Woodruff Key By Gti (Read 1,150 times)

[Gti]

For some reason I can not key woodruff keys in tact. I have not touched my scooter build in a few years due to having some other fun but now it is time to get it going again. But the problem I was having was the woodruff keys would shear off and cause some issues. I have gone through quite a few and now I am not willing to deal with that p[problem and need a good fix. The Key way on the crank is not marred in any way and the starter clutch is identical with no problems. Just to refresh I have a gy6 n case bore to 63mm and a +4 stroker crank with the piston shaved, 6 pin starter clutch, NCY variator, NCY lightened flywheel and stator set up, NCY CDI and OKO 30mm flat side carb down jetted slightly.

[Alleyoop]

How about the Flywheel itself I would imagine with several damaged keys the slot in the flywheel is most likely worn and or damaged and now the key does not fit nice and tight and has some play. And with little play it will shear the key again.

[Gti]

Hey Alley, I have a new one that is going on. However the old one is still in great condition. But to make sure that that is not an issue I just got a new one. Before I put this thing together I am not going to encounter the same problem. Now I have made several mistake when I built this engine and I wondering if a high compression issue combined with running high octane fuel would have caused this to happen. Now when it was running it ran like a bat out of hell, but this time I can not run that high test stuff. Caused to many heating issues.

[royldoc]

perhaps the taper on crank and taper in in flywheel is not a good match. If not the flywheel will not tighten on shaft properly.

Roy

[czmdiver]

Jun 2, 2015 19:35:03 GMT -6 Gti said:

Hey Alley, I have a new one that is going on. However the old one is still in great condition. But to make sure that that is not an issue I just got a new one. Before I put this thing together I am not going to encounter the same problem. Now I have made several mistake when I built this engine and I wondering if a high compression issue combined with running high octane fuel would have caused this to happen. Now when it was running it ran like a bat out of hell, but this time I can not run that high test stuff. Caused to many heating issues.

Curious, What Static or advertised Compression ratio are you running?
You Mentioned Shaved piston, Shaved as in internal Weight reduction or Shaped to Slipper Skirt or
Removed material off the dome to lower Compression Ratio?
High octane Fuel Should not cause any Heating issues, it burns slower and more controlled for higher compression engines.
Running Low Octane in a High Compression engine will cause Preignition, Detonation and Heat issues.
High Octane in a Stocker GY-6 will do nothing but waste money.

[cyborg]

Roy has the answer i think,,a missmatched swage and a junk metal key,,,,with all thats going on with the mill,(big stroke,,lightened everything),,,i think when the decelleration and acceleration of the rotational mass happens after the polar moment of the piston BAM instant bummer,,,

[cyborg]

it would help if i could spell,,,lol

[czmdiver]

Jun 3, 2015 12:44:13 GMT -6 cyborg said:

Roy has the answer i think,,a missmatched swage and a junk metal key,,,,with all thats going on with the mill,(big stroke,,lightened everything),,,i think when the decelleration and acceleration of the rotational mass happens after the polar moment of the piston BAM instant bummer,,,

Ahhhhh, I think your on to something.
I just like to ave the technical known data to procede. 

[cyborg]

You need the formulas? Then I'd need more info as well ,, weights ,, stroke length,, rod angularity ,,, ect to calculate the actual forces ,, me thinks it's a simple matter of mismatched swage angles and the nut not being able to be tightened enough to stop the movement ,,, then the key shears

[czmdiver]

Jun 3, 2015 14:05:39 GMT -6 cyborg said:

You need the formulas? Then I'd need more info as well ,, weights ,, stroke length,, rod angularity ,,, ect to calculate the actual forces ,, me thinks it's a simple matter of mismatched swage angles and the nut not being able to be tightened enough to stop the movement ,,, then the key shears

No, no ,no
I wasn't going in the direction of what I asked is the problem
I'm just technically curious.
I have the formulas.
Hope I didn't scare the poster off.

[Gti]

It has been a couple of years but I bought the +4 stroker crank from Walter at Scooter Elements (now Unique Scooter) and I bought a 180cc power kit from parts4scooters. Because I did not want to go through the issues of finding a spacer to run the stroker crank, Walter suggested that I shave the piston top, so I had the a good machine shop zero deck the cylinder with the piston at full stroke. During my build I had several issues like the inability to keep a variator on the bike and I blew the rectifier. Also getting the timing right was difficult to the point where I would get blow back between the head and cylinder at times (never constant.) So needless to say I had a hard time cranking it. I also used a high torque starter and now that I am typing this I am starting to wonder if the torque of the starter was what sheared the ops of the woodruff key off.

This is of video of the last time I think I ran it for any length of time.


Thanks Guys.

[Gti]

Also when I say high octane fuel I was experimenting with 112 octane Cam II.

[czmdiver]

Thank you.
I now have a better understanding of your build.
If you need a spacer in the future contact Cometic Gasket, send a sample base gasket in and they can Water Jet cut whatever thickness you
need in Alum.

[cyborg]

geez what kind of compression we talking about here?? 13-14 to 1 ?,,,with a two valver?? a hemi,,,no wonder youre having problems,,it's got to be the hi torque starter shearing it when you get on compression,,,boy a decomp release would be ducky right about now,,,,it would be nice if the compression was knocked down a bit,,,divers thicker base gasket would help huge,,,also i think you'd have serious fuel sensitivity issues as the hot weather gets here,,,if you don't have it already

[czmdiver]

Jun 5, 2015 12:10:03 GMT -6 cyborg said:

geez what kind of compression we talking about here?? 13-14 to 1 ?,,,with a two valver?? a hemi,,,no wonder youre having problems,,it's got to be the hi torque starter shearing it when you get on compression,,,boy a decomp release would be ducky right about now,,,,it would be nice if the compression was knocked down a bit,,,divers thicker base gasket would help huge,,,also i think you'd have serious fuel sensitivity issues as the hot weather gets here,,,if you don't have it already

I wasn't going in this direction but now I'm second guessing myself.
Wonder what the Squish clearance is?
With heating issues using 112, timing? or just need to move on to a Alky Carb and fuel?. Gasoline is for washing parts (just a joke).
Can you give us the Compression Test (PSI) numbers?
Mentioned the piston is at "Zero Deck" I'm not big in running the Piston down the hole, a thicker head gasket could be used
instead of a thicker base gasket.                                                                                                                           Cometic can custom (cheap) any thickness you want.
Is the Combustion Chamber the same Size as the Bore?
With a good Rod you need a minimum of .039 or 1mm Squish clearance.