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Electrical / Autocar Newtronics ignition review
« Last post by berniebee on July 11, 2019, 09:53:54 PM »
This is a review of the Autocar Newtronics ignition kit and the problems I encountered while installing it. If you are considering buying this unit, have a read. It may help you out.  For you TLDR-ers, there is a summary at the bottom.

Note: I bought this YAM3 system in 2013. Quality control might be improved since then. I hope so.
I put away my partially restored XS500C for several years, and got around to installing the kit only yesterday!

I blow six years of dust from the packaging and at first glance, the kit doesn't look too bad. The rotor is soldered with only one tiny dot of solder and I can easily separate the parts at one side. But having read the XS500 forum comments regarding this issue, it was not unexpected. I  spent a few minutes making a wooden jig and then out came my plumbing torch, flux, and solder to properly solder it.

Being a good little DIY-er, I read all the instructions before starting. They are fairly clear with one glaring exception: Step 9 says to "Connect the trigger leads to the switching unit using the molded plug and cover. ". But in what order are the four coloured wires installed into the black plug? The diagram teases you with the wire colour names but is no help. I read and reread the instructions. I look briefly at the black plastic plug housing, but nothing there. Sometimes things become clear as you proceed - I hope. So I start.

The first issue is setting engine on the left "F" timing mark. Using the kick starter, I keep going past the mark! Then I remember the large hex bolt just to the left of the breaker points can be removed, and once removed the same hex key is inserted into the hole and used to turn the engine more precisely.

Once you have extracted the original auto advance unit, Step 5 says to remove the (bob) weights from the advance unit so that you can remove the points cam. Which means you have to remove the springs. It turns out that 40 year old springs remain stretched once you pull them off. After reassembling, the springs are no longer exerting any tension on the weights. Surely not Autocar's fault, but I suspect most bikes will have this issue. In the end, I cut the springs a little shorter and then have to stretch the springs a little to get close to the original tension, as measured by my calibrated thumb.

Step 7: Ok, I've got the advance unit, the new baseplate and the new rotor sorta assembled together and I'm inserting all on to the drive shaft...and it's not going in. The ##$%! baseplate is too large to fit! I disassemble everything, remove the sensors from the baseplate and start filing/sanding the baseplate edges until finally it glides into place. I put everything back to together and install. The lock washer included in the kit is too small for the baseplate screw. Seriously!?!? I find a proper size lock washer. The rotor is VERY close (1 mm) to the inside side of the sensors but doesn't touch when I rotate the engine so it's a go.

Now at Step 9. After scratching my head for a while, trying to figure out in what order the wires go into the black plastic connector,  I remove the connector cover and aha, the wire colours are indicated INSIDE the housing. Might be nice if the instructions mentioned that! But not all the female electrical connectors will go into their respective slots in the housing. The ones for the red and yellow wires are fine, but the blue and black ones just won't fit. An inspection of the plug housing shows that the housing was poorly molded and there is a bulge of plastic in two of the slots. With an exacto knife, I carefully cut away. Ah, now the connectors can be inserted. But. When I attempt to test fit the plug to the switching unit, it won't mate. Looking at the ends of the female connectors, I notice that they are not quite in a straight line.  I remove and disassemble the plug once more and discover there is excess plastic in the bottom of the slots.  More carving of plastic and now the four electrical connectors are in a straight line. But it still won't seat! Because the plastic plug housing has flashing around the outside. After carving session #3, I am finally able to seat the plug fully into the switching unit. Quick, someone call the QC department!

Step 11 The blue earth (ground) wire is too short. Well, it's long enough to connect to a bolt, but once it's connected, the switching unit, which is by now glued to the inside of the right side cover must be held or it hangs by the wire. The blue wire is too short to set the switching unit on the seat. Why? The other wires to the switching unit are certainly long enough. Surely this is not a cost savings measure, just an oversight. I solder/heat shrink a six inch piece extension to the wire and set the unit on the seat, like god intended.

For some reason, the operation of the static timing lights are on this page, but the actual static timing procedure is described on a second sheet of paper.  And then you come back to the first page for the dynamic (running engine) timing. My brain starts to hurt.

"It should remembered that that the engine fires as the timing rotor leaves the lamp housing (i.e., immediately the beam of light is remade)" HUH? Maybe it is the British-centric wording of the whole document, but this sentence left me pondering existence for a while.  After some contemplation and a beer, I realize that they are saying the spark happens when a sensor sees the gap in the rotor.

The bike had not been started in six years before I installed the Newtronics ignition. It took a while to get going , but once it did start, it ran and idled smoothly. I zipped up and down my quiet street, only reaching third gear, so it's not a complete test. (The bike is not licensed .)  But it seems to run really well.


