Problem with cylinder 4.

[Dave_S]

Any thoughts on this one? On start up cylinder 4 ain't working, after a while it comes on line. The ignition side looks ok, new plugs, good blue spark, swopped over leads between 1 & 4, problem remains with 4. Fuel is flowing into carb 4.

[JeffH]

Dave,

HOWDY ............
and Welcome to XS11. Glad to have you here.


A little more info would be helpful for us.

So you are starting it COLD and using choke or not?
Waiting for #4 to fire up what happens if you hold RPM at say 2,000 and put the choke in the 3 detent positions?
Once #4 fires and you shut it off for say an hour, what happens?
Have you ridden the bike once #4 fires?
What happens on HOT start?
Had the Carbs apart recently for a good cleaning?
Curious which XS. A Standard or a Special?
Running any fuel filters?

As you said, it appears #4 is getting fuel, eventually from one of the fuel circuits.
Probably not a valve clearance thing but how long ago was that checked? Just throwing ideas out there to consider.

If you can, UPDATE your profile since it just says XS11. Model & Year would be helpful.

Jeff

[JeffH]

Dave,

I was curious about your bike year / model so I looked back a year ago to the Engine Crash Bar discussion.
If its the same bike then I guess we are talking about a 1978. Cool ........
I just might have a couple 2 or 3 of those.

Jeff

[Dave_S]

I started to run a few tests, towards the end she started to run OK on #4! This has happened before, so still perplexed re what the problem is.

A little more info would be helpful for us.

So you are starting it COLD and using choke or not?
Waiting for #4 to fire up what happens if you hold RPM at say 2,000 and put the choke in the 3 detent positions?

It will start cold (47F) without choke, needs throttle slightly open. Apply full choke revs increase by 500rpm, ticking over at 1500rpm, monitoring cylinder 1 & 4 temp, 4 lags behind 1. After 10 mins on tick over 1 = 290F, 4 = 190F.
No exhaust smoke, back fires.
Switch off ignition, plug 1 sooty black, 2 & 3 grey, 4 grey but wet.

What happens on HOT start?
Clean off plugs, start without choke, head temps have dropped to 150F, ticks over at 1200rpm. After 10 mins on tick over 1 = 290F, 4 = 240F.
Switch off ignition, plug 1, 2 & 3 dark grey slight soot deposit, 4 grey.
No exhaust smoke, back fires.

Once #4 fires and you shut it off for say an hour, what happens?
Clean off plugs, after an hour start without choke, run up & hold at 5000rpm, head temp 1 = 315, 4 = 300F, cut throttle and ignition, plugs 1 & 2 dark grey slight soot deposit, 3 & 4 grey.

Have you ridden the bike once #4 fires?
No, gone are days when I used to ride all through the winter!

Had the Carbs apart recently for a good cleaning?
Yes, overhauled at shop.

Curious which XS. A Standard or a Special?
Standard, 1978, 2H9, no mods except 4 into 1 exhaust (original rotted off), carbs replaced with 80/82 set.

Running any fuel filters?
No

As you said, it appears #4 is getting fuel, eventually from one of the fuel circuits.

Probably not a valve clearance thing but how long ago was that checked?
She's only done 5,000 miles, had her since new.

[JeffH]

Vacuum lines cracked and leaking air? -or- rubber plug caps cracked and maybe leaking? I've had that happen. A backfire actually blew #4 off the bike.

I wonder if the shop got the float levels set correctly? So it ran ok before on the 80' carbs before the shop cleaned them? Was thinking float heights but after I re-read the post I am wondering about the floats being set to 78' or 80' spec -or- not properly across all 4.

How long ago was that service? Had you ridden it since that carb servicing? Just throwing out ideas. Maybe one of the gurus can you some suggestions.

Jeff

[DiverRay]

Dave,
First easy question.
1 Has the vacuum cap on the carb boots been replaced? These are the black rubber caps over the nipples used to sync the carbs. (if you can spin the cap, it's bad!)
2 When the shop worked on the carbs, what did they use for parts? Mikuni or something else like K&L?
3 Has a sync been done after the carbs were worked on?
Now the harder question!
Have you ever cleaned all the electrical connections on the harness?
Start from the top, as I listed easy to hard as far as work.

[DiverRay]

Just thought of something else! You said you have been cleaning the spark plugs. Try four new plugs FIRST.

[Dave_S]

#4 not firing

Sorry for the late reply, other work prevented work on the old girl. Replaced the vacuum cap on #4 and it came on line straight away.

Now I have another problem, the clutch doesn't work! It was OK when she was laid up for the winter, tried adjustment at the clutch lever, no go. Removed the clutch inspection plate, all looks OK there. Any ideas?

[JeffH]

Good that it was just the vacuum cap on #4. An EZ fix.

Clutch? So to confirm, it was fine, then bike sat all winter. So now what is happening. It's stuck (as in plates stuck together)? Since you can run the bike you must be in neutral. So can't shift into gear while running? Can try put it in gear, pull in the clutch lever then try and roll the bike. Likely it is just that the plates need to break free. Have a center stand? Do it with bike up on the center stand. Just be careful and take obvious safety precautions. A couple different ways with the clutch lever pulled in and tranny in gear to free the plates.

Try something like that and report back.

Jeff

[Dave_S]

Clutch plates

Problem was the clutch plates were stuck together. Warmed engine up with her on the centre stand, applied clutch, put into gear, increased revs, applied brake, clutch freed.

[JeffH]

That's great. Two E-Z fixes.
Now hope you can Go Ride and enjoy the bike this summer.

Jeff