ChinaV's new Yingang YG250NF (YG250-6)

[euphonius]

Nice work, André. Any noticeable change in performance after bringing the tolerances back into spec? Smoother idle? Better torque?

I did the valves on my KLR a year ago and was amazed that this is accomplished with little coin-shaped lozenges! Internal combustion engines really are the ultimate Rube Goldberg machines.

cheers

[ChinaV]

I just supervised, watched & learned while assisting Zhao Feng. I have never done any valve things, my tinkering expierence is limited to 2-stroke engines on my Trabant and Simson 50cc's - these machines run magicly without any valves
Now I know - could handle it myself now if I had shims.

3 valves were out of spec by up to 0.15mm, one was okay. Initially all 4 valves were with 1.80mm shims equiped.

Out of this expierence, I guess if you get shims within 1.5mm - 2.1mm you should be fine.

I have 2.600km on the bike. Lets hope the engine is build to Honda spec and fullfills the 36.000km till next adjustment...that will take a while

I'm glad you found a mechanic that knows how to do the work. Just a little curious how you could ride your bike over there and perform the adjustment as it takes 6-8 hours for the engine to cool enough to perform the adjustment . Did you leave it overnight and perform the adjustment the next day?

Any photos of the procedure?

Cheers!
ChinaV

[andre555]

I'm glad you found a mechanic that knows how to do the work. Just a little curious how you could ride your bike over there and perform the adjustment as it takes 6-8 hours for the engine to cool enough to perform the adjustment . Did you leave it overnight and perform the adjustment the next day?

Any photos of the procedure?

Cheers!
ChinaV

...hmm, good question. Not aware of this.

Waited maybe one hour, then take it slowly apart, arrived at 1.30, left at 5.30 - so whole procedure was around 4h. This includes waiting, have smoke, talk bullshit with the little English, they know, and the little Chinese slabo and I know.
Parts were, touchable, not noticeable warm or even hot, but not "cold" either...

On slabo’s bike the valves were also checked and they waited much longer, and insisted on waiting, while slabo started taking it apart. Zhao Feng's helper only started towards my bike was already being assembled again.

Rode home afterwards, so far so good, the ticking noise that was there before is gone. Idle is more stable as before. Others no noticeable change to me, but I'm not very sensitive either...

Took few mobile phone pics, will post later.

---------------------------------------

Just checked the Honda service manual, engine temperature max 35°C for the procedure. As the parts were not noticeable warm when you touched them, I guess they were around/below this temperature.
Explains why they waited with slabo's bike longer and told him 15-20°C...

[slabo]

Thread started as ChinaV's Yingang.. funny how did it ended up about our valve clearances.
I'm surprised how fast the procedure was done on my bike. I just left to get a coke, came back, the covers were on! I had doubts they actually did anything, but it was clear when I rode the bike. Feels a bit more responsive now, and sounds better.
Thanks for everything Andre

[euphonius]

Naim, were your valves out of kilter too? By how much?

[slabo]

Like I said, I wasn't there when they did the adjustment. Aparently it's as simple as turning two screws, it was done by the time I went to buy a coke! Same as ChinaV's instructions on the 200GY Qingqi. I tried to ask how much they had to adjust, but they didn't give me a number. I gues you just keep tightning it until its tight on a .08mm (or some other value) gauge.

[MJH]

Shim Type Adjusters
Shim type adjusters are supposed to extend the valve check intervals. However, when it comes time to change things it can get expensive. Each shim is a certain thickness. If you need more valve clearance, you put in a thinner shim, at $10 to $15 per shim. Let's see... a 4 cyl, 4 valve engine has 16 shims... WOW, that adds up fast. AND you are replacing good parts. For the shims rarely wear out. Good news is you can swap shims between valves, tight one for a loose one, and save some money there.
Get the valve cover off. On most shim engines that entails 10-20 bolts, a real fragile gasket that is easy to break and a big H shaped cover. Now you will find that things look a bit different from a rocker engine... namely, there aren't any rockers. You will notice the cam and the shim are real close together. To get that shim out first rotate the shim bucket till the notch on it is out. Then rotate the engine so the cam lobe pushes the shim and shim bucket down. Now you use a special tool to hold the edge of the shim bucket down and rotate the cam lobe out of the way. Reach in the notch with a small screw driver and pop the shim up. Remove it with tweezers. Look on the down side of the shim and it will give you it's size. If you can't make out the numbers, measure it with dial calipers. Now when you put in the special too be very careful and don't force anything. Go slow. It all should feel very smooth. If it feels like it is binding... IT IS. DON'T FORCE IT you can break very expensive parts very easily. Consider yourself warned ! The Yamaha XS series of engines uses a different tool. But the idea is still the same. Naturally, there are different tools for each make of engine. The tools are not too expensive so I just buy them, but I think you could make them too. They all work on the same principle. You have to hold down the edge of the shim bucket, but not the shim, against the valve spring pressure.
Some engines, like the KX650 Kawasaki, have the shim UNDER the shim bucket. You must remove the cams to adjust the valves. There are some others that do that too. Real smart work fellows !
The shims come in different diameters too. You can use the same shim in different make engines as long as they are the same diameter and, of course, the right thickness.
Always put the side with the size stamped on it in down. That is so the cam lobe will not wear the size markings off.

[slabo]

Shim Type Adjusters
Shim type adjusters are supposed to extend the valve check intervals. However, when it comes time to change things it can get expensive. Each shim is a certain thickness. If you need more valve clearance, you put in a thinner shim, at $10 to $15 per shim. Let's see... a 4 cyl, 4 valve engine has 16 shims... WOW, that adds up fast. AND you are replacing good parts. For the shims rarely wear out. Good news is you can swap shims between valves, tight one for a loose one, and save some money there.
Get the valve cover off. On most shim engines that entails 10-20 bolts, a real fragile gasket that is easy to break and a big H shaped cover. Now you will find that things look a bit different from a rocker engine... namely, there aren't any rockers. You will notice the cam and the shim are real close together. To get that shim out first rotate the shim bucket till the notch on it is out. Then rotate the engine so the cam lobe pushes the shim and shim bucket down. Now you use a special tool to hold the edge of the shim bucket down and rotate the cam lobe out of the way. Reach in the notch with a small screw driver and pop the shim up. Remove it with tweezers. Look on the down side of the shim and it will give you it's size. If you can't make out the numbers, measure it with dial calipers. Now when you put in the special too be very careful and don't force anything. Go slow. It all should feel very smooth. If it feels like it is binding... IT IS. DON'T FORCE IT you can break very expensive parts very easily. Consider yourself warned ! The Yamaha XS series of engines uses a different tool. But the idea is still the same. Naturally, there are different tools for each make of engine. The tools are not too expensive so I just buy them, but I think you could make them too. They all work on the same principle. You have to hold down the edge of the shim bucket, but not the shim, against the valve spring pressure.
Some engines, like the KX650 Kawasaki, have the shim UNDER the shim bucket. You must remove the cams to adjust the valves. There are some others that do that too. Real smart work fellows !
The shims come in different diameters too. You can use the same shim in different make engines as long as they are the same diameter and, of course, the right thickness.
Always put the side with the size stamped on it in down. That is so the cam lobe will not wear the size markings off.

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

If you don't include a link to the original article, we'd think you came up with that stuff. Soon we'll be asking you to write books and service manuals.

[moilami]

Yes, and always give credit where credit is due.

[Gardo]

I cant say it enough that this is one of the best forums out there. All of you with your collective knowledge has been invaluable to me as a new rider and owner. Thank you all