Diesel's XS650

[Dieselchanic]

This one is for me. Most of the bikes I've built I've had the thot of selling them in the back of my mind but this ones a keeper. Having said that the build will be slow for two reasons. I want it like I want it and I'm riding it every day...

Here's how it sits now. Clock showed 52,xxx I don't have any history on the motor but it is running the stock charging and ignition systems. Gutted pipes and completely open carbs (saving for Uni's) running 145 mains (for now cuz that's what I had laying around). When I got it it had 132.5 with the open setup and the sync screw was tightened down so of course the left cylinder didn't have a chance. I cleaned the carbs and threw in the 145's and synced it by ear. Runs acceptable for now till I can get some filters and baffles to tune it right.

 

[5twins]

That combo reg/rect unit hanging off the left side was not stock for '79 and neither were 132.5 mains. However, both of those were stock for '80 and newer models. I think you may have an '80 on your hands there.

 

[jd750ace]

Might be a swinging idea to compression check it too with that kind of mileage on the clock.

Hope you're not going to use those bars. They look like they were bent in a vice!

 

[Dieselchanic]

That combo reg/rect unit hanging off the left side was not stock for '79 and neither were 132.5 mains. However, both of those were stock for '80 and newer models. I think you may have an '80 on your hands there.

I don't know the years of the xs. Titled as a '79 manufactured in '78 according to the stamp on the neck. Reg/Rec has '82 written on it and the mains are anyone's guess. This things been jimmied six ways to Sunday.

 

[Dieselchanic]

A few questions. I want to run a small lead acid battery (cuz I already have one) and run kick only. I've got the stock alternator and it seems to work fine. Will I run into trouble with this setup?

Also what ratio is the tach. Wanna run a mini.

 

[5twins]

There's something you need to check like right now. That newer combo reg/rect unit can be used on the older models like yours but only if the grounded alt. brush is ungrounded by changing it's steel mounting screws to plastic or nylon ones. If this is not done, the charging system will work for a while but put out too much charge, eventually boiling the battery dry, then frying the charging system. I know because I just helped a guy fix his because of this very same scenario. What could have been fixed for pennies (plastic screws) or about $35 (reverting back to stock type components) is now costing this guy $100 to $200. He got about 650 miles out of the bike before the charging system fried.

 

[Dieselchanic]

Thanks alot for that heads up! I will check that.

 

[jd750ace]

There's something you need to check like right now. That newer combo reg/rect unit can be used on the older models like yours but only if the grounded alt. brush is ungrounded by changing it's steel mounting screws to plastic or nylon ones. If this is not done, the charging system will work for a while but put out too much charge, eventually boiling the battery dry, then frying the charging system. I know because I just helped a guy fix his because of this very same scenario. What could have been fixed for pennies (plastic screws) or about $35 (reverting back to stock type components) is now costing this guy $100 to $200. He got about 650 miles out of the bike before the charging system fried.

I'm curious about this because neither instruction sheet for the one from Mike's or the one from Electrosport mentions the grounding issue. The Electrosport is a direct plug-in to both harness leads. I have a combo unit on mine (with no real mileage on it except what I have put on it (less than 170 miles so far) and no plastic screws. Is this a "field" revelation by users, or are the instructions lacking?

 

[5twins]

I'm talking about the stock unit that was used on the '80 and newer models. If you have an aftermarket unit designed for use on the '79 and older bikes, the brush mounting probably isn't an issue. I would think they were designed to just "plug and play", or at least I would hope so. Obviously, they must be. They wouldn't be on the market long if everybody who bought one fried their charging system, lol.

 

[jd750ace]

Thanks for the clarification. Little brother verified I have the one from Mike's on the bike.
I read some older threads and understand it now.

 

[Dieselchanic]

So which wire do I need to isolate? Or am I even looking in the right place??

 

[5twins]

JD brought up a good point. You'd better confirm that you do indeed have a reg/rect unit from an '80 or newer 650 installed and not one of the aftermarket units. The aftermarket units look very similar to the later stock ones but don't need the brush screws changed. Have you checked your charging output? That one I just worked on was putting out something like 16 or 17 volts when revved because of the incorrect installation (no plastic screws on the brush). You should only see 14 to 14.5.

I have some of the newer units. Let me dig them out and I'll see if they have any part numbers or something.

 

[5twins]

Did you do anything besides removing that cover? I ask because your brushes are missing. You're not over-charging like that, you're not charging at all, lol. The alternator is also an '80 or newer unit but the pick-up for the electronic ignition has been removed. Do you have points and 2 separate coils?

 

[Dieselchanic]

I have points. Haven't pulled the tank but I think it's two coils also. Was gonna check the output last night but forgot my meter at the shop.. It's got that giant mower battery in there so its not gonna cook it right away... I will do some more checking tonight. Not riding it at the mo till I get mess figured

 

[5twins]

Did you remove the brushes or are they just M.I.A.? Your pic just shows holes where the brushes should be.

 

[jd750ace]

I'll pull my "known" Mikes XS plug in replacement one piece this evening and see if it has any numbers on it that might help.

 

[5twins]

OK, on the stock units I have, one is labeled 3G1-50 9.G2 and is a Toshiba S-8515. The second is harder to read due to corrosion but appears to say 3GS-50 0.H4 and looks to be a Toshiba S-8515 as well. The third, the one that fried that guy's charging system has no legible factory writing on it, just "Yamaha 650 '79-'81 Good" in magic marker, and the style of the casting differs slightly. I'm thinking the P.O. got it from a parts seller who apparently doesn't know much about 650s. This combo type unit won't work on a '79 without brush mods and will work on all 650s from '80, not only up to '81. All 3 units have the same 7 wires that exit the case in no particular order (it's different on each one) - 3 whites, one red, one black, one brown, and one green.

 

[Dieselchanic]

Brushes were mia. Tested the volts and its around 12.34 off and charges about 11.1 running. Hmmm. No wonder the giant battery... Got a guy on bobberforum wants my tank and he happens to have a stock working alternator off a '78 so that's gonna be part of a swapparoo. Now my reg/rec seems to be the twin to one of yours 5twins. No markings except the paint pen...

Btw I don't think that's the original wiring setup?? LOL

 

[jd750ace]

My mikes unit has no markings at all. If you face the potted side of the unit, the row farthest from you is white, black, white, red, white. The row closest to you is brown and green. Wires are per Mike's instructions on the 6 pin, but the instructions have orange and blue on the unit. My 3-wire side matches colors to the original harness.

 

[Dieselchanic]

My wires are all dark blue metallic where they come out... Then they go to other colors.. I'll check mine against your aftermarket.