Done everything and still not starting/running! By sooonmitch (Read 2,090 times)

[sooonmitch]

How could I check this? Fuel runs out when I put pressure into the peacock tube.

[Alleyoop]

Just make sure if the you have a gravity fed system that the fuel hose there is no UPS and DOWNS and nothing lower than the carb. If fuel flows out good and the fuel filter is clean then it may be a venting problem. The Vent check you can try by just cracking the fuel cap so it vents better and ride it and see if it still does it.
Alleyoop

[Alleyoop]

ALso how do you know it already had a 80cc bbk on it? Reason being is if you put on a BBK then you need to at least go up a few sizes on your carbs main jet.
Alleyoop

[sooonmitch]

Because I bought a new 80cc kit to replace the old, since it had so many issues already. But they had the same piston size, bore size, etc. How do I know that I have the fuel/air ratio right? I have a suspicion that it is that because I noticed it runs fine when its cold. But when the engine warms up it starts to have the issue. I am thinking the engine has this issue because the f/a ratio is great for starting up and running cold but when the engine gets warmed up its just enough to 'choke' the engine on the right amount of throttle given

[Alleyoop]

How you just explained how it acts up cold and hot tells me it is running to rich ( to much gas).
So you need to lean it out just a little by turning the Fuel Ratio Mixture screw clockwise.
Alleyoop

Here is a step by step procedure on how to adjust your carbs mixture:

scooterdoc.proboards.com/thread/1499/4ts-carb-tuning

[sooonmitch]

Tomorrow I will try it out and report back, thank you for the link

[sooonmitch]

I do say. I can't get the f/a ratio correct! It's annoying. Not to hot nor cold. I still haven't got it. Just so hard to do. I followed your guide and multiple others but I can't get it right.

[Alleyoop]

Explain what is it that you cannot get it right?? You may have a air leak if you cannot get it right.
Can you put a video of what is happening that is not right?
Alleyoop

[sooonmitch]

Its just the A/F ratio. I cant find the sweet spot. The moped runs great! Just when I am riding it for a bit and let it idle the A/F ratio is off and it will stall. I keep adjusting it but ugh. Tbh I followed the guides and still really dont know what I am doing.

[Alleyoop]

If it stalls after you ride it around a bit I think it's the valves that are your problem. The valves get really hot and expand and do not seal so when you come to a stop or let it idle it will not hold the low idle and dies. It dies because the valves do not close all the way and the motor looses compression. Did you adjust the valves after you put the new top end.

So adjust both valves to .003 inchs, also before you put the cover back on rotate the motor over by hand several times and AGAIN re-check your valve gaps. The .003 feeler should go in and if you try the .004 inch feeler that should not go in then you know you have them adjusted right before you put the cover back on. You don't want to be doing this wrong and having to take things off to re-do them.
Alleyoop

[sooonmitch]

Yea I adjusted it to that when we put the head back on. The bike does run when I let it idle but it idles irregularly after a bit and eventually it does it so bad it will die. Almost like the A/F ratio is not right.

[Alleyoop]

That is a fuel delivery problem then, Try raising the idle a little bit but NOT so much as to have the REAR wheel spinning. The 50-150 cc scoots idle around 1500-1800 rpms. It may just be the idle is set to low and it will not hold.

Do you have a AIR BOX on the scoot or a air filter straight on the carb.

Also when you try to adjust the carbs mixture does turning the mixture screw CHANGE the IDLE up and down? How many turns is the Mixture screw OUT from the closed position? You can find out by turning it clockwise until it stops and counting the number of full turns before it bottomed out. Then you can turn it counter clockwise the same amount to get back to where it was.
Alleyoop

[sooonmitch]

Around 4 turns. I was thinking. Since I basically rebuilt the engine with the new kit. Is it possible that the reason the Engine is having trouble and is unpredictable on the idling side, is because it hasent been broken it yet? The reason I say this is because as I ride it, the scooter will run better over time because I am breaking it in. The idle/ a/f ratio is not correct because of this reason?

[Alleyoop]

Apr 6, 2016 11:18:56 GMT -6 Alleyoop said:

How you just explained how it acts up cold and hot tells me it is running to rich ( to much gas).
So you need to lean it out just a little by turning the Fuel Ratio Mixture screw clockwise.

I will tell you again you are NOT ADJUSTING the mixture correctly it is running RICH.

Alleyoop

Here is a step by step procedure on how to adjust your carbs mixture:
PRINT THIS OUT AND HAVE IT HANDY AS YOU GO THROUGH THE PROCEDURE.
scooterdoc.proboards.com/thread/1499/4ts-carb-tuning
[/quote]

[sooonmitch]

Alright so I been leaning it out and now I am stuck. It runs great but now I have one issue. When I am going at a high speed 40mph and stop at a stop light the rpms starts to slow down but after it gets to about 3000 rpms it starts to give and the rpms instantly drop. It drops all the way and stalls. I can sometimes catch it by giving it some gas but its tricky. Is it to lean or rich at this point? I have had no other issues at this point and the rpms are set around 2100. Or could this be another issue?