1980 xs11 Special wont run

[Sinister Imaging]

Hey guys,

I went in and cleaned the carbs on my 80 xs11 special. the float valve assemblys were destroyed by the PO, and the idle mixture screws were broken off in 2-4. got them out by pressing them out with a short bit of a #60 drill bit. i ordered 4 carb kits the piolt and main jets in the k&l kits were numbersed the same as what came out of the carbs. I bench synced the carbs. and the idle screws are 2 1/2 turns out.

the bike seems to only be running on the #1 cylinder. 2-4 pipes are cold. only idles for a couple seconds on full choke. Got snappy blue spark on all 4. is the new main and piolt jet to blame?

[natemoen]

You say the pilot jets were numbered the same but did they look the same? There are several style pilot jets that will for but only one is correct. There should be 6 holes around the side in a 2-1-2-1 pattern. If it is not like that then they are wrong.

Also sounds like there is still something clogging the passages though. Probably need to clean them again.

[James England]

1. Was the bike running before you cleaned the carbs? I suspect not, if 2. below is true...

2. What do you mean "float valves destroyed by PO".... what were they like? Totally ruined and non-functioning? Allowing bowls to overflow? No fuel going into bowls?

It looks as if you may have no fuel in 3 carbs. Have you checked that there is fuel going into all the carb bowls? You can do this by undoing the brass bolt on the bottom of each float bowl, with the petcock on 'prime'. You should find fuel comes out (onto a rag which you put under each bowl).

Did you use the correct kits? 1980 was a changeover year for some carbs. What sort of floats and valves do you have? Brass floats? Plastic? Viton-tipped needles? Solid needles?

More data please......

[natemoen]

Also does the rubber pilot plug need to be used or not? Is there a cross passage drilled between the pilot and main jet tunnle? If there is a passage then you need the plug, no passage then no plug.

[motoman]

If it hasn't already, the K&L kits are going to give you a nitemare trying to tune. No matter what the jets say, they ARE different. Gaskets, etc. in the K&L kits are fine to use......jets, including pilot jets HAVE to be Genuine Mikuni if you plan on having a smooth running scoot in ALL the rpm ranges...........BTDT.

[Sinister Imaging]

Also does the rubber pilot plug need to be used or not? Is there a cross passage drilled between the pilot and main jet tunnle? If there is a passage then you need the plug, no passage then no plug.

It lives! There was something blocking the pilot jet it was the passage plugs the po must have bought thinking they were missing.

[James England]

Jets, including pilot jets HAVE to be Genuine Mikuni if you plan on having a smooth running scoot in ALL the rpm ranges...........BTDT.


On what do you base the above statement? I keep reading on the forum about genuine Mikuni jets being essential and, certainly in my own experience, it's just not true. My XS1100 behaves like a brand-new one ( I had one and I remember it well). It pulls through all the rev range without fault and it never misfires. Blip the thottle and it drops perfectly back to tickover. Open the throttle to 6,000 rpm and hold it there and it doesn't even splutter. It starts on the button first time every time. It's as fast as a standard XS1100 can be.

It does NOT, repeat NOT, have Mikuni jets.... I know, because I put them in. Send me a set of Mikuni jets and I wouldn't swap them over because the bike runs too well on the non-Mikuni ones and why spoil a good thing?

[motoman]

Good on you and your scoot James! Guess excepion to the rule is possible.......but definitely not the norm. Based on, BTDT and among the majority BTW. As has been stated on here, Mikuni uses flow rates to come up with the jet sizes. Aftermarket manufacturers uses who-knows-what as an equivelant number size is not even close to Mikuni hole size. Aftermarket (K&L,RD) hole sizes are bigger in relationship to equivelant Mikuni number sizes. The backside where needle rides in is also a slight different angle than the Mikuni jet. May have something to do with patented rights, but I do know they are NOT the same, and the bike will NOT perform right with these jets, be it mains or pilots. Having bought THIS scoot new(never should of sold it), I know exactly what it is susposed run like in all scenarios of different elevations(sea-level to 13,000ft) and how it SHOULD act in all the prm ranges. When it wasn't 'there', suspected fingers where in there that should not of been there............sure enough, had 81Special carbs instead of the Standard 81 carbs(different metering rods and mains between the two models)......so through the Mikuni maze I went finding dead-end afer dead-end as a result of me selling it after 10yrs..........Now I gotta deal with the PO thing.

[James England]

That's interesting to know. I wonder if the fact that mine has the 'older' carbs (being a 1979) makes a difference? I mean, really, I must be very lucky indeed because I just cannot fault the kits I used. I love my bike but would be the first person to say if it wasn't performing properly. I just can't fault it.

It's something to bear in mind for the future projects, methinks. I don't want to trust to luck in getting the next one right.

Where do you get Mikuni jets from then?

[Sinister Imaging]

I was looking at the carb kit's packaging and the jets are not k&l, they were tour max.

[motoman]

Familiar with TourMax, but didn't know a branch of them did aftermarket jets. That is if they are one and the same. James, Always have been able to get the jets from ANY dealer.....just look at them if not in Mikuni packaging and make sure they are Mikuni. Their tiny logo kinda looks like a box with a swirly-qued lookin' box inside the outer. The years make no difference on our XS's, they use the large Mikuni for mains. The smaller single cyl. scoots had the the Mikuni that uses the small diamater Mikuni main jet. Was just at a dealer this afternoon checking if they had the Mikuni 42.5 pilots, BS/96 six holers, which they do and are Mikuni. Gotta watch as some of the shops and dealers alike end up with trays of jets THEY say are Mikuni, but are the look-alike K&L, RD, etc. Just beware, and look at them yourself before buying!