Excessive RPMs in Neutral.

Hi guys Noob here. And by noob, I mean I might be just a little over my head, but that’s okay. Trial by fire? :’D

I picked up an 1980 XS1100 Special a few weeks ago here in Texas, and was told by the PO that the Special was mostly interchangeable with the XJs and that he got most of his info/parts from here. The PO loved the bike and took well care of it, but one day the carbs started leaking and he just didn’t have enough time to fix it with kids and 3 other bikes. There it sat in the garage for about 2 years (after of course draining the fuel tank) PO said outside of the carbs, he drove it till he parked it.

Over the last 3 weeks, I’ve taken the carb out and apart and didn’t see anything wrong with it (probably should’ve just rebuilt it but the parts look clear and great PO said he rebuilt it 2 years earlier)

I replaced the fuel lines and fuel filters (which were straight out of the 80s and were cracked) and cleaned the rusted tank and general maintenance.

Yesterday we fired her up, and after a few minutes of shaking her and forgetting to put her in neautal, she fired up. She sounded great for exactly 10 seconds, then she started soaring to 5000 rpms. I had forgot to put the nipples on the vacuum ports, but I put them on and seemed to reduce the rpms down.

I’m a little lost to what do now? Do I need to resync the carbs or what? I was thinking that since the PO rode it till it was parked that some more “intensive” repairs wouldn’t be needed to get it running just yet.

 

Check for vacuum leaks on intake boots
Spray with anything flammable like wd40

 

I'm going to suggest you start with the basics. First, do you have a repair manual? Since you had the carbs off the bike, I'm thinking the throttle cable may not be adjusted properly, or the idle stop screw is way out of adjustment. Check the easy stuff first.

 

The XS1100 is quite a bit different from the XJ series (aside from the XJ1100, which uses basically the same engine).
We are knowledgeable here, but XS11.com is another great reource that is model-specific.

 

Carb 101 if crank case gets filled with fuel, float needle and seat have issues , if the needle has Viton tip they take on a groove and get hard hence a sealing problem , you can polish the seat with a qtip chucked in a drill and metal polish , a couple of pulls of the trigger usually does the trick. As for the needle replace them.

 

Fuel in the crank case will make it run high idling?

 

Fuel in the crankcase will lead to runied crank bearings (at best), or bent connecting rods (and sometimes fires).
The high idle is another issue, but also related to the fuel system.

Your carbs are in dire need of a full strip and refresh, and both problems are proof of that.

It is very often true that what the PO says he did, and what he actually did, are not the same.