Jet type for 1978 XS1100

[spayne83]

ok, took the carbs off over the weekend and shot some pictures. First my float height appears to be 23.5mm and not 25.7 like someone mentioned earlier so my floats could be a tad high.


but to the dilemma that probably makes all this a moot point anyway. I found 1 carb that has the mounts for the floats broken. My mechanic apparently patched it and I didn't notice that carb running over or anything but really don't like that.


then finally, the main jets look awful. Even with a magnifying glass, the corrosion had taken its toll on that numbering and I could construe those numbers as darn near anything but if I have to get a set of carbs that's going to be an issue either.

So, currently I am watching a few different carbs setups on ebay. 1 of which is a 1980 XS1100 set of carbs. Are there any other carb setups, I should look for such as a KZ1000 set or specific MM size or does someone have a carb from a broken set. I know my broken one is one of the inners. Don't remember off hand if its a left or right one though.

I was wondering if this is the correct way to set the float height? I thought it was supposed to be measured from the gasket seating surface without the gasket. At least that is what the manual says.

[motoman]

I was wondering if this is the correct way to set the float height? I thought it was supposed to be measured from the gasket seating surface without the gasket. At least that is what the manual says.

Correct.........without gasket.

[brharris27370]

well I measured from the edge of carb to float which is pretty much flush with that gasket. I could take the gasket out and measure again but that gasket is likely close to 2mm thick and would put the height pretty much correct and they all did measure within a few hundreths of each other with my incorrect measuring method.

[motoman]

well I measured from the edge of carb to float which is pretty much flush with that gasket. I could take the gasket out and measure again but that gasket is likely close to 2mm thick and would put the height pretty much correct and they all did measure within a few hundreths of each other with my incorrect measuring method.

Unfortunately, 'pretty close' isn't close enough. a half a millimeter changes actual fuel levels 1.5mm. With gasket removed, spend the time and get those 8 float settings IDENTICALLY the same. Removes any question when tuning issues arise........and they will before your done.

[spayne83]

Another question:

When setting the float height the manual says nothing about holding the float to prevent it from depressing the inlet needle valve, but here:

http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html

It says:

"Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring."

So which should we go with? It sounds like a PITA to hold the float off the needle to measure the height.

[bikerphil]

Let it rest in it's natural position, do not compress for measuring, do not lift it either.

[DGXSER]

Let it rest in it's natural position, do not compress for measuring, do not lift it either.

Exactly, the float will rest on the valve, if you push on it, you wil notice it can compress the spring in the float needle valve further. You do not want to compress it beyond what the weight of the float does.

[WMarshy]

...

but to the dilemma that probably makes all this a moot point anyway. I found 1 carb that has the mounts for the floats broken. My mechanic apparently patched it and I didn't notice that carb running over or anything but really don't like that.


...

Maybe it was like that when he opened it up but maybe not, do you think he would tell you otherwise? Just another good reason why I like to do my own work. Even if he hadn't broken it, a good mechanic would tell you about it IMO.

Glad to hear about your progress, hope you get a new carb body. Try our parts guru, forum member Andreashweiss. If you want a cheap fix there is a DIY tip what is not too involved or requires special machining tools (see link above in previous post).

[brharris27370]

Well, I didn't update when I got the carbs done because I gave the old girl a little make over. I ended up replacing the one carb that had the broken posts with a $35 used one on ebay and I then replaced all 4 main jets with new genuine mikuni 137.5 which took over 2 weeks to arrive. Now motor starts much better and runs the best it has to date. so I justified giving the old girl a little face lift and decided on a little sportier look.