1980 xs1100 F running lean, if at all on 2 cylinders.. PLEASE help!!!

[Worsley]

hey guys, im very new to the motorcycle/carburetion world, but luckly i am a licenced automotive mechanic.. so im not completly lost.

Bike is a 1980 yamaha XS eleven, i believe its an F code bike, it has 1 size larger jets, and a semi-performance(?) exhaust header. which have been on since day 1. there is 5700 miles on the bike. my dad currently owns it and we are doing this together. he has owned it since brand new, and it has ran fine up untill about 3 years ago, where is has been parked ever since. i have run out of options as to what could be the cause, of what i am about to describe.

Anyways, heres the issue..

-As noted, the bike has sat for approx 3 years, and up untill it was parked, it ran fine. The bike would not idle, and with partial throttle, only cyl 1 and 4 were firing at full, and 2 and 3 were only partial. (manifold temps were approx 160 degrees C on 1 and 4, and about 70-90 degrees C on 2 and 3)

-I verified i had spark at all 4 cylinders, and i swapped sides of the coils, and even checked resistance on both the primary and secondary side, and i am with-in spec on both, but the problem continued the same. i did a compression check and got 110 psi in all 4 cylinders, on a cold engine, 3500 feet above sea level (spec is 142psi, at sea level on warm engine) all 4 cylinders were pretty much exact, so no faults there.

-Next i removed the carbs and cleaned them the best i could with the help of my service book (which isnt exactly perfect with cleaning/rebuilding) i removed the jets, venturi's(? the opposite side to where the jets thread into) and cleaned out all orifices that i could see.

- Upon putting them back together, i also noticed that the butterfly valves on number 1 and 4 were ever so slightly open (could see a tiny bit of light through them) and number 2 and 3 were pretty much 100% cloesd (no light coming through) i eyeballed the center 2, and got them close to the same opening as number 1 and 4. (i know its not proper set up, but i will elaborate more at the end of this,

-I then reinstalled the carbs on the bike and fired it up. It is running WAY better, and it will idle on its own. but cylinder number 2, is still not really firing (no change in idle or sound when #2 wire is disconnected) Cylinder number 3 is still slightly weak, and 1 and 4 are very strong. when the bike is revved up, it seems to run much better, and on all 4 cylinders, but thats just how it sounds and feels, not a gurantee.

-My next plan is to get 4 vacuum gauges and equalize/sync the 4 carbs together. and see where that takes me.

Other then syncing them together, is there ANYTHING i could be missing in this whole diagnosis ordeal? it has brand new fuel and i will be replacing all fuel and vacuum hoses tomorrow or the next day, when ever i have time.

any help, or ideas you may have will be greatly appreciated as i am completly out of ideas. i have been told to drive it and that should clear out the gunk that i may have missed in the cleaning, but i dont want to really ride it in this state.


pleeeasseeeee help meeeeee

haha, thanks guys!!
i look forward to hearing any suggestions. and if i missed any info you need, just ask, i can get it for ya!

thanks again!!!

[bikerphil]

Might be your pick-up coil wires....

http://www.xs11.com/xs11-info/tech-t...pictorial.html

[natemoen]

Congrats on the purchase and welcome to the fun of XS11's.

First I say, figure out for sure what model you have, it does make a difference in some things. Check your steering neck vin AND your engine vin against this list.

http://www.xs11.com/faqs/153-serial-...ry-colors.html

Second, go through this thread and see what you missed when cleaning your carbs, pull everything apart and clean the crap out of them, then do it again.

http://www.xs11.com/faqs/153-serial-...ry-colors.html

[Worsley]

Pick-up Coil wires

I thought about those, BUT wouldnt that affect ALL cylinders spark? or am i misinformed about what the pick-up coil on this bike does..

XS1100 F Code

im sure its an F code, also, if after the vacuum check/sync, doesnt clear it up, i will be cleaning them AGAIN.

any other things i may have missed? or am i on the right track, with cleaning/setting up the carbs?

