Jump to content

stumpnthqldd23

1976 Tl125S Ignition Issues

Recommended Posts

Hi Everyone,

I have a TL125S lovingly restored. It has been running on battery ignition with the original points as I converted it to battery with all lights to commute to work. We had issues with the magneto style original ignition at the time of build and just went with the battery ignition option temporarily.

I recently got a new ignition coil and plastic side panels to complete the restoration and after fitting the coil/condensor I found I still have ignition dramas. The bike is very easy to start, has enough spark to hurt my foot when the timing was set a little aggressive, but as soon as you load it up it miss fires, completely looses spark and back fires through the carby.

The stator side cover was on the bike when I road it 15 odd years ago before the thing got boxed up till last year. This side cover is not a Tl125.It looks identical from the outside but the actual primary coils are different. It has 4 wires coming out of it. Black - White - Maybe Blue - Maybe green. from research I believe the magneto style ignition was a little unique for its age and not many had it. The stator cover seems the same as quite a few models, specifically the cb125 but I have read that the flywheel on the Tl is different. Even after hours of research and looking through many wiring diagrams I cannot find anything with 4 wires out of the stators, only ever 3!

I may have to resort to have the ignition stator re-wound or repaired as I see nothing else that could cause this issue, but I'm unsure of whether the stator coil goes on the top side or bottom side of the cover?

Other trouble shooting I've read online here says there should be almost no resistance with the points closed (I have about 0.4-0.8 Ohms) and very high resistance with the points open (this i do not have, about 1 - 1.2 Ohm) But looking at the wiring diagram there is no way that the resistance could be high as you have both coils in parallel with the points open? (I am an Electronic Technician by trade)

The blue wire is currently being used for charging the battery system with a plain single rectifier. It produces around 3-4.5 amps dependant on revs and this balances out nicely for the headlight draw and LED lights for tail/break/indicators.

Any help on identifying the current stator set would be a great start, and if anyone could specifically tell me whether the ignition stator belongs on the top/bottom of the cover, that would also help out.

As others have mentioned, the amount of interest the old honda bike generates any where I take it is unbelievable. I never though anyone would be remotely interested in it! I'm having major withdrawal for not being able to commute to work!

Kind Regards,

Graham.

Brisbane - Australia

Share this post


Link to post
Share on other sites
 

 

Hi Bigmike, Thanks for the reply.

The new ignition coil comes with a new condenser, but I did swap in the condenser from the battery ignition setup with no change in the symptoms.

Share this post


Link to post
Share on other sites
 

are you sure you hve a tl125 engine fitted,not cb125?the tl125 should run lights of engine not batttery.the ignition side runs of 1 coil on stator.the only reason for battery is to run horn-brake light-neutral light.the cb 125 engine charges the battery and everything runs from battery.

Share this post


Link to post
Share on other sites
 

Hi Max,

I do have the TL engine, with a CB125 Head fitted with all new valves, springs, cam chain, piston and top end all done. The gearing is definately not CB or CT. First 3 gears are all close together and used up before 25 KM/H.

I dug through the rest of my left over bits and talked with my Dad and we do think that the stator cover is off a more modern CT125 (maybe mid ninties) with a TL stator fitter for the ignition only. I have taken off the cover and checked out where exactly all the parts are. I am using winding in the top section to drive the battery charging setup, and I have fitted another ignition stator from what I believe to be a TL to the lower side and I have the issues. I'm currently searching for more information on timing setup for the ignition in case it is different from what it should be for the battery ignition. Other thoughts are whether the primary coils could be not lined up correctly with the magnets in the flywheel?

I completely done away with the idea of running 6V lights off the original primary coil as done originally in the TL for fear of road worthy issues here in Australia. It has all 12V lights, horn, indicators, number plate lights, brake lights all wired like you would find in any more modern bike.

Share this post


Link to post
Share on other sites
 

well that sounds like a bit of mixture youve got there. Is the main engine TL.

I checked my TL yesterday and that has five wires coming out from the stator, I dont have lights so only use one wire.

I have an old stator that just has one coil inside ( off a TL125E) model and that is fitted to the bottom of the case.

I am not familiar with the CT as they didnt bring many of those into the UK.

I do know from experiance that the cam shafts for these engines are not all the same and are timed differently as are the centrafugal advance unit with the points cam on. You might have to ignore the marks stamped on the cam shaft sprocket and time it manualy.

