running rough. It runs fine once I get it started. If I put 40# in the rear tire it'll get close to 40mph on a flat no problem. I have to watch the tach to make sure it won't exceed 9k.

[Alleyoop]

Well I believe it is being flooded that is a big PILOT JET for a 50cc, crap I have 182cc BBK and I have a #38 Pilot jet. I think that is why it is so hard to start.
If you have the stock Pilot jet or a smaller one put that in. You can also try disconnecting the Air Box and see if that helps to let more air in and not so much gas.
Alleyoop
This should be what you have or very similiar:
And I labeled the parts are so you know what is what.

[sprocket]

Yeah...#45 pilot is seriously large.... probably flooding it on start-ups. I think mine is #36 on a stock 150cc.

The smoke is likely fuel that is not completely burned...if you always wanted to be rich you are.. at least your scooter is

[raford3]

I read somewhere if you put in a bigger pilot jet it would help the bottom end, anyway that's why it's in there. To get it to run I had to completely close the idle screw, I tried multiple settings beginning with 1 1/2 turns open. I raised the variator weights to 7.5g so I thought more bottom would help. I really don't have a problem with the way it runs. The starting issue is only occasional which has me baffled, why isn't it the same every time? Sometimes it'll start with no throttle and sometimes it'll only start with full throttle if it starts at all with the starter.

[Alleyoop]

You just said the magic words SOMETIMES IT WILL START WITH FULL THROTLLE OPEN.
What you are doing is ALLOWING a LOT of air to mix with the excess Fuel due to the #45 Pilot jet.

Wherever you read a bigger Pilot Jet would help the bottom end is not right(unless of course you just put in a BIG BORE KIT with exhaust and free flow filter). BUT even then if the original was say a 35 going to a 38 on the pilot jet would do.

If a scoot is bascially stock and you want stronger bottom end an mid-range or better top end you need to tune your CVT. And we can help you with how to setup your CVT to get your scoot to where you want it.

Just remember You can tune your CVT for Great takeoffs and Mid-range or you can tune it for a little sluggish takeoffs and mid-range and max top end.
What most of us do is go in between get good takeoffs and mid-range and not loose to much top end or same top end but stronger on the bottom. It is all how and where you ride.
Alleyoop
I will bet if you put in a smaller jet like a #35 even a #38 you will notice better take offs and mid-range as well as start much easier. Right now you are running so rich that you actually are looseing power.
Alleyoop

[raford3]

I think I called the air/fuel screw the idle screw by mistake but it looks like it's back to the drawing board. I'll probably have to order the pilot jet as I don't know if it's in my parts box. I'll get both sizes. The reason I thought this would work is because I'd read somewhere that scoots are leaned out excessively to pass emissions, an attempt to beat the system.

[Alleyoop]

Raford3,
Yes they are leaned out but only by LEANING out the Fuel Ratio Mixture Screw. As a matter of fact some even Put a Plug on the Screw so a customer cannot change the setting. So if you happen to find the Pilot jet put it back in and then You can Adjust the Fuel Ratio Screw First put the jet in THEN since you have the carb off TURN THE Fuel Ratio Screw CLOCKWISE untile it stops DO NOT FORCE it just until it stops THEN TURN it out COUNTER CLOCKWISE 2 1/2 turns. That should be enough to start and then let it IDLE for about 5 minutes because that is the time the ENRICHER(CHOKE) will cut off the EXTRA fuel for cold starts.

Then you can fine tune the Fuel Ratio Screw TO GET THE HIGHEST IDLE.
Alleyoop

ADJUSTING YOUR FUEL RATIO SCREW:

FOLLOW THIS PROCEDURE, take your time DO NOT Be turning the SCREW fast and wait in between turns otherwise you will be off.

Warm Up the SCOOT for at least 5 minutes.

YOU WANT THE HIGHEST IDLE OUT OF THE FUEL RATIO SCREW YOU CAN GET.

ADJUST YOUR FUEL RATIO:

1. Turn the Fuel Ratio Screw Counter Clockwise 1/4 and wait 10-15 seconds to allow the engine to catch up with the new setting.

