That elusive weak spark

[dmq136]

xjwmx - thanks for the heads up on cleaning the carbs. I will have to revisit them. Also, I have never done a valve adjustment for clearance. I will also have to look in on that too.

Any links or how to's out there for the '81 XS650?

xsjohn - yeah, so far I have never removed the factory (lead plug or solder) and played with the mixture screws...

 

[Sundie]

Yeah, but it means no one has jammed them home tight yet either.

 

[xjwmx]

""""""""If you're lucky your mixture screws are still capped off from the factory."""""""

An then the 1 1/2 or so turn mix screws would be feening almost no fuel through the tiny 42.5 pilot jet .....and the log main needle would be feeding like next to no gas through the tiny 132.5 main jet........

xsjohn

Yeah, well, at least you can't deny that where it stands is known then at least

Mine's capped off, but then I sometimes hear a knock when pulling heavy and hard uphill in 5th, at a good speed for 5th, which could be a lean knock. Going to fix it by trying everything except the carbs, to start with.

 

[xsjohn]

The TCI's are a bit advanced............and if you knew how hot they get stock...especially the right...not sure I understand the paranoia about carbs especially if you know they are lean.........a lean air cooled engine doesn't have much a chance in the long run....the 80-84 were tuned buy an epa idiot in a suit and tie....hence the brass plug to start with....I was standing on the showroom floor when I worked Yamaha after we uncrated the first one and started it....my boss he said John you are going to have to fix that...........

xsjohn

 

[xjwmx]

Not really paranoia, just sounds real good to me and don't want to change big things to start with. See if the easy things work first.

Got your backer out yit or is it too early there?

 

[xsjohn]

And what would be the easy things.............when they are all easy....especially when someone has already figered them out for you.....and sounding good is all relative when you don't have something to compare it to.......the things are lean and advanced a bit too mich.......for sure....and I learned long ago not to do anything you can't back completely out of..........xsjohn

 

[xjwmx]

Kicked the habit, eh?

First easy thing is see if the egr fell off. Second easy thing would be a shot of octane booster to see if what I hear is really knock. Third easy thing would be see what a cooler plug does. Then it starts getting harder = $ + T. Time. The Big T.

 

[dmq136]

The simple test worked to check the TCI and it is good working order, not fried as I thought. Just dug out the old stock coil (which I originally thought was the problem), soldered on some wires, and will stick it back on and see if there is spark at the plugs.
There may be sufficient voltage drop across the kill switch that could account for the weak spark all along... I will know more once the coil is back on (it looks like rain for the next few days ).

 

[xsjohn]

Yea....80+ with TCI.......learned a long time ago to clean the harness well and use dielectric grease before deciding to change anything.........Yamaha was a lot smarter than most of us...including myself....I have been running the original harness including the fuse box for 76 thou....coil included.....since the fuse box sits right on top of the battery some oil on it helps too..... acid fumes there and all........TCI's are also a bit advanced so controling that will be a benifit I have found...especially for the lower rpms..or suffer...and the taller the gears the more retard is needed.........up to .168 thou which I consider max retard before high end advance becomes a problem..................xsjohn

 

[dmq136]

Second thoughts on the TCI, I think that somewhere there is a problem. I've decided to upgrade to an electronic ignition system, probably a Pamco. I am still looking for a step by step installation guide that will walk me through most of it...

 

[pamcopete]

dmq136,

www.yamahaxs650.com

 

[dmq136]

pamcopete - Thanks, I have spent a bit of time at the site and read almost everything. I also have visited the thread here. So, I feel more informed about the Pamco system.

It is possible to wire up the new "ultimate" system from mikes and also use the relay for the kill switch? Is the relay even necessary at this point? Also, if I had to choose between a 5 A or a 10 A inline fuse to the coil which would I use (I know you suggest a 7.5 A, but I haven't found one yet at the local auto-parts store...)