I wouldnt think that the magnet positition would make any difference as it is not related to the timing like a bike with cdi ignition.

Back to the electrics, It does sound like a bad earth problem, Try running an earth cable to from engine to coil / condenser, if your frame has been painted or powder coated, this can cause a problem.,

I did have a TL125S model that was fully road legal (1978) and that had a battery fitted, maybe you could find a wiring diagram for that model.

One last thing, just thinking out loud really, I think they were wired with a constant charge to the battery via a regulator / rectifier and one of the stator wires went to the light switch so was only active when the head light was turned on and there was some thing electical mounted on the fork bottom yolk that pressumably took away the power at high revs to stop the bulb blowing.

Hope this is of some help.

TLTEL

Share this post


Link to post
Share on other sites
 

I'm a bit lost here. Are you running the ignition as DC off a battery which is charged from the stator via a rectifier or are you running AC ignition direct from a stator coil as on the early pre-CDI XL models?

If you're running AC then the advance / retard is totally different than the DC version, the crank duration (time with points open) on the AC XL unit is short at 240 degrees, the DC CB 125 unit has a crank duration of 438 degrees, so the points are closed much longer on the AC unit. The CB unit springs are stronger as well.

The position of the magnet with respect to the ignition stator coil is important as well in an AC system, the points open just as the voltage wave reaches its peak to give the maximum transfer of energy. From the drawing, the stator and HT coils are shorted out by the points until the points open, the energy then surges into the HT coil to induce the spark, similar to the old Lucas ET system on some British comp bikes. If your LT/HT coils and points are wired up like this then you are correct that with the points open the HT primary coil and LT stator coil are in parallel. Also, I think the AC ignition models have a different type of HT coil.

I took those crank duration measurements myself from advancer units model 382 for the XL and 107 for the CB ( the 3 digit number on the advancer unit relates to the Honda bike model code).

Regarding 4 wire stators, I've got a drawing of a 1977 USA model CT125 which shows 4 wires but they're Bk/W, W/Y, P and Y.

Edited by dabmeister10

Share this post


Link to post
Share on other sites
 

Thanks for everyones time and input. I do certainly have a mixture of engine bits.

When we got the bike going from a fresh rebuild and complete restoration including stripping and painting everything and installing all lights and wiring new and from scratch, we never got the magneto ignition to work correctly and put it down to a faulty original secondary coil. We quickly converted it to battery ignition run straight from the battery and using the original points to switch the earth to the coil. This puts too much load on the battery system (had to charge it every week) and I wanted to convert it back to magneto for reliability reasons. I have been riding the bike to work and back for over 6 months with this setup.

The timing of the points was left and I fitted the new Secondary coil and new condenser (from Sammy Miller), new spark plug cap (non Resistor) and modified the wiring for the ignition all back to original. (ac primary coil output goes straight to the secondary coil/condenser/points) Bike started fine but when I rode it, it would loose spark all together or back fire through the carby/cough etc as soon as you asked it to work hard. (Give it a small hill to climb, or open the throttle) If I nursed it, I could get it to rev right up as normal.

The coil base is not earthed except through the frame and this will be a spot to check as with the battery ignition it would not need an earth at the frame. (Kids are asleep right now so it'll have to wait a few hours)

The engine is TL125E

The head is a 383 CB125 J/N.

I'm pretty sure the cam itself is from the TL as I don't remember having more than one of these spare.

The points base and auto advance parts have 355K stamped on them.

I have followed the TL manual for setting the points timing.

In Australia the CT is very common farm bike, my Dad has repaired hundreds of them and has a mass of parts, the 185 version of these engines is also used in junior speedway solos, and my Dad and friends have also worked on hundreds of these. This is why I have ended up with a mix and match of parts as most parts are interchangeable, or at least fit but possibly this is why we are having ignition issues. We just used the best of the bits.

It did have new piston/little end bearing/valves/springs/seats/valve inlet grind/cam chain. Basically the whole top end is brand new.

The other auto advance I have is 356STD and now that you have drawn attention to it, it is mechanically different. Counter weights look smaller.

After online research of how magneto ignition systems work, the timing of the magnets with the primary coil is very important.

The flywheel I have looks like it has 4 magnets, it has 2 dowels fitted also.

If the auto advance system was wrong, would the battery ignition still work ok? If the bike will rev up does that too therefore eliminate the auto advance? The opening duration of the points could be causing issues though, but then why does it backfire like the ignition has a mind of its own?

