Just sayn' Howdy!

[Monster Rat]

Just got my first XS650. It's a '74 and basically dead stock. Hadn't been started in 6yrs. I cleaned the tank and carbs and replaced the cracked fuel lines. I changed out the bars and removed the rack. Other than that not sure what direction I want to go. Probably street tracker or something along those lines. Maybe just trim up the rear fender, a shorter seat and roll it like that for a while.

I fires right up first kick when warm or ice cold, but I fear I may have an issue that kills the left spark plug. We'll see. Yesterday ran ok but to day it lost the left cyl. I pulled the plug and checked compression 135-140ish both cylinders. Then I checked the timing chain adjustment, the timing and point gap. Being new to these bikes, it seems as though the duration of the points being open is much greater than the time are closed. Also both are open during most of it. Is this a primitive wasted spark system? Anyway I put a new spark plug in and regained that cylinder. Hopefully it continues to contribute!

Well here it is!

 

[Monster Rat]

Going to have to figure out the pic posting thing down! Was supposed to be at the bottom lol

 

[robinc]

Welcome to the forum Monster Rat. Nice Pic!

 

[nj1639]

Not too far off from stock! Welcome aboard!
Ah, Wyoming and the constant sound of the wind in yer ears........

 

[Gcraay]

You say Howdy, I say Doody. Welcome aboard.

 

[MaxPete]

Really nice looking bike MR - very nice find!

The stock ignition is not a wasted spark system - but many of the aftermarket solid state systems are (PAMCO and Boyer-Bransden) are of that type. As you may know, in a stock 650, the two pistons rise and fall together and so when one cylinder is on a power stroke, the other is not - and so a spark in there doesn't do anything at all. Anyhow, for some reason, MamYama went with two sets of breaker points and two separate coils.

Here is a suggestion on your ignition drop-out problem (and it's an easy fix). The high voltage (aka high tension or HT) terminals in the coil and the spark plug cap are tapered screw-on terminals with a rubber grommet and a threaded cap to keep it all together.

On my bike, one of those connections was bad - and it caused an occasional cylinder drop-out. Here's how to fix it:

1. Unscrew the cap over the bad cylinder HT lead on the coil;
2. Remove the HT lead from the coil (you may find that it simply falls out);
3. Trim off a few mm (say 1/4 inch) of the end of the lead to get a fresh connection;
4. Reach down into the shrouded terminal on the coil and try to remove any rust/crap on the terminal screw;
5. Put a little dab of silicone ignition system sealing grease on the lead;
6. Insert the lead until it touches the terminal screw;
7. Rotate the lead while pushing it in and onto the terminal;
8. Turn it....maybe...4-5 revolutions until you gently feel it bottom out (the terminal end is tapered - it looks a lot like the end of a wood screw);
9. Now simply thread the cap back onto the coil and tighten the cap BY HAND - making sure that the grommet is back in place to keep water out of the connection.
10. Repeat the entire process on the spark plug cap - it uses the same type of tapered screw connector - and don't forget the silicone grease.

Here is a photo of a screw-type HT terminal on one of an ignition coil. I got this off the web.

I did this on my '76 Standard and it worked like a charm at preventing cylinder drop-outs.

Cheers,

Pete

 

[5twins]

If they're original, which they look to be, I recommend you change the whole spark plug wire and the plug cap. The original plug caps can go bad. They have a rather oddball resistance rating of something like 9K ohms. When they go bad, that starts to climb and eventually it will start choking off the spark. Get some NGK 5K ohm caps, that's the usual replacement of choice. When I prep my plug wires, I like to trim about 1/8" off the insulation and fan the wire strands out in a radial pattern like so .....

For the plug caps, I prefer the "F" type that attaches to the spark plug's stud. I think they grip better, more positively, than the terminal nut type .....

 

[MaxPete]

Yup - totally concur with 5Ts recommendations. The wires and ends will be tired after 40-odd years and I especially like the method of wire-end preparation!

THAT is a good idea for sure.

Pete

 

[Monster Rat]

WOW! You guys rock! That gives me a great place to start. Thank you for the replies.

 

[5twins]

If you do decide to replace your plug wires, just use normal metal core non-resistor wire. You'll need the 7mm stuff, the 8mm is too big. You don't want the resistor plug wire. You already have all the resistance you want in the plug caps. Use normal plugs as well, not resistor plugs.

I use silicone wire from kits for VW Bugs .....

 

[Corndog]

I love how clean it is!

 

[azman857]

Welcome to the XS world. Happy roads and wrenching!

 

[Monster Rat]

If you do decide to replace your plug wires, just use normal metal core non-resistor wire. You'll need the 7mm stuff, the 8mm is too big. You don't want the resistor plug wire. You already have all the resistance you want in the plug caps. Use normal plugs as well, not resistor plugs.

I use silicone wire from kits for VW Bugs .....

Glad you mentioned the size. I probably would have went 8mm, you saved me on that one!

 

[MaxPete]

Yup - I bought 3 feet of 8mm and it's now looking for a home, 'cause it sure doesn't fit my XS650 coils.

Oh well.

 

[azman857]

I like your choice of avatar. A big fan of "Married with Children". Especialy Al Bundy.

 

[5twins]

The 8mm wire won't fit in the plug caps either.

 

[MaxPete]

Now you tell me.....

 

[Monster Rat]

I like your choice of avatar. A big fan of "Married with Children". Especialy Al Bundy.

Thanks! Who doesn't relate to Al at some level!