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 Post subject: 84 yamaha rd 500 no spark .
PostPosted: Sat Feb 17, 2018 6:38 am 
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Joined: Thu Feb 15, 2018 4:58 pm
Posts: 7
Hi guys I have been trawling the net over the last few weeks trying to find an answer to my spark issue.
I have been brought up with the rd range and my dad is one of the founding members of our local rd club in Newcastle UK. The bike is currently being restored and almost finished it was in good condition to start with and has been sat in dry conditions for about 20 years. Spark was not verified prior to strip down unfortunately however the owner has said it was put away running.
Baisicly we have no spark, I am an electrician and have spent hours tracing wires and checking connections.
All resistance readings on coils, generator, pickup, and everything is earthed well .
Both ignition and kill switch function correctly . We have had the cdi on another 500 and it is working. In desperation we have payed a motorcycle shop to check it over and they also could not find any problems. Their report was the rotor has lost its magnatism and not producing enough power. I have measured the voltage out of the high and low speed ignitor circuits and got 4.5v ac and 25v ac .
All plugs and caps are new and primary and socondary circuits check out .
Only real discrepancie I have found was my meter cannot detect any voltage from the pickup circuit even though we have replaced the pickup. It's only ment to put out 0.3v ac I don't think my meter is accurate enough. The resistance is around 115 ohms so in spec with the manual.
I have had quite a lot of experience with other 2 strokes on the rd range almost all of them to be honest and have always found the problem any help would be much apreciated.
We have conciddered a whole new aftermarket generator as part for the 500 in the UK are rare hence expensive. To replace the flywheel, generator , pick up, cdi and coils will be are round £500 so is it worth upgrading to a newer system
Thanks
Steve


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Sat Feb 17, 2018 6:49 am 
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Joined: Thu Aug 20, 2015 4:01 pm
Posts: 134
Location: Southampton, England
Hi Steve, I had a similar issue, i.e. no spark but everything measured ok.
What fixed it for me was to modify the pick-up coil, so to move it closer to the flywheel. No spark became a running engine. Maybe weaker magnetism of the flywheel over time, or some degradation of the pick-up coil (can’t quite understand exactly what)...?
Just take out 1 of the pick-up coil mounting bolts and pivot it closer to the flywheel, and see what happens. Good luck.

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TDR250 special, carbon, lighter, faster!
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YZR500 Replica, Latest passion. A money pit!!! A keeper!
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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Sat Feb 17, 2018 4:50 pm 
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Joined: Tue Jul 19, 2011 7:49 pm
Posts: 250
Location: Toulouse France
+1 for the pickup coil.


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 Post subject: 84 yamaha rd 500 no spark .
PostPosted: Sun Feb 18, 2018 5:26 am 
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Joined: Tue Aug 14, 2007 2:14 pm
Posts: 232
Location: France - Nantes
Hello Steve, I was in the same situation few years ago. Bike stored for 10+ years in a dry barn. I wanted to start the engine to make sure it was OK before going into a deep restoration. I had no spark whereas everything was checked OK. Coils, CDI, continuity of the wiring, etc...

I found out that the rotor was demagnetized.
I replaced it for a brand new one found on eBay, and the sparks appeared and I could run the engine.


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Sun Feb 18, 2018 7:37 am 
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Joined: Tue Sep 08, 2015 5:27 pm
Posts: 50
Location: Royston, UK
Hi Steve, as you have seen you are not the only person to have battled with this problem!

Agree with the above comments, adding that (from now distant memory) it's the core of the pickup that's magnetic, not the lumps on the rotor. Over time this magnetism seems to drop off shortening the devices range.

I remember an old boy I once worked with having the magneto remanetised on his old Matchless, not sure if that's an option.

If the rotor has lost magnetism, then its most likely new electronic's won't fix the problem.

Regards
Paul


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Sun Feb 18, 2018 10:24 am 
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Joined: Thu Aug 20, 2015 4:01 pm
Posts: 134
Location: Southampton, England
New, pick-up coils are available from Borut (Zeeltronic’s), which, although universal, can be made to fit. I have one, but have yet it try it. Maybe an option?

