Why is my head set loose?

I took out the gyro parts off my bike to loose some weight, but when i put the stem back on the fork cylinder or whatever you want to call it,the whole front part of the fork and handle bars part becomes loose, and i have everything tight including the bolts for the stem, anyone know if there is another bolt i need to tighten?

ps. i can still ride the bike, but the cylinder that attaches the forks to the stem and handle bars, ends up kind of loose.

Hum...

From what you describe you have a threadless headset.
Sounds to me like you didn't get your headset back together properly. You may want to read this article on the Park Tool Website that describes servicing your headset.

http://parktool.com/repair/readhowto.asp...

Here is the ticket with a threadless headset. The top of the steering tube (top part of the fork) needs to be slightly below the top of the handlebar stem. On most threadless headset systems, there is a star nut inside the steering tube. There is a cap bolt that threads into the star nut. When you tighten the cap bolt, pushes the stem down against the headset parts so that everything tightens up. If the top of the handlebar stem is not above the top of the steering tube the assembly will not tighten up. You don't want to torque down the cap bolt hard, this will not allow the handlebars to turn freely and will cause excessive wear. You just need to get the headset parts snug, but able to turn freely.

Your headset should have had some spacers. You may have to play around with the spacers placement a bit. Spacers can go either on top of or below the handlebar stem in order to get the stem height slightly above the steering tube height.
If you took some parts out that change the overall stack height, you may have to take a trip to the bicycle shop to buy some additional spacers.

Hope this helps.

If you have a thread less stem(most are nowadays), then you first need to loosen the two nuts that hold you're stem onto the fork tube. Then tighten the center bolt until you feel no play, and then tighten the stem nuts back up. Making sure that wheel is pointing straight in relation to your bars.

For threaded, I am not altogether sure.

sfr 1224 has it right