Plastic floats and XV920 float needles in the 78-79 carbs

[natemoen]

Nate, did you also switch to the XV920 float valves? The ones with the VITON tips?

No, and I guess that could also cause a height difference if the needle is a different length.

[skids]

You definately need to check fluid heights with a manometer, and when you get that right, then measure your upside-down "height" with a caliper for your new baseline.

I believe that if the pressed-in air jets are not clear, the airbleeds in the sides of the emulsion tubes with not draw air and that would make it rich in the main jet circuit (mid to high throttle).

[DGXSER]

Skids, I did go back and check, the main air jets are open. Seems it must be down to the fluid height in the bowls.

I suppose it may be simplest to buy a bolt to match the dain bolts and put bleed nipple in it to attach a hose to check fluid height. I hope these XV920 viton tips last forever, since longevity of the float needle was the purpose of the swap.

[skids]

I have never tried the manometer thing with my 78's. I hope you find a nipple that fits. I think there was a thread about that. A drilled zerk maybe?

[DGXSER]

Well, the big push to get them ready has ended, see thread on XSively Frustrated.

On a brighter note, I put these carbs on another XSives bike to test for a low end miss, but also got that bike up to 6k with these carbs on. Did not really top out the carbs. So may try them on my bike shortly and see how they do now.

[rs2289]

I gotta love the search function. I was looking at carb parts for my rebuild and asked myself if I could replace the floats to plastics and here its, level recommendation and everything!

[conquest87tsi]

I would like to convert to the xv920 float needles and was wondering if anyone had just changed to the xv920 needles and used the xs1100 mikuni seats. I don't even know if this would dimensionally work, but it sounds like the metering hole is the same. I was just thinking this would eliminate the seat height/float height issue.

I hate to even say this, but I am still unsure as to what to set the floats too. I have two '79bikes elevens. Both with '79the carbs now. One has the brass floats and I obviously set those to 25.7mm with good results. The other, more recent purchase, had two brass and two plastic floats when I purchased it. The PO supposedly went to school for power sports, ha. So now it has 4 plastic floats.

Now..there seems to be quite a bit of controversy as to what to set the basterdized '79 carbs with plastic floats to. Originally I always had read to set to the height for the carbs, this was accompanied by statements that plastic and brass floats float nearly the same. Now I am reading, from reputable xs11 members, that they should be set for the floats.
I don't know what to believe. As there were more changes in'80 to the carbsheight than just the float material, I will probably set to 25.7ish and see were I am. Unless I get a compelling reason to not. I know I will have plenty of plug checking to do to fine tune, just want to reduce the amount of carb removal as much as I can.

I realize I didnt clarify this earlier, but I am planning to put the xv920 needles in the carbs with brass floats, and just looking for height guidance on the bastardized carbs. Looks like I will have a lot of carb disassembly in my future once I start tuning.

[mack]

viton tips

I had switched to the viton tipped needles and seats when I first finshed the SF. I'd set my float height to the usual 25.7 (brass floats). I drove it for a few hundred miles and everything was fine. Then a float developed hole and sunk on me. Felt like bad gas but I eventually figured it out. Replaced all for with the cheap plastic floats and set the height at 23mm as specified and it seemed to work fine, until I had to park on a hill. I walked back to the bike after a couple hours to find a large pond of gas surrounding it. I cleaned it up as best I could, drained the air box etc. and since it was a short ride home, I started the bike and was home in 15 minutes. Emediately drained the oil and pulled the carbs. Chased that demon for about three weeks. What I found was that the float height was incorrect on two of the plastic's. The numbers were identical but their boyancy was different I guess. The end result was that they had forced the viton tip into the seat so hard that it distorted the tip leaving a shoulder that wouldn't seal again. Scott (3Phase) was the one who told me to look for that.
To make a long story short, thats why I always check my floats manually and use the metal float pins and their proper seats now. Never had a leak since and power range is smooth and solid from 1050 to red line.

[donebysunday]

I could not find the right long nose clip pliers to re-install the clips. I ended up buying Sears mini long nose pliers and using the Dremel grinding a small notch in the end to hold the clips in the right position, worked a charm. Don };~)

[DAVINCI]

I also run a 79 standard, plastic floats, one main jet size up (since 2005 when I put a MAC exhaust on). No other carb alterations.

Not to say anyone is wrong here, or maybe I'm just the luckiest S.O.B. here, but I did this change in the winter of '11 and it went smooth as silk. I set the floats to standard height and synched, pilot adjust, et al as usual and no issues at all.

79 standard, plastic floats, one main jet size up (since 2005 when I put a MAC exhaust on). No other carb alterations.

[DGXSER]

Did you also change to the XV920 valves?

[DAVINCI]

Yes, that's where this thread started... XV920 valves... i am a convert and it was an easy change. i had read all the posts about this and the scary warnings that it's practically rocket-engineering, (different depth, blah, blah) but in the end if you set the float to the standard height you should be good to go.

All I know is, it worked for me.

P.S. I changed the valves as sets, needles and seats. i would not mix and match.