angus67
Welder's penetrate deeper!!
oh.... that makes more sense.
So if I buy the e-adv. do I have to get the 60* wheel?
So if I buy the e-adv. do I have to get the 60* wheel?
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touchy 1971 throttle
- Thread starter angus67
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angus67
Welder's penetrate deeper!!
I also took a closer look at your pulley system. I placed my finger there to simulate a pulley, and What I think is happening is without the pulley, the take up of slack is immediate. With the pulley, the slack isn't there, but the throttle is more linear? does that make sense?
Kinda. When the throttle arm is down at idle, the effective lever arm length is from the throttle shaft center to where the cable is closest to that shaft center, or about 70% of the actual lever length.
So, with this shorter lever, the shaft rotates faster when the cable is pulled. At half throttle, the shaft rotation is the slowest, since it's working the full lever arm length.
The pulley guide keeps the first half rotation linear, like you said.
I have normal slack in my cables. You may have a too-short free length issue with yours.
E-advance? That's Pete's department...
So, with this shorter lever, the shaft rotates faster when the cable is pulled. At half throttle, the shaft rotation is the slowest, since it's working the full lever arm length.
The pulley guide keeps the first half rotation linear, like you said.
I have normal slack in my cables. You may have a too-short free length issue with yours.
E-advance? That's Pete's department...
angus67
Welder's penetrate deeper!!
thank you. Im gonna hit a couple of second hand stores, and see if I can find a stereo that would have those wheels for the needle thread.
angus67
Welder's penetrate deeper!!
So I've been riding my 71 a fair amount this summer. Timing is dead on, doesn't advance too far, done idle drop. Valves set, cam chain good.
It feels like it's surging, the carbs are early 38's, stock jetting, original mufflers in pristine condition. Is it too rich? Should I drop the needles one notch?
When I checked the timing, it was just tad left of the t mark, and it flutters about.
I'm running fuel filters, fresh gas. As far as I know, timing is dead on.
5twins suggested shimming the pamco disc, but just for a test, I checked timing while dragging a screwdriver handle on the disk to take out slop. Same flutter, maybe worse, so I didn't shim it, I did remove the advance rod to service it, but seen my tell tale blue bearing grease there, so I had already done it four years ago. Did it any way with marine bearing grease.
I don't want to get the e-advance yet, is there anything else I could do?
It feels like it's surging, the carbs are early 38's, stock jetting, original mufflers in pristine condition. Is it too rich? Should I drop the needles one notch?
When I checked the timing, it was just tad left of the t mark, and it flutters about.
I'm running fuel filters, fresh gas. As far as I know, timing is dead on.
5twins suggested shimming the pamco disc, but just for a test, I checked timing while dragging a screwdriver handle on the disk to take out slop. Same flutter, maybe worse, so I didn't shim it, I did remove the advance rod to service it, but seen my tell tale blue bearing grease there, so I had already done it four years ago. Did it any way with marine bearing grease.
I don't want to get the e-advance yet, is there anything else I could do?
Hey, Angus.
Are the diaphrams ok? Is there any thin coating on the walls of the pilot jet orifice, and the air bleed jets?
Try the full-advance just a tad retarded, a bit right of the 'T' mark.
The kind of slop we're looking for here is angular slop, not endplay slop. Without points to provide a mild drag on the advance shaft, any looseness in the fit of advance weight ears to slotted disc can produce your timing scatter.
There was a 'surging' issue with the early carbs, documented in one of the early service bulletins, solved by a carb redesign, but it may not apply to yours.
Found in here:
Yamaha XS1, XS1B, XS2, TX650 Tech Bulletins, Service Data, Brochures
Are the diaphrams ok? Is there any thin coating on the walls of the pilot jet orifice, and the air bleed jets?
Try the full-advance just a tad retarded, a bit right of the 'T' mark.
The kind of slop we're looking for here is angular slop, not endplay slop. Without points to provide a mild drag on the advance shaft, any looseness in the fit of advance weight ears to slotted disc can produce your timing scatter.
There was a 'surging' issue with the early carbs, documented in one of the early service bulletins, solved by a carb redesign, but it may not apply to yours.
Found in here:
Yamaha XS1, XS1B, XS2, TX650 Tech Bulletins, Service Data, Brochures
angus67
Welder's penetrate deeper!!
How do I time it at full advance at the t mark? There is something im missing here. When I do idle timing, the line on the rotor flutters just left of the t mark. When I rev to full advance, it goes no further than the left most mark. Should I back off timing even more so at full advance, it is just right of full advance mark? I think I tried that some years ago, and kept shutting down. I also re-synced my carbs.
Interesting psa. I have a pair of 76-77(?) 38's I could slap on there and see if the stutter goes away. The 38's on it now are presumably the originals with the elevated floor, and say solex on the top. One thing I noticed when I did the dead cylinder idle drop, when they both end up running their best together, one mix screw is one full turn out, the other, 3/4 out. don't know if that matters, its basically just taking what it needs, regardless of what the other cylinder needs.
Interesting psa. I have a pair of 76-77(?) 38's I could slap on there and see if the stutter goes away. The 38's on it now are presumably the originals with the elevated floor, and say solex on the top. One thing I noticed when I did the dead cylinder idle drop, when they both end up running their best together, one mix screw is one full turn out, the other, 3/4 out. don't know if that matters, its basically just taking what it needs, regardless of what the other cylinder needs.
No, you're not missing anything. Thanx for being alert. Your setting sounds fine.
