XS400 ultimate electrical defunkification project

[Meateater]

(The day it was dropped off at my shop)

(Current state)

Hello everyone, I’m new here so I will introduce myself and my 400 project. I inherited this project from a overwhelmed friend and decided to use it as a little learning project. I’ve owned a dozen or so vintage bikes and just always seem to find myself working on the marginal electrical systems just to keep them running. So my best friend (electrical engineer) and myself (welder/electrician) decided to rebuild two old bikes to ride to South America after running them in their respective classes at the bonneville speed trials next year. There is no expectation that we are going to set any records other than most tacos eaten in a single sitting, but it just seems like a fun trophy to have on the mantle.

We have access to a dyno as well so we are planning to do some systematic testing on our modified/simplified systems, carb changes, and tuning to hopefully measure some quantifiable results. However my experience with the XS intricies is limited so I’m here to ask some advice on some things and hopefully learn some from your collective knowledge.

So far I have a ‘79 XS400 motor in a ‘77 360 chassis. I’ve cut and trimmed the frame and built an electronics tray under the new seat and gutted the entire harness. The motor shows good compression, electric start works well and it’s a pretty clean start.

The stator tested good but had 40 year old brittle wiring on it so we have replaced the AC wiring and ordered a new Ricks motorsports mosfet regulator (newly designed for the lifepo4 battery chemistry) to feed a anti-gravity 4 cell lithium ion battery. I’ve ordered a Pamco Hall effect ignition trigger to replace the points and am going to replace the coils, wires, resistor caps, and plugs.

My goal is to build an electrical system that is simple, robust, trustworthy and trouble free. Hopefully I can glean some of your wisdom to make a centralized post everyone else can use as well.

The first item of business is coil packs. I’ve been lurking here for a while and reading all I can. Pamco Petes callout says his ignition pickup can run 2.5-5 ohm coils. I read a few posts where Dwerpy recommended Rex’s coils. ( https://www.rexs-speedshop.com/prod...00-rd200-250-350-xs1-xs2-xs650-ignition-coil/ ) I wanted to ask if that recommendation still held true with the PAMCO unit or if a higher resistance coil (Dyna?) coil held any benefits?

 

[spectra]

Welcome! looks like a fun project.

As for the coils can not help as I run a Pamco on one bike but still have factory coils.

 

[NewHavenMike]

Where did you order the Pamco from? Id still be using my original coils if only the HT leads were removable. The coils you linked look like they're better quality, but I just use the generic universal coils. Ive used them on a couple different ignition setups with no problems.

Honestly, if your goal is to build a simple, robust, trustworthy and trouble free ignition, Ive had the least amount of trouble using a factory points ignition.. I know they are the "worst" ignition available, but the simplicity is what makes it superior for me. Sure, you need to check them and adjust them sometimes and thats ok. If your plan on riding cross country, I think a points ignition is the way to go for this. A couple extra sets will take up very little space.

Electronic ignitions fail and shut off immediately when they breakdown, as opposed to degradation in points. Failed points can be replaced in the dark on the side of the road in 20 minutes. You could even have a backup points plate ready to go in case a failure happens.

If your electrical system is flawless, you should have no problem running a Pamco or any other aftermarket ignition. My pamco only failed because I was using the original mechanical voltage regulator and that failed first, and fried the Pamco circuit board. After the Pamco, another aftermarket ignition failed on me, and then the 3rd aftermarket ignition was defective.. This sort of left a bad taste in my mouth about aftermarket stuff.

Theres things like ignition boosters that you can get that will bring down the voltage on the points to almost nothing, this will make your points last much much longer. I do not know much about them though.

A lot of people including myself, have changed to non-resistor caps and use iridium spark plugs. I of course, changed back to a standard set up.

