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Post by KSR Moto on Jun 17, 2018 4:23:59 GMT -5
I have recently tried many things to get my 44mm gy6 running at full speed again but everything that I tried didnt work
The scoot is going now max 30mph I replaced the carb and it was going 46mph, and then after 5 miles of riding it slowed down to 30mph, I checked my valve lash and it is 0.06mm intake and 0.08 for the exhaust, I have noticed when installing a bbk that my exhaust valve is coffe colored while intake is black could this be a burnt valve?
I have also noticed that sometimes it "farts" trough the carb, and I would say that the inatake valve may be leaking too
What are symptoms of a leaking head?
And one last thing, scoot sometimes regains its power and starts pulling like mad, is it possible for the valves to re seat for a while?
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Post by KSR Moto on Jun 17, 2018 11:52:09 GMT -5
Update:
I have noticed that when starting from cold the scoot pulls like mad but if I stop for a minute or two its power reduces ih half and I cant get it up to speed anymore, I am very frustrated and cant figure it out, wtf is wrong with this thing
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Post by scootnewb on Jun 17, 2018 14:48:49 GMT -5
When my scoot was farting through the carb and having strange problems like that it turned out to be a combination of wrong jets and the cam gear was off.
Is your engine still hitting the same RPM when it no longer goes full speed? Is it possible the transmission is slipping or something?
I used the valve clearance specs stated on the badge that sits in front of the seat. The recommenced lash was .03 - .05mm. Maybe double check on yours to see what they should be.
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Post by KSR Moto on Jun 17, 2018 16:43:00 GMT -5
When my scoot was farting through the carb and having strange problems like that it turned out to be a combination of wrong jets and the cam gear was off. Is your engine still hitting the same RPM when it no longer goes full speed? Is it possible the transmission is slipping or something? I used the valve clearance specs stated on the badge that sits in front of the seat. The recommenced lash was .03 - .05mm. Maybe double check on yours to see what they should be. Well timing is correct for sure, and I think that there is no way that it could ever reach 45mph with 2 persons on board with wrong cam timing or am I wrong? I tried many jets but nothing works it is not a carb problem And it is not slipping it just wont revv up |
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Post by KSR Moto on Jun 17, 2018 16:48:03 GMT -5
Could this be bad cdi too? I am thinking that it wont advance timing and therefore run like crap?
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Post by scootnewb on Jun 17, 2018 17:26:34 GMT -5
After market/replacement CDI's are inexpensive and sold online. May as well try that. When my cam was misaligned it pulled as strongly as it does now that it is correct. After correcting the cam, it needed a retune. Re-jetting was required.
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Post by GrumpyUnk on Jun 18, 2018 12:16:30 GMT -5
I would be checking the fuel supply, and 'stuff' in the float bowl. The running nice, and then having low power points to lack of fuel in my reasoning. Either a chunk of stuff, or a petcock that may not be woriking properly all the time seem likely.
tom
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Post by KSR Moto on Jun 18, 2018 12:37:13 GMT -5
I would be checking the fuel supply, and 'stuff' in the float bowl. The running nice, and then having low power points to lack of fuel in my reasoning. Either a chunk of stuff, or a petcock that may not be woriking properly all the time seem likely. tom I dont have petcock neither vacuum or manual I have 2 fuel filters, and a new carb, fuel comming from the lines is free flowing and it flows at very fast rate, I dont know what else to do, I have checked all the basic things I am planing on replacing a head since when I was instaling a 44mm bbk the exhaust valve was brown in color and inatake valve was black, I think that exhaust valve may either be burnt or it is sticking when hot What do you guys think? Tom? |
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Post by GrumpyUnk on Jun 19, 2018 8:58:17 GMT -5
Most times the intake will be blackened, more or less, and the exhaust kind of a tan, dry-looking slight coating. Those are the normal colors.
Have you checked that your blower housing is tight? Have you checked the 'gasket' around the spark plug socket? If missing, or the housing loose, or the shrouding not installed and 'nested' properly, you will have reduced flow of cooling air, or 'leakage' of the air to non-cooling areas.
If the blower wheel is damaged or loose, it may not be flowing as much air as desired.
If you looked at the valves, I assume you removed the cylinder head. Did you look at the cylinder walls for any evidence of scoring or other damage? Does the piston seem to have clearance to the cylinder wall, or is it real tight. There should be a slight clearance.
With the head off, does the crankshaft rotate smoothly, with low resistance? If it seems hard to turn, you may have too much friction, and damage somewhere that is causing it. The crankshaft should rotate smoothly without much effort needed.
tom
Added: Basically, friction causes heat, and if you have too much heat, you may have too much friction, or too little cooling, or, finally, the fuel:air mix may be producing too much heat. If the piston moves freely, the crankshaft moves freely, then the friction they cause should be within tolerable limits, IF the other stuff is working(cooling/fuel:air mix)
Check also that the spark timing is not retarded, as that will cause more heat production.
tom
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Post by KSR Moto on Jun 19, 2018 10:09:32 GMT -5
Most times the intake will be blackened, more or less, and the exhaust kind of a tan, dry-looking slight coating. Those are the normal colors. Have you checked that your blower housing is tight? Have you checked the 'gasket' around the spark plug socket? If missing, or the housing loose, or the shrouding not installed and 'nested' properly, you will have reduced flow of cooling air, or 'leakage' of the air to non-cooling areas. If the blower wheel is damaged or loose, it may not be flowing as much air as desired. If you looked at the valves, I assume you removed the cylinder head. Did you look at the cylinder walls for any evidence of scoring or other damage? Does the piston seem to have clearance to the cylinder wall, or is it real tight. There should be a slight clearance. With the head off, does the crankshaft rotate smoothly, with low resistance? If it seems hard to turn, you may have too much friction, and damage somewhere that is causing it. The crankshaft should rotate smoothly without much effort needed. tom Added: Basically, friction causes heat, and if you have too much heat, you may have too much friction, or too little cooling, or, finally, the fuel:air mix may be producing too much heat. If the piston moves freely, the crankshaft moves freely, then the friction they cause should be within tolerable limits, IF the other stuff is working(cooling/fuel:air mix) Check also that the spark timing is not retarded, as that will cause more heat production. tom I have checked everything you said, no issues or something looking suspicious,it is a very simple engine actually, and it kills me that I still cant figure it out, The engine is not overheating at all but exhaust seems to be quite hot(muffler) but why would that cause it to slow down after 5 miles of riding? Clogged exhausts choke the engine both hot and cold it doesnt make sense |
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