Rough running

[Oldbuthopeful]

I'd be glad of some help in curing the rough running on my 550K3.
After a rebuild 12 months ago, she never really ran sweetly and was too big for comfort so I pushed her to the back of the garage and concentrated on a 350Four.  The 350 is now up and running and is a joy to ride (me being only 5'5" and 70+ years old) but the 550 deserves to be enjoyed by someone out there as it's potentially a nice bike.
So, having had the carbs checked over and with new jets and air screws in, there was a definate improvement but still an
infuriating habit of only running/pulling with the choke out.
Timing was suspect, so I took off the camshaft cover today but found all the marks to be in the right places.
Next, I re-set all the tappet clearances and on start-up, she ran as sweet as a nut - never heard her so good.  I thought I'd
cracked it, but when I took her out on the road, she'd still only run with the choke out.
Patience is running a bit thin now, so can one of you more knowlegable guys out there offer any solutions please.
(And for Gawd's sake, don't say take the carbs off, because I think I'd lose the will to live !)
 

[Bryanj]

Did you remove the push in pilot jets and clean them when you had them off?

[Oldbuthopeful]

When I rebuilt the carbs about a year ago I replaced the push-in pilot jets with new, as well as putting in new main jets.
But the bike's been sitting idle for almost a year so maybe the jets could do with a spot of TLC ?
I didn't suspect the jets because they were new, but will certainly get them out today and have a gentle poke around.
At least dropping the bowls isn't half as bad as taking the whole bank of carbs off !

Thanks for coming back so quickly Bryanj.

[Bitsa (Ralph Wright - RIP)]

Sound to me like jets are gummed up.I would recommend when you hibernate a bike drain the bowels every time.My xjr1300 idle jets did this gum up in 6 months.
Hope this helps
Bitsa

[mickwinf]

all the above plus check the float hight as its different on the k3 carbs, also check the float needles especially the little sprung loaded bit to make sure its not stuck hence cutting off fuel supply when under load. you could spray carb cleaner around the joints when the engine is running to show up any air leaks. You may have to take carbs off again, sorry! regards Mick

[Oldbuthopeful]

I thought of you today mickwinf, as I took the carbs off for the umpteenth time, but it's coming down to 30 mins after all the practice so,  within a couple of hours, I'd checked the slow running jets (all clear) and the float heights  -  needed a bit of a tweak  -  but what's with the emulsifying jets Oddjob ?  I pulled out the two little brass tubes at the mouth of each of the inlet ports, expecting to see tubes with lots of little holes in.  Am I looking at the wrong tubes?  These were only about 10mm long and didn't have any lateral holes.  Maybe I've misunderstood !
Anyway, I put the whole shebang back together, fired her up and, when she was warm there was a significant improvement.
On the road, there was a bit of hesitancy when the throttle was opened, but she'll tick over and get me round the block, so I think it's time to look at the timing with the old strobe light.  I'm deffo not going to take the carbs off again for a while !
Holidays are looming, so I'm taking the 350 to Bakewell tomorrow for a look at the Classic Bike Sale/Show and will tackle the 550 wwhen I get back end August.
Top of the list will be spraying to check for leaks on the induction  side as suggested, so thanks one and all for your input.
It's much appreciated and is invaluable when you've reached screaming point and there's nobody to turn to !!

[LesterPiglet]

The brass tubes the needles go into, let's hope they don't look like this.



I used the flat of a screwdriver in the carb throat to push them out.

[Oldbuthopeful]

           Thanks for that Les.  The carbs are now back on the bike but when I get back off hols I'll have them off again
           and search out those tubes.  If mine are anything like those in your pic, they'll sure benefit from a good going over.
           I'll report back in about 10 days time.

           Could I just trouble you to explain whether they push up or down to extricate ?  Forgive my dimness, I don't know
           my way around these things like you guys.   Ever thought of publishing a Haynes- type manual between you ?!

           DC

[LesterPiglet]

They push down towards the float bowl.

[Oldbuthopeful]

You're right Lester Piglet, they look nothing like yours !  After taking out the (new) mainjet and removing the
throttle slide and the needle, all I'm left with is the little jobby on the right of the picture, which I drifted out
with a suitable bolt.    It looks to me as though I've got  different spec carbs on my 550K3 or am I still showing
my ignorance ?
I was really looking forward to finding something that was gummed up and would have made all the difference
to the bike's running once I'd cleaned it !   
So it's back on with the carbs again and set about using Oddjob's spit test for leaky induction seals unless someone
tells me different.
DC

[SteveD CB500K0]

Put your location in your Profile (save all those "where are you?" questions)

 

[Oldbuthopeful]

Done, Steve D.

Oddjob, a great offer but I don't like to impose.  I'm in Romiley, Stockport. 
Incidentally, didn't get to Bakewell because the rains started as I approached Chapel-en-le-Frith and I didn't fancy getting a soaking !
The 550's going back together again tomorrow so will post an update after a road test.

[Oldbuthopeful]

Amazin' Oddjob.  We could almost open the window and shout ! I'm back of Harrytown, down Clapgate.

I bought a set of Davida gauges off Ebay a while back but never used them 'cause I couldn't be arsed setting
up a temporary fuel tank thingy.  You're welcome to borrow them if you want.

As I said earlier, I'm hoping to get the 550 up and running again tomorrow so will give you a shout if there's no improvement.

[Oldbuthopeful]

Be brilliant Oddjob if you could spare the time to look at my 550.
I don't know whether I'm set up on here for you to PM me.  Could you give it a try ?

[anparkinson]

I had exactly the same issue with my K3 after rebuilding the carbs after they had sat unused for 14 years.

The push in pilot jets were furred up and I redrilled them to the correct size but it still ran weak. The main jets were new so not the problem. It turned out the needles were set too low.  I raised them 1 notch and it transformed the bike -  it runs beautifully now.

I had the carbs on and off many times while sorting them.  I could get them off in 15 mins and on in about half an hour with practice