G'day Mark,
I have restored a 1975 CB400F, every nut and bolt etc.
I went the Dyna route..lovely spark for 4000 clicks until yesterday.
Basically bike struggles to even fire..spark now very intermittent to non existent.
Have the Dyna 5ohm coils and the regulator/rectifier.
Am very disappionted ..bordering on disgusted.
I came across your transistorised Ignition unit while looking for reports of similar experiences with the Dyna stuff....seems like it is not uncommon.
..so, I'll be ordering one of your units for sure...as I particularly like the easyswap back to the original point system if needed..
...in the meantime I would like to be sure that I have run all the necessary checks to see if the problem is not the Dyna but some other wiring problem.
Even if I get it going again I will be taking it off and installing one of yours.
I would be most appreciative if you would list the sort of things I should be checking for, to trouble shoot the intermittent spark Dyna problem
I have already acted on your advice to others re checking connections,earth, fuses etc but with no success. Any suggestions will be most appreciated
so now to order one of your setups...some queries please..where have folk located the unit on the CB400?..i.e. will I need longer wires than the stock model ? Does the kill switch also switch from your setup back to the points ..I think I read that you were going to incorporate this feature. and can I run your system happily with the Dyna 5ohm coils and the Dyna rect/reg right ?..I gather with the 5 ohm coils your unit generates more heat so I will need the bigger unit with the heat sink right.. have you any feedback as to where this unit was mounted on the CB400 ?..Ok ..I await your reply with considerable interest, and can't say how pleased I was to come across your unit..thanks Ian P.S. I'm in Oz
Hi, Ian!
I'm real sorry about the Dyna: it does seem to be a common thing in the last 2 years or so. It makes me wonder if Dyna is having some sort of design issue or maybe a bad batch of parts, as they used to be better.
With the 5 ohm coils, my unit has no issues. It's the 3-ohm coils that make the heat you're referring to: in those situations it requires a Resistor Pack more to protect the bike's wiring than the Ignition, as mine now withstands those coils just fine. In particular, the RUN-OFF switch on the handlebars slowly deteriorates with those "hot" coils, and the little bullet connectors in the Blk/Wht coil feed circuit take a beating.
On the 400F, they seem to get mounted either in the tool tray (sans tools) or at the bottom of the "triangle" area under the seat, below the battery. In either position, they should be lashed down snugly with Ty-wraps or some sort of clamp or bracket. The prettiest installation on the Baby Fours I've seen was on Loonymoon's 350F: search the forum for that one. She had a bracket made that set it vertically next to the air intake under the seat: it looked factory! When I get my 350F, I'm gonna do that...
There is a separate option called the "Security Switch" (Terry in AUS calls it the 'kill switch') that can be custom-built into this box. It disconnects the coils when in the OFF mode (center position) if bike theft warrants a little more security. This option is $25, and has to be ordered at the time of build. It takes me a couple extra days to make one like that (It's a tight fit inside!). I'm making one for Wohali just now.
The Dyna: try these things, at least -
1. Lately, they seem to be exhibiting an "aging" phenomenon after a few thousand miles, where their gaps need to be reset again. Personally, I have seen this on 2 CB750 setups here in Denver in the last year. They were first installed with gaps of about .035" )one was at .038"), and after they acted up we reset them with gaps of 0.030" instead. This was last Fall. I don't think they were driven much since then, but they started and ran OK when they left and didn't strand those riders. I have also seen it the other way' round, where they came here with gaps of less than 0.022", which was just too close for them to work right. Those 2 bikes (CB550) idled poorly, and one of them would quit on 2-3 when hot.
2. Check the splice on the wire that delivers power to the plate. The 3M splice that was on the 2 units I saw here (which came with their Dynas new) was the wrong size: they received blue ones with their kits, which should have been red ones. The blue ones are for larger wire sizes than the red ones, and the thin wire to the Dyna plate was getting a too-light contact. This made one of the bikes intermittent. I changed the blue one on this bike to a red one and spliced it to the Black wire on the voltage regulator, which is an appropriate gauge size for the red splice. This wire is smaller than the main Black wire in the rest of the harness, so it makes a good matching point.