Hooo, boy, brain not work rite today. Too much yesterday, today is payback.
That 1/4 turn difference is (for me) cause for concern. The swap is a good experiment.
BTW, my mix screws work best at 5/8 turn out...
angus67
Welder's penetrate deeper!!
I'm going to clean the carbs again tomorrow and see if that helps. Perhaps idle circuit has crud in it? But it responds to adjustments.
As far as the advance rod, how do you fix 'angular' slop?
As far as the advance rod, how do you fix 'angular' slop?
I think RG came up with a method of peening the advance weight ears so that they had a better/closer fit into the slots of the 'slotted disc'.
Mine were so badly worn that I built up the ears, and filled the deep gouges in the slots, using. 023" mig, then ground everything back to original.
The other option is to replace the advancer...
angus67
Welder's penetrate deeper!!
Replace the advanced with what? A crappy mikes unit? I think not. Not my baby.
CDNTX650
XS650 Guru
Those Mikes advancers are shit. Why not just pamco and e advance and be done.
The factory advance unit is only $210. What a bargain!
http://www.boats.net/parts/detail/yamaha/Y-256-81653-10-00.html
There's some on eBay. Good welding practice.
But, does yours actually have slop in the ear/slot fitment?
http://www.boats.net/parts/detail/yamaha/Y-256-81653-10-00.html
There's some on eBay. Good welding practice.
But, does yours actually have slop in the ear/slot fitment?
angus67
Welder's penetrate deeper!!
cdn, I have a pamco, and actually, Ide rather pay $210 for a factory part since no one else makes a good repop. If that whole adv unit is available, I wonder f I could just get replacement weights.
So, I cleaned out both carbs today, and low and behold, No o-ring, and no washer in the idle screw bore.
(make stupid face here) Apperently, At some point I forgot to put them back. It was prolly when I was trying to run water instead of gas a few months ago. doh!
So anyways, yanked 2 O-rings and washers from a set of 34's, threw them in, fired right up, fiddled with the idle after it warmed up. sync the carbs, then mess with the idle screw. And as it sits now, both screws are 5/8,-+ a pinch turn out. idles great.
I checked the timing, still a bit fluttery, but much improved.
The next big purchase for this bike will be a e advance, but don't hold yer breath.
Runs WAY better now.
Thanks guys, especially two many, your thought on the idle mix screw being way off made me look closer at that area.
So, I cleaned out both carbs today, and low and behold, No o-ring, and no washer in the idle screw bore.
(make stupid face here) Apperently, At some point I forgot to put them back. It was prolly when I was trying to run water instead of gas a few months ago. doh!
So anyways, yanked 2 O-rings and washers from a set of 34's, threw them in, fired right up, fiddled with the idle after it warmed up. sync the carbs, then mess with the idle screw. And as it sits now, both screws are 5/8,-+ a pinch turn out. idles great.
I checked the timing, still a bit fluttery, but much improved.
The next big purchase for this bike will be a e advance, but don't hold yer breath.
Runs WAY better now.
Thanks guys, especially two many, your thought on the idle mix screw being way off made me look closer at that area.
Uh-oh. On our early BS38s, the only things that go into the mix holes are the tapered mix screws and springs. No washers and o-rings, like on later carbs.
I guess if it works for you, fine. But your setup is unique now.
Edit: If you want to check out the dimensions of the mix screw and port, look into this:
http://www.xs650.com/forum/showthread.php?t=42002
angus67
Welder's penetrate deeper!!
well I also did a cleaning of all passages and jets. Im using stock jets 130 main, 42.5pj, mufflers are not rotted out, and running stock air filters. I did have some very fine looks like rust particles in one of the bowls. I also have fuel filters. Tank it rust free.
It may have been just the cleaning it needed. I wonder how the o-ring and washer will work out in the long run, or if not needed at all. the factory didn't design them there. Ill test ride tomorrow and see how she goes.
The taper on the idle needle is the correct one, not stepped like the later years, and shows no damage from over tightening. In any case, the oring may just become the new cushion to prevent damage when some one tightens down that mix screw too hard?
It may have been just the cleaning it needed. I wonder how the o-ring and washer will work out in the long run, or if not needed at all. the factory didn't design them there. Ill test ride tomorrow and see how she goes.
The taper on the idle needle is the correct one, not stepped like the later years, and shows no damage from over tightening. In any case, the oring may just become the new cushion to prevent damage when some one tightens down that mix screw too hard?
angus67
Welder's penetrate deeper!!
btw, according to your service bulletin, I have the revised carbs.
If im reading it correctly, the before carbs had the idle mix passage running straight down, off to the side into the main ventury, and the revised carbs had the passage running diagonal to the center of the venture .
Is that correct? I also matched the bowls to the carb guide, they are both early bowls, not 1 early one late, as mixing has happened to some.
If im reading it correctly, the before carbs had the idle mix passage running straight down, off to the side into the main ventury, and the revised carbs had the passage running diagonal to the center of the venture .
Is that correct? I also matched the bowls to the carb guide, they are both early bowls, not 1 early one late, as mixing has happened to some.
This bulletin applies to ours. That other bulletin I believe applies to the later XS2 and up.
Our 70-71 carb bowls are unique, with left-side starter pickup tubes. Can't interchange with later BS38s...
Our 70-71 carb bowls are unique, with left-side starter pickup tubes. Can't interchange with later BS38s...
angus67
Welder's penetrate deeper!!
why does your psa say I need 45pj stock? my Haynes states 42.5
