I saw the picture in post #71 pointing to the long spacer. I can understand that if something was putting end thrust on the throttle shaft it could cause the butter fly to bind in the venturi .
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Chaising the infamous hanging idle - Carb tops possibly?
- Thread starter Sci85
- Start date
Yes, I should have mentioned to disregard that red arrow. Yes, it's pointing to the stock thin plastic shim, spacer, or bushing that was placed between the aluminum spacer and the carb body. Besides doing a little spacing, I think it was also there to avoid metal to metal contact and rubbing between the spacer and the carb body. I used the pic because it nicely showed the sync assembly.
Ok, I pulled the head, relapped and rechecked the valves, redid the butterfly's so they fit in the shaft properly and put it all back together. Fired her up and low and behold, same dam thing. Ship. Exactly the same issue as well. I would call it a high idle versus a hanging idle. Once I blip the throttle, it goes high and stays there until I back out the sync screw (counterclockwise) which I believe is closing the right side butterfly relative to the left. So it appears the left side cylinder wants more butterfly opening than the right side.
I put the straw on the spray and found the right side carb shaft seals, both left and right, are leaking. I changed all the shaft seals earlier and the left carb passes the spray test. Not sure what the deal is with the right side carb. Maybe the shaft tunnel is worn but these ran fine when I got the bike. Dang. Should I try another seal replacement or should I just toss these pieces and try with a new set? Anybody got a decent pair you can part with?
Thanks.
I put the straw on the spray and found the right side carb shaft seals, both left and right, are leaking. I changed all the shaft seals earlier and the left carb passes the spray test. Not sure what the deal is with the right side carb. Maybe the shaft tunnel is worn but these ran fine when I got the bike. Dang. Should I try another seal replacement or should I just toss these pieces and try with a new set? Anybody got a decent pair you can part with?
Thanks.
You said you weren't sure if you installed the seals correctly, open side facing out. They work on vacuum and are sucked tight to the shaft from the vacuum passing through the main bore of the carb. If you put them in backwards (closed side facing out) they may not work right.
Yeah I did check the forum before I installed them and I did install them with the open side out. They were brand new oem seals. I guess I could take it apart for the 50th time and measure the shaft and bore but I'd really like to just get another set for piece of mind to try. I'm kinda done fooling with these.
If anyone has a decent pair, I'd be interested...
If anyone has a decent pair, I'd be interested...
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Well I fiddled around some more and it seems like I'm chasing my tail. Spraying has an affect but it seems to keep moving around. I think somethings jacked with this set for some reason. I'm going to suck it up and buy another set to try something different.
I'm thinking of either getting another set of bs34's and transferring the jets over or going for the EX500 cvk's but that will require more money since I don't have any jets or rebuild kits. Thoughts?
I'm thinking of either getting another set of bs34's and transferring the jets over or going for the EX500 cvk's but that will require more money since I don't have any jets or rebuild kits. Thoughts?
Bob Kelly III
Ranch Kid from way back,.... that got Old !
fix the ones you have so you don't have 2 sets that don't work !
.....
Bob.......
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Bob.......
Haha, that's good advice Bob. But, I've tried everything to date, replacing and cleaning everything and then some. There is nothing on this set that hasn't been replaced with new except the slides and needles. Maybe it's electrical? Maybe there's a crack or something in the carb body I can't find? Maybe the throttle shaft or the bores are worn? But, I do know that I've farted around enough with no progress for too long with this set. I need to source another set just to try something different or I'm gonna lose my mind...
Bob Kelly III
Ranch Kid from way back,.... that got Old !
the carbs on these XS650's are So picky its a wonder any of them work ! Seriously ! they have very tiny passage ways and get pluged solidly often.... its the passage ways that are important not so much replacing components !!!!!!! anybody can replace parts.... as you know you already did that.... and the thing still fails to work right..... its not the components its dirt in the little passageways !
take everything off the carb that will come off except the throttle shaft and butterfly and clean the passageways with carb cleaner
especially down the idle air screw hole and where it vents into the intake of the carb.... do the same with the choke circuit make sure
both ends of the choke circuit are clear.... I fought my carbs for weeks till I discovered on the BS34CV carbs that the hole in the bowl is supposed to go through to the bottom of the float bowl.... spraying carb cleaner in the hole in the gasket surface of the bowl did not come out in the bottom of the bowl.... it took allot of work with a sharp wire to finally get both bowls clear....
