question about threadless stem on threaded fork
 

So, I would never dare to put a threadless headset and stem on a frame with a threaded fork, but in an impulsive buy i purchased a kazane track bike with a buncha good components for $200, but after inspecting the pictures of the bike more closely, the fork seems to be threaded, but it had a threadless headset on the frame. (the stem was not included in the purchase) Now that I know it is actually threaded, i want to put on a threaded headset and quill stem. But I was wondering if by clamping a threadless stem to a threaded fork would have possibly damaged the threads on the fork. I am pretty sure the aluminum stem would give first, but i have never done this before or seen this done so I am not sure. I really hope the threads are okay though as if they are that means i would have to buy a new fork or continue running that mismatched set up. thanks!

clamping a threadless stem onto threaded fork is dangerous if the stem is clamping onto threads.
possible to have steerer break off at threads just under clamped stem since they act as stress risers.

If the fork is not original, and the threaded portion is high enough that it can be completely sawed off, the reamaiing steerer can be used threadless, but this doesnt sound like your situation.

get a propor threaded headset installed.

possible kludge solution is a frankenheadset:
use the threadless cups and upper race, then use 2 threaded headset lockrings to pretension bearings in place of a threadless stem and top cap
then use a quill stem on top
again tho, due to threads being stress riser; make sure the quill is deeply set inside the steerer to a level below the headset upper race -saw off excess threads if needed

Cut the fork for a proper threaded headset, install a proper threaded headset, install a thread-less adapter, install thread-less stem and handlebars.

should look like this: http://www.youtube.com/watch?v=6kFARIR2GQ0

Thanks guys. This is what I was thinking. It looks like he had a few mm of spacers on there as well so i may be able to put a threadless headset on be able to cut off all of the threads that were being clamped on.
I would prefer to run a quill stem just for aesthetic reasons though.

Odds are that the threadless stem hasn't harmed the fork yet, since the usual harm is a fracture. You also will be cutting off much of the extended height, where the damage would have occurred (if any did), and anyway the quill will buttress the fork to beyond the thread depth, so strength won't be an issue.

But there are a few wrinkles to check on before going forward.

1- you need thread extending to below the bottom of the top bearing. As a rough guide, that means that the unthreaded section needs to be no longer than about 15mm longer than the head tube. That allows for the height of the lower bearing plus a bit of wiggle room.

2- the thread has to extend no deeper than 2-1/2" below the top of the headset, so the quill stem will end at least 1/2" below the last thread (1" is better), more than that doesn't make a difference.

You'll also need to cut the fork, which is easy enough, but measure carefully, and thread on the top bearing first so you can roll out the cutting bur on the new first thread. Threaded forks need straighter cuts than unhreaded, so either use an old steel top cup as a guide, or put a hose clamp around the fork as a cutting guide. Don't measure the fork for a super close fit on the headset, but instead allow a few millimeters for a spacer. Headsets vary in stack height and one day that extra bit of length can become very important.

Before starting, I'd drop the fork, and measure it against the head tube to see if it fits conditions 1 and 2. I suspect, that thread length may be an issue, which might explain why the prior owner went threadless. If so, the threads can be extended by a skilled shop, but figure it'll cost you about $20-25.

If the thread length means you're stuck with this hybrid arrangement, come back and I'll give you pointers on how it can be made safe.

Thank You very much for the detailed response. I actually imagine that the fork will have enough threads since it is the original fork that came with the frame. This frame set only came with a threaded option so I would be very surprised if the threads . And after talking with the guy I figured he did not know too much about bikes or mechanics. I also called the shop that he bought it from to check what the crown race diameter was and the guy i talked to on the phone had no idea what the difference was between JIS and ISO sizing so that may also explain why he was running this setup, that the mechanics might not have been too knowledeable. But i am not sure about any of this.
I have cut a threaded steerer before and I normally use the Park Tool blade guide and have had no problems as of yet.
Thank you very much for this detailed response though, i really appreciate it.
And if I do end up having to extend the threads i know a few people that could do it for me. I know a lot of machinists and kinda know one of the local framebuilders in town. I hope it all goes well.haha. For some reason I have no doubt it will be fine, but you never know. thanks again