_________________
RD400F, with Dave Freist (RIP) carb mods
TDR250 special, carbon, lighter, faster!
Harley Wide Glide, 103 cubes of torque
YZR500 Replica, Latest passion. A money pit!!! A keeper!
Latest purchase, RD500 in Marlboro colours! A project....


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Mon Feb 19, 2018 5:05 pm 
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Joined: Thu Feb 15, 2018 4:58 pm
Posts: 7
Thanks guys really appreciate the comments
Update - We have removed the generator including casing, Flywheel and cdi
it was put onto another bike and sparked after the first kick. I have checked out the wiring diagram and bypassed everything including the connectors, removed the two earth points which kill the bike (kill switch and ignition). I verified all the earth points on the bike and everything seems good but still no spark. we are going to put the coils on this other 500 to test them however the ohms readings are in spec so I am fairly confident they will work. I still need to verify the pick up. The manual states 0.3v ac from the pick up after 5 quick kicks and my meter is not picking that up we know the pick up works but only on a different bike. Could the crank have dropped a little on our bike resulting in the pick up gap being to big. I will try steveho's idea about trying to move the pick up closer but why would it work on another bike with our generator and flywheel.
I am getting around 11v ac from the generator on the red wire I am not sure what I should be getting to the cdi however I know it is working on a different bike so further investigation required.
Still to verify -
Coils work on the other rd 500, check power out of the generator on the working 500, 0.3v ac out of the pick up on both bikes.
Just to put you in the picture the bike has been stripped and totally rebuilt from the bottom up including the engine it is possible something could be out of line

thanks again guys


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Mon Feb 19, 2018 6:05 pm 
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Joined: Sat Feb 04, 2012 7:36 am
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Location: Eastern Ontario Canada
Some models have a side stand cut out switch. Does yours?

Not a fuse or fuse box issue?

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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Mon Feb 19, 2018 7:57 pm 
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Joined: Tue Sep 08, 2015 5:27 pm
Posts: 50
Location: Royston, UK
Hi Steve, where did you get the 0.3v ac target for the pickup coil? Not doubting it's in the manual, just must have missed it!

I had real problems picking up voltages with my meter and ended up using an oscilloscope to see what was happening. When mine was not sparking I was still seeing a pulse, but it was not big enough to trigger the cdi. It was about 18 months ago so can't remember the actual voltage seen, and never measured it once the pickup was moved closer.

Silly question, are all the various dowel pins in place to align everything?

Regards
Paul


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Mon Feb 19, 2018 9:18 pm 
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Joined: Mon Sep 14, 2015 12:30 pm
Posts: 634
Location: Bay Area. CA.
Also check the kill switch and ignition switch


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Tue Feb 20, 2018 3:49 am 
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Joined: Thu Feb 15, 2018 4:58 pm
Posts: 7
Paul the 0.3v ac at the pick up coil is not actually in the manual for the 500 its a post I found regarding the 350lc. The resistances are the same in the pickup coil so I assumed the voltage should be similar. That post I found also gives info about the high and low ignitor or cdi charging coil.
1. Low speed charge coil 50 Volts AC
2. High speed charge coil 4.5 Volts AC
3. Pickup coil 0.3 Volts AC
4. CDI output 24 Volts AC
All checked with 5 rapid kicks of the bike

Its from the rd lc crazy forum. http://rdlccrazy.proboards.com/thread/34844/testing-cdi
it has helped a little. I am seeing correct voltage at 1 and 2 but not 3 and 4. We have tried the above post regarding moving the pick up and still no good. I have 2 new coils on the way as resistance is 1.1 ohm across both primary coils and manual states o.6+/- 10% ohms just clutching at straws now.
The engine dowels look right the flywheel measures up with the pickup
Its really strange
oh Kill switch and ignition switch has been checked. They only earth the red wire that goes to the cdi from the generator. If you disconnect them it removes the possibility of stopping the bike once started.
And no to the side stand it has not got the switch or wires to support one installed.



