Question on Broadway Poker machines.

For those that don't know these, the game is played like VP but has a Joker that almost always comes out only on the second draw. The exception is if you are dealt five of a kind on the first draw.
Payout is 1-1 JOB, 2-1, 3-1, 5-1 on a straight, 7-1 on a flush, 10-1 on a boat, 25-1 4OAK, 50-1 straight flush or 5OAK, 100-1 royal flush.
An unusual feature allows you to bet more, up to double your original bet when making your draw. If you are betting $5 and have a pair of kings, you can raise your bet to $10, or anything inbetween your original and that amount. One credit is 25 cents and you can play a max of 80 credits, so 160 if you double.
My question concerns 4 to a flush or 4 to a straight.
What percent of your original wager would you add when faced with either of those hands?
Obviously, a winnig hand you'll max out, and its foolish to add more if you have pretty much any other hand but four to either the flush or the straight.

I would think that any hold that has a higher than 100% return you should double your money. However, it seems unlikey that a true Joker game would pay for Jacks or better.

I think you are talking about the video poker games that are found in bars in non legal gaming states. If you run the numbers, it's a 160% game if fair.

I have owned several of these machines. I'm not sure what you mean by a fair game, but they don't use the same methods as a casino VP machine.The paytable is a paytable, much like on a VLM. You can set the payback on the machine with a flip of a switch- 60%to 95%.

I'd still like an answer to my question on how much to add to your original wager when dealt a four to a flush or four to a straight.

If the game isn't random I'm not sure if you can work it out.