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Post by gabriel on Nov 5, 2013 22:20:21 GMT -5
So after you all helped me resolve a diaphragm that wasn't moving the pin in itistheride.boards.net/thread/4677/resolved-sudden-loss-power-accelerating I have a new issue.
SYMPTOMS:
- My GY6 150cc accelerates to about 35mph and struggles to get past it.
- If I twist the throttle quickly it coughs and sputters and drops back to about 30mph.
- If I twist the throttle very slowly and back off a bit just when it starts to cough and sputter, then after about 3 or 4 minutes it will clear up and I can continue to accelerate at a normal pace.
- On some rides the same thing happens a second time at about 45 mph.
Once it has been running for a good 10 or 15 minutes the problem seems to calm down a bit, but it still hesitates between 30 and 35 if I take off from a complete stop (like a traffic light).STEPS:- I replaced the entire carburetor with a brand new unit.
- I adjusted my air/fuel mix according to Alleyoop's 4TS Carb Tuning guide.
- I adjusted my valves to INTAKE = .003 and EXHAUST = .004
- I replaced the petcock with a brand new unit.
Once again, anything you can suggest I'll be happy to try and report back.Thanks in advance! Gabriel |
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Post by wilds on Nov 6, 2013 0:34:32 GMT -5
It could be and leak between the carb and the cylinder (easy to check with starter fluid), debris in the carb, main jet a bit to small. I would also re-check the valve setting...
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Post by alleyoop on Nov 6, 2013 0:47:03 GMT -5
Let me ask this, when you say it coughs and sputters is this within the first 5 minutes after you have started it?
Also have you changed the Air Filter, what I mean is put on a free flow filter and or free flow exhaust? Also check the Air filter and make sure it is not clogged with oil IF the valve cover Vent hose is attached to it.
This all is still a fuel delivery problem or a bad AIR LEAK.
Alleyoop
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Post by urbanmadness on Nov 6, 2013 8:52:27 GMT -5
sounds like a bad intake boot or bad vacuum leak to me.... When you changed the carb, did you seat it all the way into the intake boot and then clamp it down? That's where I'd start anyway. Also, make sure you are running that air cleaner... preferably the stock one, if you replaced the carb. If you have an aftermarket one, you will need to jet the carb differently but since you replaced it (assuming you didn't change the jets that came with it), it will be more or less set up for stock exhaust and intake. Also make sure that intake boot is not cracked and all the vacuum lines are hooked up properly. Also check and make sure the index mark on the carb is lined up. There is a notch on the carb and it should slide between the two notches on the outside, top of the intake boot. If this is not in correctly, the carb float may not like it much.
Here's what I do, if I have to remove the carb on a bike for jetting, or rebuild, I just go ahead and change the intake boot, unless I know it's been done recently. They crack and harden.
Any vacuum leak on one of these bikes, will just make it run weird and irratic. (Oh... Intake boot, is the intake manifold, they are cheap for 150's)
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Post by gabriel on Nov 17, 2013 13:42:15 GMT -5
Since last time I updated this I have: - Discovered that the intake manifold was cracked and replaced it with a new one.
- Discovered that the air intake tube had multiple holes in it and replaced it with a new one.
- Replaced the air filter with a new one.
- Replaced all the rubber connecting to the carburetor:
- Gas tank to shutoff valve
- Shutoff valve to fuel filter
- Fuel filter to petcock
- Petcock to carb-fuel-intake
- Petcock to Y-valve
- Y-valve to intake manifold vacuum
- Y-valve to carburetor vacuum
- Replaced the CDI with a new high-performance CDI.
- Double checked that the diaphragm on the new carb was sealing and moving okay.
- Failed to check the float bowl due to stripping the screw-heads while attempting to open it.
- Re-adjusted the valves to make sure I did it right the first time.
- Replaced the spark plug with a new one. The old one was very black and oily, which I think indicates that I was running far too rich.
- Re-adjusted the air-fuel mix screw just to be sure.
Now it will start and idle okay for a few minutes, then die. I have been playing with the air-fuel ratio and the idle screw. It seems that as long as it's adjusted lean, and the idle is set very low, it will idle for a while before it dies. If I give it any gas, it dies immediately. If I richen the mixture it dies immediately. If I tighten the idle screw it dies immediately.
I have sprayed carb cleaner around all the connecting points of my air and gas flow system (both sides of the new intake manifold, the entire length and both ends of the air intake tube), and it doesn't affect the RPMs, which I think means that there are no large air leaks going on there.
I'm ready to start over my troubleshooting from the beginning here. Is it likely that the new carb I bought has a problem right out of the box? Any trouble shooting advice and steps offered will be attempted and appreciated!
Gabriel
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Post by alleyoop on Nov 17, 2013 14:32:20 GMT -5
Check your compression, the plug should not be oily, wet from fuel or sooty yes(if to rich) but not oily. It may be your rings are shot and you have very low compression.
Alleyoop
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Post by gabriel on Nov 17, 2013 14:59:02 GMT -5
Okay, so the only way I know to check compression is to push the kickstart and see how much resistance there is. And... before all this started the kick start would move twice easily and have a LOT of resistance on the third push. Now I'm getting a mild resistance maybe once every 9 or 10 pushes. This is getting into brand new areas for me. Any suggestions on what to do about this? I'm afraid I don't know what the "rings" are or how to troubleshoot those!
In the meantime you can find me pouring over YouTube videos on the topic...
Thanks for all the help you've provided so far!
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Post by alleyoop on Nov 17, 2013 15:20:05 GMT -5
Ok, take the plug out and stick your finger in the hole and hold it nice and snuge. Then hold the throttle wide open and crank it. If it has descent compression it will push your finger off the hole. If you just feel some pressure then something is not sealing EITHER the rings on the piston or the Valves are not sealing.
Alleyoop
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Post by alleyoop on Nov 17, 2013 15:53:22 GMT -5
Just so you guys know, putting your finger in the plug hole is not going to hurt your finger it will just push it off the hole.
Now if you have a big enough thumb you can just cover the hole with your thumb and it will push your thumb off the hole. But I always say use your finger because the hole around the plug is pretty big and you would have to have a KING KONG THUMB(HAHA).
Alleyoop
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Post by gabriel on Nov 17, 2013 16:22:38 GMT -5
It does push my finger off the hole, but it doesn't feel super strong. I actually have a compression tester (bought it months ago and forgot all about it, never used it) but I don't have an adapter that fits this spark plug. I'll hit up the auto parts store and see if I can buy one instead of ordering it. In the meantime, I'll be studying up on rings and valves to see if there's anything within my skill level to attempt there.
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Post by alleyoop on Nov 17, 2013 16:29:15 GMT -5
Yea take the plug with you and they will find the right size adapter for your the plug hole.
Alleyoop
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..BAD TO THE BONE..