.... their great carbs... but PICKY !!!! they have to be kept clean ! an in line fuel filter is a must in my mind !
I was at my wits end as well after the 4th time taking the carbs off everything was correct (i thought) just as you think now....
but there was one passage way that was still plugged in my carbs once that was opened they worked just like they were supposed to !
...... switching carbs won't help if you can't get the new ones any cleaner than these ! see what I'm saying ?
I got pissed at myself and took all day to tear the carbs apart and clean everything once and for all ! and then I found the passageway in the float bowl plugged ! LOL.....
.....don't give up ! you can do it ! just double check every passageway 2 or 3 times and be extra careful on assembly re check float height and the whole shabang ! ..... you'll get it !
hang in there !
Bob........
take everything off the carb that will come off except the throttle shaft and butterfly and clean the passageways with carb cleaner
especially down the idle air screw hole and where it vents into the intake of the carb.... do the same with the choke circuit make sure
both ends of the choke circuit are clear.... I fought my carbs for weeks till I discovered on the BS34CV carbs that the hole in the bowl is supposed to go through to the bottom of the float bowl.... spraying carb cleaner in the hole in the gasket surface of the bowl did not come out in the bottom of the bowl.... it took allot of work with a sharp wire to finally get both bowls clear....
.... their great carbs... but PICKY !!!! they have to be kept clean ! an in line fuel filter is a must in my mind !
I was at my wits end as well after the 4th time taking the carbs off everything was correct (i thought) just as you think now....
but there was one passage way that was still plugged in my carbs once that was opened they worked just like they were supposed to !
...... switching carbs won't help if you can't get the new ones any cleaner than these ! see what I'm saying ?
I got pissed at myself and took all day to tear the carbs apart and clean everything once and for all ! and then I found the passageway in the float bowl plugged ! LOL.....
.....don't give up ! you can do it ! just double check every passageway 2 or 3 times and be extra careful on assembly re check float height and the whole shabang ! ..... you'll get it !
hang in there !
Bob........
Bob Kelly III
Ranch Kid from way back,.... that got Old !
LOL nothing wrong with that plan !!!!!
....
Bob.......
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Bob.......
Might also have a bent throttle shaft. Both of mine were slightly bent. Couldn't see it, and can't really roll them on a flat surface. The only way to check was to chuck them up in the lathe, clamping only the outer 1/2" of the shaft, the rest dangling out there, and take readings with the Dial Test Indicator. Easily straightened while still chucked up...
Sci...here is the clue and answer to your high idle issue right there in your statement.
if your idle changes for the better when you adjust either the throttle stop or sync setting then the issue lies with the butterflys not closing off properly .
This is why I asked you to press hard down on the throttle shaft stop lever and force the butterflys closed to see if the idle rpm dropped .
Like you I chased my tail on this issue for nearly a year in my case. Nothing I did improved things and after taking the carbs off 10+ times and cleaning and adjusting them I put my bike away in the garage for a year in complete frustration.
Two of the things that made the biggest improvement in my case was
1. reducing the sideways float of the throttle shafts and butterflys, by fitting a new white polyurethane spacing bushes and
2. By fitting much stronger throttle shaft springs which shuts off the throttle sharply and strongly , forcing the butterflys closed . it will make the throttle feel a little stiffer to operate but the shut off response is brilliant.
ps.. never mess with the sync adjustment screw once the carb butterflys have been set in sync.
Hi peanut, I did do what you said. I pushed on the end of the right side carb shaft but it didn't have any effect. They do move a little bit left to right so not sure if that means anything. I agree, something is funky with these carbs. I've cleaned them a bunch of times and just did another solid cleaning. Everything blows through properly. Maybe the issue isn't the carbs at all and it's just manifesting itself as carb related. Maybe it's an electrical issue. I don't know. Here's what I can tell you:
If the carbs are in sync, it high idles. Turning the idle screw out will bring the idle down but once it starts coming down, then it's too low to idle properly. If I turn the sync screw counterclockwise, or out, then I can also bring the idle down while NOT having to mess with the idle adjuster. But then the right cylinder runs weaker than the left obviously since it's not getting the same flow. It will run and ride like this. Pretty good too once the rpms pick up. But, it still wants to try and idle high. I've sprayed around using the straw and sometimes that will bring the idle down but the area that causes the change seems to move around. At first, it was the right end shaft area. Then that stopped having an affect. Then, it was the left side inside shaft. It's crazy.
