TheHaflinger.com

Replacement of the mechanical governor with an electronic rev limiter has been discussed in various threads a few times.

AccuSpark have just got a new batch in and are on sale through ebay at the moment for £33.95.

http://www.ebay.co.uk/itm/AccuSpark-Rev ... 2a4f1e8561

My understanding that it works fine on a 2 cylinder engine as you just rev the engine to the required revs and set the rev limiter.

Hope this helps someone.

Garry

That seems a very "practical" way of doing things, but I can see it being difficult to know what the correct revs are without some sort of RPM counter. If I didn't have the mechanical governor already, I would buy one of these things.

The Strobe light unit I have has a REV COUNTER setting and seems to be accurate even on a two cylinder engine as I have compared it with the rev counter on my Smart (3 cylinder), Ford Focus (4 cylinder), Simitar (6 cylinder) and MGB V8.

You can buy rev counters that use a HALL effect sensor and a magnet. You glue the tiny magnet to the Crank pulley and then position the sensor to pick up when it goes by.

Do you know if it is a "soft" limiter in that it brings in a random misfire or does it have a set pattern to the missfire? The mechanical governor just strangle the air/fuel intake so you lose power.

Hope the Hafi's exhaust system does not get hot enough to start lighting the un-burnt mixture that results from the missfire in the cylinders! Could make for some nice sterotype noises from an "old" machine!

John

Yes most timing lights and twell meters have a tach function. Yes it is a soft cutout so no huge backfire when the ignition cuts back in - there are various Youtube vids on this.

I have not used one and was taking a recommendation made on the forum some time back that these worked. Unfortunately I have not been able to find that recommendation.

I have ordered one and will see how it goes - the issue is what revs to set it at. 4500rpm, 4800rpm or even 5000rpm.

Older engines have a redline of 4500rpm but in later engines the mechanical governor starts to cut in at 4800rpm and has completely cut out at 5200rpm. So I am tempted to go for 4800rpm but am not sure. The issue I have is that my engine is a later engine but it has a No 2 camshaft from an early engine - as I understand things, it is the camshaft that determines the redline but I do not know if it has been reprofiled or not.

For me the main chance of overrevving is in 4th gear when I change down from 5th gear as there is a huge gap between the two gears so when going up long hills that 5th will not pull there is always the chance of overrevving in 4th when only doing 43kph.

Garry

Hi Garry - I have one fitted (and made the original recommendation) - as I recall, because it's only twin cylinder you have to adjust the screw to the limit of it's setting to (softly) cause cut-out while approaching max-speed in 5th (about 48mph).

I have been aware of it working when trialling off-road, powering up steep hills in a low gear.

I've been very happy with mine - though I can't say I've noticed the extra horses liberated by removing the mechanical governor.

Thanks for the original advice.

jhon wrote:Hi Garry - I have one fitted (and made the original recommendation) - as I recall, because it's only twin cylinder you have to adjust the screw to the limit of it's setting to (softly) cause cut-out while approaching max-speed in 5th (about 48mph).

My Haf has a placarded max speed of 36 mph (4 speed) - would I be able to adjust the screw sufficiently to limit the engine to 4,500?

Julian B wrote:

jhon wrote:Hi Garry - I have one fitted (and made the original recommendation) - as I recall, because it's only twin cylinder you have to adjust the screw to the limit of it's setting to (softly) cause cut-out while approaching max-speed in 5th (about 48mph).

My Haf has a placarded max speed of 36 mph (4 speed) - would I be able to adjust the screw sufficiently to limit the engine to 4,500?

Hi Julian - sorry, I can't say for sure; I remember contacting the manufacturer and asking if it would work for a twin cylinder engine. As I recall, they said that it would but that the operational rev range would be different (higher) - i.e. you couldn't set it as low as 2000rpm per 4 cylinder; unfortunately I can't remember what the minimum was for the twin, but 4000rpm comes to mind.

I do know that setting the adjustment screw all the way back resulted in it cutting-in at max speed in 5th, which if I recall from the manual is about 4800rpm (ish). (I don't have access to an electronic rev-counter to confirm). I was happy to leave it at that.

(note - I do have larger diameter 13'' wheels which would raise the gearing - so maybe the revs are actually less than 4800rpm)

Sorry I can't be more specific, or definitive. It might be worth contacting the manufacturer and asking them. (you can do that through the ebay link)

Standard settings are:

2000-12000 Revs 4 cyl engines
3000 - 8000 Revs 6 cyl engines
4000 - 6000 Revs 8 cyl engines

so ergo - 1000 -16000rpm for 2 cylinder engines

garrycol wrote:

so ergo - 1000 -16000rpm for 2 cylinder engines

So you would think.

I'm pretty sure that's not the reality though; at least it wasn't in the one I received.

I just ordered one. Thanks for the tip.

G,,day .
i am curious .
i have set up a number of the original governers .
and have not had a problem .

please explain the need to fix a problem that i thought did not exist .

or am i just old fashioned and like mechanical things that work . and can be fixed .


kerry

In my case I do not have the "Heath Robinson" mechanical governor on my engine so the electronic version is a cheap easily fitted alternative.

Garry

In my case, my original Weber intake manifold was rotten. I found a replacement, but the hole for the governor butterfly had been sealed up. Easy solution: electronic cut off.

Have you ever had a vacuum leak through that shaft? It seems like a likely place for air to get in...

There is supposed to be an "o" ring seal on that shaft as it goes into the Carb mounting block. If the "O" ring is worn out, then you will get erratic idle and possible too lean a mixture at higher revs.

John

all very logical reasons

i cant recall any spindle leakage

kerry

Hi Kerry, the main reason I did it was to remove the drag on the engine from running the belt and the governor; it probably didn't free very much (and it wasn't noticeable), but hey, when you haven't got much HP to start with, every bit helps!
Also, I figured that removing the spindle and butterflys would smooth out the airflow.