If been said many times before on here dont expect to see a strong B-TH spark it was shown to me by the developer of the B-TH system under test and I could not see one but I could see the pin hole it burnt through a piece of normal weight paper!
ET: Engine (Twin) Seeking Ignition Suggestions For Twin - Can't Get The ATD Fitted
- Thread starter CarlHungness
- Start date
I see...I did not realize the ATD had to be in working order to use the Thorspark., same as on the stock unit. The man who fixes ATD doesn't
do so during the summer. the Thorspark website doesn't explain use of the AT D in the same manner you did. It states you use it, but doesn't say it has to work just as it does on the stock Lucas. And I'm glad to hear you had the same problem, and did get it fixed. I've just written to
the B-TH folks and asked if they've fixed some of the old units...it would be worth my while even with high postage
rates to send it to them if there's a chance it can be repaired. My B-TH is sparking, but one can barely see the sparks
at the plug and the sparks are ultra-short. I now understand a spark has to be 3/8" long to work under compression.
That being said I am now of the opinion my original problem was, is, the spark.
I now recall reading what you've stated about the B-TH..so I'm flummoxed. I re-installed the B-TH yesterday and could not get the bike to start..or pop..and it does show very small sparks when bench tested. Now I'm doubting myself once again. I'm as sure as can be there is nothing wrong with the fuel system. Float level is OK, have new jets, carbs
are clean, pilot hole is clean, etc. I DID get it to run rough with the B-TH a couple of weeks back, Magneto man here says one needs a 3/8" spark under compression to have it work. My compression is 90, has been for years with old and new pistons, and John Healy from Coventry Spares says 130 minimum needed to make it run. Wow! If...if..my B-TH is working I am really out of options. I just wrote to them asking if they'll test it..postage is horrendous from US. I KNOW the Lucas is newly rebuilt and you've read of my ATD problems...so this problem(s) is on going and taking up more hours that I could have ever imagined..I have two full weeks in trying to solve it.
Do you have an extra mag like the ones you have installed...if you did the mods to make them work, someone else
could do the same..I am at wit's end here. Now I'm reading the B-TH spark looks weak on the bench..and mine does, and sparks...barely, but installed it again yesterday and could not start the machine. I've already gotten ultra-angry
and I know that emotion doesn't work, so am tranquil once again and disappointed in myself.
Carl, I am not sure that I have absorbed everything in this thread but I think that the current situation is as follows. Last time the bike was used it worked perfectly. Nothing was done to it until recently. The BTH has a weak spark and I think that more time spent on that will not be productive. The Lucas mag gives a decent spark but the connection to the ATD is suspect. It seems to me that would be a good place to start to sort things out, one at a time. Once that is sorted and the bike retimed and you are sure that the timing is not slipping when the bike fires then you could try starting it. If it does not start readily then at least you are sure that ii is not the quality of the spark or the timing which is causing trouble.
I do not know the circumstances in which you live or how close you are to any fellow bike enthusiasts, they do not have to know anything about Vincents. Can you find someone to help? What I have in mind it to tow the bike on a quiet road, or take it to the top of a quiet steep hill. Tickle the bike up and prepare it as for kick starting and then either get it towed at about 30mph or run it down the hill till it gets to 30 mph, put it into second gear and let the clutch out quickly. This will spin the engine and keep it spinning until it either starts or it become clear that it will not start. Because either gravity or your friends car is still working the engine will keep turning at a reasonable speed and you can try opening and closing the throttle or the chokes and see if it makes any difference. Make sure both fuel taps are open and that there is plenty of fuel in the tank. If you can organise this and it does not try to fire then report back on here and we can try to think of something other than black magic or a curse on the bike which might be causing these problems.
As I understand it you are a man with both the patience and manual dexterity to build violins. I am sure that you will overcome this and if you had access to a rolling road then I would suggest that but lacking that the tow or steep hill is the best idea I can come up with at the moment.
I do not know the circumstances in which you live or how close you are to any fellow bike enthusiasts, they do not have to know anything about Vincents. Can you find someone to help? What I have in mind it to tow the bike on a quiet road, or take it to the top of a quiet steep hill. Tickle the bike up and prepare it as for kick starting and then either get it towed at about 30mph or run it down the hill till it gets to 30 mph, put it into second gear and let the clutch out quickly. This will spin the engine and keep it spinning until it either starts or it become clear that it will not start. Because either gravity or your friends car is still working the engine will keep turning at a reasonable speed and you can try opening and closing the throttle or the chokes and see if it makes any difference. Make sure both fuel taps are open and that there is plenty of fuel in the tank. If you can organise this and it does not try to fire then report back on here and we can try to think of something other than black magic or a curse on the bike which might be causing these problems.
As I understand it you are a man with both the patience and manual dexterity to build violins. I am sure that you will overcome this and if you had access to a rolling road then I would suggest that but lacking that the tow or steep hill is the best idea I can come up with at the moment.
