Best electronic ignition 750 Combat

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@MexicoMike no difference at all in timing for standard vs combat.
In terms of setup and maintenance, the factory manual calls out the difference in valve clearances only.
Same with the factory issued service notes.

Bear in mind some electronic ignition vendors call out a 31 degree advance instead of 28 degrees.
This is a generalisation and of course won’t cover every bike in every state of tune.

A good practice is to dial in advance until it kicks back, then back it off toward the original 28 degrees until it behaves.
However, for units like the Tri-Spark with it’s idle stabilisation and advance curve that’s been optimised for starting, it can make it difficult to tweak - which is why they prescribe strobing it at 3,500rpm


The Pazon instructions ask for strobing at 4,000rpm
The Boyer wants you to strobe at 5,000rpm
The RITA looks for 28 degrees at between 6,000 and 6,500rpm
All these differences show that each vendor is making changes all the way up through the rev band.
And to compound it, the digital systems will further tweak this curve on-the-fly based on what’s happening at the camshaft.
 
It’s my hypothesis that +/- 2/3 degrees doesn’t actually make a blind bit of difference in these old lumps.

And that (within reason) the earlier they advance, the better.

It would be a good feature, to aid set up and carb tuning etc, if the idle stabilisation function was able to be switched off IMHO.
 
A good friend of mine has been using an old Boyer MKIII on his combat for 20 years without any issues.
 
My hypothesis is based on my play time on the dyno, with careful measuring of the timing, and careful measuring of adjustments, and careful monitoring of the effect... of which there was practically none within +/- 2/3 degrees of ‘correct’ !

Also, the advance curves of the different EI types are so wildly different (as you have demonstrated), and some of them only reach full advance at revs seldom seen by some riders. So, however precisely the timing is ‘set’, the actual timing that the bike has at any given revs below full advance can vary tremendously from ign to ign.
 
Fast Eddie said:
the actual timing that the bike has at any given revs below full advance can vary tremendously from ign to ign
Click to expand...

First glimmer of ignition understanding I may have ever noticed on the forum
I picked up about 2 hp at the upper end by tweeking my combat/ RITA for final of 47 RWHP.
Still no wins at new england dragway as I had 21t sprocket and 190lb pilot. Finished the 1/4 in 3rd gear
I would LOVE to get a trispark Tuneable system for tuning especially for the drouin/920 going into the slimline.
Too much money...
 
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Any opinions on the Boyer Mk IV? I fitted one earlier this year, along with an Alton electric start to my '72 Combat. Pickup plate dates to the 70's - likely a Mk 1a version (has a screw terminal block for wire connections)

Seems to work very well. The performance at idle is outstanding and fires right up with the Alton or when kicked (always was a one kick bike). I am running Amal 932's with brass sleeved slides.

I really do not see any advantage to using anything else personally. Is there something I am missing out on?
 
Please do not accuse me of having any understanding of ignition... :oops:

Ref the tuneable system, I put an earlier version on a very highly tuned 988cc BSA/Triumph triple some time ago. I went forwards and backwards with the curve like a mad thing, in search of ‘secret’ potential. It made very little noticeable difference, basically not possible plot within the normal variance seen between runs. Perhaps a better dyno and / or dyno operator may have found something, but I believe it would have been small.

What I did learn was that a big, fat, powerful spark does yield big dividends. I replaced an aged Boyer and 4v coils with a tuneable Tri Spark, with a dedicated spark, and 3 very high output 12v Dyna coils. That change yielded almost a 5bhp increase.
 
“First glimmer of ignition understanding I may have ever noticed on the forum”

@dynodave we tolerate your rudeness and abruptness because you are a clever guy and you know what you’re talking about.

But how about you make an effort to be a little more polite - it would make this place a much nicer place to be for the rest of us.
 
gtiller said:
it shows they understand the market they are in, and listen to feedback from their customers.
...
I plan to try the new Fire Box Pro which has the separate ‘brain box’
Click to expand...

I am a fan of tuning capability and generally agree with your 'keep away from the heat' strategy. However modern electronics are much less prone to heat and vibration as they were even 20 years ago. But yes if I had my druthers, I'd have the trigger-device and brain box separated. However try-spark lost me on their marketing/sales strategy (I removed a senseless rant here, as its just my opinion).
 
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So the problem is ignition - losing spark intermittently to the left cylinder after temperature rises . Time to put it on the lift , remove the tank and go through everything. This is fun , right ?
 
I use the old type Boyer with a double-ended Honda coil. It has been reliable, but I know a guy with a Triumph who had reliability problems with the same type Boyer. If I was looking for more go, I would play with a programmable EI. But because I use methanol fuel, there is much more margin for tuning errors. So I don't bother. For a road bike, all you probably need, (even with petrol ) - is fixed advance timing EI is better than points.
 
If you use petrol as fuel, have a programmable EI and tune your carburation and advance curve to the optimum settings for power, your tuning would probably become much more weather-dependent.
 
I vote Tri-Spark for its easy starting and idle stabilization.
~998cc
 
gtiller said:
@Richard Tool before you start digging too deep, try swapping your coils and plug leads from left to right, and see if the problem stays on the same cylinder.

It’s not unusual for a coil to start breaking down.
Click to expand...

+1. Coil breaking down is def suspect #1 for heat related spark woes...

So the coil swap over should be your next test AFTER NEW SPARK PLUGS...

Seriously... we’re 3 pages and nearly 60 posts into this thing... and we’re talking about new ign systems and coils... and you ain’t told us whether or not you’ve tried new plugs yet...!
 
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I bought a RITA twice, one for my mk3 in the mid 80s and another when i got my mk2 in 89.

At that time Boyer had a bad rap for failing.

The RITA never failed me, but could be a bastard for kick back on a start. I most often timed it by ear/feel and it ran great.

I replaced it with a TriSpark and new TS coils about four years ago, and it has been great. Nary a kick back and great perf all the way up and down.

I think the lions share of the failures, at least the ones i have seen about, were on the earlier production versions and this has been sorted now.

My RITA is in the spares bin, happily, waiting for any unfortunate future incident.
 
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