Getting valves to right position for adjustment

[richard1958]

Dumb question but my documentation doesn't tell me which way to turn the engine to get the valves into position.  Clockwise or counter-clockwise?  THanks.

[de dee]

you turn the same way as the drive shaft turns the wheel, my downtown from the right side I turn clock wise,.  that's the bolt under the plastic cover on the other end of the drive shaft, the right side of the scoot,.

[zombie]

It really makes no difference. The engine is dumb, and has no clue or need to know which direction it is turned.

[BettinANDlosing]

It's pretty hard to turn the 250 engines backwards because of the starter clutch, but zombie is totally right it doesn't matter! My favorite way of doing it on the 250 is either under the silver cap with three 8mm bolts by the dipstick, or by the variator. I run my 250 without the plastic cover on the variator so the 19mm bolt is assessable at all times. If you use the first suggestion, there will be a small piece of metal with a spring behind it about the size of a .22 this brings oil from the crank lubrication to the valve lubrication circuit make sure you get it back in!

[richard1958]

Thanks guys for the help.   

Rich

[mrbios]

Good question but my documentation doesn't tell me which way to turn the engine to get the valves into position.  Clockwise or counter-clockwise?  THanks.

Motors should always be cranked the way the motor turns when running.  You can blip the starter to confirm this (with run switch in the off position).  On some engines damage can result to the timing chain / valves etc if rotated backward.  Once proper direction is determined you can draw a small arrow with a magic marker so you don't accidentally go the wrong way.  Great question.

[BettinANDlosing]

A good rule of thumb, everything except some wacky Hondas turn counter clockwise looking from the variator. Any of these Kymco engines won't be damaged by turning backwards tho.

[mrbios]

.... Any of these Kymco engines won't be damaged by turning backwards tho.

I didn't think they would be but I was just putting it out there as a general FYI and forming good habits and awareness.

[windwheeler]

I do strongly advise not to turn the engine against its normal turning direction. If you turn backwards your valve clearance settings may vary or be even incorrect. 
I learned it the hard way on a 150cc GY6 engine.  Once I read up "why" and turned it in normal running direction the valve clearance was perfectly constant.

[BettinANDlosing]

Some gy6 have s funky compression release weird thing on the valves, Kymco doesn't use that. It is however more difficult to turn backwards because of the starter tho.

[zombie]

What a bunch of hog wash. TDC is TDC regardless of how it got there. You can actually run the engine backwards. Of course the clutch / starter won't work but it makes 0 difference.

I build counter rotating engines all the time for marine use, and all the blocks/parts are the same. It's just the ignition systems that are set to fire in the opposite direction.
No dis respect...

[windwheeler]

Not so fast Mr. Zombie, even though it is apparently no issue on the Grand Vista and your "marine engines" it IS an issue on GY6 SCOOTER engines.  

[zombie]

I don't understand how you get that conclusion.
They do have that goofy spring type timing chain tensioner but that will make no difference. The slack will be on the bottom of the chain vs. the top of the chain.
Yes the chain will flop, and eventually fail but that can be avoided by installing a tensioner at the bottom. The engine will run backwards.

Just sayin'.

[windwheeler]

I had this problem on a GY6 150cc engine, and could not figure out why the valve clearance was inconstant and changed by turning the engine backwards.  Then I read that it has a specific mechanism to avoid running in revers...  it is called a "camshaft stopper plate".

To quote another post on ScootDawg: "...it only rotates in one direction and is held in place by the metal bridge that runs between the rocker arms. There is a flat spot on the camshaft stopper where the exhaust rocker rests. If the engine tries to run backwards it holds the exhaust valve open."

[zombie]

Now that I get...
I can only assume that is there to prevent the timing chain issue I posted. I also understand how that will effect the valve adjustment.