E: Engine My BT-H Is Not Providing Spark

[CarlHungness]

I've never heard of a B-TH 'going bad', so I may have set a precedent.
Last year as I was moving from one shop to another the last thing in the old shop was my '54 Shadow and I must have kicked it for half an hour to get it started, never had such a serious problem. I had no tools in the shop at all, so just kicked until it fired.
Upon inspection I DID find oil had seeped down a plug wire, through the now supple spark wire caps and into the bottom where the wire attaches to the coil(s). So I thought oil on a plug wire was my problem.
I ordered new coils and wire and paid very close attention, I hope, as to how to unhook the old and install the new without mixing up the wires.
Just tried to start the bike, and seemingly not getting any spark. All alone I can kick the machine over with no plugs and hold a spark plug to the head. I have a center stand now that allows me to stand next to the machine and kick it through. I've held the plug to the head, put my finger on the electrode(s) and no spark. I tried both plugs and am sure they were grounded as I kicked. I've done this previously years ago with a helper and did get spark
Suggestions?
Second, if I do have to remove the unit I wish to ask the group for some advice please. It has been well over ten years since I installed the unit, have had it out once and used my degree wheel, etc. to re-install.
I don't recall the exact procedure, but do remember there is a 'pin,' that one drops into a hole in the shaft when everything is timed as it should be.
Can I do the following: Turn the engine over until I find the hole in the shaft, drop the pin in and remove the unit...am trying not to re-time the whole plot if in fact the B-TH needs work. Can I get it 180 degrees out of phase easily?
And/or, can use your suggestions as how to remove the unit and be able to re-install without using a degree wheel, etc.
I think I can just take off the ATD cover, then the drive gear and the three bolts that hold the unit in place.
I did unhook my kill switch wire just in case it may have been shorting out (where it passes through my handlebars, it runs
inside them) and still no spark.
I just don't have enough knowledge to know how to test the BT-H, so need some assistance.
Thanks in advance.
Best,
Carl Hungness

 

[greg brillus]

Carl, like any of these ignitions either magneto or coil, they can and do fail........The BTH's I've seen seem good for around 10 years or so and then issues can happen........One issue i had was light corrosion on the ends of the internal coil armature faces........these are soft iron and tend to rust.......Remove the end cap, after the small cap screws are undone......then ease the cap off whilst sliding the wiring and grommet from the slot in the cap......once removed you can see the coils I mentioned, and if the ends are rusty, simply polish this off with a dremel and tiny wire wheel if you have one......lightly coat the ends with smear of grease, or a coat of oil to stop the rust forming again........reinstall the end cap carefully watching the wires dont get damaged.........this could be the fix.......if not, you may have to remove the unit and return it for further inspection.......you can time it via the pin you mentioned.......just set the engine on the firing stroke of the rear cylinder first, then turn the engine to the advanced location to install the pin........best to do this turning the rear wheel in top gear with the plugs out and the inspection caps off the rear cylinder so you can tell if you are on the overlap or compression stroke.......Good luck with it.......Cheers........Greg.

 

[CarlHungness]

Carl, like any of these ignitions either magneto or coil, they can and do fail........The BTH's I've seen seem good for around 10 years or so and then issues can happen........One issue i had was light corrosion on the ends of the internal coil armature faces........these are soft iron and tend to rust.......Remove the end cap, after the small cap screws are undone......then ease the cap off whilst sliding the wiring and grommet from the slot in the cap......once removed you can see the coils I mentioned, and if the ends are rusty, simply polish this off with a dremel and tiny wire wheel if you have one......lightly coat the ends with smear of grease, or a coat of oil to stop the rust forming again........reinstall the end cap carefully watching the wires dont get damaged.........this could be the fix.......if not, you may have to remove the unit and return it for further inspection.......you can time it via the pin you mentioned.......just set the engine on the firing stroke of the rear cylinder first, then turn the engine to the advanced location to install the pin........best to do this turning the rear wheel in top gear with the plugs out and the inspection caps off the rear cylinder so you can tell if you are on the overlap or compression stroke.......Good luck with it.......Cheers........Greg.

