does not idle down when hot

[putty]

idles perfect when cool after about 1/2 hour of riding will not idle back down cleaned carbs, electronic ignition any sugedtions on what is the problem.
btw 81 xs650 special on phone battery low will log back when home lol

[weekendrider]

double post

[weekendrider]

Welcome to the forums putty.
Grizld1 has your back in this post.
I have edited to only what pertains to this current post

Jul 15, 2013 8:55:39 GMT -5 grizld1 said:

Your hanging idle is due either to vacuum leak, lean pilot mixture setting, or, if you have breaker point ignition, to failure of the ignition rod to return to the full retard position. US models used electronic ignition after 1979, but in some other venues points continued to be used, so if you have no points, check for air leaks at the mounts, throttle shafts, and vacuum barbs in the mounts.

[putty]

Thanks weekend sorry about the double post was taking to long to search on my phone and battery was almost dead. will check for leaks stopped at uncles and he being old and very knowledgeable suggested dirt in carb so he dumped some stuff called seafoam in the carb and now after riding home seems to be working better who would have thought i am not a supporter of quick fix addatives but maybe this one is good only time will tell.

[weekendrider]

putty the double post was my bad. My system doesn't seem to play well with the new format.
Getting a 504 gateway time out error when I hit the reply button.

If the SeaFoam seem to have helped I would think about the "lean pilot setting" part of Grizld1's post.
May be it isn't a setting per se but a lean condition from blockage. The Sea Foam is helping clean the circuit out.
BUT I dunno sicum from shinola so it would be others advise to listen to.

[putty]

thanks weekend i'm going to let it work through the system for a day or so as it just started behaving like this a couple days ago so i'm hoping it's just dirt and will work it's way out. and putting on a new fuel filter also to keep the dirt out.

[richard]

Sounds like you have an air leak on your intake/ Carb boots, or a Carb diaphragm leak. You can figure out which side it is by putting you hands next to the exhaust and feeling which side is blowing harder, then start trouble shooting on that side. An 81 should have no centrifugal advance to look at so I won't mention that.

[putty]

thanks richard I tightened up the boots and put a clamp on the vacuum hose, the diaphragms looked good when i tore it down to clean the carbs seems to be running okay for now will know better after i take it out for a ride tomorrow.

A ride a day keeps me smilin'

[richard]

Cool most of the time that is all it takes

One indication of leaking diaphragm is that it will suck air in through the weep hole in the top cover over the diaphragm. We used to squirt starting fluid around that and the boot to check for leaks then listen for a change in idle. A stumble in idle indicates the leak. If you shoot starting fluid or WD40 do it sparingly because it could flash if the engine is hot or it finds a source of ignition. WD-40 is probably much safer than starting fluid because it has a lower flash point, ether one will work. If you find you have one leaky boot I would suspect the other too which means it's time to start thinking about replacing them both. That is unless you think the leak problem has been solved. On XS650 air intake leaks or lean carburetion mixtures make bad things happen, so that is something you want to be sure about before any long rides.

Richard

[putty]

thanks richard I got lots of little parts and stuff to get most do not affect riding so i'm making a list as mikes xs / xs650 direct needs a min 150 buck order for free shipping lol

[putty]

Jul 15, 2013 18:11:07 GMT -5 richard said:

Sounds like you have an air leak on your intake/ Carb boots, or a Carb diaphragm leak. You can figure out which side it is by putting you hands next to the exhaust and feeling which side is blowing harder, then start trouble shooting on that side. An 81 should have no centrifugal advance to look at so I won't mention that.

checked xs650.com (mike's Canadian site) and they will not have them in for a couple months maybe, can i replace mine with a non- vacuum type. the other option is maybe to find a compatible gasket that fits another bike which is more common for parts or perhaps make one,

[richard]

Try these guys I got mine from them and they are very high quality. jbmindustries.com/HOLDERS.html

I used JBM because there was a known problem with the carb boot from Mikes and exposure to ethanol fuel. In fact I still have a set of carb boot I got from Mike's and never used for that reason. JBM makes carb boot for airplanes that are made to a very high standard so I feel safe with them under any condition or fuel.

They're nice people. . Made in America doesn't hurt either :-) .

Richard

[putty]

just my luck sold out lol but found some on e-bay may order from there 

[grizld1]

If you're using JBM boots on OE vacuum carbs with pod filters, be sure to support the carbs. If you don't, the boots will split at the spigot stops. Don James is a good man, but the "airplanes" with which he's experienced are ultralights, which typically use light mechanical carburetors. His boots are not up to the job of hanging heavy bracketed vacuum carb banks without a little help, either from the airbox or a well-damped support bracket. Mike's XS Chinese boots will fail regardless of fuel; ethanol was merely a convenient excuse for failures. The original equipment manufacturer is the Japanese firm ARS, and those boots are still available for 1974 and forward, sold under the Tour Max label. ARS boots are available from 650 Central and any shop that orders from K&L Supply. Here in Illinois it's been hard to get anything but 10% ethanol fuel for over 20 years, and there are many original ARS boots still in service on older machines. Be sure to retain the metal shrouds from the old boots--they're not there for decoration.