Hi I'm Tim and I got into ebikes as I have a knee problem and need to keep fit, I found info on this site on line and thought it might help with problems that I might have. I have two ebikes a kalkhoff 350 watt impulse and a 250 watt active line Bosch. I'm looking to change the motor on the Kalkhoff from a 350 watt to a 250 watt, the bike was a gift from a friend but I don't fancy affecting my car licence by riding this bike on the road and 15 mph is fine for me it's the range I like. So my point is if I buy a 250 watt engine will the rest of the electronics work on it. I'm fairly new to ebikes and have converted a normal bike with a hub motor but found it didn't match my needs. Thanks for any help that I might receive as I've found reading other people's problems and answers very enlightening.
Impulse engine exchange
- Thread starter Tim Davies
- Start date
AFAIK these motors are manufacturer replace only. The 350W rating is only the continuous rating of the motor and nothing to do with the actual power consumed. The cut of speed should be 15.5mph (or thereabouts) anyway. The only issue you have as regards legality is the 350w label. Others will know more precisely (Flecc) but I believe it needs to have power (250w), and manufacturers name. It is possible to get one made and stuck onto your existing motor.
What continuous rating means is that the motor can run for 1 hour, at the rating stated, without overheating. As far as I can see the only test for this would be to run the motor and see that it doesn't overheat. Proving only that the motor doesn't overheat. All pedelecs conume way more wattage than 250 on higher settings, the law has nothing to say on this, only that the rating is 250w. This has the effect of limiting the time that higher power can be drawn.
The power rating limit, as stated, is a nonsense and meaningless in practice.
What continuous rating means is that the motor can run for 1 hour, at the rating stated, without overheating. As far as I can see the only test for this would be to run the motor and see that it doesn't overheat. Proving only that the motor doesn't overheat. All pedelecs conume way more wattage than 250 on higher settings, the law has nothing to say on this, only that the rating is 250w. This has the effect of limiting the time that higher power can be drawn.
The power rating limit, as stated, is a nonsense and meaningless in practice.
id sell it asap if i was you 
http://www.pedelecs.co.uk/forum/threads/ongoing-reliability-of-kalkhoff-focus-impulse-2-motors.24290/
http://www.pedelecs.co.uk/forum/threads/ongoing-reliability-of-kalkhoff-focus-impulse-2-motors.24290/
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Hi thanks for that so can I then place a label on motor and then change cut off speed in some way?
That could be an option but it's 4 years old and I've ridden it off road and given it some stick with no problems, it doesn't owe me anything and if it did go wrong I could break it as it has good cycle parts on it and I couldn't see it returning the value of the bits. I'm just feeling the lay of the land and have read all about problems related to impuIse motors. Thanks anywayid sell it asap if i was you
http://www.pedelecs.co.uk/forum/threads/ongoing-reliability-of-kalkhoff-focus-impulse-2-motors.24290/
Hi Tim. As the Kalkhoff is a 350 watt bike it's likely that it's an S class bike capable of assisting to 28 mph, way above the pedelec limit. That's definitely illegal unless registered and insured and used as an L1e-A moped.
I'm afraid I can't answer your question on the compatibility of the peripherals, or whether you can just buy a 250 watt unit, some makes will only exchange like for like.
Kalkhoff UK won't deal directly with retail customers, only through their dealers, but the "find a dealer" search page is on this link to ask your questions.
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Hi I already found a motor but wanted to confirm peripherals would work with new motor, it is an s class bike which is why I wanted to change. Thanks anyway
Thanks for the confirmation Tim. I can only suggest you ask one of their dealers to query this with them. I'm fairly sure that all the Impulse motor changes that have cropped up in here have been warranty like for like following failures.
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Hi flecc. Just to keep you informed I've purchased a 250 watt motor from Germany and got it quite cheap, also I've been in contact with someone who has reviewed Impulse motors stripped them and it seems a few cheap bearing changed now and again could be an answer. I'll keep you informed on how I get on as I intend to strip 350 watt motor to see how viable it is to change bearings, the motor I have dosen't owe me anything so if it doesn't work out then not much lost as I don't think I'd get much for it. Will keep you posted as and when I get around to doing anything about it. Thanks for your info by the way.
Hi flecc
Just to add to your info stash, I have received 250 watt motor and have fitted it and as far as I can tell all works well with the exception of the gear power shift switch ( no connection on replacement motor ) and the lights which were directly from motor, and no connection for those. The bike response is good and not much different to other motor and looses puff at 16.5 to 17 mph which runs with the guide lines that you posted in another tread and is a speed roughly where I like to ride. Gear change detection and lights things are not to much of a problem for me as I intend to have a play ie change wheels to 26 inch 6 or 7 speed deraileur which will be lighter might put drop bars fit saddle bag and loose racks lighter forks. Anyways thought you might be interested in the fact the peripherals seem to working ok. Cheers Tim
Thanks for the information Tim, added to files since it could well prove useful for someone else at a later date.
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