E: Engine BTH magneto

[vibrac]

He sold those spike ones cheap some years ago I snapped a few up dear old tie wraps kept the leads in
I do hope the current anti plastic wave just results in glass milk bottles and 3D for a lemonade bottle returns and doesn't get to tie wraps!

 

[minivin]

I have a BT-H on a B Rapide with 7.3:1 MK1's and 1 1/16 carbs. The only issue I have ever had with it was trying to run NGK 7 plugs. They are really hard starting especially if it is cool out. Put 6's in and the starting was transformed. We also have a big bore Comet around here that has a BT-H and also a real pig to start on a 7 but is fine with a 6.

Hello Robert,

Was that the non resistorised, or the resistorised i.e. B6ES versus BPR6ES? The leads on my BTH on my unfinished B' engine appear to have no resistors, so maybe the latter should be used?

Regards

Rob

 

[Robert Watson]

Hi Rob, nice to see you getting active again.......

I only use BPR's on the HD ignition and not on the BT-H which is a CDI setup. And I run BPR7ES on the HD with NO issues. I think I have changed them twice in the last 20 odd years!

 

[minivin]

Hello Robert,

Yup, been quietly chasing a career in aerospace engineering again over the previous few years and as always in the UK, it's gone "Pete Tong", I'm back self employed and thinking that I should just focus on getting my projects finished rather than work!.

Thanks for those comments, I'm hoping to time the valves and ignition over the next few weeks. At which point I'll need to fill the holes in the cylinder heads.

Regards

Rob

 

[vibrac]

I note you guys are quoting NGK plugs do I detect that the poor press centering on the porcelain surface treatment of NGK was either a bad batch or is no longer a problem I do hope so the idea of going back to Champion might have been well advised but would be a struggle after all those years
and I am looking for a suitable pkug for my big bore 8 ish:1 comet

 

[BigEd]

I note you guys are quoting NGK plugs do I detect that the poor press centering on the porcelain surface treatment of NGK was either a bad batch or is no longer a problem I do hope so the idea of going back to Champion might have been well advised but would be a struggle after all those years
and I am looking for a suitable plug for my big bore 8 ish:1 comet

Not used anything but NGK in any of my bikes for years and that includes when we were racing. I wonder if most of the bad press about NGK was probly to do with fake "NGK" made god knows where that were about a few years ago.

 

[stumpy lord]

Not used anything but NGK in any of my bikes for years and that includes when we were racing. I wonder if most of the bad press about NGK was probly to do with fake "NGK" made god knows where that were about a few years ago.

I have always used Japanese manufactured "ngk" plugs with no problems. the country of manufacture is stamped on the body of the plug, the only other manufacturer that I have seen is French.

 

[Old Bill]

Having fitted several bth mags over the years l have found that 34-36 for the timing is about right for a street motor (nothing new there) non resistor caps, NGK BP6ES plugs at 20 thou gap. My understanding of the bth info is that the timing automatically alters as the revs vary like the old ATD units which with a 32 degree advance range gives 2-4 btdc at kickstart speed with the aforementioned ignition settings. Just my take on it, others with more in depth knowledge may advise differently? Hope this helps, good luck...

 

[Sakura]

Lots of good info in this thread but when it comes down to it it's just as BigEd says, "you just have to accept that somethings work even if you don't understand why".

 

[Pete Appleton]

Here be dragons?

I don't accept that there is anything you can't understand. Just loads of things you don't understand yet.