I purchased a BMX 500 ( XY 500U) from my neighbor who had it sitting under some evergreen trees for a couple of years. I looked at it for him in the past because it had a primary clutch issue ( if i remember correctly), I feel that i am fairly mechanically inclined and have a good working understanding of small motors ( Ranger, Snowmobiles, Mustang 310 skidloaders, etc...) When i looked at it for him in the past, it started fairly easily, and from what i knew, he didnt do anything with it since i last looked at it.
SO lets start the list, It doesnt start, it turns over, it has spark, it has fuel to the carb, and it has compression enough that ONE TIME i was able to get it to pop off with brake cleaner and help from a buddy, but as of right now, it is dead in the water.
I confirmed the following:
Spark - i pulled the plug and held it to the frame, decently blue spark, not crisp like my Arctic cat snowmobile, but good enough in my opinion to ignite
**UPDATE** I was wrong on spark, it is inconsistent and have since learned that i only now have 1 spark per start cycle. I have detailed that information below, but as i get more into this i believe inconsistent/only 1 spark is what is causing my no start. i do however KNOW that it ran for about 30 seconds because i witnessed it, which makes me believe that this is a grounding issue, I will dig into this deeper, but a wiring diagram for the 188 motor would be awesome if someone has one they will let me download
Fuel - I pulled the fuel line off the carb, and using the fuel pump i pumped into a glass jar, i confirmed the fuel was not nasty coming out of the tank and I put 2 gallons of fresh 91 octane into it.
Carb - I bulled the carb, and all of its contents, it really wasnt too bad, no clogged jets that i could see, nothing crazy, reassembled and installed, same crank no start
Compression - it had enough compression to pop off and continue running one time with help from a friend and some starting fluid, after we stopped the motor it would not start again 5 minutes later
I pulled the sight plug on the flywheel side, and confirmed top dead, then pulled the camshaft cover/sight hole and confirmed the lines all matched up. they were almost spot on.
I lashed the intake valves at .076mm, and the exhaust at .20 mm, rechecked, cranks no start
I pulled the tensioner off, evaluated proper function, checked the chain guide and noticed a small stamp/divot being created due to the tensioner. Probly something to replace if i ever get this bugger goin....
I then decided to re-time the whole unit, so I pulled the valve cover and confirmed my timing marks all aligned properly, reinstalled tensioner with valve cover off, confirmed timing marks still, confirmed my chain was tight with no slop, reinstalled valve cover, re-lashed valves, hand turned over the motor twice to make sure valves were set properly, rechecked timing, crank no start.
I have been following these posts below as they seem to have VERY similar instances of crank/no start, and i have been doing my best to not replicate an existing forum.
https://cfmoto-forum.com/general-discussion/cfmoto-uforce-500-hard-to-start-when-setting-over-night/https://cfmoto-forum.com/cforce-500/not-starting/I have the same motor (and similar no start problem) as this guy, and he has pictures of the motor:
https://cfmoto-forum.com/general-discussion/500-issues/Here is the link to the manual that i am using to diagnose this unit, it has exactly the same pictures and troubleshooting information as the CFMOTO 500 one that i also found.
https://www.manualslib.com/manual/1065015/Xy-Powersports-Xy500utv.html#manualAt this point I am pulling out my hair, does anyone have some insight into these motors and would be able to give me a pointer or two? I know I am close, I just need a little push to get over the edge here!