Throughout production Yamaha basically installed the same charging technology. Rotor spun inside a battery induced magnetic field creating an AC current converted to DC by a slicone rectifier (6 diodes).
Pre 80 models had a mechanical regulator controlling voltage before the rotor.
80 on used a solid-state rectifier/regulator combi which controls voltage after the rotor.
These systems have provided reliable service for a long time now. Most problems stem from bad battery, worn rotor brushes, dirty or broken wire connections, dirty or worn ignition cylinder. If you have charging problems best fix it. Better sooner than later.
A bad battery kills a good charging system. A bad charging system kills a good battery.
Although easy to troubleshoot and repair good parts are becoming harder to find. Rewound rotors expensive and not necessarily reliable.
Earlier adaptations of later model RD350 alternators provided relief – but were still old. Advantages were instant current production and the ability to run battery-free. Today, off-the-shelf bolt-in kits are available.
In the garage are 2 bikes with PMA conversions (1 an RD350 conversion, the other from Ants – both points), 1 with total loss, and 2 with original systems (1points, 1 Boyer). One of the original chargers, 79, with mechanical regulator has decided to rebel. Battery flat after a couple of hours riding, headlight on.
I have a spare RD350 conversion boxed, in the corner. Do I put it in?
If your battery is suspect, the ignition-block, fusebox or wiring damaged or dirty – nothing you do will solve your problem. When you are absolutely positive these are ok, check them again. This is actually most of your work done.
What do you know about your bike? Curly rulz!!
Battery voltage: Static? (around 12.5VDC) … Active? (max. 14.5VDC @ 2000 rpm)
A quick Slap-test gives an indication how good your Regulator and Rotor are. I hang a 17mm ring spanner off a screwdriver, poition it close to the alternator cover and turn the key on. It should pull into the cover and release when the key is turned off. The more positive it reacts the better. Mine was good.
Check voltage at your brushes. Green wire. Key on. Motor not running. It should be max. 0.3VDC less than your battery reading. Weak voltages create weak magnetic fields. Check your wires. Battery, earth, fusebox, ignition block. No real point in going any further until you solve this. First time I had 5.4VDC. Cleaning the 6 wire connector gave me 11.5VDC. Battery earth strap both ends sanded and washed, 11.9VDC. Battery +ve, heavy end to starter solenoid. red to fusebox and ignition-block. Washing the ignition-block out with brake cleaner and cleaning the brush connection gave me the rest.
You may, now, only need new brushes. Check them. Min 7mm. The outside brush will be shorter than the inner. Its’ path each rotation is longer.
I usually remove the stator.
Gives direct access to the rotor. Meter on Ω, Ohms. Ring/Ring should be 5.0 – 5.5 Ω. Ring/Earth, infinity. Inspect for damage, discolouration. The dirtier and darker the windings the more likely the rotor is defect.
Check the stator. Damaged wiring? Discolouration? Smell? Mine was quite oily. Where did it come from? Crankseal? Cable-pass hole? Gave a quick sqiurt with brake cleaner. Unplug the 6-wire connector. White/White should be around 0.5Ω. All 3 combinations. If not disconnct the single yellow wire and repeat (tests the safety relay). White/Earth – infinite. Plug together. Motor running. Meter to VAC. White/White 10.5-11.0 VAC. Low readings indicate a grounded Stator. High readings, a bad Rectifier.
TBC: pics, rectifier and regulator tests
So, if you’re having problems with your original charging system don’t simply throw it away and get a PMA. Check it. When you find a problem keep checking – there may well be more than one issue.
For me here, once I sorted the voltage at the brushes I was fine. A quick readjustment of the regulator and all was good – didn’t even need to replace he brushes.
If you do decide to replace it, be aware that if you have electronic ignition you will need to replace that too.
Ants produces a direct swap kit for points models that i am personally very happy with. Powerdynamo also have a combi PMA/Ignition.
