'83 XS650 throttle slide sticking

[SoILSpecial]

I pulled off my carbs to clean them, and because it seemed like it would rev up and down a tiny bit when idling, my buddy who is more experienced in repairing motorcycles noticed that the throttle slide in the left carb doesn't operate nearly as smooth as the right side. Upon inspection, when viewed under the light it seems that the slide that is sticking has some more wear and tare than the one that isn't but you've got to reaallly look to see it, is that me grasping at straws or is it possibly damaged?

When it's running it seems to have a bit of a "cough" too, would that be caused by the throttle slide sticking, and do I need a new slide or to just clean the chamber and slide?

 

[gggGary]

There will sometimes be a scratch with raised edges from dirt/grit or more often, a mark where someone pried open a stuck slide. I will work SUPER CAREFULLY with 1500 grit paper either wet or with mineral spirits to remove any raised area on slide or the bore. Note; don't try to remove scratches just any RAISED edges. Check frequently to see if it moves freely then stop, remove all grit before reassembly. Also check slide action with and without the oval port blocked with your thumb.

 

[SoILSpecial]

Thank you I will try this exactly as you've said when I'm able to get to the shop. Hopefully tonight. I didn't see any raised edges when I was there last, but I so wasn't looking for them in particular so I will definitely check and report back.

 

[gggGary]

Uneven idle can be many things, carb synch is a favorite "gotcha". A plugged idle circuit, plugged orifice in the float bowl, plugged pilot jet. Were o-rings on the float valves replaced, screens above them cleaned? Leaking o-rings is very common. Have fuel lines been replaced. Old lines shed fine slivers creating carb problems.
The carb guide read till your eyes bleed. http://redirect.viglink.com/?format=go&jsonp=vglnk_157546362951812&key=57794247816f5a0d18aec760cae5766d&libId=k3rad2u1010005ar000DAibxhcmc9&loc=http://www.xs650.com/threads/carbs-carburetors.43/&v=1&opt=true&out=http://www.amckayltd.com/carbguide.pdf&ref=http://www.xs650.com/pages/tech/&title=Carbs - Carburetors | Yamaha XS650 Forum&txt=http://www.amckayltd.com/carbguide.pdf
As always cam chain slack set using the engine at idle method and valves set. Compression tested, look for hot spark both sides. (never crank motor unless two grounded plugs are on the plug wires.)
If bike has factory TCI ignition a WORKING charging system is critical, low voltage causes spark issues. Get a voltmeter on it watch for good numbers. Bad fuse box dirty ignition switch and kill switch contacts can cause issues also. Are the correct NGK BP7ES plugs installed and gapped?

 

[SoILSpecial]

Holy crap thanks for the guide! Definitely going to be using that. I haven't cleaned the screens or replaced any o-rings it was just a few days ago that I took them off and noticed the problem. I believe it has factory ignition, it starts up just fine. I'm gonna assume that it's got the correct plugs if it's starting but to be honest I don't know a whole hell of a lot.

 

[gggGary]

Often the best way to "correct a problem" is to do a systematic round of maintenance, all the things that should be done on a regular basis but on most old bikes have been ignored for decades and thousands of miles. 650Skull's thread new to me is a good read.
http://www.xs650.com/threads/guide-...checklist-for-the-condition-of-your-find.367/

 

[fredintoon]

I pulled off my carbs to clean them, and because it seemed like it would rev up and down a tiny bit when idling, my buddy who is more experienced in repairing motorcycles noticed that the throttle slide in the left carb doesn't operate nearly as smooth as the right side. Upon inspection, when viewed under the light it seems that the slide that is sticking has some more wear and tare than the one that isn't but you've got to reaallly look to see it, is that me grasping at straws or is it possibly damaged?
When it's running it seems to have a bit of a "cough" too, would that be caused by the throttle slide sticking, and do I need a new slide or to just clean the chamber and slide?

Hi Sol and welcome,
like they all said:- first, read the Tech section's carb write-up. Note that the XS650 stock carbs are vacuum operated.
The uneven slide lift could also be caused by a partial failure in the carb slide lifting diaphragm.

 

[5twins]

Since you're new at this, a word of caution - don't use carb cleaner anywhere near those rubber diaphragms on the slides. They'll shrivel up like a used condom, lol.

 

[SoILSpecial]

Since you're new at this, a word of caution - don't use carb cleaner anywhere near those rubber diaphragms on the slides. They'll shrivel up like a used condom, lol.

That's funny because my buddy who is more experienced did just that and then was told by his friend explicitly not to do that directly after it was done. He rinsed it in warm water immediately though.

 

[member28833]

Believe it or not I've pondered plenty as to how to treat the diaphrams. Here at work there are all kinds of oils and greases but I use this Shea Butter on my hands and like it enough that I experimented on a set of 77 diaphrams. It seems great! In fact I've now Shea buttered up my own personally stashed 79 diaphrams too