[French MK]

Hello,

New to the forum and my first post. I recently purchased a 1992 Trail conversion 500cc Bullet. Starts fine and ticks over a treat after abit of adjustment then. When pulling away it starts to "splutter" and miss a little. Now me being me introduced too many factors to try and eliminate the issue. Now i changed the condenser and points. I went up a main jet size and pilot (125 from 120 and 30 from 25) so not to drastic. The Throttle needle was on position 2 and i went up to the middle position. I never re-tried the bike at that point.

I decided firstly to measure the voltage when running to check if the battery was charging. When slowly revving the bike it started to rise up to 17 volts and over before i decided thats not right it should be around 14.9 volts? It was then i decided to buy Hitchcocks Power Box. Connecting up was pretty straight forward and a simple swap.

So today was the first start up since all that. In total i kicked it over a fair few times with no joy on actually starting it although it did try at the very first. On measuring the voltage just to check, it had gone from 13 plus volts down to 12 volts. The battery had drained. Its now on charge and i have put the original rectifier back on just to try and carb back to normal jets. I think the carb thing isnt the problem. I am concerned about the power box though.

Has anyone any thoughts on this at all? Sorry its long winded but i had to get this all down lol.

kind Regards

Mark (French MK)

[Adrian II]

Ref the carb, did you try changing to a richer throttle slide?

The Boyer Power Box COULD be a faulty one, in which case it should be replaced under guarantee/warranty, it it's allowing the battery to discharge, though it might be worth checking the rest of your electrics. Presumably the battery itself is a good one? I have had other reg/rectifiers fail and have taken to wiring in an isolator switch between the battery + terminal and the reg/rectifier + feed. This sort of thing.

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A.

[AzCal Retred]

My powerbox works perfectly. As this is a brand new install, I would double-check my wiring hook up. The Boyer website and Hitchcock's have wiring/schematic diagrams. It's possible this is a case of electronic "infant mortality", but Boyer stuff is normally a very safe bet. Recheck the install. "Trust but Verify"....

[stinkwheel]

I'd expect it to make a spark on 12v left in a battery. In my experience of touring Spain for 2 weeks on battery power only, they don't start stuttering until it gets down to 8V.  Is the ammeter deflecting when you kick it over? If it's not, something is wrong with the ignition wiring. For sanity, check the earth connection is good, so the resistance between the earth connection to the power box and the battery negative terminal should be near zero. Is the main fuse intact? Also have a good look at your points wiring.

If it's been going over 17V, it could have damaged the battery and/or the stator wiring. It should still make a spark on even a pretty discharged battery unless it's completely dead (they can show 12v and have next to no power in them). Do any of the lights work with the battery connected? If they light up reasonably brightly, there should be enough in it to make a spark.

Is it one of the boyer type boxes? If so, might be worth a try with the battery disconnected, they have an internal capacitor which should let it run without one. Connect the earth to the frame earth and connect any terminals that were on the battery positive together with a nut and bolt and wrap them in insulating tape. Then pull the plug and kick it over fairly vigorously to see if it's making a spark. If it is, it should start and run like that. I'd try charging the battery and trying it again and if you run into problems, replace the battery.

If it isn't you have bigger problems and need to start checking the stator integrity. You have a meter so a good start is to measure resistance between the two wires that connect into the power box (usually two violet wires) with it disconnected. It should have a very low resistance between those two wires, maybe in the single digit or lower ohm range. It should have an open circuit between any one of those wires and earth.

Not all meters respond quickly enough but you could also set it to measure AC volts between those two wires and kick it over vigorously. You should get a transient voltage reading (easier on an analogue meter, you see the needle deflecting).

[French MK]

Hi, and thankyou for replies, its still ongoing as i type. I will look into throttle slide for final carb setup.

As regards to wiring the actual power box, it was wired as per instructions. However....

I must verify that i have no lights only a brake light. The ignition switch is just that, a simple toggle switch "On" and "Off".

I was told the battery was brand new and i have "drop tested" it. I tried to start it this morning and it started straight away for a few moments and now back to not starting.

I have found after i got a kick off the plug.... when i turn off the ignition i get a spark on the plug every time i switch off. I have never seen this before.

So would i be right in thinking a "short" or the coil? maybe?

regards

mark

[Adrian II]

I think it's just the ignition switch doing what the points do, interrupting to current to the coil! Don't forget your Power Box has a capacitor inside it, which would not have been a part of your previous reg/rectifier.

Have you tried running the bike without the battery? Provided you have a healthy alternator the Power Box should handle this with no trouble, just remember to kick the engine over a couple of times on the decompressor first to charge the capacitor up. You can also replace the brake light bulb with a LED so that it draws less power when the alternator is at lower revs.

Chinese single-phase reg-rectifiers are almost cheap enough now to consider as a consumable item, one of those (with a spare in the toolkit) plus an external capacitor similar to the old Lucas 2MC will do the same job for a fraction of the price, if you have to get a refund for the Boyer.

A.

