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Retaining Disk
- Thread starter motorshag
- Start date
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- Tags
- carb diaphragm carb help
OhBoy, wierd stuff! Engage fantasy mode.
If spring is correct, and disc is correct -
Wrong/short needle, catching on needle jet somewhere and pushing up?
Bad intake valve, causing rapid/ultra-strong pulses making slide jitter up/down too much?
Neighborhood mechanic strapped for cash, sneaks in, diddles with bike, hopes for repair job?
Small child discovers daddy's toolbox?
Reengage reality mode...
If spring is correct, and disc is correct -
Wrong/short needle, catching on needle jet somewhere and pushing up?
Bad intake valve, causing rapid/ultra-strong pulses making slide jitter up/down too much?
Neighborhood mechanic strapped for cash, sneaks in, diddles with bike, hopes for repair job?
Small child discovers daddy's toolbox?
Reengage reality mode...
motorshag
XS650 Enthusiast
I am unclear the whole slide is hanging or just the needle and it's retaining disk?
What ari filters are you running? In the first pic the slide looks to have some scratching.
Always be very cautious not to let any chemicals to touch the diaphragm, wipe slide and bore with spray carb cleaner on a paper tower till the towel comes out clean. carefully finger slide and bore for any burrs rough edges, touch up if needed with very fine sand paper, less sanding is better.... 1000 or 1500 grit helps keep you from overdoing the sanding. I finger a bit of syl-glide on the diaphragms, seems to help keep them soft and pliable.
What ari filters are you running? In the first pic the slide looks to have some scratching.
Always be very cautious not to let any chemicals to touch the diaphragm, wipe slide and bore with spray carb cleaner on a paper tower till the towel comes out clean. carefully finger slide and bore for any burrs rough edges, touch up if needed with very fine sand paper, less sanding is better.... 1000 or 1500 grit helps keep you from overdoing the sanding. I finger a bit of syl-glide on the diaphragms, seems to help keep them soft and pliable.
motorshag
XS650 Enthusiast
It's the bore side that is causing trouble. The Retaining Disk gets stuck. Running stock everything. The retaining disk slids fine on the other side, no choke side. So I know it's the choke side bore that is causing the trouble. Think a little 1500 grit rubed in and out of the bore for a bit, would help? I've noticed it's gotten worse over time. Just that side..
That disk can't shouldn't (can't?) rise if the spring #20 is in place.....
If the spring is in place I might suggest; a bent needle is sitting on the edge of the taper jet body?
One test would be to swap parts side to side.
If the spring is in place I might suggest; a bent needle is sitting on the edge of the taper jet body?
One test would be to swap parts side to side.
motorshag
XS650 Enthusiast
Unfortunately gggGary, the retaining disk does rise. Not sure what is casing it to rise, but once it does, it gets stuck about half an inch up from being flush with the bottom of the bore. The other car bore and retaining disk slid up and down smoothly. The bike is going out to the EDR tomorrow and I am at a loss...
Is the spring in place? Does the disk stick when you raise and drop the slide manually with the engine off? I am going with bent needle or something cocking the needle in the seat, the disk should never "rise" so any sticking after it rises is irrelevant. Again swap sides see if the problem follows the parts.
motorshag
XS650 Enthusiast
Spring is in place. Yes, it sticks farily often when I raise and lower manually with the engine off. Ok, something cocking the needle in the seat. I will try and swap sides and see if it does it. Thanks.
I want to be 100% clear we are calling the parts correctly.
I agree with gggary swapping parts should show where the issue lyes. You could also try sanding the needle itself, it could have a burr. 1000 grit or finer paper, light sanding and follow up with a good cleaning and a lubricant.
mrzw, welcome to the forum.
Sanding the needle is never a good idea, it changes the gas metering. In fact, just normal wear of the needle rubbing against the nozzle (slide jet) will thin a needle enough to throw off the metering.
motorshag, really weird problem, I'll be watching this thread.
Sanding the needle is never a good idea, it changes the gas metering. In fact, just normal wear of the needle rubbing against the nozzle (slide jet) will thin a needle enough to throw off the metering.
motorshag, really weird problem, I'll be watching this thread.
motorshag
XS650 Enthusiast
So all this/that being said. What would cause the retaining disk and pin to move up? a weak spring? Or to much pressure coming from the intake?
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After pondering this for a while, I can only come up with one possible explanation. Either you have the wrong needle (one that is too short), and/or you have the wrong diaphragm (one with too short of a slide, possibly from some other model BS38, I don't know if such a slide even exists).
With such a needle and/or slide, at full lift, the needle would clear the nozzle. Then when the slide drops, instead of going back into the nozzle, the needle gets off center, and ends up like your photo. That's when the disc gets pushed up, and gets cocked stuck.
So, I would compare the needles and diaphragms to each other, and to what is spec'ed for your year BS38.
With such a needle and/or slide, at full lift, the needle would clear the nozzle. Then when the slide drops, instead of going back into the nozzle, the needle gets off center, and ends up like your photo. That's when the disc gets pushed up, and gets cocked stuck.
So, I would compare the needles and diaphragms to each other, and to what is spec'ed for your year BS38.
motorshag
XS650 Enthusiast
Interesting. I will look. Ive been riding it like this for about 2 years, and just started. But I welcome ideas. Thanks!
A way to test my idea would be to put the disc and everything in their proper places, and push the diaphragm slide all the way up, and see if the needle clears the nozzle. (It shouldn't.)
On further reflection, mrzw70's bur idea has merit. If you have a bur or something in the nozzle, the needle could catch on it as the diaphragm comes down, pushing the disc up which then cocks and sticks. Then, during the next full lift, vacuum sucks the needle up, the needle clears the nozzle, and it ends up like your photo.
motorshag
XS650 Enthusiast
Ok. So...I stopped by Ace. Got 1500 grit paper. Sanded the bore. Very slightly. I put the spring, and the pin, and disk all back in. I manually tried to move the disk and pin up and done. It moves as smoothly as the good side does. So that disk shouldn't get stuck again, unless the pin comes all the way out of the guide. Which the bur theory could be causeing it to jump. But if the disk moves freely, it should come to rest more readily now. I'll test it tonight, and keep you all posted. Thx!
motorshag
XS650 Enthusiast
Just wanted to give everyone an update. The disk, and needle were moving and adjusting out of whack do to the.....wait for it.....Pin Hole in the Diaphragms. The PO (not that I am blaming him) coated the holes with some type of silicone caulk. it was black, so with the lighting and my eyes not able to distinguish between blue and black. I didn't see it. Needless to say. I didn't find the problem in time, to take the bike to the EDR 2013. I however did take my newer bike, but that is a different story. I ordered and purchased a pair of diaphragms from www.jbmindustries.com. Installed and put the bike all back together. The bike is back to normal. Just need to find where that bird chirp is coming from....Probably need to sync the carbs again too. Hope this helps someone from making the dumb mistakes I've made. Ride safe! 
