Spark, fuel, compression, but no start!! By mossy173 (Read 17,308 times)

[Alleyoop]

FANTASTIC A MOONDOUGH!! ok since you have to hold the throttle open it needs more air and it is getting to much fuel which you have verified many times that the spark plug was always wet.

Since you really don't know how much the butterfly is open with the throttle closed it could be that it is so closed that it is not allowing enough air and or fuel for the proper mixture. And the other thing is it could be also getting to much fuel. To much fuel and not enough air.

I would first try setting the IDLE up, by turning the idle speed screw clockwise about 1/8 to 1/4 turn and and when you do see that it DOES MOVE the throttle control wheel DOWN when you turn it. As you turn it it should move the control wheel down which opens the butterfly some.

If that still requires you to open the throttle some then I would take some fuel away and set the Fuel Ratio Screw out about 1 to 1 1/2 turns out to cut some of the fuel.
Alleyoop

[mossy173]

Hey guys, great news. The idle tuned really nicely and now it's running just fine. Victory video below. You know what the biggest problem was? I was trying to prime it with gas for the weedwhacker, which had oil in it. I might just be dumb. The muffler smoked all to hell when it got hot until all that oil burned out. Sigh. Running great, and the extra 50 cc's really give it a nice oomph in traffic now.

Thanks for all your help!!!



It still doesn't want to start with the kickstarter, though. Any suggestions?

[Alleyoop]

FANTASTIC!!! YEAAAAAAAAAAAAAAA, good job Mossy you stuck with it and now after all the checking and farting around you learned a hell of a lot during the process as well. You now know your scoot very well and can probably fix anything that comes up.

Now about the kickstart what is it that seems to be the problem. Does the kickstart work but the motor won't start or something else.

Will it kickstart after it warms up or not even then.

With the electric start does it start good COLD or does it have a hard time starting cold.
Usually if it is hard to start when cold is just a matter of tweaking the fuel delivery. The motors are very finicky when cold and if the carb is not tuned pretty good they will have a hard time starting.
Alleyoop

[rob63]

Oddly enough I`ve just rebuilt a gy6 at work , same situation, everything in place but non start.
The OP`s use of a boost starter is interesting, a few years back I was working in a shop rebuilding 2 strokes and every now and then one would refuse to start even though all the necessaries were in place. I used to connect up a boost starter and spin them fast, they would gradually cough into life after about 30 seconds. I kept them at 1/4 throttle for a couple of minutes then let them die down and they would start perfectly after that.
Never had it happen with a 4 stroke before though.

[Alleyoop]

Yea, if the battery is weak or not strong enough you can jump the battery with your car's battery or a jumper battery.
Alleyoop

[rob63]

Nov 21, 2012 14:25:54 GMT -6 Alleyoop said:

Yea, if the battery is weak or not strong enough you can jump the battery with your car's battery or a jumper battery.
Alleyoop

Yep that`s true, but this was on scoots with good batteries. For some reason the engines wouldn`t fire at normal starter motor speed. By chucking an 80a boost through the battery the engine was almost at warp speed before it would cough into life.

[mossy173]

Well, I can report that it's starting and running beautifully now, better than before I started. there's a new drill--crank the throttle two or three times to shoot a bit of gas in the carb, hold the throttle about 1/4 open, hit the button, and vroom. I think it took some running for everything to loosen up, or something?

[Alleyoop]

That is great news, now enjoy and ride safe
Alleyoop

[mossy173]

aaaw, I'm back. Right back where I started, more or less. Here's the story--

Since the BBK install and ensuing hijinks, the scooter never really started very easy. That video above is the best it was, and it's been going downhill since. It got to the point where it would finally start after fifteen minutes of cranking and starter fluid, and that's where it is now.

It won't idle except very fast, and it likes to stall, even when warm. I've checked the valves, they're set at .004" intake and .005" exhaust. There's still spark, and being as it will reluctantly run, I guess there's no serious fuel issue. When it is running there's still a normal amount of power. I noticed it smoking for a few minutes once, but after turning it off and back on again I haven't seen smoke since, hot or cold. I've done the "finger test" for compression, and it feels like it always has, blowing my finger off the spark plug hole.

One more thing--it hasn't been able to kick start since the replacement at all.

My guess is maybe low compression due to incorrect piston ring gap? Would that do it? I thought I gapped the rings right, but maybe I didn't, or maybe they chipped.

[mossy173]

One last thing, before anyone asks--the oil level is fine now, I did have to top it off.

[mossy173]

more potentially useful information--in attempting to get the scooter to idle, I tried moving the fuel mixture screw in and out. Screwing it in (clockwise) didn't seem to cause any change even when screwed all the way in, and screwing it out cause the motor to bog down and die around 2.5 revolutions.

[Alleyoop]

Well if you have to use starter fluid to get it going, that tells me it is not getting gas. So next time just give it a few cranks without starter fluid and take out the plug and see if it is WET OR DRY. Also check your enricher before you try to start it. Pull it off and see if it is EXTENDED when cold, if it is extended it is not feeding fuel for cold starts.

Also how many turns is the FUEL RATIO MIXTURE turned out from the closed position.
Alleyoop

[mossy173]

Hey, Alleyoop! Good to hear from you again.

I did check the plug, and it seemed to be dry. turning the mixture screw three turns out didn't change that, though. But if there isn't gas coming through, how could it start and run?

Also, how do I remove the enricher?

The fuel ratio mixture screw is currently turned out 1.5 turns, although i've tried it at all positions 0-3 turns out without too much effect aside from what I've already mentioned.

[Alleyoop]

I think the reason it finally starts and runs is because the IDLE is so high at 3000 rpms it is being feed by the Main Jet mostly.

The ENRICHER is held on by two screws just take the two screws out and slide the C hold down out and then just pull the enricher out. Here is what it SHOULD LOOK LIKE when it is COLD and the motor has not been running for at least 5 minutes.
Alleyoop
When you pull the enricher out and it is COLD it should look like this NOTICE the GOLD CYCLINER where it is at:


If it looks like this when you pull it out NOTICE THE CYCLINDER is EXTENDED OUT it is not working:

[mossy173]

Well, nuts. In attempting to pull the enricher, I stripped the brass screws holding it on. They are really on there. But maybe that's ok--couldn't we rule out the enricher just by the fact that there's a stalling problem even when it's thoroughly warmed up? Maybe the idle jet is clogged?