Replacing needle seat and float..

[Riddle]

Ok I'm in the process of ordering parts...I'm lookin on mikesxs.net Should I go with platic or brass float? Is the threaded type needle and seat the rite one? I would hate to order the wrong parts. I have stock mikuni cv carbs. 34mm or 38mm?

[geobiker]

Floats

If your carbs are indeed stock on your 78XS, then they are 34 mm Mikuni carbs. I was likewise interested in the brass floats from Mikes, however I did a Yamaha part number search for the carb floats on the 650 and it is not the same part number as for the XS1100. From the picture shown on Mikes website, the picture looks identical to my floats, but I am wondering if the dimensions are different. They are reasonably priced compared to any Yamaha NOS floats that I have seen on e-bay, so I am also interested as to whether they would fit my 79F model, which also has the 34 mm Mikuni carbs.

[dbeardslee]

The brass mikes floats will not fit an XS11 - they're way wider and for 38mm mikuni carbs. The plastic ones will fit fine in 78/79 carbs, and IMHO are superior to the brass floats anyway. Might I suggest the XV920 fuel valves to go with them? When I first put the plastic floats in my '79 I had to bend the tabs so far that I had to round off the ends to keep them from sticking on the lip of the seat. The XV920 valves, in addition to being viton tipped with clips, got the seat up high enough that I barely had to bend the tabs at all.

[Riddle]

Thanks I've sreaching post and I read that also. I think it was actually one of your post.. Why do some say they shaved the plastic floats?

[geobiker]

I was interested in trying the plastic floats, but in a previous post some time ago, someone said that they had problems with them hanging-up on the side of the float bowl. I would agree that the platic floats would be superior to the brass floats in that they are probably more uniform in mass. Based on the height that you set your floats, is it safe to assume that I could measure and set the heights of the plastic floats the same that I have my brass floats set?

[dbeardslee]

Yes - you set them the same way as the brass ones, but they'll never leak. Some people have shaved them to keep them from hanging up on the bowl, but I don't think it really does anything - voice of experience speaking . I've got three that I shaved a little off of, and one that I didn't. They all work fine, and if I had it to do over again, I would just have left them alone. Make sure you set both tabs when you install - the one that makes contact with the needle, and the one that limits the floats movement by making contact with the float tower. They can get hung up sometimes if they're too 'loose', for lack of a better term. When I drain the bowls, without fail I'll get one or two floats that stick when I first put gas to them. A tap with the back of a big screwdriver and they're ready for another season. I've had the brass ones hang up too though, so I don't think the plastic ones are any worse about it.

[Riddle]

I did a little test by swapping out the float , needle and seat from a non leaking carb and put it into the leaking carb and it still leaked and the carb the with the parts I thought were at fault didn't leak at all!!!! What else could it be?

[dbeardslee]

When it starts leaking, have you tried tapping it with the back end of a large screwdriver? Whenever I drain my bowls all the way and let them dry out, I'll get one or two that stick when I first turn the gas on. Tap with a screwdriver and they behave. Did you change the float pins with the floats? A bent one might make a float hang up. Just thinking of stuff.

[Riddle]

Ya I gave it a pretty good whack. Nothing happened.

[dbeardslee]

Did the carbs you swapped the parts between share a fuel "T", or were they on different ones?

[Riddle]

Yes they shared the fuel and vent T...?

[Riddle]

Parts where fine. The problem was a clogged "T" Vent. The T between carbs 3&4! no need to replace yet

[dbeardslee]

I\'ve been having trouble for the last week accessing the site (my isp has done something stupid - again). I kept trying to post to check the vents again, but looks like you already did it. Doesn\'t it feel good when you finally find that little piece of crud that\'s been blocking things and making your life miserable ?

[Riddle]

Ya I was so stoked. A weight was lifted off my shoulders.