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Boyer bransden ignition system

2437 Views 25 Replies 4 Participants Last post by  Feanor_twh
Boyer bransden ignition system new in box Fits Z400 to Z1000 fours and Z400 Z440 twins. Wiring info on boyer site.Comes with new twin coil and new regulator rectifier unit.
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I really need a Boyer Bransden for my '76 KZ400, but I can't find the exact model I need.
I finally talked to them (Boyer Bransden) and they offered to modify the Kit87 to work on my twin. Very happy. The package has yet to arrive, I'll post the result for future reference.
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I finally received the Modified Kit for my KZ400, but it comes with a CDI for the Yamaha XS650/Triumph/BSA twins.

I have found that the power curve of my KZ is not the same as the Yam650, so I thought maybe the electronic spark advance would not be optimal. But from what I see the curve of the Triumph and the BSA is not the same either, and they share CDI.

Boyer Bransden's answer is that "it will work reasonably well in the KZ". My conclusion is that maybe the power curve is not that important when programming the CDI, but I don't know if I'm right.

Maybe someone can provide some more information.

Soon I will install it on the bike and I will comment on the results.
The power curve is very important. There are kits for your bike that will do the job, and were meant for your bike. This site has tons of info on your bike : kz400.com

The Boyer Brandsen kit in the link below is specific to your bike, I think that's the best route to go. You run out of much options for older Japanese motorcycles.:

That was the kit I wanted. Unfortunately it is not valid for twins (only four)
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The Boyer Bransden Kit87 fits the KZ400 "J" (a very rare four cylinder version), and for the KZ650 and KZ1000 I think.

But I still don't understand why other kits fits bikes with different power curves, like the Box00010 (Triumph/BSA/Yamaha XS650 twins)

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I don't either. A 440 Kawasaki version of your bike wouldn't work? :)
It would probably do. But KZ400 parts are 40 years old, hard to get.

At the moment I have the Box00010 (Yam650/Tri/BSA twins) which I have to try at least. As soon as I'm finish another bike I'll get on it and tell you about.

Thanks mate.
Link to points conversion for your bike, (should work, your bike is listed): 1974-1978 KZ400 D ELECTRONIC IGNITION POINTS PLATE ADVANCER TYTRONIC | eBay
Here's a CDI listed for your bike: OEM Kawasaki KZ400 400 CDI Ignition Igniter | eBay

It seems that this would work, you would have to look up the schematics to see how you would wire it. :)
In the first case it is a transistorized ignition that only replaces points and condenser (it does not have CDI functions). I used one for a while, it worked fine but doesn't add much (maybe better spark, better starting and better idling). If anyone wants it, I still have it available.

In the second, that's a voltage regulator. Some time ago I replaced it with an electronic one, much more effective.
With the points the bike doesn't go smooth, especially at low RPM, and I think the mechanical ignition advance doesn't offer the performance of a CDI.

When you have an old engine with limited power, you want it to run as well as possible within its possibilities hehe
The CD400F is a very cool bike, too bad there is no Yoshima kit for me haha

I understand what you are saying about the points and I think you are right, although I still think that they are not as precise as an electronic breaker, and that the mechanical advance does not offer the benefits of a CDI. But maybe this doesn't make as big a difference as I thought.
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How did you adjust the CDI from the Suzuki 1150 to work on the GS750ES?

I always lubed the cam, but thought the fit might not be quite exact. I have ordered a strobe lamp to make sure of the adjustment and correct operation of the advance.

You're slowly convincing me that points are almost as effective as CDI, so your effort isn't being wasted ;-)
I can't find the power curve of the Yam650, but...

-Yamaha XS650: Max Power: 53hp @ 7200rpm. Max Torque: 54Nm @ 6800rpm
-Kawasaki KZ400: Max Power: 36hp @ 8500rpm. Max Torque: 32.3Nm @ 7500rpm

Do you think that the Boyer Bransden CDI (that I have) designed for the Yam650 could be adapted to the KZ400 by advancing the ignition timing a little?

It is not because I have insisted on mounting it whatever happens, it is an attempt to adapt it because otherwise I will have to sell it.
Today I have done tests with the strobe lamp and I have seen that it has a fixed idle advance, and then at 3000rpm it advances a few degrees and from here it stays fixed at the following useful rpm's (which go up to more than 8000).

That makes me think that even a CDI for Yamaha XS650 (which does not match in terms of power curve) may perform better than the centrifugal advance that remains fixed from 3000rpm.

What do you think about this?
I finally returned it. I am now waiting for a specific kit from 7thgeardesigns (7th Gear Designs - Ignition Kits). Although it is expensive, it looks very good. The points/mechanical advance system seems too imprecise to me and I don't mind investing in upgrades for a bike I'm going to spend a lot of time with.

I'll post the results, in case anyone might be interested.
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