Disable tumblers RD400 gas cap

[Hawaii-Mike]

I have an RD400 stock gas cap, the key doesn't match the ignition key.  I'd like to remove or disable the tumblers so that any Yamaha key will open the gas cap.  Has anyone tried this?

[RDryan]

Did you consider taking a small enough drill bit and just drilling it out without visabily malling it out too bad? I did just that too one of the hard bags on my KTM Superduke. It worked pretty good I can basically open it with just about anything that will fit into the slotted key way, for example a flat head screwdriver will do it and yes I can put my key all the way in the keyway and twist and turn, works well. I don't mind that it looks a little buggered and it doesn't actually lock so long as I can gain access and it stays shut and attached to the bike. What happened when I drilled mine out was it immediately twisted and took off the little circular sheetmetal tab that you initially stick the key into before it even touches a tumbler then the drill bit just reamed thru all the tumblers. I was able to salvage that circular piece and pounded it out flat after the drille deformed it a bit and I took a smidge of JBWeld to reattach it just to make it look somewhat original. Just a thought to consider that's on the cheap although fair warning it's one of those form follows function approaches that I guess ultimately I may not recommend if you don't wanna chance making it look kinda messed up. To that effect I would suggest don't even consider what I'm saying to do as I really have no idea if what works for me would be the same for your situation but just to make things interesting I figure I'll post this for consideration and further discussion. 

[Hawaii-Mike]

RD Ryan yes that's what I had in mind.  I tried it today on a spare old tank cap and it worked.  Next I drilled out the lock on the tank cap I intend to use.  The second time, the lock was a little fussier but patience with the drill and a screwdriver eventually got it working with any standard Yamaha RD400 key.

Basically you need to drill out all the guts (tumblers, I guess) so that you have a clear view through the hole.  I started bottom up first then turned it over and drilled top down.  It took awhile, maybe half an hour of careful drilling then turning the lock with a screwdriver.  Eventually it opened smoothly with the screwdriver and I got it working with the key.

Before installing the cap, make sure and clean all the metal shavings so that they don't go into the gas tank. I used brake cleaning fluid.

[RDryan]

Sweet glad it turned out well for you.  With my situation it was recommended by the locksmith since KTM use these special square shaped keys. He'd have a hard time making me a copy and like I said it just wasn't worth the trouble to make the hard bag keep honest thieves honest. Oddly enough though KTM did actually sell just the lock with the tumblers separate and it was up to you the buyer to take all that to a locksmith to have it cut and matched to your key.