Dies at Idle Only

[Delta869]

(please send this post to the correct area, my bad for not choosing a Topic) Stock '75, only mod is airbox removed for Unipods... Dies at idle like the kill switch was flipped then I can fire it right back up like nothing ever happened. Dies at random, sometimes it will idle long enough I can walk away then will die again. After it's fully warmed it will still die when I come to a stop. Not until I have ran it "hot" so everything is goose loose and the pistons can coast thru to the next firing stroke will it stay running but then it will still miss (just once). Bumped the idle up to 1800 just to keep it running so it will sit and warm up, but once it's warm-hot the idle doesn't want to come back down (3k or so) but will slowly drop back down (annoying).

Carbs have recently been cleaned/rebuilt, new petcocks, inside of tank isn't perfect but acceptable. No line leaks that I can see..

Other than this little problem it runs like it should... Like a Beast! lol , Is this a carb problem? Elec? Any suggestions would be greatly appreciated

 

[cros36]

clutch adjustment.

 

[weekendrider]

Check your float height and the pj circuit again.

 

[Delta869]

1st season owning lol... by PJ you mean Pilot Jet Circuit? Previous owner did the cleaning/rebuild, by chance could you direct me to a diagram or instructions on how to check this please? Sorry, total Newb here lol and thanks so much for your reply!

 

[weekendrider]

Welcome to the site and XS650 Delta869,
This will help you understand carbs.
http://www.amckayltd.com/carbguide.pdf

Posts by 5twins, Grizld1, bluebikerblan, xsjohn will help you.
5twins and xsjohn also do some good photos for refferance. Unfortunately you just have to hunt those down in different threads. Neither have "albums" on site.

 

[Delta869]

I'll check it out, Thanks again!!

 

[retiredgentleman]

Dies at idle.................study the carb guide, but it could be due to low battery voltage. Get a VOM and measure battery voltage at idle and at 3000 rpm. At idle you need to have 13.1 to 13.5 volts,and at 3000 rpm you want to see 14.1 to 14.5 volts.

If you have the old original ignition coils, they are likely giving very poor spark at idle. A new dual output coil/spark plug leads will do wonders for how the engine runs.

A high idle that hovers and does not want to come down...............replace the needle jet O-rings.

 

[Delta869]

Read the Carb Guide start to finish, my old VOM toasted in (past) VW hell lol will pick up a new one... While cleaning the pj circuit/checking float, quick inspection of the float valves don't look so good so ordered 2 new assemblies so the carb prob for now is shelved until parts arrive.

Glanced at the coil while I had the tank off routing new cables and it appears to be newer than it's surroundings, the plugs & wires are new for sure. Good rapport with the PO, I'll shoot him an email, find out if it's new/what type.

Just checked his parts list/receipts and seeing 4 new jets & 2 Needle Jet (Nozzle Main) O-rings.

 

[weekendrider]

So if you start it, you can keep it running by playing with the throttle or turning the idle screw in?
Once running and warm it will run but only at high idle?
Or it won't idle high or low for any length of time?
Balls to the wall or nothing?

 

[XSLeo]

The high idle and won't drop back fast is often a lean condition. Check for air leaks around the carb boots, throttle shaft seals.
It can also be advance rod sticking. If it is then the timing is staying to advanced.
Leo

 

[Delta869]

Thanks Leo!

 

[Delta869]

OK, accomplished all of the checks suggested, everything is good! ... and it still dies but not as often. Ordered new springs for the Advance (hovering idle) and the coils are stock but not sure how old. Over the winter I will probably upgrade the entire Ignition system, in the mean time I'll deal with it as is.

Thanks so much everyone for your help!

 

[weekendrider]

Checked out your album. Ugly Betty is coming along.
Did you decide on the standard bars?

 

[Delta869]

until the Superbike bars came in