The idea of having a cross country rider and a Bonneville racer collide IMO. For cross country and ease of repair, I lean toward factory settings. For Bonneville, Im sure an aftermarket set of carbs will come into play here along with gearing and weight reduction and tires etc. You will more than likely have to re-tune the bike when you get to Bonneville anyways due to slight elevation changes. This is why Id probably ride with the points, and change over to the Pamco when I got to the flats.

The Pamco is by far the best upgrade you can do and it will give you trouble free service as long as everything else is in perfect order.

 

[BBS360]

Cool project.

Curious which regulator you bought.
These older bikes regulate the excited field coil and need a different type of regulation than modern bikes.
A combined regulator/rectifier would need 6 or more wires.

 

[Meateater]

Mike,

Where did you order the Pamco from? Id still be using my original coils if only the HT leads were removable. The coils you linked look like they're better quality, but I just use the generic universal coils. Ive used them on a couple different ignition setups with no problems.

Honestly, if your goal is to build a simple, robust, trustworthy and trouble free ignition, Ive had the least amount of trouble using a factory points ignition.. I know they are the "worst" ignition available, but the simplicity is what makes it superior for me. Sure, you need to check them and adjust them sometimes and thats ok. If your plan on riding cross country, I think a points ignition is the way to go for this. A couple extra sets will take up very little space.

Electronic ignitions fail and shut off immediately when they breakdown, as opposed to degradation in points. Failed points can be replaced in the dark on the side of the road in 20 minutes. You could even have a backup points plate ready to go in case a failure happens.

If your electrical system is flawless, you should have no problem running a Pamco or any other aftermarket ignition. My pamco only failed because I was using the original mechanical voltage regulator and that failed first, and fried the Pamco circuit board. After the Pamco, another aftermarket ignition failed on me, and then the 3rd aftermarket ignition was defective.. This sort of left a bad taste in my mouth about aftermarket stuff.

Theres things like ignition boosters that you can get that will bring down the voltage on the points to almost nothing, this will make your points last much much longer. I do not know much about them though.

A lot of people including myself, have changed to non-resistor caps and use iridium spark plugs. I of course, changed back to a standard set up.

The idea of having a cross country rider and a Bonneville racer collide IMO. For cross country and ease of repair, I lean toward factory settings. For Bonneville, Im sure an aftermarket set of carbs will come into play here along with gearing and weight reduction and tires etc. You will more than likely have to re-tune the bike when you get to Bonneville anyways due to slight elevation changes. This is why Id probably ride with the points, and change over to the Pamco when I got to the flats.

The Pamco is by far the best upgrade you can do and it will give you trouble free service as long as everything else is in perfect order.

Thanks for the response Mike. I ordered my pamco from Pete a few days ago. I’m assuming/hoping it’s in transit now. My logic is that with a new simplified harness, fresh weatherpack connections, high quality MOSFET rectifier/regulator and coils that I can solve all the little quirky fixes in one winter instead of every two weeks along the road. It may be wishful thinking but worst case scenario I learn all the things I don’t know and go back to the stock harness, points and condenser on the shelf. I feel like a large part of my life is spent dealing with just what you experienced- replacing great parts that got smoked by marginal parts. So we will experiment and see.

I’ve shaved almost 40 pounds off this bike so far. Center stand, seat, pegs, side covers, battery, and all the electronics. and hand controls. I added dual front brakes and kept the electric start. I figure I can pull all of that, change sprockets, wheel set etc in a few hours in true “run what you brung” fashion on the salt. High speed sprockets, rear drum brake and think skinny! I only live a few miles from bonneville so it’s not a major change up in tuning etc and I have access to a dyno that is within 50’ MSL of elevation. I figure that’s within daily density altitude calculation range of being do-able off a baseline tune. I have a set of mikuni VM34’s (or trade for some 30’s) that might become my top end carb set. I’m just not familiar enough with the xs motor to know if I’m in the range or not yet.

In a true statement of self hate I have been considering building a turboed motor for the salt since it narrows the contender pool exponentially. It’s a lot more fun to say I won 2nd in my class and omit the fact that there were only 2 contenders than to say I was 37th out of 40 and 3 guys didn’t show up.