There were five quality control issues.
1: Rotor improperly soldered
2: Baseplate too large
3: Poor molding (moulding) of the plastic connector
4: Wrong size lock washer for the baseplate screw
5: Blue ground (earth) wire is too short

The documentation could be improved. Most importantly, the instructions should mention that the order of the four coloured wires is indicated on the inside of the black plastic connector housing! Next is the regrettable fact that you have to jump between two sheets of paper for the timing description and procedure. Leaving aside that it is a British-centric document, referring to an optical sensor as a lamp is confusing. The instructions should mention that while the advance assembly is apart, now is a good time to clean and lubricate the moving parts.

The kit should include a few tie wraps to organize and group the wiring. I used eight or nine. 

You are probably going to stretch your auto advance springs when removing them.

Once finally installed, the bike ran and idled beautifully!

Electrical / XS500C ignition auto advance/governor springs - where to get them?
« Last post by berniebee on July 11, 2019, 02:41:22 AM »
The advance springs on my '76 XS500C are so weak that I'm seeing full advance at idle!
I have the newer style advance unit, where the springs are short and anchored to the weight close to the pivot point.

Has anyone confirmed that the springs at MikesXS (Part #14-0651) work with the XS500C?  (The advance unit pictured at MikesXS certainly LOOKS very similar.)

Any other supplier?
Electrical / Re: Spark Advancer Springs
« Last post by berniebee on July 10, 2019, 08:14:37 PM »
A very old thread, but since I'm working on my bike after a long lay off, I thought I would add my 2 cents.

I have an American market XS500C and it has the later type governor (short springs) as pictured in CrouchyUK's post.

In reply to kckranz, I noticed the black coating on the weights also. You'll notice that the curved part of the weight, where it contacts the advance shaft actually has a thicker coating. Maybe 1/16" think. I think that's the area the coating is intended for. And yes mine is messy too, with bits of coating on the top and bottom of the weights.  Messy application or perhaps heat melting?  In any case I scraped off the bits of coating from the top and bottom as I cleaned up the area for the Newtronics ignition installation.
Introductions / Re: Hi from Sweden!
« Last post by Puttiplatt on July 10, 2019, 07:51:03 AM »
I  will update when the bike is ready, i have a lot of photos of the restoration.
Introductions / Re: Hi from Sweden!
« Last post by guylr on July 09, 2019, 05:25:48 PM »
Welcome to the forum, we hope you find it useful. Your bike is in the registry now so keep us up on your progress.

Introductions / Hi from Sweden!
« Last post by Puttiplatt on July 08, 2019, 09:24:39 PM »
Hi everyone!
I am a 55 year old swede and owner of some bikes
I have 2 xs500 from 1977, and a spare engine. Both bikes were bougt more tha 20 years ago. The fist one was a non runner and is still because the engine (cylinder head) is bad. The second one was a runner and i drove it for some time. But i was noticing that it was losing compression and was finally impossible to start.
I am now in progress of restoring that bike and see if i can get it running again.
Brakes / Re: 1976 master cylinder reservoir seal
« Last post by berniebee on July 04, 2019, 03:23:16 AM »
Hi all, I know this thread is old, but my master cylinder reservoir ('76 XS500C) is leaking slightly too. I brought the assembly to my local General Bearing Supply here in Ottawa, where they have a very helpful crew.

The counter guy measured the old o-ring and came up with 44mm x 2.5 mm. (Actual measurement of old o-ring=2.67 mm) Not in stock, but they could order it. But he found that the 1-3/4" x 3/32" was very, very close and sold me a pack of five for under $5. I decided to try it and bingo, no leaks!

General Discussion / Re: This old stale forum!
« Last post by Chris99D on June 18, 2019, 10:30:36 PM »
I still look at this site often, if it was deleted it would be a shame as this is a massive bank of knowledge. Unfortunately/fortunately I haven't had the opportunity to post much as my questions have always been answered with a quick search, but I definitely appreciate those here who have had the questions and answers before me. :)
Electrical / Re: Field coil tape
« Last post by guylr on June 16, 2019, 11:15:08 PM »
The stator coil does not affect your spark unless the battery goes dead. The stator windings are lacquer coated and won't be troubled by oil unless the windings have shorted to themselves. If you are still getting a charge to the battery that goes above 12.7v at around 1700 rpm them it's not the problem.

For weak spark, check the voltage at the ignition coils red/white wires with the key on. Optimally what you want to see is no more than a 0.5v drop compared to battery terminal voltage. If it does have a big voltage drop then suspect, the ignition fuse, handlebar kill switch contacts, mainswitch contacts and all harness connectors on the Red/White ignition circuit.

Electrical / Field coil tape
« Last post by cmjp74 on June 15, 2019, 09:00:21 PM »
My field coil tape has flaked off in places. It's now obviously got oil in the winding. My question is can I just re-wrap it ? I've been told that bias tape will do the trick, or do I need to throw the field coil away?

Something's causing crappy spark, but with all old bikes whever you look something's amiss. It might be the coil, but then again.......
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