Misc: Ignition Modern BTH Ignition

Albervin

Well Known and Active Forum User
VOC Member
Mine is an earlier one from the previous owner of BTH, it failed on one cylinder earlier this year and the new BTH owner fitted all new internals to it. With this done it has still got a messy mass of black sealant/silicone in it (I think Vibrac posted a picture of the inside of one some time back)
I found after refitting it to exactly the same timing as previously using the same piston stop, that the bike didn’t run too well. I did the wrong thing and messed with the carbs (which Alyn may recall being a problem in Paris) but having now advanced the timing several degrees to about 37btdc the bike runs as it did before.
Notwithstanding this I like the BTH and the bike is a reliable starter and has never kicked back when trying to start which is a great benefit.
WOW> 37º is certainly not an optimum. There must be an internal issue with the BTH or your timing disc is not calibrated :) On the ride back from the motordrome your bike was certainly not a happy bike. My BTH is an original new one; the coils just had points for the leads not screws. It was set up at 34º originally and again when I rebuilt the engine in 2014. I have never pulled the body apart and I live 800m from the sea.I will need to replicate the easy starting I had this week to "prove" it was the coil change that has made the difference. Anyway, if it runs and behaves then enjoy. I trust the big storm didn't impact too much on you.
 

Normski

Well Known and Active Forum User
Non-VOC Member
The bike didn’t run very well for the whole of that French trip Alyn, it took the edge off what was otherwise a really good holiday. I’d got the repaired BTH back only a few days before setting off and when refitted it immediately felt woolly at low revs and the tick over dropped off a lot. I didn’t have the courage to advance the timing until my return but I wish I had before I set off. I suspect that there’s been a change to the relationship between the position of the cross drilling on the BTH shaft for the timing pin and the trigger point for the cdi modules. I did take the end off the BTH for a look inside but it was such a mess of wires and silicone that I went no further. The current BTH people are nice to deal with and I should really speak to them about the change in behaviour to see if they can explain. They were selling old style coils (push in leads onto a spike) cheaply at Stafford Show a few years ago and said they had only stopped using them because some people had problems with the HT leads pulling out and had superseded them with coils where the HT leads are held more securely. There was no mention of any electrical inferiority.
We had some high winds and heavy rain but we’ve had these nearly every year I can remember - without crisis. Your problems with the bushfires are much more significant, I hope you get the forecast rain to help with these.
 
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