Topic: Float bowl threads stripped... now what?

[jorwesflow]

After reading the last thread on Pods ("...I Surrender!") I realized that I needed to get back to stock, me being a rookie in the SOHC4 world and all, and not having the expertise to tinker around with the carbs to tune them in to the pods. Part of that was going back to #98 Jets on my 1976 CB550F.
So I took the carbs off the bike, took the bowls off, and went to put the new jets in. Upon remounting the bowls, I apparently over tightened two of them, although I wasn't going Hulk-style on tightening them, they still stripped. Now I've read a few different threads on how to remedy, but I don't have the tools handy to re-tap, nor have i ever done that before, and i know how brittle that carb body is. I don't want to crack anything.

My only solution was to find some longer pan screws (stock is 10mm long) and use a nut to tighten down. There's only about 2mm of clearance on the top side because the carb plate is there. I don't have any 12mm pan screws on hand, so I was looking here to buy: http://www.microfasteners.com/catalog/products/METMSPPS.cfm but i have no idea what their measurements are referring to. What is M3? or M4? what does that mean? And is there a nut thin enough to fit in that 2mm clearance?

Any other ideas? thanks   

[mitch500]

same thing happened to me... i used this DIY to repair them. i have the same bike as you also.
http://forums.sohc4.net/index.php?topic=37129.msg383375#msg383375


oh and i didn't do all the holes just the 2 that were stripped.

[Jon]

M3 is 3mm & M4 is 4mm standard pitch metric bolt.

Not sure that there will be enough room for the diameter of a nut against the side of the main carb body.

I would use a heli-coil type repair, something like this;

http://item.mobileweb.ebay.com/viewitem?itemId=290576516991&index=0&nav=SEARCH&nid=71048045523

Cheers
jon

[bollingball]

You have 2 or 3 options  (1) file down a nut for the 2mm clearance (2) re tap for the next size larger (3) use a self tapping screw

M3 & M4 is just talking about the (m) metric diameter 3MM or next size larger 4mm


                Ken

[jorwesflow]

same thing happened to me... i used this DIY to repair them. i have the same bike as you also.
http://forums.sohc4.net/index.php?topic=37129.msg383375#msg383375

yeah i read that same thread. i may give it a shot. don't be surprised if I break something!

M3 is 3mm & M4 is 4mm standard pitch metric bolt.

ok, so what are the stock screws? M3? and what is that 3mm referring to?

I would use a heli-coil type repair, something like this;

i've never used one of those before. is that what i need to do what Mitch said?

(3) use a self tapping screw

this seems the least time consuming and easiest for a rookie like me. is it dangerous? i.e. will i crack anything?

[WarwickE36]

Tapping new threads is super easy, I hate to say it but "A caveman can do it"

go to the hardware store and get a tap for 1 size up from stock, on the back of the packaging it should tell you the proper drill bit size to use as well... drill out the bad threads with the bit, then use the tap to tap new threads... you will need either a tap bit holder or a proper sized wrench to turn the tap.. the tap holder is better because if used properly keep even pressure on the tap keeping it perpendicular to the hole you are threading.  get the right size bolts when you are done with the right threads and you're done.

[SurfinBird]

I'm having a similar problem. I was thinking of using jb weld and re tapping. Anyone try that? Would it hold? Not to worried about heat and it's only 2 screws out of 3.

[bollingball]

Jorwetflo: If you go the drilling route be carfull if the drill grabs it could go further in than you want. Go slooow and be ready to pull back fast on the drill motor. If you have not done this before practice on something first. The pic. shows a though hole as opposed to a blind hole.

After thinking about this I have in the past just used the next larger screw 4mm instead of 3 and it is still holding good this was on a through hole like your pic. These carb bodies are soft so the screw will cut new threads

                         Ken

[jorwesflow]

After thinking about this I have in the past just used the next larger screw 4mm instead of 3 and it is still holding good this was on a through hole like your pic. These carb bodies are soft so the screw will cut new threads

i may try that first. help me understand, isn't the stock screw already 4mm? the fiche says 4x10. that's 4mm width (i.e. the diameter of the part that screws in) by 10mm long (i.e. length of the screw, not including the head). and how does "M3" or "M4" translate into these two measurements? i'm sorry for all the ?'s, just trying to decode this stuff.

[bollingball]

jor: Take one of your screws to the hardware store if it 4mm then you need to go up to a 5mm that is the diameter. Now that next size bolt what ever it turns out to be may not slide through the bowl so you may need to enlarge that whole. I have a spare rack just took one out it was 4mm x 15mm. From now on when when you tighten these small bolts just use two fingers on the driver they don't need to be super tight.

It translate like you said it is 4mm in diameter and 12mm long. The 3mm just came from your first post. Just take yours with you an get the same length as your old one but one size wider. Sorry if I'm not making this clear. Just keep asking we will get it sooner or later If you get a 5mm tap you could re-tap no need to drill

                     Ken