Howto: Replace your stuck carb drain screws

Umm, I dunno about the Mikuni carb bowls with Stainless steel drain screws but I put them in my Hitachi carb bowls and I had seen a picture of them installed before hand.
The picture depicted them with the head of the drain screws not seated. As in they are a bit too long looking when installed.
If memory serves me, I believe, if you bought from chacal, yes just looked here it is
This is what the description said:

Aftermarket Mikuni bowl drain screws:

The HCP6279 screw is correct for all XJ700-X and XJ750-X models with Mikuni carbs. This screw will also work just fine in all XJ550, XJ650 Turbo, XJ900RK, and XJ1100 carb bowls. The original drain screws on those models had an integral o-ring, which is not present on this replacement screw. The lack of the o-ring on this replacement screw presents absolutely no fit or sealing/leakage issues on those models originally equipped with a bowl drain screw that used an o-ring. Note that by their design, the large allen head portion of this drain screw will be located OUTSIDE of the drain screw bore hole in the bowl, and sticks out about 1/4" from the bowl body. This additonal length does not cause any problems, and after looking at them (installed) on the carb bowls, at first glance they might look "odd" the way the stick out, but after the third or fourth look, they appear normal and oddly interesting with that extended length.


SO when I installed mine I was careful to detect when they bottomed out.
To be honest it sounds like you over tightened them. But again I don't have Mikuni carbs so I'm not certain on that.

 

With a lot of patience and heat i cooked out all of my buggered and rusted-in drain screws with a propane torch. It worked like a charm and i was able to re-use my screws after cutting a nice notch into them with a hack saw and then tapping my favorite craftsman flathead screw driver into the notch so it fits perfectly. Don't forget to apply some anti-seize to the threads before re-inserting the screws after cleaning.

Just apply a couple drops of "olive-oil" onto the screw and place the bowl snugly into a vice. Heat the surrounding aluminum with the torch until the oil starts to boil. Then tap your screwdriver into the screw and turn it out. If it gives you too much resistance, apply more heat and oil. Don't worry they'll come out nice and easy if you repeat the process.

 

After having a miserable time with the screws on my master cylinder. I was not looking forward to trying to get out the carb drain screws on the rack I am rebuilding. In under 20 minutes, using heat and olive oil, I have removed my first carb drain screw. I am so happy right now!

Thanks so much for sharing that tip, Palmer. Makes me wonder if the candle wax got those exhaust bolts out in that other thread.

 

Got all four drain screws out now. Had to use heat and olive oil on all of them. Here are some things that helped me as I went along: clean out the bowls before using any heat as mentioned in this thread (didn't do that on the first one), use a dental pick to clean up the threads on the screws and the area around the head of the screw (mine were rusty and this made a huge difference), and modify a slot screwdriver to fit the head of the screw as best as can be expected.

 

check this out, 2 drain scres, no problem. 3rd drain screw - screw extracter bit, no problem. 4th hah! extracter bit just kept goin in, and in, and in, and in, and in, and in, then BAM! So I think it's safe to say these bowls aren't matched to the main body, right?

 

^^^ Oops!

 

Replacement bowls available if needed, just PM me!

 

Gamuru, I just have to say you have an uncanny ability to state the obvious. OOPS!!!! Your comment probably holds more humor for me since in this particular case it isn't MY carb with the expanded volume float bowl.

I am getting ready to rebuild my ebay carbs so I will be VERY careful to learn from the sad stories in this thread.

I plan to get the Craftsman extractor tool, and I think I will replace my old non self-lighting porpane torch with a new one. Would MAPP gas be a better choice since I'm replacing my propane torch anyway? I understand MAPP is hotter but would it possibly be too hot? I also have oxy-acetylene but I have sworn myself to never get it near the bike. 6000+ deg. seems way hot for anything but steel on steel.

 

I'm no thermal expert, but I don't see any problem using just regular old propane. The carb bowl is probably some sort of pot metal, so it will have a pretty low melting point. The idea--as I understand it--is to expand--using heat--the carb bowl while leaving the drain screw the same size. This will increase the tolerance between the two thread faces and allow you to easily extract the screws. Too much heat could warp or melt the bowl. I've also been told that hitting the screw with penetrating oil after heat has been applied will pull the penatrant up into the threads. This will, of course, cool the area down so you'll need to again apply the heat for a bit.

 

wamaxim, I used a small 5 piece Black & Decker set, it works great too... We know it's stronger than than the screw and bowl!

 

I just got through performing this task with varying success. The #1 screw had a large flat-head and was easy to get out. The rest were, or got buggered up, and need to be extracted. I used this craftsman micro extractor, and #2 came right out. The tool ate through it's own threads on #3 and #4. So on #3, I got the bright idea of just trying to use the next size up - not a good idea. Needless to say, with a little heat and PB Blaster, I got #4 out by just drilling deeper and trying again with the right size and some heat, but broke off the bit in #3 after trying lots of different stuff.

As a testament to how amazing chacal is, I asked him what the prices were on his bowls, but also asked if I could set the float height by switching with a good bowl. He gave me the price and the honest answer that yes, float height could be set with any bowl. So I'm just gonna jb weld the drain shut on #3, and make a little extra work for myself when setting the float height.

 

Before I got my screws out I did the same thing - I had one that worked and swapped it along. I'll pass along a tip - I found 2 screws held the bowl without leaking for the adjustment - saves a good bit of time.

 

I was going to say just bang it against a curb... but not only will that not work... not even on a dirt bike where that method of repair might actually make a difference, but this is a very nifty, step by step process. One which I am saving in my favorites.

 

Can someone please tell me where the carb drain screws are located I would like to know how to drain them for winter storage. thanks, Ricksta 1981 XJ 550 Maxim

 

Go here, enter your bike information, click on 'CARBURETOR XJ550H - J - K' on the left-hand column, then look for #47.

(I'm not sure if this link will last, but here's the Carb diagram for your bike.)

 

If the part will come off and fit in my hand (IE bowls) my prefered method of applying heat is a fondue pot of brake fluid on a hot plate. Works wonders on those gummed solid starter jets too. Usual precautions apply, don't hurt yourself.

 

I got mine loose with a fry daddy full of wd-40 . It worked like a charm . Oh and it got them clean too !!!!

 

Sometimes, them who are not totally familiar with the way the Carb Bowls are supposed to be oriented, ... will "Reverse" the order that the Fuel Bowls are meant to be installed.

That is to say, ... the Fuel Bowls with Drain Screws which are supposed to be installed with the Drain Screws facing OUTBOARD: <</<<[]>>\>> get them on back-on there "Bass-ackwards": >>/>>[]<<\<< and the two Drain Screws that you would have easily found and undone ... are facing the wrong darn way.

 

can't see them pitches

hi guys, I cannot see the pictures in post #1. Is it just me?
Aharon

 

"Bass-ackwards" is really funny! Being a bass player myself, I felt "Bass-awkward" when I first read this! lol
Aharon