What percentage of my investment portfolio should be high risk investments?

I'm 29. What percentage of my investment portfolio should be high risk investments? When do I begin to move these to more conservative investments?

Personally, I wont go for high risk investment . It gives you high yield and on the other hand, mind you can lose your capital. I go for conservative that offers a better deal. Or you can use your excess funds in doing some home-based business. You not enjoy time freedom but earning big with little risk. I believe there are lots of it there.

at age 29 should almost of it stocks. as you get closer to retirement you move it into a annuity or cash. i would say a good 80% or better in stocks, 20% bonds.

At your age you should have 30 (your approx. age) percent in bonds and 70 (100 minuse your age) percent in equities, as a rule of thumb.

Usually your age (actually it is the number of years before you will need to cash in the investment), risk tolerance are the key factors. First, you need to make sure you have 4 to 6 months of expenses covered with savings - before you start to invest a lot of money. If you lose your job or get sick and need money you don't want to have to cash in your investments.
You should try to make the investments in a 401k or Roth IRA if possible to defer or avoid taxes.
Now to determine your risk tolerence you should go to the Vanguard, Fidelity, t.Rowe Price or Money Magazine web sites and look for some tools that are free to help you determine how much risk you are comfortable with and what allocation between large, small and international stocks and bonds you should consider.
For moderate risk takers at your age and saving for retirement in 25 to 30 years it is probably 60 to 70 in stocks and the rest in bonds.