Combat performance issue - RITA

To be honest it sounds like your Commando is down on torque. Sometimes a lack of stomp can't easily be detected in the lower gears. Perhaps you need to look elsewhere for answers?
I've never heard of a RITA with different advance curves. When I bought mine they came with a set of instructions to cover all Lucas 6CA equipped twins.

SR

NickZ said:

38* at 6,500 rpm is close to what I am seeing, but I don't follow how the pick-up can change the advance curve, other than to move the point at which it starts advancing forward or back.

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That is flat out wrong. I have had two on two different Commandos and mine never behaved like that. Something is wrong with your RITA. Put the new board in and see how it goes.

gortnipper said:

That is flat out wrong. I have had two on two different Commandos and mine never behaved like that. Something is wrong with your RITA. Put the new board in and see how it goes.

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Good info. That is what I was thinking my next step would be.

NickZ said:

Good info. That is what I was thinking my next step would be.

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Do you mean the one from "Rex's speedshop" if so let us know how it goes,I'd been considering one myself

NickZ said:

Thanks David. I actually bought one of those a while back to have as a spare.
Have you strobed the timing of your RITA on the Norton? If so, does yours act like it is supposed to, meaning advance tops out near 28 deg at high rpms?

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Yes I set my RITA to 28 degrees at 4000 rpm using a Penske strobe gun.
Honestly I have not pushed the engine to 100mph. It does strongly accelerate to 90. Compared to the problem I first posted in 2015 I’m satisfied.

baz said:

Do you mean the one from "Rex's speedshop" if so let us know how it goes,I'd been considering one myself

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Yes, that's the one. I hope to get to that next week and will report back.

Nick,

Of all the electronic ignitions I’ve tried the RITA is the best with regard to pre ignition on my combat. I believe Dave’s charts show it being the closest advance curve to the original auto advance unit. TriSpark has very good performance, but I ride sometimes in the high Sierra with no cell coverage. I don’t trust the TriSpark not to fail….experience.

My Rita went on in '82 and problem free.

Had two boyers on my MK3, both black boxes went bad in a short amount of time ( wasted money). Put a pazon on it and have never had a bit of trouble and that has been years ago. My advice, put a Pazon on it and go riding!!!!

hershey said:

Had two boyers on my MK3, both black boxes went bad in a short amount of time ( wasted money). Put a pazon on it and have never had a bit of trouble and that has been years ago. My advice, put a Pazon on it and go riding!!!!

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750 combat engines are a different animal particularly since the fuel they were intended to use is no longer available at the pump.

ILLF8ED said:

750 combat engines are a different animal particularly since the fuel they were intended to use is no longer available at the pump.

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Right. My preference is to get the RITA sorted out. As mentioned, I have the new circuit board, but I also have a spare pick-up unit and reluctor so I should be able to isolate the fault.
I should also note that for most of the miles I put on this bike it was running Sunoco Optima 95 octane fuel:

NickZ said:

Right. My preference is to get the RITA sorted out. As mentioned, I have the new circuit board, but I also have a spare pick-up unit and reluctor so I should be able to isolate the fault.
I should also note that for most of the miles I put on this bike it was running Sunoco Optima 95 octane fuel:
View attachment 101027

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I just use the highest rated fuel at the pump. The local Shell dealer had 110 octane leaded hand cranked out of a 50 gallon drum, but it only lasts one tankful then 100 miles out I still have to refuel from a pump.

RITA seems to have the best advance curve for the combat spec engines.

Have you looked at the mufflers? My my old 750 was struggling to increse RPM in top gear. I noticed that the pattern pea-shooters I had were pretty restrictive so I punched a big hole in the baffle. Problem solved.

Big_Jim59 said:

Have you looked at the mufflers? My my old 750 was struggling to increse RPM in top gear. I noticed that the pattern pea-shooters I had were pretty restrictive so I punched a big hole in the baffle. Problem solved.

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Mine are the original glass pac type and the glass is pretty much blown out….a bit too loud.

tri-man said:

To be honest it sounds like your Commando is down on torque. Sometimes a lack of stomp can't easily be detected in the lower gears. Perhaps you need to look elsewhere for answers?
I've never heard of a RITA with different advance curves. When I bought mine they came with a set of instructions to cover all Lucas 6CA equipped twins.

SR

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The Rita on my Hemmings Norvil rep, 850 & 4S is marked" 4s advance curve"

Anxious to hear more on the new Rita board being mentioned here.

For advance curves, why does it seem like folks prefer the mechanical AA vs EI curves? I'd think an EI could be made to better match what the ideal curve would be.

850cmndo said:

Anxious to hear more on the new Rita board being mentioned here.

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Go here, however most electronic ignition systems will not have any problem on an 850 engine.

For those who expressed interest in Rex's "RITA Revival" repair, I will try to document the process of replacing the circuit board here.
First, disassembly:



Existing unit in place.


Existing unit removed from bike.


View of other side.


Backplate removed. Four 5.5mm screws, gasket and RTV like sealing material.


Detach old circuit board. Six 5.5mm screws. There is still a wire from the circuit board soldered to a component that is anchored in the case. I'm guessing this is a zener diode for voltage regulation, and requires heat sinking of the case. I unsoldered that wire from the component terminal, but did not attempt to remove the component.


The new stuff. Rex's kit consists of a circuit board with lots of wire coming from it (color coded same as original board), a bag of replacement male & female crimp on terminals, terminal insulators and screws with washers, and a length of black insulating tubing (don't know if it is heat shrink).

It is interesting that although the components were facing down on the original board, it appears that they will be facing up for the replacement board.

I hope to get to the re-assembly this weekend and will have more to post then.

Continuing the process, I have encountered 3 challenges that make this upgrade not as easy as it could be.

The first 2 are issues because Rex's kit did not include a plastic connector terminal housing or rubber wire interface seal, both of which are integral to the wires soldered to the old circuit board, and will have to be safely removed in order to be re-used.
Removing the old male terminals from the housing was easy after I made an extractor out of a spare female terminal.


My plan for the wire seal (shown in the photo above where the wires reach the circuit board) is to unsolder the wires that attach to the board, remove the crimped on shrouds that terminate them and pull the wires thru the rubber seal. Hopefully it won't be too difficult to feed the new wires back thru the seal.

The 3rd challenge is how to eliminate the interference that will exist between the new circuit board and the terminal of the component that is mounted in the housing. The old board has a hole in it for the terminal and this hole allows the terminal to protrude above the circuit board without interference. The new board has no such hole and none can be drilled there without breaking printed circuit connections. My current idea for a solution to this is to remove the component from the housing by machining off the 2 rivets that attach the component's mount to the housing. Will have to make sure these holes remain sealed.

This one is only a challenge because one of my objectives is to be able to revert to an old style circuit board in the future, if desirable for some reason. Otherwise, I would just cut the terminal off.

If anyone has any ideas for more clever ways to deal with these issues, please let me know.