Seeing the brass washers on the 4 outer head bolts would suggest it wasn't just thrown back together without thought.
Nice ride and 750 to boot!
Nice ride and 750 to boot!
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New owner of a 1981 XS650 and I don’t know where to start
- Thread starter JFAIR1
- Start date
Sweet bike JFAIR1 !
Welcome to the forum - it is a great place full of generous people.
Welcome to the forum - it is a great place full of generous people.
Looks like the TCI timing has been "tweaked" a bit, but it's been advanced, not retarded like we usually do. To retard it, you need to rotate the pick-up to the left .....
His has been rotated to the right and advanced. This would explain the kickback he's getting from the kicker.
His has been rotated to the right and advanced. This would explain the kickback he's getting from the kicker.
^
That makes sense by course. Seeing the first set of pics including the stator and pickup, the stock rivets ( screws without slots, that is) holding the pickup in place are there - at least the lower one is visible. Seeing the second set of pics shows both in place. Led me to think it hadn't been molested.
Seeing the shift shaft without the guard and what appears to be some metal swarth on it makes me wonder if there's an 18 tooth front sprocket......could be the angle of the shot.
That makes sense by course. Seeing the first set of pics including the stator and pickup, the stock rivets ( screws without slots, that is) holding the pickup in place are there - at least the lower one is visible. Seeing the second set of pics shows both in place. Led me to think it hadn't been molested.
Seeing the shift shaft without the guard and what appears to be some metal swarth on it makes me wonder if there's an 18 tooth front sprocket......could be the angle of the shot.
There’s more to be done. That’s for another day.
The carburetors are BS38, maybe the ‘77 version. They likely need syncing.
It sounds like the chain is rubbing on something.
The carburetors are BS38, maybe the ‘77 version. They likely need syncing.
It sounds like the chain is rubbing on something.
JFAIR1
XS650 Member
I can't thank Marty and this forum enough for all the knowledge and support. He let me come to his house and work on my bike for several hours. We went through the whole thing. Bike is running great. Thank again Marty. We'll have to get a ride in, soon.
JFAIR1
XS650 Member
Any recommendations on air filters for those BS38 that won't restrict the ports?
JFAIR1
XS650 Member
Thanks 5twins on the TCI timing recommendation. I'll put it on the "to do" list.
Did you guys actually do a timing check with a timing light, and if so, is it advanced a little?
The best pod filter to use is the straight foam UNI. For your BS38 carbs, you'll want the UP4200 or UP4200ST (dual layer) ......
Pictured above is the UP4200. The dual layer ST version is nothing more than this same filter with a red foam "sock" slipped over it. Remove it and you're left with the plain 4200 as seen above. You don't need the dual layer ST, and it costs a few dollars more. For oil, don't use the special foam filter oil they make, it's too thick and can clog the filter. Instead, just use a simple 50-50 mix of motor oil and gas. I bought a bottle of cheap Walmart brand straight 30wt. to use specifically for this ......
Yes, even though they're not needed, I do have the dual layer ST filters on my BS34 equipped '83. The only reason I have them is because I got them cheap from a local guy who bought them for his bobber and they wouldn't fit.
The best pod filter to use is the straight foam UNI. For your BS38 carbs, you'll want the UP4200 or UP4200ST (dual layer) ......
Pictured above is the UP4200. The dual layer ST version is nothing more than this same filter with a red foam "sock" slipped over it. Remove it and you're left with the plain 4200 as seen above. You don't need the dual layer ST, and it costs a few dollars more. For oil, don't use the special foam filter oil they make, it's too thick and can clog the filter. Instead, just use a simple 50-50 mix of motor oil and gas. I bought a bottle of cheap Walmart brand straight 30wt. to use specifically for this ......
Yes, even though they're not needed, I do have the dual layer ST filters on my BS34 equipped '83. The only reason I have them is because I got them cheap from a local guy who bought them for his bobber and they wouldn't fit.
No. This project started a bit late in the day. My goal was to quickly clarify whether or not we were dealing with mayor issues. Once we got it back together, it went off the lift, kick started, and test driven. It was time to put it back on the trailer. We got a lot sorted out, but there's plenty still on the table. He did go home with a running bike. Timing is suspect as kick starting this bike isn't easy.
