Now I did it. Stripped a carb diaphram cover screw. 2009 F model.
Diagram: http://www.bikebandit.com/2009-suzuki-gs500f-carburetor/o/m19099sch650007
Looking at the diagram, This is #39 that is 180 degrees from where #39 is in the picture (meaning the other screw). There is something that is blocking my tap and die set from going all the way through. Need to tap to the next size bigger since the other threads are toast.
My question is, can I take the carbs apart in any way to tap all the way though, or should I source some new carbs? Bike still runs (for now), but I feel that this will need fixed. Putting washers on the old screw does no good.
EDIT: Look down a few posts. Added a better picture.
If you can't get to the backside of the hole, I would say look into getting either a bottoming tap or some self-tapping helicoils. Don't forget new screws too. You don't want screws with buggered threads going into a new helicoil.
EDIT: or maybe a really tiny c-clamp? :P
Here's the screw (A better picture. Not my bike, but you get the idea):
(http://i1260.photobucket.com/albums/ii569/jestercinti/CarbScrew.jpg)
Dont use a cutting tap on soft alloy, especialy small diameter ones. You need to use a forming tap.
(http://image.thefabricator.com/a/articles/photos/1057/fig1.jpg)
Forming tap on the right.
Thanks for the tip. Knowing me, I would have used a cutting tap, cause that's what I have.
Update: Made it to work today. The screw goes in hand tight with a washer, then 'pops' out of the threads. Bike does not seem to run any different for now. Will not go on any long trips until its fixed.
Ordered a quality forming tap on e-bay. May wait until closer to Winter to do this in case I really screw this up and need to source a new set of carbs, or helicoil.
I've tapped before, just not a forming tap, more a typical cutting tap. It's a blind hole, so this is also new to me as well. I'll try tapping on a scrap piece of metal first.
So, for the curious.. What's the difference between a "forming tap", and just having a screw type that's hard enough, and just ramming it in there? :D
Forming tap uses and information: http://www.cnczone.com/forums/general_metalwork_discussion/137203-when_use_forming_tap.html
Having a screw and ramming it in there - While inserting a screw at ramming speed will work for a short yet undetermined about of time, I'd like to do it right the first time. Not doing the job right the first time can and WILL cause breakdowns on the road in the middle of nowhere in the rain with drop bears and angry mad kangaroos during the next zombie apocalypse.
Remember also that forming taps need a slightly larger diameter pilot hole than cutting taps do :thumb:
Actually, that is not a blind hole. There is a hollow rod that is in between the 2 carbs for support and a large screw with a large phillips head that comes in through the side of the carb holding it all together. Look on the outside of the carb in question just under the lip of the carb case where the diaphragm sits for this screw head. Once you remove the large screw, the hole you need to tap will open up into the passageway where the large screw was.
My concern with enlarging the hole with the bad threads is that there is not much material between the inner threads of that hole and the lip of the diaphragm. Another option would be to fill this hole with metal epoxy and redrill and tap the hole to the original size. After filling the hole, you can use the diaphragm cover as a guide for redrilling the hole.
HTH
Quote from: pardegt on September 07, 2012, 03:09:42 PM
Actually, that is not a blind hole. There is a hollow rod that is in between the 2 carbs for support and a large screw with a large phillips head that comes in through the side of the carb holding it all together. Look on the outside of the carb in question just under the lip of the carb case where the diaphragm sits for this screw head. Once you remove the large screw, the hole you need to tap will open up into the passageway where the large screw was.
My concern with enlarging the hole with the bad threads is that there is not much material between the inner threads of that hole and the lip of the diaphragm. Another option would be to fill this hole with metal epoxy and redrill and tap the hole to the original size. After filling the hole, you can use the diaphragm cover as a guide for redrilling the hole.
HTH
I just went outside and looked at the carb in question, and I now see what you mean.
I noticed that running the bike with 1 screw, and the other stripped screw on hand-tight, the bike runs OK. I won't go on any long trips like this, but I'll likely run to and from work (12 miles) for the rest of the season (likely 1 month or so) and then over the winter, disassemble the carbs and fix.
Thank you for all of the ideas guys!
Update 9/23/12: After a hectic week at work and busy few weeks with family stuff, I was finally able to fix. I was a bit nervous, since this was my first experience with a forming tap.
Took everything apart, including the screw and pipe spacer holding the carbs together (Screw is made of cheese like the float bowl screws). Used the forming tap to cut new threads. Took a bit of torque, but I went slowly until the job was done.
Installed a new cap screw, and it's all fixed! WooHoo!
Awesome work!