Normans idea is quite good but i would use not the clutch .I would engage second gear and pulling the decompression lever.Then when the bike is about 20 miles fast I would let the lever go slowly to the point where full compression lies on. Regards Erik
Based on what you have stated so far, I think it is safe to say the ATD is knackered. If you are reasonably sure the taper is still ok, just as a test, you could take the ATD and lock it solid. Then reinstall it on the bike and time the engine so it is firing a few degrees before TDC. It won’t make your compression any better, but if it started before, there’s a reasonable chance it should start now. Or you could just spend the energy pushing the PayPal button for your new ATD.
The second last page has a note about installing the ATD.
The second last page has a note about installing the ATD.
When looking at fitting instructions in my link below at bottom page I get the idea that the mistake might come from not holding the central nut plus any washers to go with it closely onto the ATD unit. There is a right hand plus a left hand thread on the ATD and it may happen that by not following the instruction both threads can be in a meshed state and doing the nut up in this state will not get you a seated ATD on its taper. So see that the nut and washers are pressed onto the ATD whenn threading it onto the mag shaft .
Vic
ATD mounting
Vic
ATD mounting
I HAVE had it running with the old B-TH. It ran fine for years, then couldn't start..finally got it to fire, rode seven
miles to new shop, replaced coils...got it to fire again, ran rough. Put in the old Lucas...fired briefly...had Lucas rebuilt, and got it to fire for 60 seconds and it died. Since, have a devil of a time with the ATD, and I used to install it and believe I have the drill down...in fact now I remove the whole damn timing cover, drain oil, pipes, etc to make sure i have lots of space to install the ATD...I've even taken the mag out and installed the ATD on the bench, Lucas in the vise. Same problem, once on the taper, ears are stuck open. The ATD man (who advertises) seems to re-state my problem, ears stay popped open upon installation. Thus I'm hoping the ATD is knackered and I had some good luck installing it twice, but no more. I feel confident the bike will fire OK now if the timing/ATD are in order. The ATD man doesn't accept work June July August.
However, reading here about the B-TH spark a fellow member said the spark 'looked' so weak he and a friend put a piece of paper on electrode of spark plug and they burned a hole in it, and the B-TH worked! Thus, it seems as though the possibility exists the B-TH appears to put out a weak spark when in reality it actually works. I re-installed it yesterday after doing a bench test (it sparks with the plugs, but spark seems to go BACK from the electrode, but I can sure see sparks...small as they are). Another mag man who does it full time says 3/8" spark needed and I'm getting 3/16". The original ATD must wear just enough to make the 'ears' wobble and stick open, that seems to be the 'normal' problem. Thus much as I hate to miss the whole summer of riding, I think my best option is to wait until September to have the ATD rebuilt. I DID re-install the Lucas with ears closed and timed it at 3 degrees BTDC and got the ears to stay open, but the bolt was just a tad tighter than finger tight, and I didn't want to try and start it, too afraid the bolt may back out, then have the gear slip and cause more aggravation.
I am SO intrigued by the post about the 'weak looking spark from the B-TH I am considering sending the unit back to the factory, he said he'd take a look at it, but tone of voice tells me he isn't real interested. Nevertheless, I keep harking back to the fact I AM getting sparks out of the B-TH at ultra low RPM's with my power drill that I can regulate..I think I'm spinning it at less than 300 RPM, which I believe is about the speed we're kicking with our leg.
I just don't think it would serve any purpose to start the bike on a hill because I know I've kicked it well enough for it to fire with both mags. Thus maybe my B-TH is bad and it sure seems as though the ATD must have slipped when I got it going with the Lucas because it sounded as normal as could be for about a minute.
I think I'm just going to swallow and wait until end of summer to have the ATD rebuilt. It feels like a failure on my part. So my wishy-washy attitude just might send the B-TH back and if they say it's no good I'll tell them to keep it. Then at least I'll have a definitive answer as to its effectiveness.
I've experienced the left-hand, right hand dilemma years ago and learned that all one has to do is PULL the whole unit backwards, screw in the bolt with the left hand thread til you feel it clear the boss, pull it back some more until you feel the right hand threads grip the nose of the mag, and then it screws right on. Easy to say, especially for someone who has two good thumbs (my right thumb DID NOT MOVE for 37 years) and after operations I now have about 50% usage. But I've worked with my hands long enough to know how to use my other fingers, awkward as hell, but I finally get the job done. Thus I CAN get the right hand threads started after fiddling, and can get the ATD onto the shaft as it ought to be, and can get it set...and burp when I see the darn ears won't retract. So I loosen, fiddle, tighten..etc, and when I JUST tighten the bolt with fingers...the ears lock...and I try to feel if there's slop in the unit. There must be. So hopefully an ATD rebuild will solve the issue. Anyhow, if you'd build me a magneto with welding strength spark I'd be happier.