Forum

[RayBeech]

Haha, Jefrs, all of what you just said is what made me dump the PCV and injection system and put a carb on, I have no idea what all that meant but fair play to you I have what I want out of the bike, I hope you get the electronics sorted so you are happy with your bike and can spread the info around to others who want to go that way.
As I said earlier, too old and not really interested in computer sh*t! just needed a ride when I didn't want to wear the Matchlesses out.

[Tim NZ]

I have recently been advised that the carb kits (200118) have been further refined and spark correctly at all times, as such the original rotor etc no longer needs to be replaced. Hence the cheaper price.


The A/R is a simple linear action regulated by frequency and amplitude, much the same as any other basic EI unit functions

[RayBeech]

Thanks Tim, I ordered the kit and was surprised that it was a lot cheaper than the catalogue price, so I contacted Hitchcocks and they told me that they had refined it to require non of the extra ignition bits. I think the lad realised he was talking to an electronics and computer duffer so he explained it quite simply, anyhow it runs a treat, hope your explaination helps Jefrs better than mine.

[jefrs]

Tim NZ - I am a little confused because the EFI has no rotor. It takes its basic timing off the "long" 5°BTDC pulse from the alternator. I have half an idea it also uses the other 23(?) alternator pulses fed to the ECU for timing as well as engine rev speed (it is able to spark before it gets to the long pulse). From what I have seen the A/R is controlled both by the engine speed and the throttle opening - we have different A/R at different stages of throttle opening for the same engine revs; it is non-linear.


The EI as described could only A/R by engine rpm i.e. the frequency (rpm) and amplitude (speed of passing the sensor, length of pulse) of the timing pulse, it can only be linear with rpm, no dynamic A/R. One big improvement on cars was using a vacuum on the distributor for dynamic A/R, which is why the ecu takes equivalent input from the TPS and/or APS sensors.


With ye olde points cam there are a couple of centripetal weights on springs doing the A/R which don't just regulate by rpm but also on acceleration and deceleration, non-linear and it works rather well.

[Thack]

jefrs: Why do you say that the sensor in the manifold is actually an APS, and not a MAP?



And what is the difference?

[jefrs]

Thack - no special reason other than the workshop manual gives it several names, usually "manifold pressure sensor (MAP)" but unlike the MAP on the car which measures air-flow (the "A" in MAP), I think this one measures pressure, like wot they say. As the book says under:- Function Of Components - Throttle Body Module, "The throttle body is a part of the air induction system. It controls the amount of air flowing into the engine, in response to throttle opening. Athrottle plate (butterfly calve is use for regulating the airflow) The throttle body also has a throttle position sensor (TPS), a manifold pressure sensor (MAP) and a manual Bi Starter." I've tried to keep the indlish grammar and tpyoes for amusement. Further, "The MAP provides instantaneous manifold pressure information to the ECU. This is necessary to calculate the air density and determine the engine's air mass flow rate, which in turn is used to calculate the approximate fuel flow to the engine through the injector." So it measures pressure and the ECU calculates air-flow, known volume 500cc every suck. I guess I dislike calling it a MAP 'cos it's not like one on a car which draw current (a heater) this one is passive, MPS or APS then; no biggie.

[Boxerman]

MAP stands for Manifold Absolute Pressure. Its a binary signal, either on or off. It does not measure air pressure or air flow.

Frank

[jefrs]

Thanks Boxerman, my old Benz had MAF and MAP sensors, it's easy to confuse them.

[jefrs]

.. in any casse losing the MAP is not the problem as a carb will take care of itself there, it's losing the TPS throttle position that will cripple the ECU electronic ignition. Perhaps the TPS could be connected to the throttle cable in some way, maybe twin cable?
Just playing devils avocado really?

[vill98]

If the carb conversion works why all the arguing shut up