Well, that TCI sensor looks a tad advanced to me too... still has the original screws, so that seems odd... but anything's possible I guess.
I run the TCI about 35-37°. Seems to run a tad smoother and no change in engine feel as far as power. And that would definitely help starting it.
I run the TCI about 35-37°. Seems to run a tad smoother and no change in engine feel as far as power. And that would definitely help starting it.
Are the pickup coil fasteners factory for a 1980 stator? Stators in my collection only go back to 1981. The pickup coils are attached by screws. I didn’t want to futz wit it based upon the available time.
Another thing that needs to be addressed is the drive chain. It’s contacting something and it’s easily heard when riding the bike. Rubbing is visible on the chain.
Yes, they used screws that sheared off the (driving) head when it was torqued. Tamper proof....
Cut a slot in 'em with a dremel or die grinder cutoff wheel and they'll usually unscrew pretty easily.
They're 4mm screws... just like the rest of the screws on the stator.
Question, when using this filter, does jetting change from stock?
Depends.
With the narrow double walled stock exhaust, maybe not.
Mine with the more free flowing 1 1/2" headers and Commando muffs, yes.
One way to find out.
Probably. When I went from OE mouse fur filters to K&N, jetting changed.
I have two nearly identical Specials. Both have stock carburetors, stock airbox, stock exhaust. Neither has exactly stock jetting. One has K&N filter. The other has Uni. They aren’t jetted the same.
Maybe yes, maybe no, depending on how much other modding you do. If the filters are your only change then you may get away with not having to re-jet. Only some road testing will tell you for sure. But the Mikuni jets used in these carbs are very common types, readily available, and not very expensive. And if you did need a change, it wouldn't be much, maybe one up on the pilots, one up on the mains, and the needles leaned a step. Now, this is for a '78-'79 BS38 set. The '76-'77 BS38 set that JFair has is different. It came with much smaller mains and usually requires several sizes larger for mods (like 3 to 4). The pilot circuit would get the same one size up and the needle the same one step leaner setting.
Marty has the later BS34 carbs on both of his bikes. They were more pollution controlled and leaner from the factory so any little change at all usually requires some carb changes. In fact, a totally stock bike runs better if you up the mains a size.
Marty has the later BS34 carbs on both of his bikes. They were more pollution controlled and leaner from the factory so any little change at all usually requires some carb changes. In fact, a totally stock bike runs better if you up the mains a size.
JFAIR1
XS650 Member
Update on the bike. I purchased the UNI air filters and installed them. The bike was on a float charger for several days. The starter did not want to turn the bike over. Not a real surprise considering I have not ridden the bike in days. I went to kick on it and it turned over no problem. Nice and smooth. The bike did not try and kick me back. I took it for a quick 15 minute ride. The bike ran great. No issues. I also checked to see if the headlight would brighten when I revved the motor and it did as well. So I assumed the bike was charging correctly. When I got home I turned the bike off and left it for 2 to 3 hours. Key was out of the ignition. When I went to start it again the stater gave me one weak little attempt and died. I could not kick the bike over either. I put it back on the float charger for 20 minutes. I came back to the bike, kicked it once and it immediately started. I tested the voltage at the battery and it read 9.00. I revved the motor and it went up to 9.30. That was as high as it would go. I put it back on the charger overnight. Battery read 13.35 in the morning. Could something be draining the battery with the ignition key out? Could the charging system be charging the bike but not enough to sustain the system? I checked the rotor again and it read 5.2-5.5. I tested the battery 6 months ago and it was good. Could the battery be bad now from all my issues? When Marty and myself were working on the bike he mentioned that the head light is not factory. Could the aftermarket headlight be pulling to much power? Ill attach a few pictures of the headlight. Thanks again for all the feedback.
Attachments
We need to put a test light on that thing. Do you have one? Disconnect the ground cable from the battery. Key off and out. Place the test light one end on ground and the other on the negative battery terminal. Any glow means there is a drain on the battery when it’s sleeping. I’m afraid I’m out of pocket until after Thanksgiving, but eager to have another go after that or first thing 2024.
That would be my guess.
In addition to what Marty suggested above, you could charge the battery, disconnect it from the bike and let it sit the same time it previously took to drain. If it does drain, the battery's bad. If it stays charged, then a parasitic drain is a good possibility.