Thanks again guys


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Tue Feb 20, 2018 4:59 pm 
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Joined: Tue Sep 08, 2015 5:27 pm
Posts: 50
Location: Royston, UK
Hi Steve, a bit curious about the 0.3v output of the pickup coil (not what my poor memory expected), so borrowed a better multi-meter from one of the guys at work. The fairings off my bike at present and took the opportunity to measure the voltage. With a few firm kicks (plugs still in place) I see 0.78 V ac. This is with a pickup to rotor bump gap of approx 0.5mm (initial gap was 1.1mm).

Is the resistance on the HT side of the coils to spec? Mine were shot as the HT lead connections had rotted away inside the coil bodies.

Good luck
Paul


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Wed Feb 21, 2018 2:37 pm 
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Joined: Thu Mar 09, 2006 12:54 pm
Posts: 258
Location: Germany
Well if you're a sparky I'd expect nobody should have to explain to you that measuring a VR output voltage with a standard multimeter doesn't make too much sense ;-)
Depending on internals of the device the reading can be in a large range. At best it's suited to deceive "output yes/no"
If you combine it with a diode & capacitor you can half way excatly measure peak voltage.
https://goo.gl/images/f7jNBc

Get yourself an oscilloscope and capture voltage vs. time. Do it on the running bike and on your problem child and compare results. If it's too low, adjust the distance to the rotor.
If you don't have one: They became incredibly cheap, got mine from ebay for some 25 Eur.

You can also check ignition coil primary signal (orange) and tach signal (black yellow on CDI) with the oscilloscope. They should show a "periodic & rectangular" signal when kicking. If not, the ignition does may not "see" a pickup signal.
One good trick to do that without equipment: The tach should jerk a bit during kicking if there is a pickup signal and the CDI gets enough juice to produce a spark.

If you can confirm a pickup signal we can try more options.


In any case my favorite solution is a DC CDI that runs from 12V and not from the source coils (red/green/brown): http://zeeltronic.com/page/pdci-24v.php
If you combine it with a new pickup, you're done with most of the usual suspects plus it adds more performance than most aftermarket pipes.

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Martin


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Wed Feb 21, 2018 4:11 pm 
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Joined: Tue Apr 18, 2017 7:10 am
Posts: 32
This i posted some weeks ago concerning gap adjustment:
Another simple thing is to measure the pickup gap. 1. Measure the diameter of the rotor between the two pickup surfaces. Devide by two- that’s no.1 to note.
Then measure the diameter of the stator . These core segments are turned precisely to a fine diameter. Devide by 2 and note. Then measure the gap X between the pickup and the stator . Add this to note 2, this is note3.
The difference of note 3 and note 1 is your gap.

To adjust to 0.5-0.7 just bend carefully the ears of the pickup.
Control by measuring again the gap X and recalculate.

I did it within 15 min. Incl. assembly times of covers.

Be careful not to adjust gap too small <0.5 . The rotor will grow some tenths mm at 11000 revs ;-)

By the way, the zeeltronic worked from the first kick on ;-)
.... after many evenings of wire clamping.


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 Post subject: Re: 84 yamaha rd 500 no spark .
PostPosted: Wed Feb 21, 2018 5:13 pm 
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Joined: Thu Feb 15, 2018 4:58 pm
Posts: 7
I know the 0.3v ac was just a guide I could not find any info on the web for this bike. Thanks for measuring your pickup Paulrs...

I knew my meter would struggle to pick that low voltage up and have looked at getting an oscilloscope. I have been working on these 2 strokes for the past 15 years and never needed one till now.
The problem is all of the bits from the problem bike work on a good bike.
I have not seen the good bike so have not been able to take any test results

I will double check the gap on the pickup the only thing I can think of is when the engine has been rebuilt its possible that the crank is not true or the bearing is incorrect causing the gap to be to big.
I will verify gap and also pickup voltage
Thanks again guys great input

Going back to your comment about the tacho (black/yellow) signal Martin is it possible a fault on the tacho could be causing problems ?
I have bypassed all the harness/connections from the generator
red/green/brown (generator) and also red/white and green/white (pick up) I have removed the plug on the power valve servo control box. the only wires left are the black and yellow (tacho) and black (earth) and 2x orange out to the coils.
Just a thought.


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