PDA

View Full Version : Xingyue ITA150 rebuild


taz001
06-24-2013, 09:35 AM
I recently rebuilt my scooter with new: crank, rod, pistion, rings, wrist pin, and cylinder. It turns over, seems to have compression, I took the spark plug out and grounded it against the valve cover and it has spark. Took the carb off and squirted starting fluid down the intake. Just won't start. Not even a pop. Exhaust dosen't seem to puff out the exhaust stroke as hard as I think it should. Maybe even has a little "suck" to it. The old piston came off the rod and I'm assuming slammed against the head, as evidenced by the bent rod. I didn't take the old valves out of the head and check to see if they were straight. I'm gonna do a compression check, as soon as my 10mm adapter gets here. What kind of number should I get? 20, 30, 40, 50, etc. psi? The rings haven't seated yet, as I have yet to have it running. Bad compression, I'm thinking bent valve(s), good compression I'm thinking timing. What say you?

inuyasha
06-24-2013, 09:58 AM
Hi
100-125 psi is good, 125-150 psi is very good, and 150+ psi is great. If you don't have this level of compression then you have bad valves and/or bad piston rings. If you want, you can add a teaspoon or so of oil to the engine through the spark plug hole. Then try the compression test again. If compression is higher, then it's likely you have bad rings. The oil will seal the rings and give you better compression. If compression is the same, then you have bad/improper adjusted valves.
Try that and then we can go from there
Take care and ride safely my friend
Yours Hank

DW
06-27-2013, 09:52 PM
If you get a vacuum at the exhaust your valves are to tight or your timing is off.

taz001
07-08-2013, 07:03 PM
Well guys I got my new tool, a 10mm to 14mm compression checker adapter. Did a compression test on my freshly reguilt engine. Guess what? NO compression---zero, zilch. So I removed the engine AGAIN. Pulled the head and took a look at the valves. Looky, Looky what no cookie. guess what I saw.
.
.
.
.
.
.
.
.
.
.
.
.
wait for it,
.
.
.
.
.
.
.
.
.
.
.
.
Tada:

http://i178.photobucket.com/albums/w255/tazman001/exhaust20valve_zpsa287f743.jpg

Here's a shot up the ol' exhaust port. Guess I shouldn't be able to see daylight between the valve and seat! Valve end is definately bent. Gonna buy a new set of valves, reassemble and try it again.:no:

blueboy5000
07-12-2013, 09:45 AM
You also need a head! Get a new complete head, as lapping these valve seats is nearly impossible.

taz001
07-15-2013, 07:55 PM
When I line up on the green mark which is the end of the box enclosing the arrow beside the "T", the cam will not get horizontal in relationship to the top of the head. but when I line up either the individual red mark beside the "F" or the end of the arrow(depending on which tooth I use on the cam), the cam will get horizontal in relationship to the top of the head. Which mark then would be TDC? I'm thinking the end of the arrow, correct me if I'm wrong. Where I have the blue mark is the TDC indicator, also correct?

http://i178.photobucket.com/albums/w255/tazman001/gy620flywheel_zpsfad84fb4.jpg

Cam is horizontal like this in reference to the top of the head, correct?

http://i178.photobucket.com/albums/w255/tazman001/gy620cam_zps41d919f1.jpg

Thanks for the help guys.

blueboy5000
07-16-2013, 07:28 AM
The bottom pick is where your cam should be at TDC.

taz001
08-04-2013, 07:26 AM
Well set the timing just as it was in the picture. Installed and lapped the valves in the old head, took about 25-30 minutes because I hadn't already removed the intake valve. Put it all back together. Tried to start it and the battery wasn't up to it, so jumped it off and with the extra juice popped right off. Runs like a timex. Real jewel this one.

Questions again though. In general where do the fly weights on these 150cc GY6es engage? On my chinameter it also includes a tach. The fly weights seem to engage on this scoot at about 3-4 grand according to the onboard tach. I got it going real easy like then gave it 2/3 throttle and it ran up about 6 grand as the speed on ran up to 40-45 chinameters. The revs weren't changing but the speed kept increasing. Due to the varator closing up? When I first started it there was a little bogging and hesitation, but after it warmed up, the throttle response was very crisp with the pipe and K&N air filter. Yes, I did rejet. Also in general with these 150cc GY6es what is a safe redline? I'm gonna run it easy for the break in. On a rebuilt engine how many chinameters should break in be? I can tell this one's gonna be alot of fun. Thanks any response guys.

blueboy5000
08-05-2013, 03:19 PM
Safe redline is about 8000. The clutch (flyweights) engage at different rpms depending on the springs in the clutch.