Zong not starting again

[TCCKSR]

verify your carb float is not stuck up constantly flooding your motor too while you do your carb testing.

[Pabesco]

I checked the tank and float bowl for gas flow and nothing seems to be clogged. I did check the float while I had the carb out and it wasn't sticking or had any type of resistance moving.
The mechanic still hasn't shown up so I have to move to plan B. the compression tester should be here in a few days but I really don't think that's the problem. But reading dans manual it seems you might be fooled thinking you have great compression when in fact you don't. I'll recheck that. Also I will recheck the fire from the carb to make sure I have enough spark. Seems that it's supposed to be a really strong highly noticible spark.
I got some starter fluid and I will try to spray a bit behind the air filter so it would be a vapor entering the engine instead of liquid. I already checked the valve lash and they are both set to spec. I checked the timing and it seems to be right (timi g chain is very very tight). I didn't see the dis ribed "T" mark on the roter so I just set the piston TDC and checked the mark on the cam gear and it looks right.
I'll keep reading and troubleshooting until my bike runs again.
Thanks guys. Great ideas and I check all as I go along.

[66Sprint]

Please check that the rotor key is in place and not sheared

[SpudRider]

Are you talking about the woodruff key which holds the flywheel to the crankshaft, Steve? :?:

Spud

[66Sprint]

Yes...a cracked or bent key can change the timing a few degrees and the rotor MAY not stay in one position so it can "wander".... overheating is a common symptom and produces an odd ehaust smell (Cooking aluminum as the piston "holes")
The key doesn't actually "hold" the rotor (the taper does), but it does "index" it for timing purposes....
His rotor may just be "off" enough that he can't see the timing mark when close to TDC on the compression stroke

[SpudRider]

Thanks for the good tip, Steve.

I have rebuilt the top end of my Zong's engine twice. In both instances I removed the flywheel in order to replace the timing chain. I have twice inspected my Zong's woodruff key, and it is very substantial. Therefore, I doubt the woodruff key is causing a problem. However, if the left crankcase cover is removed, one could easily check for this condition by trying to twist the flywheel on the crankshaft, checking for looseness.

Spud

[66Sprint]

The times we have found this problem did not have to do with how substantial the key was....It concerned how tightly it sat in its cuts....(and this problem was found mostly on the GY-6 scooter engines)...each time you rev suddenly or let off the throttle quickly, the mass off the rotor attempts to remain at the speed it was rotating, while the crank speed suddenly accelerates or decelerates relative to it... Theoretically, the taper should hold/bind them together, but any dust, grit, oil, or a slightly "off" taper cut, can prevent this interlock... As does a loose retaining nut ot bolt....and the rotor literally hammers at the loose key, ultimately shearing it or deforming it enough to alter the timing very slightly....
While I don't think this is the likeliest cause of the problem, I just thought it should be one more thing to check......
I recommend spraying carb cleaner on/in both sides of the tapers while apart to prevent any doubts as to the accuracy/quality of the "bind".... If the rotor can shift/wobble at all, there is a possibility it could damage the pick-up or internal coils....we actually had the trigger "button" tear the windings out of the pick-up on a customer's quad due to his improper install of the rotor.....

[SpudRider]

As always, thank you for posting the excellent information, Steve. We are very glad you joined us on these forums.

Spud

[Pabesco]

I will have to do some more reading to see exactly what you guys are referring to. I did experience, as mentioned early in this post, that there was a difference In smell. I will remove the left crank case cover again and recheck everything. I didn't know there was something on the rotor that could be shered off. Any instructions as to how to check this or what to look for would be greatly appreciated.
Thanks guys.

[66Sprint]

Not ON the rotor, the key indexes the rotor to the crankshaft ... It might be able to be seen with a flashlight if you remove the nut or bolt in the center of the rotor....

However, before you go there, check the intake manifold "boot" for air leaks/cracking/etc.....These can also cause a lean condition that can change the exhaust smell, cause hard-starting, etc........

[SpudRider]

I agree with Steve. I would concentrate on troubleshooting the carburetor before I pulled the left crankcase cover to inspect the flywheel.

However, if you wish to examine the flywheel after you drain the motor oil, the process should be simple. After removing the left crankcase cover, you can merely try twisting the flywheel on the crankshaft to see if the woodruff key has failed. You cannot examine the Zong's woodruff key by merely removing the bolt at the end of the crankshaft.

Spud

[Wild_Alaskan]

here is a video on removing the flywheel



if you dont have a flywheel holder you can usually get the nut off by jaming the drive gear with an aluminum or copper washer, or if the engine is in the bike putting it in 5th gear and having someone push the rear brake.

you probably will need the pulling tool though


have you gotten no reaction from spraying starting fluid down the throat of the carb? Ive seen motors with almost no compression at least fire a couple times on starting fluid. It is extremely easy to ignite.

[66Sprint]

Thanks Spud.....I wasn't sure if the machined cut the key fits in was all the way to the end.....Hence the "might be able".... Understand, that my experiences are mostly with similar circumstances on the "Big 4" (mostly Hondas) and some with the little GY-6 49cc scooter engines (and their up to 80cc "kit" mods)....
I'm just suggesting from similar symptoms and general mechanical eperience..... I WILL be wrong sometimes....maybe even often until I learn more about the Chinese engine versions....
I'm learning from you guys as we go as well, so PLEASE don't hesitate to correct me...It speeds up the learning process..... Steve

[SpudRider]

I really don't think anything is wrong with the woodruff key. The Zong's engine is a faithful copy of the currently produced, Yamaha TW200 engine. I have never heard of anyone having this problem with the TW200. Also, I have removed my flywheel twice to replace my cam timing chain; the woodruff key was very robust, and well secured in both instances.

I strongly encourage you to make sure your carburetor is working properly. Then I encourage you to test your electrical components with a digital multimeter, as specified in the TW200 Service Manual. After you do all those things, I am sure you will discover the problem.

Spud

[SpudRider]

Originally Posted by 66Sprint

Thanks Spud.....I wasn't sure if the machined cut the key fits in was all the way to the end.....Hence the "might be able".... Understand, that my experiences are mostly with similar circumstances on the "Big 4" (mostly Hondas) and some with the little GY-6 49cc scooter engines (and their up to 80cc "kit" mods)....
I'm just suggesting from similar symptoms and general mechanical eperience..... I WILL be wrong sometimes....maybe even often until I learn more about the Chinese engine versions....
I'm learning from you guys as we go as well, so PLEASE don't hesitate to correct me...It speeds up the learning process..... Steve

As always, we appreciate your thoughtful input, Steve. Thank you for your willingness to help.

Spud