B25 1969 starting problems

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bonnietiler
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B25 1969 starting problems

Post by bonnietiler » Mon Jun 08, 2020 10:58 am

Bike has always been sweet no problems it is running a Boyer...Go to newsagents bike starts easily after only 800 yes starts to misbehave then grinds to halt..
I do the "push of shame" back home bike refuses to start and backfires spectacularly.
.am I missing something obvious?

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Re: B25 1969 starting problems

Post by Canberra » Mon Jun 08, 2020 11:20 am

How is the battery? I've had the misfortune of running a Boyer with the battery on it's way out. I had huge problems starting until I replaced the battery. I use a different electronic system now which is less prone to voltage drop.

John

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Re: B25 1969 starting problems

Post by madsundaysurvivor » Mon Jun 08, 2020 3:01 pm

Hello, I think the same,
If the battery is OK, see if the pickup has moved (it is rare but sometimes it could happen).
The next thing would be to check the spark plug and the spark plug cap, and the HT wire, it may be old, it hardens and cracks and makes intermittent failures

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Re: B25 1969 starting problems

Post by Jeff K » Mon Jun 08, 2020 3:46 pm

Voltage is critical to electronic ignitions, low voltage will cause them be in full advance when starting. The Norton 850 MKIII had a nasty habit of dropping the voltage when using it's starter, this would cause the Boyer to go to full advance and kick back hard enough to break the electric starter one way clutch. That is why Fred at Old Brits only uses the Power Arc units. They are the only one that I know of that still work down to 6 volts. http://www.oldbritts.com/powerarc.html

I would check battery voltage 1st.
Then pull the plug and check for spark.
If you have spark, check for fuel.
If you have spark, fuel and compression, then your timing is off. Start checking the Boyer components.
If it sparks and then stops, check your wiring.

Jeff

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Re: B25 1969 starting problems

Post by bonnietiler » Mon Jun 08, 2020 5:14 pm

Got a brilliant spark..got fuel too... occasionally it starts for a second or 2 then coughs and stops it kicks back and spectacularly goes bang (Like a Lee-Enfield), I'm just confused how it works perfectly then gives up the ghost, I'm thinking that the Boyer has died...it is like its on full advance, its an old boyer and looks quite tired is a Boyer the best way to go? I used to retail these back in the day and Lucas Rita and Tri-Spark

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Re: B25 1969 starting problems

Post by hhh » Mon Jun 08, 2020 7:45 pm

I wouldn't do anything until load testing the battery voltage. If that passes, Boyers can develop nasty problems from the slightest intermittent connections, either in their power wires, or the trigger wires, all the way to the stator plate itself. They can fail right where they are epoxied. Make sure all connections are clean and the ignition switch isn't slightly faulty. These can drive you insane when they only happen at certain frequencies of vibration brought on by certain RPM.

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Re: B25 1969 starting problems

Post by Jeff K » Mon Jun 08, 2020 8:33 pm

The proper voltage is critical with the Boyer. Once it gets too low the unit will go to full advance even at idle or starting it. Like HHH said also a intermittent short or open connection will also result in no spark and then full advance. Check you battery and then start checking all of the wires that deal with the ignition. I would also look for a wire the is rubbed bare. you could have a fleeting short that is not blowing the fuse, but is enough to pull down the voltage enough for the Boyer to jump to full advance.
Jeff

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Re: B25 1969 starting problems

Post by Canberra » Tue Jun 09, 2020 1:01 am

There are a range of electronic ignitions on the market nowadays and we all have preferences and comments on them. Boyer had to upgrade their units as the earlier ones was severely affected by even a small battery drop. Pazon which I am using recommend replacing most original ignition components although I am still using their surefire system with a high capacity coil from Trispark (who also make good units for B50s). Pazon found some people had a problem with their surefire unit when trying to start B50s with the low cranking speeds and now recommend their smartfire units. Touch wood all going well with my surefire system and starting OK. It isn't an issue with the surefire on a B25 as they are significantly easier to kick over.

I would start with battery and have a battery shop test it otherwise you can end up going down a rabbit hole with the wiring and charging/ignition circuits. You could still have a good spark with an aging battery but it'll not be in the correct place.

Big thing to look out for is how the unit operates if there is a low voltage from an aging battery. Pazon works down to 8 volts so a dud cell will not affect it. I believe that also applies to many other newer units.

John

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Re: B25 1969 starting problems

Post by kommando » Tue Jun 09, 2020 7:38 am

Boyer MK4 matches the low voltage performance of the Pazon.

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Re: B25 1969 starting problems

Post by minetymenace » Tue Jun 09, 2020 8:04 am

My money is on a loose/intermittent connection. Everything checks out OK when static, shakes and pops and bangs when running (love the Lee Enfield reference, at least its not Martini Henry!)
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Re: B25 1969 starting problems

Post by tridentperu » Wed Jun 10, 2020 1:44 pm

Could you not just hook a pair of jump leads to it from a car, and if it starts fine then it's def the battery.

I had a similar problem with my B44 running a Boyer - a poorly functioning reg/rectifier was allowing the battery to run down when using the lights - all sorts of popping banging and misfiring ensued. Turned the lights off, prob solved temporarily at least. Changed the R/R and it is now fine.

J

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