Idles but won't accelerate?

[warlock60]

'79 XS11 Special This bike was stored since last July while I was away on business-back from Baghdad and now it won't run.

Engine idles at mid-choke about 1000rpm, at high choke 4-5K, no choke- no run. At mid choke any advance of the throttle instantly kills the engine with no acceleration. I put a visual spark tester on it. All leads seem to be the same with plenty of spark. Is there an easy reason why the engine dies instantly with any advancement of the throttle? Any suggestions? I've followed most of the links at the XS11 pages and am lost.

[ratbyk]

Won't run!

Strongly suggest that you pull the carbs and do a thourgh cleaning. Use carb cleaner or laquor thinner and disolve the crap that has bunged up your carbs. Make sure that you blow out all galleries and channels and reset float levels. Fill tank with fresh fuel and make sure that you have a good fuel flow from the petcocks.
Ke/Sooke
78E Ratbyk

[Jeff]

Especially check the pilot jets. They are a rather small jet and prone to filling up with varnish and such. Mine had this problem when I bought it after it was stored for over a year. There is no such thing as too thorough a cleaning. Even after the first cleaning on mine.... I still found jellied gas and residue in the carbs when I tore them down a second time.

[sam_cg_cook]

Lean Lag

Possibly too cold a plug?... I had similar problems when I swapped my coils / wires / plugs... I ran 8's, needed 6's... She started hard... didn't want to idle, and had MAJOR lag on acceleration...

Read your plugs as described in any repair manual...

This may or may not be your trouble... but it's a good, cheap, not too labor intensive, place to start.

[MartyA]

Hey warlock60, glad you are back and able to work on your scoot.

You said it will only idle with the choke, won't rev at all? Seems you are not getting gas to the engine. Check for glop that has settled around the petcocks, and in the float chambers. These things don't have a fuel pump, when you open the throttle you need more gas, and should get more gas from the jets. I don't believe you should have too much varnish built up in less than a year of storage, but I can believe you have water or other weird things at the bottom of the tank, and at the bottom of the floats, most of which may not be flammable, and might be blocking the fuel flow from the tank or up throught the jets.

I store my bike from Oct to the last of April each winter, never had the carbs off for cleaning. Try draining the tank, drain the floats, add some fresh gas. Then if that doesn't work you will have to take the fuel system out for a cleaning.

If all you can do is idle with the choke on, do that too long and you will eventually foul your plugs. Might want to watch for that.

[Dennyz]

sounds like the motor is not running on all cylinders. Use a crayon on the each exhasut pipe to find out which cylinders are not firing. That will help identify the problem area.

out side or inside cylinders points to ignition
left or right cylinders points to fuel delivery to the carbs.
single cylinder points to carb.

[warlock60]

OK, good advise. I took off the carbs and cleaned them. The diaphram pistons in each were gummed stuck shut. Also, there was alot of varnish throughout.

Now the bike runs better. Idles as if one or two cylinders aren't firing. I'll check the coils this weekend. I may have had two problems.

However, I was a bit apprehensive about taking out the jets, so I didn't. I blow carb cleaner through all ports until they were similar and clear. I may regret that soon. Could the jets responsible for low rpm (below 3-4k) be still gunked?

The bike runs like a champ between 50 and 95mph. Below 40 mph and at idle it misses.

[Ken Talbot]

If you had varnish and gunk (closely related to spooge) throughout, and if you didn't actually completely remove all the jets for cleaning, you've still got varnish and gunk throughout. Maybe not as much as before, but it will still be there. Just think of it this way - your next strip-down will be number 2 of your first triple-clean.

[Hobbit]

carb cleaning

I know what your going through. I just picked up a XS11 Special that has been sitting for a long time and I am now in the process of rebuilding the carbs.
They were so bad that number three carb had actually had one of the float pivot points erode off the carb body!
I found that soaking them in MEK overnight (after removing everything that would melt) and blowing them out with compressed air works pretty good.
I hope to find out how good this weekend.

[warlock60]

OK, I got the carbs off again for cleaning. These time I'm cleaning the jets.
So, #1 comes apart (off) for cleaning. But do #2 and/or #3 from this picture come apart? If so, is there any precautions or special hints?

For S&Gs I rang out the ignition: #1 coil= 1.9 #2= 1.6 ohms.
pick up coils: #1= 1160 ohms #2= 780 ohms
across the plug caps: #1 = 30.9 and #2= 16

I'm thinking the one side may be weak, but not that bad?

[Hobbit]

Hey Warlock,

Number 2 can be removed and there are more passages off to the side in that area. Also there is another smaller jet under the cover screw (#3).

[Snow]

#2 is your main jet, #3 is the cover to your pilot jet. #1 is your float valve.

When you remove #2, you can push your needle jet (emulsion tube) out through the top of the carb. My needle jets all had crap in their holes and I used compressed air to blow everything out.

You will need a small flat-head screwdriver to remove the pilot jet after you remove that cover. Again, compressed air is your friend.

Make sure your float valve springs are sticking, you may consider getting new ones if they stick or you experience floatbowl overflow.

[Ken Talbot]

Great photo, Warlock. See all that nasty brown stuff where things have been sitting in the fuel? That same stuff is up inside too, and it all needs to come off, both outside where you can see it and inside where you can't. It will even be on the inside of the piece you remove whan you take #2 off. Get it all...

[BigDaddy]

I had the exact same problem after letting my bike sit for a long time. After taking apart the jets and soaking them in carb cleaner for a few days, everything ran great. You can also buy carb kits for them at merriamcycle.

[warlock60]

Do I need to count turns on the jets, or do they just screw in and out? Hate to mess up an adjustment.