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Post by markavionics on Aug 26, 2015 10:25:48 GMT -5
So I removed the Uni-filter to view the needle assembly during start. What I saw was the needle/air valve bouncing as the engine cranked, due to the vacuum being generated I assume. It would seem to me that my mixture is too lean with the throttle off and by opening to about 1/4 the vacuum is causing the needle valve to open briefly, introducing more fuel to the mixture. Appreciate any thoughts on my theory... Cheers, Mark.  |
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Post by markavionics on Aug 25, 2015 18:28:30 GMT -5
"In theory" below 25% throttle the main jet isn't doing anything. "Should not" be affecting how it starts. Air and fuel should be coming through the idle circuit. Cracking the throttle to start will let in more air and overriding whatever the choke might be doing. It might also possibly be lifting the needle enough to let fuel through the main jet depending on your estimation of 25% Really need to get it started and then dial it down so it will idle properly. Sounds like right now it will only run at the transition point. If it's partly running on the main jet then you're going to have a hard time adjusting the idle mixture until you get it down below the transition point. Maybe you do have a vacuum leak and it won't start until you open the throttle enough to add fuel from the main to compensate. Thanks pmatulew.
This "theory" is interesting. I do find that if I give it too much throttle (50% or more) the engine won't crank over as quickly and it won't start.
So, assuming I'm too rich - opening the throttle a little adds more air to lean it out; but opening it too much and I start to introduce more fuel as well from the main jet circuit making the mixture too rich again....
I'll have another look over the vacuum lines tonight.
Cheers, Mark.
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Post by markavionics on Aug 25, 2015 18:01:08 GMT -5
Thanks Scooter...I have a look and give it a try tonight.
Cheers,
Mark.
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Post by markavionics on Aug 25, 2015 16:49:48 GMT -5
Hmmmm,
pmatulew says I'm too rich....
lain says I'm too lean....
I'm still stumped, but appreciate your comments.
Cheers,
Mark
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Post by markavionics on Aug 25, 2015 16:47:12 GMT -5
High idle, if not adjusted that way by the rider, is a sign of running lean. Check to make sure there isn't any openeings in the vaccuum lines somewhere, that could let in more air. What did you do with the lines that were connected to the old air box?
I had previously removed the emissions crap and capped off the lines.
The line coming off the valve cover that WAS going to the airbox is now routed up high and just secured to the frame....this is still open and I can feel air moving when revving the engine.
The line coming off the aft end of the drive (at the rear wheel) is just secured to the body, open to the air.
Thanks for the help.
Cheers, Mark.
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Post by markavionics on Aug 25, 2015 16:42:45 GMT -5
Are the jets the same size as the ones in the old carb? If so, you may need to change them, due to the uni intake. A uni usually allows more air in, meaning you need more fuel. I would start with the next size jet up.
Thanks for responding....I also figured the main jet would need to be up-sized based on other posts in this forum.
Original jets were 35 and 110
Now jets are 35 and 120
Cheers, Mark.
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Post by markavionics on Aug 24, 2015 20:03:55 GMT -5
Hello Dawgs!
I've been up and down this forum looking for a similar problem...but no luck. I finally broke down and will submit my situation to the community, hope you can help me.
Ride:
- 2008 150cc GY6, distributed by Saga Canada, basically your typical Chinese scooter. Valves adjusted to 0.004/0.006 intake/exhaust. Mostly stock except;
Installed NEW:
- Replaced the stock carb with the same model, but better quality. 35 idle jet / 120 main jet
- Removed the stock air box, installed a Uni Filter
- Installed iridium spark plug
- New battery installed
- Vacuum lines all new
- Fuel filter new
Symptoms:
- Scoot requires several seconds of cranking (5 - 10s) to start. I have to crack the throttle about 25% open to get it to finally catch. More or less throttle and it won't catch.
- Once it is running the scoot seems to run ok, although a little less power than before the new parts were installed. (maybe the main jet isn't quite right?)
- I'm having trouble getting the idle right. Been messing with A/F screw but it doesn't want to idle under 2000 rpm...but over 2000 my drive is starting to kick in.
I'm thinking my A/F mixture is not right when at idle but not sure if it is too lean or too rich. By opening the throttle am I adding more air to lean out the mixture? Or adding more fuel to rich'en it up?
Scoot used to start within 1 - 2s of cranking....not sure what is going on now...I'm afraid I'm going to get stuck somewhere and run the battery down trying to get started.
Appreciate any help you can offer.
Cheers,
Mark.
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