View Full Version : rev limits on EC25PS

profqwerty - n/a
18-Oct-07, 03:07 PM

Does anyone know what a good idle speed is on the EC25PS?

I can't find a manual anywhere (the one on ultralight news doesn't link to anything).

I have put my rotax tacho onto the engine's generator output. I'm assuming it works on the rate of pulsing of the gen, but does the ec25ps pulse at the same rate as the rotax (guessing one pulse/rotation?).

otherwise it would be giving me 2x / 0.5x the actual speed!



Pat Tobin - n/a
18-Oct-07, 03:31 PM

Can't help with the idle speed but the rotax tacho thats on my 503 is essentially a frequency meter. It measures the frequency of the generator/magneto. The number of pulses (sine wave output really) will depend on the number of magnets on the rotating part. I think its three on the 503 but not sure. that would mean three pulses per revolution.

If you can determine how many magnets then you will know how many pulses per rev.


Don83000 - n/a
19-Oct-07, 12:56 AM
A Rotax rev counter will read very wrong on a Fuji Robin as we found out and a ex hover racing guy thought he could alter it as from memory there are twice the amount of magnets in the Fuji MAG so he tried putting a 2-1 divider circuit in but it still read very wrong he then tried using his oscilloscope to check it but to no avail it seems to be more than the magnet count that is the problem in the end we got a digital rev counter that just has a wire wrapped around the plug lead and this worked well and we had our Fuji at 2200rpm on idle.

Try this site I just checked the link I have and it still works.


Hornet - n/a
19-Oct-07, 05:25 AM
Idle should be between 2000 to 2500 RPM. Max power is 18PS at 6500.

profqwerty - n/a
19-Oct-07, 09:54 AM

Thanks for the replies!

The digital rev counter looks like a good idea. I will get one and use that i think.

What I was really after is a graph of the EC25PS's rpm/ps output, as that would determine what ps is being used by the fan at it's maximum speed.



Jamie Lewendon - n/a
19-Oct-07, 10:40 PM
As Hornet said:

Idle at 2K.

Max power 18PS at 6.5K


profqwerty - n/a
23-Oct-07, 11:39 AM
sorry but this is rediculous. All the tachos seem to be optical and designed to work with 2,3,4 blades, or for use on multiple cylinders (and therefore +).

Can anyone suggest any cheap and simple rev counter makes/models please? skydrive, km, various aviation people, don't seem to have a suitable one.

Maplin's was doing a kit that looked ideal, is now not available http://hovercraft.org.uk/images/icons/smiley_icons/icon_rolleyes.gif



nickyd - n/a
23-Oct-07, 01:51 PM

I've just bought a PET 2000DX tacho. Kartingdirect.co.uk do them but I got mine slightly cheaper from a Mini Moto supplier, but I can't remember who.

I'm pretty sure that is a fairly cheap one. But it is a lot lot cheaper than an engine re-build, trust me.......

I used to use a cheaper flappy wire one and that said our engine was doing 6800 when it was actually doing 7700!


Don83000 - n/a
23-Oct-07, 02:33 PM
http://cgi.ebay.co.uk/KART-2-STROKE-4-STROKE-REV-COUNTER-WIT (cgi.ebay.co.uk/KART-2-STROKE-4-STROKE-REV-COUNTER-WITH-FREE-HOLDER_W0QQitemZ280138818859QQihZ018QQcategoryZ122 308QQrdZ1QQssPageNameZWD1VQQcmdZViewItem) H-FREE-HOLDER_W0QQitemZ280138818859QQihZ018QQcategoryZ122 308 QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

http://www.psukracing.com/product_reviews_info.php?products_ (http://www.psukracing.com/product_reviews_info.php?products_id=964&reviews_id=4) id=964&reviews_id=4

Paul - n/a
23-Oct-07, 03:55 PM
or try this http://www.ready2race.co.uk/shop/shop.php?action=full&id (http://www.ready2race.co.uk/shop/shop.php?action=full&id=1910&PHPSESSID=94e87b2f8194abfbbb3e2947514bd72f) =1910&PHPSESSID=94e87b2f8194abfbbb3e2947514bd72f

hovmart - n/a
23-Oct-07, 04:01 PM
or this http://www.tinytach.com/tinytach/index.php

hovmart - n/a
23-Oct-07, 04:04 PM
english agent :- England

PH: 0044) 7860 323255 Message: 1 342 305114

Contact: Richard Dunn

Email: itco@btopenworld.com

Website: Tinytach UK

profqwerty - n/a
23-Oct-07, 06:38 PM
Right I have ordered the PS UK one. Not the cheapest, but as you said it'll save money in rebuilds later!

Should hopefully have that going at some point this week.