Zongshen compression, low power

[Dragon]

Does this meaning the a-spoonful-of-oil trick doesn't work?

[forchetto]

Shocked and stunned...the oil test should have confirmed worn bore and if it made no difference it would point to the valves. Still, all's well that ends well, glad you got it sorted.

I promise I didn't invent that procedure. It's in my gauge's users manual. I would have thought that after that mileage the rings would be a bit worn as well as the valves.

[katoranger]

Just good that the problem is solved. Good for another 25K.

Allen

[SpudRider]

Originally Posted by katoranger

Just good that the problem is solved. Good for another 25K.

Allen

Amen on both counts, Allen! Max has got a tough little Zong! His 25,000 kilometers is equal to 15,500 miles; that's not too bad for a chinabike. Today I just passed 10,000 miles on my Zong; it is still purring like a kitten.

Spud

[max_damage]

Originally Posted by forchetto

Shocked and stunned...the oil test should have confirmed worn bore and if it made no difference it would point to the valves. Still, all's well that ends well, glad you got it sorted.

I promise I didn't invent that procedure. It's in my gauge's users manual. I would have thought that after that mileage the rings would be a bit worn as well as the valves.

Well, i think my compression gauge was faulty and not reading very well, every time when i was testing compression i got different values. So i dissable the engine, i putted some gas in cylinder and left it for 15minutes, not a single drop hasnt gone trough bore , so i assumed that valves was burned. I did the same test, putted valves in closed position, putted some gas in intake mainflood, wow :x , it just flood away in 5 sec, same thing for exhaust valve :evil: . I didnt want to refubrish valves becouse the new one are not so expensive, putted the new one, same test, not a single drop of gas .

But i think this engine faliure is my foult, becouse the last time iv checked valve clearrance was on about 8 000 km, becouse when i opened camhead there was no clearance between valves, so the valves didnt get back all way,and there was little micro-space between valves and head and the valves got burned slowly but noticable.

[max_damage]

Originally Posted by SpudRider

Amen on both counts, Allen! Max has got a tough little Zong! His 25,000 kilometers is equal to 15,500 miles; that's not too bad for a chinabike. Today I just passed 10,000 miles on my Zong; it is still purring like a kitten.

Spud

Great Spud, do not make mistake like me, check valves clearance every 6 000 km, good to know the bike is running strong

[katoranger]

I should have 10,000 miles shortly. I rode today.

I was only planning for this bike to last 15,000 miles, but it runs great.

Allen

[phil]

i have been fooled by the oil test myself here is my theory of why the valves the one i had was leaking and out of adjustment the oil will seal up valves just like it will for ring the test is still good just check the valves closely at the first sign of poor compression

[SpudRider]

Originally Posted by max_damage

...Great Spud, do not make mistake like me, check valves clearance every 6 000 km, good to know the bike is running strong

Thank you for the good tip, Max. When you said the valves were damaged, I was tempted to ask if you had been checking your valve clearances.

I adjusted my valve clearance two days ago. This was the second valve adjustment I have done on my Zong, and the procedure went very fast; I was easily done in 30 minutes. After you do the procedure once, it becomes much easier the second time.

I am very pleased to hear that your piston rings and bore are still in good shape after 15,500 miles. The 167FML engine in the Sierra 200GY-2 is a bulletproof little powerplant!

Based on your experience, and mine, I strongly encourage all motorcycle owners to read Red's superb Valve Adjustment Tutorial.

http://chinariders.net/modules.php?n...ewtopic&t=1655

If riders own a Zongshen 200GY-2, they also might enjoy seeing the photos I took during my first valve adjustment.

http://chinariders.net/modules.php?n...ewtopic&t=6458

Spud

[katoranger]

I have purchase several parts bikes with broken valves from lack of adjustments.

Allen

[SpudRider]

Originally Posted by phil

i have been fooled by the oil test myself here is my theory of why the valves the one i had was leaking and out of adjustment the oil will seal up valves just like it will for ring the test is still good just check the valves closely at the first sign of poor compression

I was thinking the same thing; the oil sealed the bad valves.

Forchetto offered his usual, superb advice, which quickly diagnosed the compression problem. While checking the rings and bore, Max was easily able to discover the damaged valves.

You also offer excellent advice, Phil. If a bike owner has bad engine compression, he should always check the valves also, even if the piston rings are bad.

Originally Posted by katoranger

I have purchase several parts bikes with broken valves from lack of adjustments.

Allen

Allen’s remark prompts me to make another observation. I think that chinabikes in general, and the Zongshen Sierra 200GY-2 in particular, have acquired a bad reputation for the wrong reasons. I believe that many new riders purchase these bikes used, and abused, from previous owners who did little or no maintenance on them. Then the new owners also neglect the motorcycles. I think they might do this for several reasons. First, they can’t get any local mechanics to work on them. Second, they are new riders, unfamiliar with motorcycle maintenance. Third, they do not value the Chinese motorcycle as much as a Japanese bike; they consider the chinabike to be a cheap, “throw-away” item. If they had spent a lot more money on a Japanese bike, they might have taken much better care of it. Finally, after the motorcycle inevitably fails, they badmouth Chinese motorcycles as junk. It is easier to blame the motorcycle than admit they did not maintain it properly.

Spud

[SpudRider]

I would like to add an update to my previous post in this thread. I recently tested the engine compression on my Zongshen Sierra 200GY-2 motorcycle. After making a valve adjustment, I measured engine compression with the throttle held wide open; I obtained a reading of 148 psi. This reading is much higher, and more reasonable, than the compression reading of 105 psi I reported in my previous post.

Spud