Finally, when I mentioned a walk-through, I meant a dummies guide with pictures. I can probably figure it out; however, seeing is believing.... I sure don't want to ruin anything by using a hammer or some other primitive technique when first installing everything .

 

[pamcopete]

dmq136,

You can wire the coil directly to the battery through a 10 Amp fuse under the seat, then connect the red wire from the PAMCO to the red/white wire from the kill switch. That makes the PAMCO work just like a relay because even though the coil is wired directly to the battery, there is no current flow unless the PAMCO is turned on by the kill switch.

 

[dmq136]

You can wire the coil directly to the battery through a 10 Amp fuse under the seat, then connect the red wire from the PAMCO to the red/white wire from the kill switch.

So, basically wire it up through the existing ignition fuse (10A) in the fuse box under the seat. Would it be better to use a new inline fuse that is dedicated solely to the coil or does it matter?

Thanks for all you input!

BTW - I get my Pamco today, I can't wait to get it in and be done with some of these problems! (at least the ignition side of things )

 

[pamcopete]

dmq136,

You have to wire it directly from the coil to the battery through a separate dedicated fuse. The ignition fuse in the holder also powers the red/white wire and the safety relay which you do not want to have on permanently. The red/white wire will also be used to power the red wire to the PAMCO so it has to turn off when you turn off the ignition switch.

Disconnect the red/white wire on the coil and connect a wire with an inline fuse from the terminal on the coil where the red/white wire was connected to the battery.

 

[dmq136]

pamcopete,

So, let me make sure I am clear on the wiring (still haven't seen the Pamco unit yet). For the wiring, I can connect the coil (+) terminal to the battery via a 10 A inline fuse. Then, the red/white wire from the original coil (kill switch) will go the the red wire on the Pamco. Green wire goes to the (-) or other terminal on the coil (are the terminals on the coil marked?). Coil is grounded to the frame as well as the Pamco unit.

Now, the kill switch will now still kill the engine, and when I work on the bike, I can remove the 10 A fuse to avoid damage to the coil from having the key in the on/run position.

Here is my simple sketch -

 

[pamcopete]

dmq136,

You got it. Just a couple of notes:

1. The coil is not polarity sensitive. The fused power from the battery can be connected to either terminal.
1a.Connect the green PAMCO wire to the other terminal.
2. The black wire from the PAMCO can be connected at any convenient screw on the frame, it doesn't have to be connected right at the coil.
3. Yes. Remove the fuse when working on the bike because the coil has battery voltage on at all times.
4. The plug wires can also be connected to either spark plug.
5. The timing light will work better on one of the plug wires. If you get erratic operation on one wire, just switch to the other or flip the timing light clamp around the other way.

By providing a direct connection from the battery to the coil you are supplying the maximum possible current to the coil for a really hot spark.

 

[dmq136]

pamcopete - thank you for these clarifications! Now, I am confident that I am clear on the wiring.

I will just follow the directions (www.yamahaxs650.com) on installing the advance mechanism and doing the timing.

Any other hints that I should know? (Remove the TCI and cash in on it, tape up TCI plug connector from main harness and hide it away, and remove turn-signal autocancel... anything else?) -Thanks

 

[pamcopete]

dmq136,

Nope...that's it...

 

[dmq136]

pamcopete,

I am about 1/3 the way through the installation, I have installed the mechanical advance, the Pamco unit plate, and the advance rod.

Okay, now for clarification - the advance rod has the necessary locating pins in it already, so therefore two of the three in the kit are unused? Also, how snug should the large nut be that holds the advance mechanism in place (I don't want to over tighten it)? Now, I noticed a little bit of play in the advance rod (it will move in and out, moving toward or away from the outer engine covers. It only moves a little bit, probably a few millimeters nothing extreme, - is this normal?). Finally, is there a suggested route for the wire lead that comes from the Pamco unit? I don't want to melt them on the engine, yet it seems that the wires will have to route through a cooling fin or straight up to the coil above...

Sorry, for a load of questions, I just don't want to mess anything up too much.