I read a book a long time ago about a guy that waterproofed a flatfender jeep and sailed it across the Atlantic with his wife and I’ve thought to myself “this guy is crazy, but he’s my brand of crazy”. So while I’m pretty sure I won’t be any kind of contender on the salt and I may have to abandon the bike to cannibals in Ecuador, I don’t really mind. As long as I have enough money hidden in my sock I’ll make it to the next taco stand then I can still laugh at all the storm troopers on their BMW’s and KLR’s with their 401K’s and life insurance. Gluttonous bastards!

My wireset looks like it got drug on the ground behind a stagecoach so I’ll replace coils and get some that I can push/screw a plug wire onto. That way on the long trip if I take one spare pamco, one coil, and steal a spark plug wire off an old broken ford I’ll still be able to make it to the next phone.

 

[Meateater]

Cool project.

Curious which regulator you bought.
These older bikes regulate the excited field coil and need a different type of regulation than modern bikes.
A combined regulator/rectifier would need 6 or more wires.

The ricks part number I went with is a 14-503.

Field excited universal with voltage disconnects set for lithium ion charging friendly voltages (13.5)


3 - AC legs (yellow)
1- 12VDC ground (green)
1 - 12VDC positive (red)
1 - Field exciter feedback leg (black?) If i am understanding correctly this is basically just a high voltage disconnect that deenergises the field lead when the battery is full and turns it into heat instead.


I’m assuming. I haven’t actually seen the regulator yet so I’ll let you know when it gets here.

Rectifiers are new to me. But regulators are my daily grind. So admittedly I’m leaning on my electrical engineer buddy for this parts selection. My logic is that I’m decreasing the draw as much as possible. 1 LED headlight, 1 LED tail/brake combo, and 2 LED signals in the bar ends. That leaves every spare watt produced for the ignition coils and charging. By getting rid of the points arcing loss and going solid state with the PAMCO Im hopeful I’ve eliminated all the inefficient losses.

In my personal experience I’ve never had a problem with field coil generators producing power, they are just all over the board voltage wise. So I’m betting on the efficient MOSFETS, and a 4X larger heatsink being a lot better at handling the excess more effectively.

Next step is to decide on a mounting location. Maybe make a 7075 skid plate and mount it above it under the trans and let the skid plate serve as an extension of the heat sink.

Or

Up front on the downtube below the headlight. But I hate long wire runs. Especially in unregulated alternating current. So I’m leaning toward the skid plate idea.

Time for some testing with airflow and a laser thermometer.

 

[spectra]

I mounted mine right under the pan. First build used a pan just like yours and the factory one is kind of in the same location.

I have a Ricks Rec also and no issues so far. Picking up another for a future build.

 

[Meateater]

I mounted mine right under the pan. First build used a pan just like yours and the factory one is kind of in the same location.

I have a Ricks Rec also and no issues so far. Picking up another for a future build.

That’s good to hear. I’m always nervous buying custom parts like that online. I will take one personal positive review of them over a hundred online reviews.

Spectra, what battery are you running? And what kind of wattage is your system putting out?

 

[NewHavenMike]

I haven't had any problems with the stock rectifiers. As for regulators, ive been using an automotive solid state. The regulator is a BWD R292 and can be found at Oreillys auto, among a few other places.

I have the reg and rec mounted off the frame, behind the top trans mount off the back of the engine. Theres mounting points for the original stash/toolbox kit. You can fashion up a mounting bracket there and that will keep them in a nice open area.

I run a AGM 120 CCA battery. Voltage is anywhere from 12.5 with all lights on, to 14.9 with no lights on and picking up a charge.

 

[spectra]

Running a 8 cell Antigravity but wish I would have went with a 4 cell as it kick starts so easy. As for volts have never even checked it.......it ran and keeps working I am lazy when it comes to those things........