I will attached a couple of photos that may help and will try a direct earth on the secondary coil asap.

Sorry if we are getting lost in some of the technical terms here.

Edited by stumpnthqldd23

Share this post


Link to post
Share on other sites
 

Earthing the secondary coil shows no improvement.I did have to drill 2 small holes through the metal of the coil in order to bolt it on the original mounting. (it was just a universal coil)

Share this post


Link to post
Share on other sites
 

Hi

Just a thought on your advance / retard unit, i had one from an xl engine and tried to use it, just because it looked newer than the TL one I was using, on close inspection the slot that lines up with the dowel on camshaft was in a different position and the springs and weights were different too.

So it may be that you need the camshaft and advance unit from a CT to make it all work properly with the CT stator..

Interesting about the stator / magnet positions being crucial, I supose it is not normaly some thing that crops up as its not usually variable.

Presumably the reason it worked ok with the battery set up is because you had a constant power at the coil/points.

Hope you get it sorted.

TLTEL

Just wanted to add, If the advance / retard is wrong it might rev if you raise revs slowly, but not under load or quick opening of throttle

Edited by tltel

Share this post


Link to post
Share on other sites
 

According to the model codes here http://oldmanhonda.com/MC/HCodes.html , the advancer unit you have is from the TL so it should have the correct duration.

I once fitted a different rotor to my CB alternator but there was no output, turned out it had 4 magnets as opposed to the 6 on the CB one.

It might be that you need the complete set-up off the same engine, the keyway in the rotor may be at a different position. As tltel says, some of the cam dowels are different, I had to rotate the points back plate about 90 degrees on the last one I built with a one piece head so not beyond the realms of possibility.

I'd imagine the crank keyways are all the same but it's not something I'm sure of.

Share this post


Link to post
Share on other sites
 

Thanks for everyones input. See attached images of points/advancer/Stator/flywheel.

Does anyone know if the TL ignition should have some sort of a suppressor or resistor in the plug cap/lead?

Could someone compare the the magnet placement vs timing marks on the flywheel?

The ignition stator is on the bottom in both the picture and on the bike.

the old man honda link with the part number information is very helpful, thank you so much!

post-18208-0-21431300-1364904439_thumb.jpg

post-18208-0-36468900-1364904458_thumb.jpg

post-18208-0-13363700-1364904481_thumb.jpg

post-18208-0-09498100-1364904502_thumb.jpg

Share this post


Link to post
Share on other sites
 

sorry I cant help with the magnet positions at the moment, but it does look the same as the TL set up I think I have got a spare I will try to have a look.

The advance unit does look different to mine (from memory, not seen it for a while) yours does look very dry, a bit of lubrication might help things move a little easier.

No supressor in plug lead on mine.

TLTEL

Share this post


Link to post
Share on other sites
 
 
On 3/31/2013 at 11:47 AM, tltel said:

well that sounds like a bit of mixture youve got there. Is the main engine TL.

I checked my TL yesterday and that has five wires coming out from the stator, I dont have lights so only use one wire.

I have an old stator that just has one coil inside ( off a TL125E) model and that is fitted to the bottom of the case.

I am not familiar with the CT as they didnt bring many of those into the UK.

I do know from experiance that the cam shafts for these engines are not all the same and are timed differently as are the centrafugal advance unit with the points cam on. You might have to ignore the marks stamped on the cam shaft sprocket and time it manualy.

I wouldnt think that the magnet positition would make any difference as it is not related to the timing like a bike with cdi ignition.

Back to the electrics, It does sound like a bad earth problem, Try running an earth cable to from engine to coil / condenser, if your frame has been painted or powder coated, this can cause a problem.,

I did have a TL125S model that was fully road legal (1978) and that had a battery fitted, maybe you could find a wiring diagram for that model.

One last thing, just thinking out loud really, I think they were wired with a constant charge to the battery via a regulator / rectifier and one of the stator wires went to the light switch so was only active when the head light was turned on and there was some thing electical mounted on the fork bottom yolk that pressumably took away the power at high revs to stop the bulb blowing.

Hope this is of some help.

TLTEL

Old post I know, but this post could confuse others searching for information.  The poster actually has four wires coming out of the stator.  The fifth is the neutral switch wire (green) which runs very close to the stator, before connecting to the neutral sender switch next to it. 

Edited by stpauls

Share this post


Link to post
Share on other sites
 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...