Carb ID and spec questions

[jonathacvb]

Thanks again for all the input. It’s rather enjoyable learning and problem solving.

The retaining clip is currently set in the lowest notch on the needle. Thanks for confirming about the plastic piece fitting in the hole. I though that was the case but wasn’t 100% sure.

Does the slide needle only have a function in correlation to the Main Jet, or does the slide needle work along side the pilot jet aswell?

[Schming]

Thanks for the input fellas, it’s gonna take me reading it all a number of times to understand it clearer. However, does it make sense that the needle has been adjusted to compensate for the smaller pilot jets?

also, thinking about it. All the jets are brand new (from what my limited experience tells me). However, one of the jets was seized and so it never got replaced. I was able to extract it and have any extra from a salvage bike I was planning to use. I’m not sure this plays into it at all but it begs the question.. do jets need to be replaced occasionally or can you use them for a long time provided there maintained well?

Make sure the new jets are genuine Mikuni. They'll have a small square inside the corner of a larger square.

[cajun31]

The mark that he mentioned. All Mikuni jets will have this square within a square on them.

If you need new parts you need to order the correct parts. For the xs1100 carbs you need to order BS30/96 pilot jets and N100.604 main jets. one source for jets is Jets R Us Mikuni carburetor jets and parts - Jets R Us. You can also find them on Ebay.

[jonathacvb]

Ok, so I have thoroughly dismantled and cleaned the carbs. Yes, I confirmed all the jets are genuine mikuni.

- I adjusted the float bowls to 23mm from the base
- I bench synched the throttle valves in the correct order
- I seated the fuel mix screw and backed it off 2 complete turns

I then reinstalled the carbs and tested it in the shop and took it for a ride. Here's what I am facing.

- Bike starts no problem with no leaks and sounds better than previously (MUCH less popping and sputtering but still a little bit when riding
- Bike will not stay idling. I played around with idle adjuster but it forces me to adjust it to a high idle (1500 and up) and then seems to not idle consistently. I was able to get it to idle somewhat smoothly between 1000 and 1500 but it eventually it will slow down and die.
- I pulled the spark plugs (which are new) and recognize that since they were new they have been running VERY rich (dark black fouling around)
- There is oil surrounding the seats and threads of the plugs (2 worse than the others)

I understand there are a few more adjustments I may need to be looking into such as the valve clearances, cam chain tension and perhaps timing? In your opinion are these other adjustments likely to help with the idle, or were there some steps I missed prior to this that I should be going back to check?

When riding the bike it feels and sounds significantly better than before I pulled the carbs apart (more power and response) but it dies anytime I come to a complete stop unless I hold the throttle open. All feedback is appreciated

[DEEBS11]

A possibility with these old bikes is even though your jets look genuine they could be possibly drilled out by a hack-artist. Also, you could have a bad coil. Clue: "There is oil surrounding the seats and threads of the plugs (2 worse than the others)". Might look like oil but could be raw fuel. Follow those plugs to the coils and see if they both go to the same unit. (Make sure your firing order is correct).

Another thing you said was "Clip on the lowest notch". If you are holding a needle with the point down like it is situated in a carb, then the lowest notch is the richest setting. Try about two steps up. Pay close attention to the plastic spacer orientation. If the needle does not fit down flush it will run crazy rich because the needle will be too high.

[cajun31]

you also need to do a true synch on the carbs with gauges. If popping still remains after that then I would suspect you have a vacuum leak. The intake manifolds may be leaking where they meet the engine. Another source of popping is out of tune pilot jet screws and if popping is occurring on deceleration then suspect the exhaust gaskets. From where you are now though I would do what deebs has suggested and then do the true synchronization with gauges. These bikes only have to be a little bit off to cause what you are experiencing.