People – I’m on the search … have almost finished my XS1 engine rebuild … it has taken a long time to find the correct original parts – and the last piece still eludes me
If anyone has an original early model left hand engine cover – for the alternator – with the screw-in clutch adjuster cover and is willing to pass it on I would be very happy
enjoy
Well, I’ve been incommunicado for a good while …
Photobucket fukt me off with their stand-over tactics … ‘pay me for your (up to now, agreed, free) photo storage or lose all contact to third parties’ … I cant seem to be able to even copy the photos now
Naya – my contract with wordpress includes enough storage to directly load the photos there – and I’ve slowly been doing just that, some may have noticed more and more posts have their deco back – it’s a shit job, takes a lot of time, and is the third time I’ve had to do it – thankfully my mate Phil backed-up most of 2011-13 or I would have simply walked. All eggs are now in a single basket. Bad luck if they later decide they want (more) money – perhaps at some time I can set-up a donation function, or start merchandising (patches, t-shirts, caps, stickers, etc …). I’ve been trying to avoid that as I am not commercial and have other shit to do
As you read through, let me know if you find links that dont work or anything I have missed
Anyway, I’ve moved. Small village. Large Garage. Now full. Large garden – yes, I know, it’s hard to believe – but – there is life outside XS
Sitting here listening to Jeff Beck and Friends playing Purple Rain – and thinking, this ‘dauerregen – geht mir auf den sack’ .. kinda like living in Vancouver without the beauty
Enough about me … we live in (very) interesting times, multi-d power chess, just how deep is the swamp? Whose pyramid will rule the dust?
I wish you all well.
Keep your heads low.
guten Rutsch ins neue Jahr
Been building myself a couple of XS motors lately. 277° and 360°. Have had the blocks together for some time – gearbox and crank, new bearings and seals etc.
Got round to stripping down an old XS1 head the other day. Just to check her out. Actually not too bad, some leakage around the top of the inlet valves, guides ok, valve stems straight. Cam ok. Rockers starting to wear a little. Decided to replace them and the shafts as I had a new set lying around and I have a new cam.
First you need to remove the 4 press fit sleeves that seal the outer-headstuds. You can simply bash these out but I wanted to remove the rockers and the shafts sit pretty tight (unlike the SR500) so I popped the rockerbox in the oven for a while.
The sleeves knock out easily with an 8mm socket.
Then you can get to the rocker shafts. These are tight.The puller I had rustled up for the SR500 wasnt up for the job but still had the longest 6mm thread I had on hand so I simply packed the outside with a socket and an old gearbox bearing and wound the shafts out.
Total time, less than 5 minutes once heated (if you heat use the oven and not a torch – no point in risking warping the box).
Slapped her back into the oven for a few minutes before inserting the new shafts and rockers. Dont forget to blow out the oil galleries first, and lube.
If wanting to reuse remember to bag and label: left/right, inlet/outlet
enjoy
Full moon. Tonight. Likely to draw the witch out of those you love.
Had my hands in a couple of motors last week. An early XS1 that, judging from the bearing seats, has had as hard a life as Keith Richards face. An XS-D that looks pretty clean inside. Both had what look like original filters.
Top: XS-D .. Bottom: XS1 – both showed damage from over-tightening the screws.
Neither gasket had been pre-treated before installation. An SF hammer was required. The gaskets did separate. In half.
Early filter left with full metal jacket. Right: pleated mesh with magnet, right-hand end slightly crushed. Mesh on both sides intact.
Rear: Early filter has no magnets. Mesh is only spot-welded. Later filter has magnets both sides. Mesh is fully cemented. Much more surface area. Mesh is finer.
Early oil flow problems? Filtration issues? Strange the prone corner was never properly reinforced.
Left ends intact.
Fronts. XS1 filter, mesh has started to separate at the spot-welds.
Although I’ve seen much worse both these motors could have benefited from a few more oil changes.
Was pleasantly surprised to see the original XS1 filter here. And that it had survived so much punishment for so long before giving out.
Both engines have obviously been warmed up slowly-the ends are still intact. The mesh separation on the early filter probably derives from crankshaft rotation – from the look of the bearing seats this motor has sung – full throat – louder than Sleazy Joe.
(143.2dB in Hassleholm, Sweden, 2008)
The XS-D filter could make a good emergency reserve. After fitting an end protector. And rechecking each oil change.
Take care of your engines and they will take care of you. These are very much ladies.
Have been cleaning up a couple of SR500 heads. Ready for porting, new valves and rocker shaft bushing. Needed to remove the shafts. Rooted around in the odds’n’sods bin.
- 2 x pieces 6mm threaded rod
- 1 x long open ended 6mm joiner
- 2 x 6mm nuts
- 1 x 6mm dome nut
- 12 x large 6.5mm washers
- 1 x piece duct tape
5 minutes. No cutting. A perfectly good 6mm slide hammer.
Screw into the rocker shaft. Off you go.
Same principle for the XS.
