carb bowl drain screws

i saw in some pictures, where a member had replaced the drain screws in their carb bowls with a socket head screw or bolt...

does anyone know who it was and how i can find out what they did exactly?

thanks

 

I've done mine on the 750, but I don't have pics handy. Got the aftermarket ones from Chacal.

 

HITACHI CARB BOWL DRAIN SCREWS:

g5) Aftermarket Hitachi carb BOWL DRAIN SCREW. Bright finish 18-8 stainless steel allen head (hex-drive socket head), taper-point screw fits into the drain hole passage of each carb bowl. Works better than the original Yamaha screw; not only is it made of stainless steel, but the larger allen-head design allows for more torque to be applied to the screw, forever ending the stripped/stuck/ruined drain screw problem that has plagued Yamaha owners forever! 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 additional 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.

Fits all XJ650 (except Turbo) models, all XJ700 non-X, and all XJ750 models using the Hitachi HSC-32 or -33 series factory carbs.

It is recommended that anti-seize compound be used on the screw threads when fitting them into the carb bowl passage.

HCP54 Aftermarket Hitachi allen-head stainless-steel carb BOWL DRAIN SCREW, each:
$ 5.00

HCP54SET4 Aftermarket Hitachi allen-head stainless-steel carb BOWL DRAIN SCREWS, set of 4:
$ 16.00




MIKUNI CARB BOWL DRAIN SCREWS:

g5m) OEM and aftermarket Mikuni carb BOWL DRAIN SCREW....the ones that are always such a bear to remove. OEM screws are bright-plated alloy steel with a panhead, phillips-drive design, and come in both the version WITH the o-ring under the screw head (all XJ550, XJ650 Turbo, XJ900RK, and XJ1100 models) and the style WITHOUT the o-ring under the screw head (all XJ700-X and XJ750-X models).

NOTE: If you plan on using the HCP865 screws WITHOUT any o-rings, I very STRONGLY suggest you use the HCP4399 drain screws instead, and here's why: for whatever reason that Mikuni/Yamaha decided to use the o-rings on these bowl drain screws, the fact is that in order to make the o-ring land or "groove" (where the o-ring sits), they turned down the shaft of the screw by almost 2mm total, thus turning an M6 sized screw (that's the nominal size of both the HCP865 and the HCP4399 drain screws) into an M4 sized screw......kind of a "chain only as strong as it's weakest link" kinda thing......since the "skinniest" part of the HCP865 screw shaft is now just a hair over 4mm diameter, and in effect this is now a M4 (4mm diameter shaft) screw.

Since these screws tend to get stuck in the bowls after a few years of non-use, I believe what Yamaha discovered very quickly was that these o-ringed type screws---the HCP865's with an "in reality" size of just M4---were getting stuck and shearing off right at that "weakest link" portion of the shaft....the o-ring land.....and that is why they did away with the o-ring land on the later model versions of the Mikuni carbs, and started using an unmodified version of the same screw (which is the HCP4399 screw), which is a "true" M6 screw.

In fact, the HCP865 screw and the HCP4399 screw are identical, it's just that the HCP4399 screw is not machined for a ring land.

Aftermarket socket head cap screws are an improved "never-get-stuck-again" version that are made as an 18-8 stainless steel allen head (a/k/a hex-drive socket head cap). This style works much better than the original Yamaha screw; not only is it made of stainless steel, but the larger allen-head design allows for more torque to be applied to the screw, forever ending the stripped/stuck/ruined drain screw problem that has plagued Yamaha owners forever! 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.

It is HIGHLY recommended that anti-seize compound be used on the screw threads when fitting any bowl drain screws into the carb bowl passage.


OEM Mikuni carb bowl drain screws:


HCP865 OEM Mikuni carb BOWL DRAIN SCREW, correct bright plated, alloy steel, panhead phillips drive drain screw features the machined land just below the head for the acceptance of the HCP4400 o-ring listed below. This style drain screw is used on all XJ550, XJ650 Turbo, XJ900, and XJ1100 models, although it will also fit all XJ700-X and XJ750-X models also. Each:
$ 6.00

HCP865SET4 OEM Mikuni carb BOWL DRAIN SCREWS, correct bright plated, alloy steel, panhead phillips drive drain screw features the machined land just below the head for the acceptance of the HCP4400 o-ring listed below, set of 4:
$ 22.00

HCP4400 OEM Mikuni carb bowl drain screw O-RING, for the HCP865 drain screw listed above. Each:
$ 2.00

HCP4400SET4 OEM Mikuni carb bowl drain screw O-RING, for the HCP865 drain screw listed above, set of 4:
$ 7.50



HCP4399 OEM Mikuni carb BOWL DRAIN SCREW, correct bright plated, alloy steel, panhead phillips drive drain screw. This style drain screw does NOT use an o-ring and is correct for all XJ700-X and XJ750-X models, but can also be used successfully on all XJ550, XJ650 Turbo, XJ900, and XJ1100 models, each:
$ 6.20

HCP4399SET4 OEM Mikuni carb BOWL DRAIN SCREWS, correct bright plated, alloy steel, panhead phillips drive drain screw features the machined land just below the head for the acceptance of the HCP4400 o-ring listed below, set of 4:
$ 23.00



Aftermarket Mikuni carb 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 additional 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.

It is recommended that anti-seize compound be used on the screw threads when fitting them into the carb bowl passage.


HCP6279 aftermarket allen-head stainless-steel carb BOWL DRAIN SCREW, large socket-head cap screw (a/k/a allen-head or hex-key drive), 18-8 stainless steel, each:
$ 6.50

HCP6279SET4 aftermarket allen-head stainless-steel carb BOWL DRAIN SCREWS, set of 4:
$ 24.00

 

I changed to the Allen head carb bowl drain screws.

Soooooooo much easier to work with them now.

and my original screws weren't too bad just seemed iffy
as to when it would be a problem. You will be happy you changed.