Adjusting Valves

Corsair · Post by **Corsair** » Sat Jun 28, 2008 4:32 am

Anyone got a tutorial on that? Tips/Pics/Vid?

jfrost2 · Post by **jfrost2** » Sat Jun 28, 2008 4:36 am

One on modernvespa, but I think one off a gy6 based engine would be more helpful.

jim_0068 · Post by **jim_0068** » Sat Jun 28, 2008 6:03 am

Very simply...

Adjust the intake valve when the exhaust valve is completely open adjust the exhaust valve when the intake valve is completely open. This is how i adjusted the valves on any lash motor forever, including 700-900hp turbo motors i used to help build/work on. I even used this method on my chinese gy6 scoot as well. It will work fine.

Some people will tell you that it's hearsay and you need a micrometer this and a micrometer that, blah blah blah. The fact remains that this type of cam/valve setup uses LASH and that means as the springs heat up/cool down the lash will change slightly so allllllllll that hard work you went through with finding top dead center just perfectly is wasted. Finding TDC is really only imperative when setting CAM TIMING, not valve lash.

Also, make sure you allow enough room for when the motor warms up as your clearance will shrink. Thats why the valves are louder when they are cold. IF you set it too tight when they are cold, once they heat up you won't have enough clearance and a valve will hang open because there isn't enough lash to let it close completely and your scooter will run like poop.

babblefish · Post by **babblefish** » Sat Jun 28, 2008 6:59 am

+1 to what Jim said plus a couple of extra comments.

Most manufacturers say to adjust the valve clearance with the engine hot just to make sure you don't end up with a hung valve. Some have you adjust valve clearance with the engine running - a messy job for sure!

You can get to your valves by removing the pet carrier bin and then removing the valve cover. Be careful to not damage the cover gasket, or buy a new one just in case. You'll also have to remove the transmission cover in order to turn the engine over (by hand) to open and close the intake/exhaust valves.

enzomatic · Post by **enzomatic** » Sat Jun 28, 2008 9:05 am

I really want to get my hands dirty with my scoot, so I kind of want to know why one would do this and under what circumstance I would need to.

Corsair · Post by **Corsair** » Sat Jun 28, 2008 1:35 pm

This is where pics would definitely help out. Thanks for the tips though. I'll pretty much be taking my entire scoot a part today so I'll try posting pics of all the dirty scooter guts

Here's My To Do List:
Check Valves
Check Spark Plug
Clean Air Filter
Clean Carb and Jet
Check Belt

(replace what's needed)

I'm all for hearing from you. Any tips you have please send them through.

vaderscoot · Post by **vaderscoot** » Sat Jun 28, 2008 2:20 pm

check your rollers too

Corsair wrote:This is where pics would definitely help out. Thanks for the tips though. I'll pretty much be taking my entire scoot a part today so I'll try posting pics of all the dirty scooter guts

Here's My To Do List:
Check Valves
Check Spark Plug
Clean Air Filter
Clean Carb and Jet
Check Belt

(replace what's needed)

I'm all for hearing from you. Any tips you have please send them through.

rajron · Post by **rajron** » Sat Jun 28, 2008 2:48 pm

I thought the valves are to be adjusted cold???

To adjust valves while running is extremely dangerous; if you tighten up on a sticky valve, the rocker could break off and fly like a bullet!!!! – I am surprised anyone would do that.

Corsair · Post by **Corsair** » Sat Jun 28, 2008 2:50 pm

vaderscoot wrote:check your rollers too

Definitely. I was just planning to order the Dr. Pulley Sliding Rollers. Also, even if the belt doesn't need to be replaced I'm going to go ahead and order it. Scooter sales are up so much that pretty much everything seems to be on back order. The local scooter shop here has so many scooters to service that they wouldn't be able to get to my scoot for close to two weeks

jim_0068 · Post by **jim_0068** » Sat Jun 28, 2008 6:31 pm

You should adjust valves cold not hot. Valve lash settings are given from the factory and to be adjusted when cold to allow for the motor to warm up. If you want to adjust your valves "hot" you will have to set them to a different lash.

The only motors that you can adjust valves when they are "running" are hydraulic cam setups. However even those you are supposed to do cold but because they have hydraulic lifters, sometims it's easier to adjust when the motor is running to get the right amount of preload on the lifter.

babblefish · Post by **babblefish** » Sat Jun 28, 2008 6:46 pm

Except the 289 HiPo engine in my Mustang. It has factory mechanical lifters and calls for adjustment with the engine hot and running. My friends '66 327 Chevy calls for the same thing. The factory service manual for my 750 Suzuki says to adjust valves when the engine is hot, but not running. But I understand that "your milage may vary".

jim_0068 · Post by **jim_0068** » Sat Jun 28, 2008 9:36 pm

babblefish wrote:Except the 289 HiPo engine in my Mustang. It has factory mechanical lifters and calls for adjustment with the engine hot and running. My friends '66 327 Chevy calls for the same thing. The factory service manual for my 750 Suzuki says to adjust valves when the engine is hot, but not running. But I understand that "your milage may vary".

As long as the manual says to adjust valves hot it's fine, the problem comes when the manual says cold and you adjust hot or vice versa. Then the lash will be all wrong.

I'd love to know how you adjust mechanical valves with the motor running and how you can be accurate lol.

babblefish · Post by **babblefish** » Sun Jun 29, 2008 4:25 am

jim_0068 wrote:I'd love to know how you adjust mechanical valves with the motor running and how you can be accurate lol.

I can tell you first hand that it ain't easy and it's messy. Your feeler gauge doesn't last very long either...

Although, I've seen these clip/shield thingys that clip onto the rockers to deflect the oil downward, but I'm too cheap to buy them. I've also seen people using a modified valve covers that are nothing more than the top half cut off to allow access to the adjusters, but captures most of the oil that sprays out the top of the rockers...ok, some of it.

jim_0068 · Post by **jim_0068** » Sun Jun 29, 2008 4:05 pm

ah ok. I'm a youngin and grew up with fuel injection and mechanical ROLLER valves. I have seen some setups like you've described.just never really worked on them before.