Post by fxingserious on Nov 6, 2020 4:02:27 GMT -5
TLDR: Found my intake valve had no clearance whatsoever. Rocker arm wouldn't move at all. Tried to loosen it but I couldn't create any sort of gap. The spring is essentially pushing the rocker arm tip. I dunno all the terminology here. This is the best way I can describe what I am experiencing.
A while ago I started a thread that went to nowhere. I was trying to figure out why I was getting a backfire when decelerating. My scooter was dying when coming to a stop and I had to keep throttle open while waiting at a stoplight to keep it running. It was also difficult to start unless I applied a bit of throttle.
Other than idle and starting issues the scooter is pretty responsive.
However, no amount of carburetor tuning was able to fix my problem. I installed a new carb, and also found no leaks anywhere.
I have adjusted the valves at the same time I changed the oil. After a week I started to add a new exhaust and replaced the air filter so we all thought it was something related to carburetor tuning. I never suspected the valves.
There are videos here that show how to adjust the valves. The engine must be rotated to a very specific point to adjust them. It must be at Top dead center TDC of the compression stroke where both valves are CLOSED to adjust the valves. Otherwise the cam will be trying to operate one or both of the valves.
If the camshaft sprocket has the largest hole at about 12;00 o'clock, and the two small holes at 3 and 9, just about even with the top of the cylinder head, both valves should be closed. The 'T' mark may(should) be aligned with the 'rib' on the side case.(pretty close to the 9 o'clock position.) The crankshaft T mark will align two times for every ONE cam rotation. It is the cam that determines whether on compression or exhaust, and thus the I and E valve position. If you have the cam aligned properly, the piston will be at TDC. When I read the description, I wondered if the valve spring keepers had come off, allowing the spring to extend fully and push against the lower side of the cam follower. The springs should never touch the cam follower, only the tip of the valve stem. If they do touch, and the keepers are in place, I would be looking at the rocker arm/follower assembly to see if it was the proper one. Two different length valve stems were used, and they require rocker arm assemblies that match. tom
It's not how hard you work, it's how much you get done. simplificate & add lightness
Post by fxingserious on Nov 9, 2020 22:47:45 GMT -5
Hello all, you guys were right... It was not in compression stroke. I turned the crank around and was able to adjust my valves. Don't think they were not properly adjusted as the same problem I had still persist. Can't get it to idle properly. I am able to start the scooter but as soon as the choke shuts off it will die. If I ride around and come to a stop it will also die. Only revving it will keep it running. =(
Post by FrankenMech on Nov 10, 2020 1:50:01 GMT -5
I don't trust the markings on cam sprockets. I watch the valves themselves. Even TDC markings on the crank assy can be off on these cheap China scoots. A probe through the spark plug hole into the cylinder to feel the piston motion is sometimes required.
It sounds like you now need carb adjustments. Have you modified the air filter box in any way?
Post by fxingserious on Nov 10, 2020 2:19:52 GMT -5
I will go with your method next time. I did not know this. And yes I did. I replaced the stock airbox and exhaust.
I do not know the stock carb jet sizes. I replaced it with a carb I got on partsforscooters.
Currently running 78 main. Needle height towards rich. Performs really well like this. Except that I have no idea where I should in which direction I should head with my pilot jet. I tried size 30, 31, 32. No luck.
Post by fxingserious on Nov 12, 2020 18:31:38 GMT -5
Hello all. I reinstalled the stock airbox. Makes no difference. I went up in jet size. Finally got to unseal the stock carburetor and found the pilot was 30 and main was 75. I tried 30, 31, 32, 33, and now I am sitting at 34 pilot. Main jet is 78.
I can get it to idle but as soon as I start opening the throttle it wants to die, unless I open the throttle some more. At mid throttle it will begin to sputter. If I let go the throttle to 0% it dies.
I moved the needle one notch in either direction. Made no difference. The more I move the needle towards lean the sputter seems to move further and further back towards 100% throttle. Go rich and it will sputter towards 0%.
I am thinking just to give up the aftermarket exhaust.... I hate how the stock exhaust sounds but I can't use my scooter at all.
Also... It seems like my scooter didn't come with a charcoal canister??!?!?! The big hose that comes out of the valve cover vents to the atmosphere?!?! There is only one vacuum fitting on the intake boot for the petcock.
Senna1Rossi: Thanks renagade281!
May 23, 2016 14:59:12 GMT -5
Fox: I don't really know how to say this but straight. I am Dave's Girlfriend Kellilee and bluntly and VERY SADLY he passed away early Tuesday morning. I know he would want ya all to know this. Thank You Brent for befriending my love he was very happy on here!
Jun 18, 2016 16:26:04 GMT -5
Fox: www.gofundme.com/29mgf6b8 I hope it is ok to pass on his gofundme page link. If not you will un-post it I'm sure. Thanks again all!!
Jun 18, 2016 16:31:18 GMT -5