BMW k75 triple
russbost - 24/11/09 at 11:04 AM
Can anyone answer this Q?
Was taking an enquiry re Acewell instruments at the Exeter Show & the Q was:-
The BMW k75 3 cylinder engine fires all 3 plugs on each cylinder firing stroke - in other words 3 sparks per cycle, a bit like wasted spark & a
half! Will the Acewell handle this.
Now my Q is this, is what he's saying about the engine wasted spark thing correct? I've spoken to Acewell Uk who think it highly unlikely
can anyone confirm or deny that BMW use this system - it seems really strange as I would expect it to cause a partial burn on either the induction or
exhaust stroke of the 2 cyls not on their firing stroke. I can't answer his Q until I know if the info he's given is correct.
Any info re the engine welcome - I've googled it but can't find anything about this weird wasted spark system???
graememk - 24/11/09 at 12:20 PM
who cares get a k100 or a k1100, the k75 is underpowered, and very old.
MikeRJ - 24/11/09 at 01:41 PM
quote:
Originally posted by russbost
Can anyone answer this Q?
Was taking an enquiry re Acewell instruments at the Exeter Show & the Q was:-
The BMW k75 3 cylinder engine fires all 3 plugs on each cylinder firing stroke - in other words 3 sparks per cycle, a bit like wasted spark & a
half! Will the Acewell handle this.
The K75 does use a wasted spark system, but not in the way described above! The system uses three individual ignition coils, and they are all fired
separately. However, every cylinder gets a spark at the top of the compression stroke and also the top of the exhaust stroke, i.e. for each cylinder
the coils are fired on every engine revolution.
This is not a traditional "wasted spark" system where two plugs are fired simultaneously, but nonetheless one of the sparks is wasted .
I would expect the Acewell to handle this since the signature of a single coil output would be exactly the same as one coil of a four cylinder engine
with wasted spark, i.e. you would get one spark event per engine revolution.
quote:
Originally posted by graememk
who cares get a k100 or a k1100, the k75 is underpowered, and very old.
I would imagine Russ's (potential) customer cares.
[Edited on 24/11/09 by MikeRJ]
russbost - 24/11/09 at 09:52 PM
Excellent, thanks for that, I was sure what he was saying couldn't be right, but couldn't find the info to say so. & yes the Acewell
will handle that with no problem at all.
russbost - 24/11/09 at 09:52 PM
Excellent, thanks for that, I was sure what he was saying couldn't be right, but couldn't find the info to say so. & yes the Acewell
will handle that with no problem at all.