Want to kick my bike in the carbs

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retroLS1

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Was supposed to go out on my first "real ride" with some friends today on my newly finished bike. Didn't make it obviously.

First issue I've had was my advance sticking. I narrowed it down to that and not the throttle sticking or anything. Popped the advance cover off and could see the two arms hanging open after I would rev and not snap back. I pulled the advance rod yesterday and cleaned and greased the rod and bushings with moly grease. Thought that would solve it but not totally. Today I popped the arms and springs off and cleaned/greased the posts they sit on. Reassembled and no more sticking from what I could see.

That led me to my newest problem. Something with the carbs maybe. I am getting a tapping/knocking/hesitation randomly that causes the idle/throttle to cut out. Didn't know if it was doing it before but if it did, it wasn't this bad. I took it for a spin down the road and it just got worse and worse. Throttle was boggy/hesitant right when you cracked it but then smoothed out midrange except for the tapping. If you put your hand on the carbs you can feel it. I pulled my UNI pods to look at the slides and they were moving freely. I took one video that captured a few of the noises. Just want to kick this damn thing sometimes. Good thing is, it starts up first or second kick when cold... Then just runs like this.


Pic of the headache:

9c55343d-7fca-4c81-80ff-4e9a4f82d5b5_zps12976bb7.jpg
 
If you continue to have advance problems, and you are using the MikesXS springs, then you should try cutting just one turn off of just one spring. There are lots of threads on this fix.

I would love to know what that noise in your video is. I have had many XS650's pass through my hands, and every once in awhile I get one with that hiccough. Some just do it once or twice only when very cold. I would like to think that I know my way around these bikes, I know carbs, jets, tuning, exhaust, valve lash, cam chain tension, electrics, etc., etc.
I have seen lots of others start threads and describe the hiccough, but I have never seen a good explanation for it.

Regarding your bogging when you crack the throttle, that sounds like a jetting or jet needle clip position problem, or you just need to put baffles in your open pipes to cure your reversion. See my thread here:
http://www.xs650.com/forum/showthread.php?t=26822
 
It probably could be a combination of those things with the bogging throttle. There's a crappy cut off exhaust on it right now while I wait for my Pandemonium 'ya mama' pipes to come in. I'll have to get the Canadian needle for these since I am running BS34's with the fixed needle.

The hiccup is throwing me for a loop. I don't think it was doing it the first few times I ran the bike if I recall. And it got worse as I rode and the bike warmed up more. Seemed ok idling when cold at first, then got worse.

I'll see how it goes with the sticking advance and if it keeps up, I'll cut a coil.
 
Just pulled the plugs to see how they look. What say you folks? They don't have a TON of run time on them but I can't really tell if they're normal or too lean. Definitely not rich.

null_zps91bf07af.jpg


null_zps299f873a.jpg
 
Looking at those plugs again, and listening to the sound of the video you could try running on the richer side (less chance of heat damage while you find the solution).

Anlaf
 
The clatter sounds like camchain. Check your ign timing with a timing light. Look for spark scatter, i.e., timing mark moving about while idling. Check the fit of the advance weight ears in the slots of the advance wheel...
 
I do remember when I was doing the timing that the timing mark was bouncing around a bit. Not a lot - staying within the fire range marking, but it wasn't hitting in the same exact spot every time. I have not done timing on any motorcycle before, so didn't know if this was normal or not. The fit of the advance weights on their respective slots on the advance wheel seem ok. I don't have any other ones to compare it to but from what I can see, there shouldn't be any issues.

My idle screws are both at 3 turns out right now. I think I had read to not go any more than 4 or 4.5 turns out but I hopefully wouldn't need to go that far.

Now, according to this image - which I'm sure all of us have seen:

carb_page.jpg


Reading the last couple sentences after the description of the BS34 carbs, that definitely sounds like it's my situation. Hovering idle that is slow to fall - check. Stumble on acceleration - check. It mentions to go larger on the main and smaller on the pilot jet. I know my main is already larger than stock, it's a 145 compared to 132.5 stock. Factory pilot jet is 42.5 and I believe that is what's in mine right now, but I will check. If I do have the stock size in, should I drop down to maybe a 37.5? I have a handful of jets that the PO gave me when I bought it and I feel like I have that size but again I will check.

At least it feels like I'm starting to get somewhere with this...
 
Others can confirm, but if you are going to use Canadian needles in your carbs, I think I remember seeing advice on this forum also to use the Canadian jets.
 
Ah interesting, didn't know that - I thought they might have been the same. Good to know, thanks.
 
Read that MikesXS stuff over again carefully. It's not telling you to decrease the pilot jet (that should be increased usually), it's telling you to decrease the pilot air jet, two different jets completely.
 
5twins said:
Read that MikesXS stuff over again carefully. It's not telling you to decrease the pilot jet (that should be increased usually), it's telling you to decrease the pilot air jet, two different jets completely.
Click to expand...

Wow thanks, good catch. Been a long today if you couldn't tell. I just went out and popped the carbs off and brought them to the work bench to take a look. Like I thought, I have 42.5 pilot jets. I do have a pair of 45's from the PO so I will pop those in and see where it gets me. My idle mix screws were set 3 turns out so I increased them to 3.75 turns as well.

I am Carbon - thanks for the videos. Mine definitely snaps back like those, especially now that they are well-greased.
 
Whenever you change pilot jet size, you must re-visit the mix screw setting. 3 to 3.5 turns out is what these BS34s normally like. Get out to 4 or so and that's telling you to make a jet change.

The pilot air jet is another way of tuning the pilot (low speed) circuit. It doesn't have as much of an effect as a pilot jet size change so can be considered as a "fine" tuning aid. Say for example a 45 isn't quite rich enough but a 47.5 is too rich. You could play with the air jet size to achieve a richness level somewhere in between the two.
 
Ah gotcha. Right now it still has the 42.5's in it, so maybe I will try reinstalling and running it with just the 3.75 turns out and see how it is. If it is still rough/lean, I will pop the carbs off again and change the pilot jets to 45 and bring the turns back down to maybe 2.5-3ish.

Never tuned a carbed bike before so this is rocket science to me. Getting there though, with the help from you folks. I gotta say - this is probably the most helpful forum I have ever been on and it is awesome.
 
There are established baselines for jetting the BS34s with mods like yours but if you'd like to try and re-invent the wheel, be my guest. I watched your video and you're exhibiting classic lean symptoms. The idle is inconsistent and wandering, not steady as it should be. The popping is probably a lean misfire. Your 145 mains may be too large and your pilots are too small. About a 140 main should do, maybe even a 137.5. Any of them aren't going to do much for your idle problem though. For that, you need to play with pilots and mix screw settings. The carbs also need to be in sync, or at least close, or you'll have a hard time sorting the idle problems.
 
I like the wheel perfectly fine as-is so I'll do some searching and see what I come up with.
 

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