More BS38 hassles with my 73 TX.

I found the screws I bought sat a little deeper in the countersink of the butterfly shaft. So I thought 8mm long was a bit on the generous side. I have no idea how consistent the manufacture of these screws is. They're Chinese I guess. So I think it's moot whether you will also find that 8mm is a bit too long. At least with buying 8mm you can make them shorter if you wish. Good luck.

Personally I wouldn't convert away from the stock charging system to a PMA, though I know many have. I did the recommended checks, put new brushes in, bought a three phase bridge rectifier and an automotive regulator. It works really well. Buying the rectifier, regulator and bits to make a new sub harness cost me less than £25. Like this, unfortunately the Lucas regulator seems unobtainable these days. But there's alternatives out there. -

Post in thread 'UK source voltage regulator.' https://www.xs650.com/threads/uk-source-voltage-regulator.65543/post-832950
 
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If it was dead with a new battery, sounds like you have a power drain somewhere, I’m guessing but If you put a meter from ground to the other side of the iggy switch with it off see if it reads anything. I had one do that with an aftermarket switch because you had to turn it completely till the key stopped before it actually turned off. If I left even a bit of slack it drained my battery.
 
[If you put a meter from ground to the other side of the iggy switch with it off see if it reads anything.
[/QUOTE]
I did the equivalent, as I understand it. I disconnected the battery's positive lead and put a meter between the lead and the battery terminal, so if there was any current flow with the switch off it woukd show, but it shows zero amps. But I was very surprised indeed to see a brand new lithium battery go to absolutely flat in a couple of hrs. Well, the lithium batteries don't go flat, they have a safety cutoff at a certain voltage, so that's what probably happened. The ignition switch is the original switch and is worn, in that the key can be removed even when the switch is moved into the 'on' position, so maybe a good idea to change it. Only worry doing this woukd be the previous owner, who did the original resto job, fitted a brand new wiring harness, but they aren't available for the TX in the UK, so he fitted a 79 XS one from Yambits. Not sure if the wiring for the TX iggy switch is the same as for a 79 xs. So might be some messing about figuring how he's spliced the old switch into the new harness. To help, what are the 3 switch positions on the 73 TX iggy switch, as in left, centre, right position?
 
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Ok, just re-checked the iggy switch. Left is 'off' (and the neutral light is off, so probably is 'off'. Centre position is 'on', for all circuits, and what I never realised before is that the 'right' switch position only lights up the tail light and the clocks, so I'm guessing its a parking circuit.

So, the switch 'appears' to be functioning ok BUT I have just done another parasytical discharge test of the battery and found that there definitely is a discharge. I disconnected the positive lead off the battery and connected a meter between it and the battery terminal and it shows a discharge of 0.37A or 0.166A, depending how you connect the leads on the meter (which I find a bit odd tbh). So 0.37A is going to flatten my battery pretty quick, especially after bike has sat for a while, then only done a 3 mile trip and then sat a couple of hrs. So need to figure how to find where the discharge is occurring. Hmmmm...
 
Mannyroad said:
So need to figure how to find where the discharge is occurring. Hmmmm...
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First thing I'd try is the rectifier. Disconnect it and see if your drain disappears.

The rec is the only unit on the bike that's live to the battery no matter the switch position. It gets away with that because of the blocking diodes not allowing battery power to drain back through. If one of those diodes goes bad, it could pass current back to ground like you're seeing.
 
Jim said:
First thing I'd try is the rectifier. Disconnect it and see if your drain disappears.

The rec is the only unit on the bike that's live to the battery no matter the switch position. It gets away with that because of the blocking diodes not allowing battery power to drain back through. If one of those diodes goes bad, it could pass current back to ground like you're seeing.
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Thanks for that info Jim. I thought the only route for the current to get back to ground before the switch was via the starter solenoid, so its good to get better info than my knowledge. Will check that out once I find where the rectifier is on the bike. Does it look like the one in the pic?
 

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Mannyroad said:
Thanks for that info Jim. I thought the only route for the current to get back to ground before the switch was via the starter solenoid, so its good to get better info than my knowledge. Will check that out once I find where the rectifier is on the bike. Does it look like the one in the pic?
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It does look like that, and in later bikes it was mounted to the bottom of the battery box...(probably but) not sure on your '73?

And BTW, the photo caption on the pic says "Regulator Rectifier", but that is just a rectifier. The separate regulator is typically mounted on the left side of the battery box.
 
Jim said:
IF I'm not mistaken, it's on the left side back somewhere around the rear fender.
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I think you are exactly right! My memory's a bit fuzzy from years ago on my XS2, but it was behind the battery box, attached - I think - to the lower fender. I guess probably the same on '73 TX.
 
Ok guys, sorry its been a few days before getting back. Been sorting a horn gremlin on my new chop build, so now its ready for its first fire up since completed with 277 750 full rebuild - but that's another story.
So, just re-checked the discharge test on the TX. Result: only draw with iggy switch 'off' is 4.5mA. And 0mA with rec disconnected. So I'm happy there's no significant discharging issue. Can only think I must've left iggy switch on, but don't think so. So no idea why battery was dead. Anyway, its charged and been holding it fine for a few days, so I'm going to put this to bed and just keep my eye on it.
Ok, back to the thread title, the BS38's. Bought new throttle shaft seals, all thanks to 'Its been a long time' and Jim for their posts which included the part number for the Suzy seals (13651-51011), which arrived today, along with the M3x8 raised head c'sunk screws. So, tonight I pulled the carbs off the bike (gettin sick of doing this) and stripped the carbs as far as I think I need to, which is pretty much all but the choke lever linkage. You guys have been making wooden supports to carry the throttle shaft when its time to put some pressure on the butterfly screws. I made a similar support and when it came to removing the screws they can out quite easily tbh. And they definitely look to be original judging by the bronzed looking finish on the screws and the back face of the shafts are completely unmarked, having all the original milling marks. Took a bit of effort getting the throttle/butterfly plate out of the slot, it was well gummed in. Anyways, new seals in, with some red rubber grease, all jets and carb body internal passageways cleaned again, with carb cleaner and blown out with compressed air and judging by the carb cleaner spraying out of the finer pilot passageways etc they're definitely not blocked. Mixture screws in good condition and all choke passageways clear. Reassembled everything, checking throttle plates are centred properly and free moving. Sync'd them with a 4 thou feeler guage and then just the pj's (30/96-40) to install along with the floats and new float valves and seats. Then I looked at the float bowl and suddenly was unsure if I had carbs for 30/96 pj's or for vm22/210 pj's. I recall seeing a post by 5twins showing the two float bowl types but can't find it again. Anyone able to send me a link, or confirm that my bowls are the correct type for 30/96 pj's?
 

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