Considering the humidity we have in Indiana there's a good chance you have identified the problem. Tools will
rust in your tool box, even with lots of dessicant silicagel to soak up moisture. I'll take the cap off tomorrow and see if I can identify the armature faces. I do have a Dremel and wire brush. I also have a piston stop at 34 degrees, so should be able to find the 'hole' and can pop my degree wheel on to check. Will leave the unit on and see what it takes to get the end cap off and do the maintenance. Thanks Greg.

 

[Normski]

The timing pin is 6mm diameter (1/4” will not fit.) The hole for this is fully cross drilled so it is possible to be 180 degrees out.
With the unit removed you can see a small arrow etched on the end where the pinion fits, that should be pointing up to where the rod enters for correct timing. If you install the rod and then remove the mag you only need to look at where the arrow is pointing when removed and refit in the same orientation to keep your original timing. (If you fit the rod with rear cylinder at firing point on compression stroke then the arrow will be up.) Do not turn engine with mag removed as without the spindle to run on the pinion will jam up and strip teeth.

 

[Normski]

 

[CarlHungness]

Thanks for the tips, I have installed the mag on a couple of previous occasions and was
wondering how to not have to re-time the plot.

 

[bmetcalf]

https://www.bt-h.biz/Graphics/Home/...-instructions-template-no-photos-25.03.14.pdf

 

[Simon Dinsdale]

I have a BTH that was bought around 2006/07. At first it was great but during a very wet ride to the Scottish Applecross rally in 2009 the bike got harder to start but once started ran fine and this is a bike that I have done thousands of miles on over 30 years and is usually a 1 or 2 kick starter. Eventually the BTH failed and refused all efforts to start but there was still a visible spark at the plugs. I replaced the HT coils and leads and rechecked the static timing it made no difference so removed the BTH and returned it to the the manufacturer at the time which in 2009 was different to the guy who makes them today. At the same time I refitted the old points /coil ignition unit and suprise the bike started first kick which to me proved the BTH was the problem. The unit was returned to me with a note saying there was no problems with it so I refitted it and went back to virtually impossible starting. So the BTH was thrown on the shelf in disgust and the bike has successfully run on the old points ignition since them.

So I have just dug out the old BTH from the back of the workshop and opened it up. First thing was I removed the small cover off the end which has BTH engraved into it and I was suprised to find 9 threaded holes in the end of the main cover but the smaller BTH cover only uses 3 of those. There was no sealing of the smaller cover to the unit and no sealing of the unused holes so an easy path for water to get in. I then removed the main larger body cover which again had no gasket or sealing at all. The two screws which hold the pickup coils are rusty and the magnet in the rotating arm has loose rust particles magnetically attached to it and when rotated to line up with the picup coils the rust particles bridge the air gap and this will result in a varying timing and is probably the cause of my problems. I may de-rust these pickup areas sometime and try the BTH on a bike againg but the Rapide is running fine so I'm loathed to start messing with it.

Please note BTH is now owned by a different person and I believe he doesn't service devices made under the previous owner, but you would need to check that. I have no experience as to how they are assembled today.

These photos were taken today:

 

[greg brillus]

Polish up those ends that look like screws like you say, and wipe the magnet on the rotating arm clean, and i bet it will be fine again......put a light smear of grease on those pole ends to stop them rusting.........had this happen to a Shadow years ago.......the bike was kept in a damp shed, and the bike got harder to start.......normally a 1 to 2 kicker to fire up.

 

[CarlHungness]

Polish up those ends that look like screws like you say, and wipe the magnet on the rotating arm clean, and i bet it will be fine again......put a light smear of grease on those pole ends to stop them rusting.........had this happen to a Shadow years ago.......the bike was kept in a damp shed, and the bike got harder to start.......normally a 1 to 2 kicker to fire up.

I just took the rear cover off my B-TH per Greg's instructions and could find no rust anywhere. I did see some
condensation. I've just asked B-TH if they will service the unit. I'm in the US and don't know of anyone here
who works on the B-TH. So I may be looking for alternatives.