Runs good then runs bad

[Ottis]

Sounds like a good time to pull the heads, shave em, port/polish, and valve job! Any excuse to do some headwork is a good one. Wake that ole thing right up. lol

All of these situations are so hard to even take a guess at without really getting your hands on it and seeing for yourself. Like I said, I would gladly help T ray out if he wants to head up my way. . . . . . . Offers on the table.

 

[retiredgentleman]

J ray;
It may be a good idea to look at the electrical side of things. The original type fuse panels with the clips and glass fuses are totally worn out and can cause intermittant problems, such as ignition cutting out etc. If you still have that panel, its time to cut it out of the harness and replace with automotive blade type fuses..............solder them in and use heat shrink insulation.

 

[J ray]

RetiredG. Thats a good idea and I might do that but I've replaced with new glass fuses and there is continuity, no corrosion or cracked fuse connections in the panel. Its also a newer fuse panel that the p.o. spliced in, which I had to solder the splices because he had neglected to.
Ottis. Yup, top end job will have to be done, I think, but that still doesn't explain the lack of spark as I try to rev the engine. As soon as I twist the throttle the timing light slows and lights up erratically.
Banging my head makes me want to "kick the gong".

 

[Gordon]

Ok, on the forum page is a link to the electrical trouble shooting. In there is a link about the transister going bad in the igniter module. If not, go to 650 rider .com, it's definately in there. If you are absolutely sure about carburetion, and the wiring & connectors, then give that a shout. No, the newer pick up don't matter, same part, different wire color.
Back to the module, there are several transisters, get the one that is closest to the stock part number. Also, it reads to check ALL the soldered connections on the PC board, resoldering them (with a heatsink on the three legs from the transister. Those hemostats you used for a roach clip are perfect heat sink.), & then see if you timing lite still does the watoosy.

 

[xsjohn]

Ebay ignitor........there is more.......having a spare makes testing a lot easier.....

390116939886
200393342633

xsjohn

 

[J ray]

Well, the transistor tested bad, according to the posted link, so I replaced this with a new one from radioshak... No GO
Is it possible that the rect/reg could cause the fucked up spark?
Remember, fully charged battery and ign is normal at closed throttle but as soon as I twist the grip, the spark slows, still in time but misses and wont advance

 

[xsjohn]

Did you check the pickup coil............3 wires.........at the plug the odd one is common and the 2 straight ones are the seperate coils...........should read 700 ohms or so from each of the straight ones to the odd one which is common for both coils........

xsjohn

 

[J ray]

Yup. Tested the pu coil. It read about 710 for each.

 

[J ray]

Okay, just for shits and giggles I tested the combined rectifier regulator on an analog meter at the 10x's scale. The 3 white leads to black lead read 30. Then the 3 white leads to the red lead show 30 This is not what clymer says I should be reading but the book recommends I should be using a yamameter "due to the internal characteristics of different meters" blah blah blah. Does this really matter??
Is the rectifier/regulator shot?

 

[blue900]

I feel your Pain, and to top it off the info in the aftermarket Manuel can be plain wrong, and missing info = Much frustration.
Try Here http://biker.net/ get the XS650 Service Manuel 1978-1981 its a pdf Go to Page 173 it shows how to test the Rectifier/regulator 3 white, 1 black, 1 Red (it also has a Green shown) My 82 Service Manuel shows the same test info. It says its just a continuity test using a regular test meter and has a chart to test each circuit. Not as nice as the Real Manuel but close.
If I had a scanner I could just post my pages, Sorry.
Hope that helps.
Ron

 

[J ray]

Thanks Blue. I like more pdf's to add to my digital library

 

[XSLeo]

You said that after moving the tank aroud it ran ok for awhile. It's posible that crud in the tank is restricting fuel flow. It could also be the vent in the gas cap is plugged and after awhile a vaccum builds up in the tank, slowing the fuel flow.
Take it for a ride, when it acts up, open the gas cap. If it runs right then unplug the vent hole.

 

[J ray]

Leo. I wish it were as simple as that. The tank has been relined, new fuel lines, clean carbs and clear cap vent. The r&r was testing goofy so I replaced that too. I've a intermittant lack of power to the ignitor or ign coils but haven't been able to find the leak. A rewire may be the only cure.
Thanks for your input though. J R

 

[emzdogz]

so, whatever happened?

 

[J ray]

it was bad diodes in the ignitor box. I replaced it with a second hand ignitor that I got for nothing and it has run like a champ ever since. I've put about 10,000 on the ticker since then. now it is in pieces in the basement. the compression is starting to get weak so I think it's time for top end work. Hey, thanks for asking, Emz!

 

[emzdogz]

thx for the info!