[stinkwheel]

The fact it started tends to suggest there isn't a wiring fault with the points. The ignition coil could be a problem if it's been running very over-voltage for a period of time and they are certainly something that can "break down" as they get hot. Is it the original coil?

I suppose the logical thing to check is if it has a spark when it refuses to start. You can even do this with a spare sparkplug if you don't want to be taking it in and out. You can put the spare plug on the cap and kick it over with the decompressor held in.

The other really useful test would be to have a voltmeter connected across the boyer output next time you try starting it so you can see if you get an output from it if/when it fires up. Then yopu can eliminate that from the list of possible faults.

As above, if it's only running a brake light (and presumably horn) as accessories, it might be worth just running it without a battery altogether, this should be perfectly fine with the boyer box. The only real downside is you don't get ammeter deflection when you start it.

I'm not familiar with the bike but I presume if it only has a brake light and a toggle switch for the ignition, it's been fairly heavily modified? Did you do this work yourself? I'm just wondering what's been done with the surplus electrics. Has the original loom been used and reduced or was it totally re-wired? Did you do the work yourself? I find a lot of amateur (and in fact, professional) motorcycle mechanics do wiring very poorly.

Is your toggle switch a six pin one that makes and breaks a connection in each position or is it just a 2 or 4-pin make and break one in the power side? The standard setup disconnects the battery power and connects the low-tension side of the ignition to earth in the off position and reverses this situation in the on position.

It is not uncommon to trap the wire coming from the points under the distributor cap and cause a short circuit. Also I have seen aftermarket points where the spring on the points was too long and allowed the spark to earth to the distributor housing.

[French MK]

OK just tried it without battery and just with the "Boyer Power Box" it fired straight away for a second, then nothing. I rested plug on the bike and kicked over several times and the spark is very weak and sometimes not at all for several kicks. Would that indicate the coil is breaking down?

I will try and put some pics up here if i can, but anyway no i havnt done any of the electric work and dont know history of coil. There is no horn either, i used a wireless one for MOT (Daylight). The electrics are very basic. The toggle switch is 2 way thats it.

As i said on initial post, i have ridden it (with original rectifier) but it was just "stuttering" when going through the gears. Up and down the drive in first gear was fine, but i was thinking the major increase in voltage may have damaged the coil then. At least the powerbox works as should.

Regards

Mark

[AzCal Retred]

I would toss the condenser/capacitor as it is the most degradable part. Coils usually fail as they get hotter.

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Mallory Condensers 400
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[stinkwheel]

Lovely looking bike.

One thing that jumped out at me. The main frame earth looks very dirty. It also looks to be trying to earth that ring terminal to the frame through the battery box. It wants clean metal on metal contact between that ring terminal and the frame. I'd take it off, emery paper off the corrosion, scrape off paint under the ring terminal to bare metal if necessary and reconnect. Then apply dielectric grease over it or at a pinch, a smear of vaseline.

I would personally have the ring terminal directly against the frame so either moving it so it's between the battery box and the frame or moving it to the other side so it's trapped between the nut and the frame.

Circled in red.

I'm also not a fan of single spade connectors on motorcycles, they seem to have a tendancy to become loose or dirty and not make proper contact despite appearing to be together. Bullet ones don't seem to be as bad for this.

EDIT: The connections on your coil are also very dirty/corroded and those screw-in chocolate block connectors have no place in motorcycle wiring, they are a failure waiting to happen.

[French MK]

OK, Will sort all that and try again.... watch this space and thankyou i appreciate it.

[Adrian II]

and those screw-in chocolate block connectors have no place in motorcycle wiring, they are a failure waiting to happen

Ah yes, emergency use only. That DOES remind me of my first ever re-wire of a bike, my old BSA C15, though I'd hope my wiring has improved a lot since 1977.

A.

[French MK]

Hi Stinkwheel, All electrics re-done as you suggested. I have replaced the coil for new (keep old as spare) and now removed the old regulator. I tried hand turning the bike over because its on the bench with the "power Box" only, but i dont think it had the "ummph" or the capacitor charge, to do sparks. Had a couple of tiny ones.
Re-connected the battery and there is now spark.

Took off the bench. Having abit of blowback through the carb now. So going to check timing next. Just thought I would update here. Cheers

[French MK]

Update: Starts well and a good spark, battery is charging via "Power Box" so quite happy with that. Took it out for a spin and mid throttle is abit "stuttery" not picking up then. First gear fine, second "stuttery" mid throttle but change into third quickish and is ok until mid throttle again..... (if this makes sense!!). Carb settings?
At the moment its running a:
                                             125 main jet.
                                             30 pilot.
                                             2.5 slide.
                                             position 2 on throttle needle. (from bottom)
                                             needle jet (08 standard), have ordered a P2.

[stinkwheel]

Couple of things to check which are easy. Fuel flow from the tap, standard taps can have terrible fuel flow. Also check the auto-advance is working properly if you are still on points. At simplest, just a case of seeing if you can turn the cam with your fingers.