Zong not starting again

[SpudRider]

Yes, you need the 12mm adapter.

Spud

[Pabesco]

I'll do that tomorrow

Thanks

[Pabesco]

Ok thanks spud. Just ordered it. I'll see if I can find something tomorrow to convert from 10 to 12 so I can test ASAP.

[Pabesco]

Good evening guys. Hope all is well. I finally got the correct size adapter for the compression tester and performed the test. It was performed four times and the pics above are the results. Is this good compression or do I need to check the engine now?
Thanks guys and hope to get some feed back soon. I'm desperate to be back on the road.

[Pabesco]

I also purchased the recomended battery so I don't have a problem while testing again

[Wild_Alaskan]

looks good, this also means your valve timing is correct, this narrows down the potential problems alot.

I would say its either:

the ignition timing is off via sheared flywheel woodruff key

your gas is bad or there is water in the lower part and you have switched to reserve.

since it wont start or pop on starting fluid, i would bank on there being a problem with he ignition timing.

[SpudRider]

This thread is now eleven pages long, so I don't remember all the details. Did Pabesco say he couldn't get the bike started with starting fluid? Did he say he can't push start the bike?

Having torn my Zong's engine apart several times, I am well familiar with its design and manufacturing quality. Based upon my experience, I would be extremely surprised to discover the bike had either a sheared woodruff key, or any timing problems. Therefore, I think the problem is fuel related.

If you need the bike for transportation, and you can't fix the problem yourself, perhaps you should take the bike to a Yamaha mechanic. Your Zong's engine and Teikei carburetor are virtually identical to the engine and carburetor in the 2013 Yamaha TW200 motorcycle. Any competent Yamaha mechanic should be able to diagnose the problem.

You've acquired a lot of tools, experience, and knowledge working on this problem. You will never lose the skills you have gained. However, if you can't fix the problem, perhaps it's time to let a professional mechanic take a look at your bike.

Spud

[Weldangrind]

I agree that it sounds like a fuel problem. If you can drain the fuel and replace with fresh fuel, perhaps that will help.

[katoranger]

It should run with 115psi of compression. I think its alittle low, but you are reading on a cold engine too.

http://www.dansmc.com/compression_test.htm

With the spark we saw it has to be fuel related.

[FastDoc]

Was that taken with the choke and throttle open?

I don't know Zong specs but I would think normal to be around 150.

[SpudRider]

FastDoc is correct. If measured properly with the throttle wide open, a healthly Zong engine should have compression closer to 150 psi. Pabesco's compression readings indicate one of two things. Either he didn't hold open the throttle while testing the compression, or he has compression problems.

Once again, I encourage you to read, and follow the techniques detailed in the following thread.

http://chinariders.net/modules.php?n...ewtopic&t=7807

Spud

[Pabesco]

all four times was with the throtle wide open and cranking for a total of 10 seconds each time.
i drained the gas and replaced with fresh gas also. i attempted to start it a few times and one time i heard some type of knock (only one time and loud enough to really hear), i decided to try rolling the engine again and didnt hear it again after trying to start it three more times,
if the throttle was wide open and tested with that compression then it means i will have to lift the head?
according to doc and spud this is showing bad compression? is this correct?

[Pabesco]

hi spud do you think i should start a new thread now that the problem has been narrowed down?

[FastDoc]

http://www.dansmc.com/compression_test.htm

Even if 150 is normal it should still run well enough on 125, and it should start on 115.

According to Dan 100 PSI is the minimum. It should be 125 to 150.

[SpudRider]

A compression reading of 117 psi at sea level for the Zong is not that great. I regularly get compression readings of 148-157 psi at 4,600 feet above sea level, with a cold engine.

The Yamaha TW200 Service Manual describes how to check the engine compression on pages 3-10 to 3-11. I suggest you read that part of the service manual, Pabesco. The service manual states the minimum compression is 114 psi, at sea level, with a warm engine. Therefore, if your compression gauge is accurate, you are barely above the minimum compression.

However, if the compression is above the minimum level, the bike should still start. You would notice reduced power while riding as the engine loses compression.

I'll ask again. Have you noticed either of the valves getting tighter between valve lash inspections? Are either of the valves completely tight when you check the valve lash?

Spud