Open Service Shop in Argentina

[pepelepua]

Around a month ago a local distributor invited RX3 owners to show us a complete bike service, including valve adjustment.
They gave a free service for 2 of the bikes, unfortunately not mine.
One of the things they told us is that they adjust to 0,10 the valves clearance that is much higher than the values I can read at this forum.
You can see some pictures of the event and a video in their facebook.
In the pictures I´m the second guy from the left.





This is a link to the work shop video ...
https://www.facebook.com/zmotos/vide...type=2&theater

[SpudRider]

Zongshen recommends setting the valve lash for all four valves at 0.04-0.06 millimeters. I personally set the valve lash to 0.08 mm for all four valves in my RX3 engine. Setting the valve lash to 0.10 mm is a little too large, but it shouldn't cause any problems, other than a minor loss of power.

[superdude]

Originally Posted by SpudRider

Zongshen recommends setting the valve lash for all four valves at 0.04-0.06 millimeters. I personally set the valve lash to 0.08 mm for all four valves in my RX3 engine. Setting the valve lash to 0.10 mm is a little too large, but it shouldn't cause any problems, other than a minor loss of power.

Hey Spud. About to do this valve check/adjustment soon and gonna have 2 other RX-3 guys there to watch and help. Whats reason you adjust to .08 instead of the .04-.06? Apologies if you're already answered this elsewhere.

[keithmaine]

Originally Posted by SpudRider

Zongshen recommends setting the valve lash for all four valves at 0.04-0.06 millimeters. I personally set the valve lash to 0.08 mm for all four valves in my RX3 engine. Setting the valve lash to 0.10 mm is a little too large, but it shouldn't cause any problems, other than a minor loss of power.

The valve setting on the RX3 always seemed very tight (.0016" - .0024") to me. Most bikes I have owned have been .004"-.006" or .008" -.010" some as high as .012" usually larger for the exhaust valves.

[SpudRider]

Originally Posted by superdude

Hey Spud. About to do this valve check/adjustment soon and gonna have 2 other RX-3 guys there to watch and help. Whats reason you adjust to .08 instead of the .04-.06? Apologies if you're already answered this elsewhere.

I haven't noticed any power loss by setting the valve lash a little on the loose side, and I prefer to have the valves adjusted a little too loose, rather than a little too tight. Also, setting the valve lash to 0.08 mm gives me an additional safety margin to avoid tight valves, in case I am a little delayed with my valve inspection, or the valve seats more quickly than usual. Finally, I believe I read somewhere that CSC sets the valve lash to 0.08 mm at the dealership before they ship the new bikes.

[superdude]

Originally Posted by SpudRider

I haven't noticed any power loss by setting the valve lash a little on the loose side, and I prefer to have the valves adjusted a little too loose, rather than a little too tight. Also, setting the valve lash to 0.08 mm gives me an additional safety margin to avoid tight valves, in case I am a little delayed with my valve inspection, or the valve seats more quickly than usual. Finally, I believe I read somewhere that CSC sets the valve lash to 0.08 mm at the dealership before they ship the new bikes.

Thanks for the advice Spud. I will set to .08. When my RX-3 buddies and me are working on bikes together, "Spud does it like this" has come out of our mouths more than the words CSC or Zongshen.

[SpudRider]

Thanks for the kind words, amigo.

To be more accurate, I place a 0.08 feeler gauge under the tappet as I tighten the lock nut. Usually, when I check the valve lash, it has been set to 0.08 mm. Sometimes I tighten the lock nut a little too much, and the valve lash might end up a little tighter, perhaps closer to 0.06 mm. In that case I don't bother to loosen the lock nut. I am within specifications, so I close everything up and finish the job.

[Jay In Milpitas]

Originally Posted by keithmaine

The valve setting on the RX3 always seemed very tight (.0016" - .0024") to me. Most bikes I have owned have been .004"-.006" or .008" -.010" some as high as .012" usually larger for the exhaust valves.

Keith, from my experience on Honda OHC engines with rocker arms they ranged from .002" intake .004" exhaust to only .002" on both. This was on models from 50cc up through 750cc. The little pushrod engines were always larger than that. So perhaps with advances in metallurgy and forming processes, things have only improved to allow makers like Zongshen to reduce tolerances.

[jbfla]

Originally Posted by SpudRider

....... Finally, I believe I read somewhere that CSC sets the valve lash to 0.08 mm at the dealership before they ship the new bikes.

Before my valve clearance check, I emailed Gerry at CSC to confirm the setting.