** IF ON THE FIRST TURN IT DOES NOTHING OR IDLE GOES DOWN- GO to 2.*** Otherwise GO to a. below.

a. If the IDLE GOES up repeat 1.
b. If the IDLE does not go up or it does nothing turn the Fuel Ratio Screw 1/8 Clockwise that should be the highest IDLE you can get out of the Fuel Ratio Screw-- GO to FINISH UP.

2. Turn the Screw Back 1/4 and GO to 3..

3. Turn the Fuel Ratio Screw Clockwise 1/4 and wait 10-15 seconds to allow the engine to catch up with the new setting.

** IF ON THE FIRST TURN IT DOES NOTHING YOUR PILOT JET AND OR PASSAGES ARE CLOGGED*** GO to CLEAN CARB*** Otherwise GO to a. below.

a. If the IDLE GOES up repeat 3.
b. If the IDLE does not go up or it does nothing turn the Fuel Ratio Screw 1/8 Counter Clockwise that should be the highest IDLE you can get out of the Fuel Ratio Screw-- GO to FINISH UP.

FINISH UP:
SET IDLE USING IDLE SPEED SCREW:
USING the IDLE SPEED SCREW set the Idle to 1500-1800 where it IDLES the smoothest AND the REAR WHEEL IS NOT Spinning-

TEST YOUR ADJUSTMENT:
Now while on the Center Stand GIVE THE THROTTLE a GOOD QUICK TWIST and Let go,
It should REV UP with with a nice VROOOOOOOOOM with no Bogging or Hesitation and Come back down to where you set your Idle.
DONE RIDE SAFE.

CLEAN CARB:
Take Carb Bowl off and clean Pilot Jet and Pilot Jet Passage and Main Jet and Passage.
Then come back and repeat this procedure.

[kz1000st]

How old is the battery and the spark plug. Sometimes a problem using the electric start is that it reveals a weakness in the battery. I had a similar problem with a 50cc I fixed once. You could crank and crank on the electric start with no success but one kick and it fired right off. I knew the battery was bad though so I knew where the problem lay.

[sprocket]

Also adjust the valve gaps I think they set 50cc at .003 INCHES for both...

Tight valves can cause all kinds of weird starting problems...and you are likely due for an adjustment anyways

[kz1000st]

Nov 30, 2011 11:42:00 GMT -6 sprocket said:

Also adjust the valve gaps I think they set 50cc at .003 INCHES for both...

Tight valves can cause all kinds of weird starting problems...and you are likely due for an adjustment anyways

Actually they're set even tighter. The gap on a 50cc is something like .002 inches and they probably tighten up fast on a 50cc Chinese scooter. Good catch Sprocket, I always forget about the valves.

[sprocket]

Yes.. valve gaps are very importnat on these GY6 engines and they can close tight in 500-800 miles.

If people would only

Check the valve gaps

Check the fuel flow to the carb

Check the spark

Check the compression

Drain the fuel system for storage more than a month or two

Replace the belt, weights and petcock, brake pads, flush the brake lines every two years

my life would be much simpler

[raford3]

Well, I think for practicality and to cover all the bases I'm going to try kz1000's suggestion first as I have a new battery in my other scoot. I also like the no money thing. My 150 doesn't give me any greif it just runs, stock no mods. The scoot didn't used to do this. Then I'll look for/order the pilot jets. I set the valve lash but I'm not sure I got it right. I didn't have a complete set of feeler guages so I found a spec of one I figured was like mine and it had 2 settings for intake and exhaust, I spilt the difference. It's working OK though as far a power when it's running so I figure the valves are closing. No noticeable tapping or anything. I just put a new spark plug wire and NGK plug in the thing. It was missing then got to the point it wouldn't hardly run at all. The insulation around the center electrode had eroded some and the connection at the end of the plug wire came off when I checked the plug, simplifying diagnosis. It ran like a scaulded dog after I replaced that stuff.

[sprocket]

This is really simple... do you have spark at the plug? Does it ZAP with a blue spark? Check it in the valve cover and a clean non-painted part of the frame... it should be the same...

Test that first it is free...

Scooters run from the stator... batteries have nothing to do with the engine.. you can disconnect and throw it away...they only effect how fast the starer motor turns over the engine.. this could effect starting as kz1000st mentioned...

What is your CDI Ac or Dc?