Newbie here- trouble stalling at idle

LeCookie

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Hi everyone!

Brand new xs650 owner (1976) and I’m having issues with the bike stalling out. Happening at idle while in neutral, as well as at low speed in first gear.

I’m not too knowledgeable about this model or bikes in general so bear with me, but I do know that carbs were very recently cleaned, and spark plugs and battery and brand new. Aside from some aesthetic mods I BELIEVE everything is stock.

I’ve tried starting with/without choke and adjusting the mix screw. Haven’t noticed anything conclusive. Any thoughts??

Thanks!
 
Hi everyone!

Brand new xs650 owner (1976) and I’m having issues with the bike stalling out. Happening at idle while in neutral, as well as at low speed in first gear.

I’m not too knowledgeable about this model or bikes in general so bear with me, but I do know that carbs were very recently cleaned, and spark plugs and battery and brand new. Aside from some aesthetic mods I BELIEVE everything is stock.

I’ve tried starting with/without choke and adjusting the mix screw. Haven’t noticed anything conclusive. Any thoughts??

Thanks!
Your carburetors are not properly tuned and probably not synced. You're going to have to go through them. All passages have to be clean, floats properly set and do a bench sync. Getting it right will build a lot of confidence in this old bike.
 
Your carburetors are not properly tuned and probably not synced. You're going to have to go through them. All passages have to be clean, floats properly set and do a bench sync. Getting it right will build a lot of confidence in this old bike.
Interesting. I was told by the previous owner that the carbs had just undergone maintenance… anything else it might be?
 
We might need to get more specific with history and symptoms: "maintenance" is a very broad term.

First the symptom "stalling": if it's occasional or "won't idle at all - ever" ?

Idle speed should be around 1200rpm's on an average XS. An XS in very good tune might reliably idle at a lower rpm, but 1200 is the spec and a good place to start on a new-to-you bike

Does it start-up cold ok with the choke? Does it start up warm ok without the choke?

Once running decently if you rev it to ~ 3000rpm (neutral) and release the throttle, do rpm's fall right back to idle, or does it fall slowly back in maybe erratic fashion?
 
Yes, you need the idle speed set to 1100-1200 rpms or the bike will just randomly stall at idle. Also, you set idle speed when the bike is fully warmed up and hot. If you set it on a cold motor, it will idle too high once warmed up.
 
Interesting. I was told by the previous owner that the carbs had just undergone maintenance… anything else it might be?
The odds of a previous owner's carb "maintenance" having improved the situation is 50/50 at best....
But stock points ignition has plenty of room to create less than perfect idle.
Cam chain and valve settings too;
No answer here other than complete and thorough maintenance by a competent mechanic or someone willing to spend the time to learn how to do it.
 
We might need to get more specific with history and symptoms: "maintenance" is a very broad term.

First the symptom "stalling": if it's occasional or "won't idle at all - ever" ?

Idle speed should be around 1200rpm's on an average XS. An XS in very good tune might reliably idle at a lower rpm, but 1200 is the spec and a good place to start on a new-to-you bike

Does it start-up cold ok with the choke? Does it start up warm ok without the choke?

Once running decently if you rev it to ~ 3000rpm (neutral) and release the throttle, do rpm's fall right back to idle, or does it fall slowly back in maybe erratic fashion?
Basically what happens is once you get it going, it will idle at 1800-2000 rpm for anywhere from 10 seconds to a minute, before eventually sputtering out and dying.
Once you get it going, it will run on the road fine, but as soon as you slow down and get into a lower rpm, it starts to sputter and eventually die.
 
Yes, you need the idle speed set to 1100-1200 rpms or the bike will just randomly stall at idle. Also, you set idle speed when the bike is fully warmed up and hot. If you set it on a cold motor, it will idle too high once warmed up.
How does one set the idle speed? (apologies if this is an obvious question)
 
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In the meantime while waiting for answers.......
Post a couple pics of your bike so the peanut gallery knows what you're working with.
We love pics plus they give clues.
For sure!

(Let me know if you want a close-up of anything)
 

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For sure!

(Let me know if you want a close-up of anything)
Hmm.....I was about to post the lengthy "Dead Cyl Method" (for earlier carbs), but it appears those may be linked, single cable set-up (?).

1685911691947.jpeg
1685911720039.png


Do you have a second throttle cable entering the right carb that I can't see?
 
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You may have this set-up with a single throttle cable (or two throttle cables)
1685912961252.png
 
Most likely with more detailed explain is unbalanced carbs ie need to be synced. A step often left out during maint.
 
Your carburetors are not properly tuned and probably not synced. You're going to have to go through them. All passages have to be clean, floats properly set and do a bench sync. Getting it right will build a lot of confidence in this old bike.
I was told by the previous owner that the carbs had just undergone maintenance…
Most likely with more detailed explain is unbalanced carbs ie need to be synced. A step often left out during maint.
It's always suspect until you've done it yourself. To thoroughly enjoy this bike, and it's a lovely bike, you need to embrace doing the maintenance on it yourself. We're here to see to that end.
 
Basically what happens is once you get it going, it will idle at 1800-2000 rpm for anywhere from 10 seconds to a minute, before eventually sputtering out and dying.
Once you get it going, it will run on the road fine, but as soon as you slow down and get into a lower rpm, it starts to sputter and eventually die.
If it's that far "out of whack" on a new-to-me bike, I would also be checking ignition timing (strobe), air leaks and valves (as Gary mentioned) in addition to carb synch (actually I'd do the ignition and other stuff first).
 
Aee ... hhh lets try the CSF rule ..Cheapest Simplest First
Cleaning a carburetor can be a to big task for a Newbie --Tools Compressor Skills

This is not things I know but putting it out here for others to chime in on

I would as always measure the charging across Battery
Would it not be rational to try clean the Pilot jet and Idle circuit first.

I don't know this carburetor ..but some jets are possible to get out --- carbs still in the bike
And i myself recently missed a tiny hole in the float bowl exactly for idling circuit .
 
Hi everyone!

Brand new xs650 owner (1976) and I’m having issues with the bike stalling out. Happening at idle while in neutral, as well as at low speed in first gear.

I’m not too knowledgeable about this model or bikes in general so bear with me, but I do know that carbs were very recently cleaned, and spark plugs and battery and brand new. Aside from some aesthetic mods I BELIEVE everything is stock.

I’ve tried starting with/without choke and adjusting the mix screw. Haven’t noticed anything conclusive. Any thoughts??

Thanks!
Welcome to the site! These guys will definitely get you going in the right direction!
 
Nice looking bike

Looks like the PO built a nice bike with a proper build. Fork brace, Fork Damper, braided brake line, brembo, (from what i can see), 4 pot front caliper, (nice upgrade), and drilled front disk. replaced a lot of screws with Allen key sets, (think you call then hex head screws).

I would check the charging system and the condition of the battery. Tappets and points and set cam chain and do the timing. make sure you have an inline filter from the tank to the carbs, or check and replace the existing if it ha one and needs it.

Now check the carbs for sync and clean. As Jan suggests check the idle circuit in the bowl. If the screw have been replaced with Allen keys the bowls will be able to be taken off quite easy while the carbs are on the bike
 
Excellent idea that is something I Will do next time
I have had problems hitting the Phillips JIS ones when Carbs in the bike

" with Allen keys the bowls will be able to be taken off quite easy while the carbs are on the bike "
 
Hi all,

Wow! Thanks so much for all the support and suggestions. This seems like a great community.

First bit of tinkering done, and it LOOKS like to be a battery issue. I'm hesitant to say for sure at this point but fingers crossed. Will provide an update soon.
 
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