He said that during the CSC "setup", the valve clearances are set to .003"

jb

[SpudRider]

Originally Posted by jbfla

Before my valve clearance check, I emailed Gerry at CSC to confirm the setting.

He said that during the CSC "setup", the valve clearances are set to .003"

jb

Thank you, I read the information from one of your posts. A valve lash of .003 inches is equal to .0762 millimeters.

[willy dog]

Originally Posted by SpudRider

Thank you, I read the information from one of your posts. A valve lash of .003 inches is equal to .0762 millimeters.

i too will adj. valves at .003" all my gauges are in thous. little loose is ok from what i am reading

[Weldangrind]

Originally Posted by Jay In Milpitas

Keith, from my experience on Honda OHC engines with rocker arms they ranged from .002" intake .004" exhaust to only .002" on both. This was on models from 50cc up through 750cc. The little pushrod engines were always larger than that. So perhaps with advances in metallurgy and forming processes, things have only improved to allow makers like Zongshen to reduce tolerances.

That's an interesting thought. Perhaps since the pushrod (in a CG engine, for example) is quite long, it has more material to thermally expand and grow. The counter-attack would be to set the clearance a little looser than an OHC engine.

I learn stuff on this forum every day.

[Jay In Milpitas]

Originally Posted by Weldangrind

That's an interesting thought. Perhaps since the pushrod (in a CG engine, for example) is quite long, it has more material to thermally expand and grow. The counter-attack would be to set the clearance a little looser than an OHC engine.

I learn stuff on this forum every day.

If I remember correctly the rough rule is that metals expand about .001" per 100 degrees (F) per 1 inch of material.

In that vein, a 3" long pushrod will lengthen about .006" at 200F. The distance from the cam to the rocker end will also grow, but as various metals will run plus or minus to the general rule, the maker will undoubtedly determine actual recommended tolerance after running a number of practical tests.

Now for overhead cam (OHC) applications it would be a bit different. The cam lobe and valve stem will expand which should reduce the cold set clearance. However the rocker arm pivot hole will also enlarge (get more sloppy) and give some clearance back. On our engines with the roller type cam follower there is also slight sloppiness.

So tight is not good as it can give grief to the valve face. Loose is not good as it reduces amount of valve lift while also reducing duration, but that only affects performance. It also creates an impact that can defeat the thin oil film that would normally cushion the contact between the cam and follower, and again between the valve stem and the valve lifting end of the rocker arm.

Darn, got sidetracked and forgot what I was going to say. Oh, just remembered, I had pudding for dessert.

[rjmorel]

"Darn, got sidetracked and forgot what I was going to say. Oh, just remembered, I had pudding for dessert."

What flavor ? any sprinkles? Your leaving us hanging here Jay rj

[RedHawk47]

Originally Posted by Jay In Milpitas

If I remember correctly the rough rule is that metals expand about .001" per 100 degrees (F) per 1 inch of material.

In that vein, a 3" long pushrod will lengthen about .006" at 200F. The distance from the cam to the rocker end will also grow, but as various metals will run plus or minus to the general rule, the maker will undoubtedly determine actual recommended tolerance after running a number of practical tests.

Now for overhead cam (OHC) applications it would be a bit different. The cam lobe and valve stem will expand which should reduce the cold set clearance. However the rocker arm pivot hole will also enlarge (get more sloppy) and give some clearance back. On our engines with the roller type cam follower there is also slight sloppiness.

So tight is not good as it can give grief to the valve face. Loose is not good as it reduces amount of valve lift while also reducing duration, but that only affects performance. It also creates an impact that can defeat the thin oil film that would normally cushion the contact between the cam and follower, and again between the valve stem and the valve lifting end of the rocker arm.

Darn, got sidetracked and forgot what I was going to say. Oh, just remembered, I had pudding for dessert.

More data points for your theory:
Thermal expansion coefficient for carbon steels is 6.33xE-6 in/in/degF; a 100 deg F temp change adds .000633" per inch of material (the alloy steel used for the valve stems may have a different coefficient).
At 200 deg F that is a 130 deg F temperature increase, so a 3" stem would grow 6.33xE-6 x 3 x 130 = .0025"
But the head will also grow and it is usually aluminum; the coefficient of thermal expansion for aluminum is twice that of steel.

If the rocker arm pivot hole also enlarges, the pin it pivots on will too, making that a net zero.

Man, you opened a can of worms. I going to leave it for the engineers at the factory.