I've just got to get a different set of carbs on this thing to determine once and for all if it's carb, or something else causing all this...
I appreciate everyone's help. This has been a real booger.
If the carbs are in sync, it high idles. Turning the idle screw out will bring the idle down but once it starts coming down, then it's too low to idle properly. If I turn the sync screw counterclockwise, or out, then I can also bring the idle down while NOT having to mess with the idle adjuster. But then the right cylinder runs weaker than the left obviously since it's not getting the same flow. It will run and ride like this. Pretty good too once the rpms pick up. But, it still wants to try and idle high. I've sprayed around using the straw and sometimes that will bring the idle down but the area that causes the change seems to move around. At first, it was the right end shaft area. Then that stopped having an affect. Then, it was the left side inside shaft. It's crazy.
I've just got to get a different set of carbs on this thing to determine once and for all if it's carb, or something else causing all this...
I appreciate everyone's help. This has been a real booger.
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sorry Sci I obviously didn't make myself clear .
What I was suggesting you do is to ..............force the butterflys closed
This needs you to press the throttle shaft stop lever against the throttle adjust screw
What you are trying to achieve here is to ascertain whether the throttle springs are fully returning the throttle butterflys .
When you blip the throttle you are twisting the throttle against the throttle return springs . When you return the throttle to idle the return springs should return the butterflys fully .
If the return springs are too weak or there is some friction somewhere in the throttle cable or the throttle shafts or the butterlys etc etc then this test will show it.
Bob Kelly III
Ranch Kid from way back,.... that got Old !
I know this sounds stupid but doesn't anybody round the butterfly plates slightly anymore so their not sharp edged ????
I used to do this every time I took a butterfly out ! it helps eliminate sticking ...it doesn't take much just to round the edges slightly
I used a file most of the time but have also done it with a sharpening stone (course)
sense the throttle butterflys are Punched out they have a really sharp edge and if you try to use them like that they have a tenancy to stick when closed or when they touch instead of sliding.... rounding the edges slightly cures that problem...
..... try it next time you have the butterflys out you may find as I did that they are much easier to open after being slammed shut!
.....
Bob..........
I used to do this every time I took a butterfly out ! it helps eliminate sticking ...it doesn't take much just to round the edges slightly
I used a file most of the time but have also done it with a sharpening stone (course)
sense the throttle butterflys are Punched out they have a really sharp edge and if you try to use them like that they have a tenancy to stick when closed or when they touch instead of sliding.... rounding the edges slightly cures that problem...
..... try it next time you have the butterflys out you may find as I did that they are much easier to open after being slammed shut!
.....
Bob..........
Another cheep/simple test.
Have the engine do its high-idle thing.
Shut it off.
Cycle the throttle grip once.
Without touching the throttle, start it up.
If it idles differently, that's significant...
Have the engine do its high-idle thing.
Shut it off.
Cycle the throttle grip once.
Without touching the throttle, start it up.
If it idles differently, that's significant...
Bob Kelly III
Ranch Kid from way back,.... that got Old !
good thinking 2M !
I wonder if your thinking what I am thinking now ! LOL
....
Bob........
I wonder if your thinking what I am thinking now ! LOL
....
Bob........
Ok, I did a little more testing. I recleaned everything for the 50th time. Re-installed the carbs. Same thing of course. I tried what you suggested Peanut. No Change. Video here.
https://goo.gl/photos/3YKzTYuNKmZVPvhw8
Spraying the right side shaft seal still affects the idle so I guess my attempt at replacing the seals with OEM units proved fruitless.
I'm calling it on these boogers. Gonna source some CVK's or another set of BS's and try that.
https://goo.gl/photos/3YKzTYuNKmZVPvhw8
Spraying the right side shaft seal still affects the idle so I guess my attempt at replacing the seals with OEM units proved fruitless.
I'm calling it on these boogers. Gonna source some CVK's or another set of BS's and try that.