[DGXSER]

Like Phil sugested, and you may have figured out, 2 and 3 are linked electronically. One pickup coil signals the TCI to fire one coil. That coil will fire both spark plugs it feeds each time, only one will be on compression. So your issue could be the pickup coil wires, a very common issue on these bikes. It could also be the TCI, a bad or loose solder joint in there. Check the electrical connectors at the coils for corrosion. Check the plug wire caps.

Basically, go through the entire path and see what may be there.

[SFerinTEXAS]

May not be but sounds like a classic pick up coil wire problem. There are 2 p/u coils under the lh crank cover.1 for cyls 1 &4 and the other for 2 &3. The test specs are in the manual. The top 2 wires at the 4 wire connector at the TCI are for 1 p/u and the bottom are for the other. Connect an ohm meter to the top 2 harness wires (unplugged) and move the timing advance plate to test for loss of continuity. Do the same for the 2 lower .

[natemoen]

I agree with pickup coils.

Also if it is an F then it would be a 1979. That is why I gave you the link to the VIN list so that you can check and make sure because it does make a difference.

[natemoen]

Also here is a link to the thread about the pickup coils. I would add though that you pull the wire loom back (dont cut it just pull it back) and check the wires all the way to the factory splice that is about 6 inches back in the wire loom.

http://www.xs11.com/forum/showthread.php?t=543

[planedick]

I disagree

The openings of the butterfies must be the same. 2 & 3 are closed and that's why they are not running as strong as 1 & 4. Set them all the same and probably your problem goes away, but it is absolutely necessary to have them properly synched in order for them to really be right and the bike to be running good.

[cywelchjr]

+1 on the sync. The first step if you know the butterflies are off that much is to do a good bench sync as a start, and see where you are. If that gets things a lot better, then finish up with a good dynamic sync and it may well fix everything.

Mine idled like crap. I found that #1 was far more open than all the rest, pulling the rest of the engine along with it. When I started the adjustment process the engine died. Had to adjust the idle speed before I could continue with the sync (the carbs were already on the bike) didn't do a bench sync cause I wasn't pulling the carbs, but since I had gauges I just went direct to dynamic sync (you CAN bypass a bench sync if the bike is already in running condition).

Once I got done, it was amazing how much smoothing idle and running was, and even how much more power it had (not like huge percent, but it was noticeable).

So, if the carbs are off, do a quick bench sync before you put them back on, if they are on and you have gauges, just throw the gauges on and sync them, if you don't have the gauges and want it running good fast, pull the carbs and do a very careful and as accurate as possible bench sync.

[natemoen]

he didn't say in the original post day notice that the butterflies were off so he made even.

[cywelchjr]

he didn't say in the original post day notice that the butterflies were off so he made even.

If he did it by light gap, that's likely not nearly close enough. I find that the idle port method is actually even more accurate than the bread tie or feeler gauge method because it actually gets them closer to be fully in sync with each other, as there is far more movement forward and back as you adjust then there is in the gap between the butterfly and the carb throat. And at least for the XS400, the factory manual suggests using the idle ports for doing a bench sync before installing the carbs back into the bike. This is a newer manual than ours, as it was issued for the 80 model year rather than being for the older models with an addendum, so may have updated procedures that are considered more accurate.

I only have that manual in paper, and I don't know where it is right now (it's in a box somewhere in my garage right now, you know how THAT is) and since I'm not working on that bike, it's really not much of a priority to find it at the moment. But that manual is why *I* don't recommend the bread tie sync, but recommend that method instead, not because the bread tie method doesn't work, it clearly does, I just think the idle port method is a little more accurate.

[planedick]

Bench synch

If you look in the top area of the intake where the butterfly is, you will see 3 small holes. If you adjust the throttle plates so all just cover half of the first hole your synch will be very close. Of course this is only if you have the carbs off the bike.