Chinese Scooter Club

stelriah · Tue Mar 04, 2008 4:03 am Non-Starters

Can a idle screw set too low keep a scooter from starting? A badly set air mixture screw?

I know they're are certain elements that will keep a scooter from running properly but right now my scooter doesn't want to start up and those are the only things I can think of that might be wrong.

Any advice?

Fox · Tue Mar 04, 2008 4:11 am

Are you sure you have a spark? The best way to tell is to remove the plug, put it into the plug cap and hold the metal part against the engine while cranking the starter with all switches set to run. You should see a nice blue spark. Wear a glove so you don't get zapped!

stelriah · Tue Mar 04, 2008 4:45 am

Thanks for the fast response and the picture. I've been reading how to check the spark plug but the descriptions haven't been as helpful and direct as that pic.

The scooter isn't with me at the moment so I can check just now. It just occurred to me though that the spark plug was only hand tightened last time I put in so I'm thinking that it came loose after the last time I rode it and ruined the necessary compression.

jpmacd733 · Tue Mar 04, 2008 5:12 am

stelriah wrote: Thanks for the fast response and the picture. I've been reading how to check the spark plug but the descriptions haven't been as helpful and direct as that pic.

The scooter isn't with me at the moment so I can check just now. It just occurred to me though that the spark plug was only hand tightened last time I put in so I'm thinking that it came loose after the last time I rode it and ruined the necessary compression.

Stelriah, an engine needs only three things to run.

fuel, proper grade and quality, and mix ratio
spark, at the proper time
Compression, minimum of 90lbs at cranking speed

If your engine does not start, your missing one or more of the three.

Start a systemitic check to see what your missing. As suggested, check for a good spark always seem to be the best place to begin. Things to check after that go in completely different directions depending if you have a spark or not.

Yes, the idle mix screw setting may have an effect on starting. Turn it in all the way but not tight, then turn out 2 1/2 turns as a starting point. That may or may not be the best setting for a good idle but should be close enough to get the engine started.

Joe

stelriah · Tue Mar 04, 2008 6:29 am

I am thinking that maybe I have a weak spark. Could a slightly loose spark plug be enough to ruin the compression?

It's always had a little trouble getting started. The first time it wouldn't start up was right after I had taken it to a friends house. 20 minutes after having arrived I was getting ready to leave and I noticed that the airbox was leaking gas. It had also started to rain a bit since I parked it. It didn't want to start.

Actually just the night before that I had duct taped up my airbox because it was cracked and I was attempting to solve my problem of the engine stalling at half throttle. This seemed to be the solution but it didn't not seem to have any effect on the problem of starting up. Do you think this could have been the cause of my shift from hard start to no start?

Also while I'm at it I thought I would throw in some other questions:
Where is the air bleeder on the gas tank located?

Also is there a way to set my idle mixture screw without a pressure gauge tool?

Fox · Tue Mar 04, 2008 1:18 pm

stelriah wrote: I am thinking that maybe I have a weak spark. Could a slightly loose spark plug be enough to ruin the compression?

It's always had a little trouble getting started. The first time it wouldn't start up was right after I had taken it to a friends house. 20 minutes after having arrived I was getting ready to leave and I noticed that the airbox was leaking gas. It had also started to rain a bit since I parked it. It didn't want to start.

Actually just the night before that I had duct taped up my airbox because it was cracked and I was attempting to solve my problem of the engine stalling at half throttle. This seemed to be the solution but it didn't not seem to have any effect on the problem of starting up. Do you think this could have been the cause of my shift from hard start to no start?

Also while I'm at it I thought I would throw in some other questions:
Where is the air bleeder on the gas tank located?

Also is there a way to set my idle mixture screw without a pressure gauge tool?

Seems you have left out a few details....

Gas leaking from the air box means you have a stuck float or some debris in the float needle causing it to stay open and overflow the carb. Stuck float will also cause bogging down and hard starting.

I think you should remove,dis-assemble and clean the entire carb. If you don't feel confident in your ability to do the job, then I would say not to attempt it. It's not that difficult, but if you are unfamiliar with the carb and all the connections it can be daugnting. You can maybe see if there is a member close to you who can come by and assist you, or take it to a mechanic.

I would still check the spark, and to adjust the mixture screw follow the instructions here:
http://chinesescoots.forumwise.com/chinesescoots-thread4683.html

The pressure gauge is for compression check and has nothing to do with the mixture adjustment.

Good luck

stelriah · Tue Mar 04, 2008 2:49 pm

The carburetor is brand new but I guess it wouldn't hurt to double check it. I installed it the same night I taped up the airbox. The spark plug is also brand new and was installed at the same time. I set the gap to .26.

Fox · Tue Mar 04, 2008 8:12 pm

It is very common for brand new carbs to have debris in them.

stelriah · Wed Mar 05, 2008 6:18 am

I haven't taken the carb apart yet but I tried getting it to start today and it would start a little and die, start and die but only while I held the start button. What would cause it to do this? Could this mean that it's flooded? There was gas leaking out of the airbox and I was told that this could mean that my float could be stuck.

The scooter was towed the other day and it's stuck in the yard until I can get it running so I really want to get it out of there.

I am going to try checking the spark plug, even though it's brand new. I couldn't do it today because it was raining and I was stuck in the tow yard. They were nice enough to let me keep it there one more night but I don't think that deal will last long and it's tough having to get this done under the gun. The towing service is robbery, flat out robbery.

So like I said I've made a checklist of things to do while I'm there: Check the spark plug, disassemble the carb and clean it out, try to let any gas in the chamber evaporate by leaving the spark plug out and running the starter motor, and then putting it all back together and hoping for the best. Did I miss anything? Should I mess with the idle or mixture screws?

I really appreciate the kind of help I get around here. Hopefully you guys can save me.

px166bajaj · Wed Mar 05, 2008 1:04 pm

Don't forget even a brand new plug can get coated in black muck if the engine is running a bit rich. Buy a second plug as a spare, and clean the other one up.

stelriah · Wed Mar 05, 2008 8:07 pm

Success! She runs. I replaced the CDI, checked the spark plug, cleaned the spark plug (only used the spark plug for one ride ever and it was covered in grease/oil. does this mean I'm running rich or I need an oil change or both?)

Also I gotta say it doesn't have much acceleration. I've never had a 4 stroke before. I've noticed before by my speedometer goes up to 60 while the bike gets 25 max. How do you determine how many CC's you have?

stelriah · Thu Mar 06, 2008 9:31 pm

Just thought I would mention this here b/c I'm a novice and with all the reading I've done on "Reasons For Not Starting" I haven't come across anything about the idle being set too low and fixing that today seemed to fix my hard start.

I noticed this because I leaned down to take a look at the carb and I happen to be holding on to the throttle for balance. By holding the throttle I was opening the throttle plate a little which simulated a higher set idle and started the scoot right up as soon as I hit the button.

Then again I could be wrong.