Knock sensor anyone ?

[HWB]

Has anyone here added a knock sensor to their bike ?

Im thinking of a way to install one on my high comp build. Also wondering how it would cope with the rattling of the flatslides. 

Is this even possible to do ? Im not saying i wanr to relay it to the ignition or anything (tho that would be cool) just need it to tell me if knock is occuring.

Flatslides rattle is confusing me and i dont want to damage the newly built motor.

 

Cheers

[Gixer1460]

Knock sensors need to be secured to the block or head, solidly to get the hi frequency vibrations so I think the rubber inlets will isolate the carb rattles. Bike engines are pretty mechanically noisy so could give false signals?

[HWB]

Any idea where would be optimal to mount ? How is this done really

[clivegto]

As the man said block or head. Let us know how you get on. 

[TLRS]

Probably a lot to learn from where the manufacturers put them. Metal doesn't dampen noise much I think, so maybe it is not so location sensitive?

[Fazz711]

Somewhere very close to the combustion chamber I would have thought.

How are you going to calibrate it?

[Gixer1460]

15 hours ago, HWB said:

Any idea where would be optimal to mount ? How is this done really

OEM's spend loads of design hrs and £££ to get that right! A boss is usually cast in for the sensors. Bosch is a popular make and they use either M8 or M10 studs into a substantial bit of metal.

[colinworth79]

The vw car engine stuff I've worked on have 2 sensors one in the head and one mounted on the side of the block up near the head gasket area . This is on high comp turbo engine.  The idea is to retard the timing if low grade fuel is used or going to see high inlet temps ect .

[HWB]

I know how its mounted on engines that already come with a knock sensor. It obviously is mounted in its bung that came cast from the factory.

I was asking how can i fit it on an engine that did not come with one, was seeing if anyone did it before and so where did they mount it. 

I also said i dont want it to control timing as im not going to overcomplicate things and f*ck about just to make something cool. I only need it to indicate knock presence.

So if anyone has done this before and can share some wisdome!

 

Cheers 

[jonny1bump]

Never seen it done and if not trying to do anything clever are you gonna really see it when pushing it at speed and concentrating on next corner come up. If take it too pub fair enough you probably will see it.

[TLRS]

With a shift light sort of contraption it might be useful?

Just had a look on that popular video website and there's defo useful info out there.

[HWB]

TLRs name of the video ? Link maybe ?

Edited August 14, 2022 by HWB

[TLRS]

"knock sensor retrofit"

[imago]

20 hours ago, HWB said:

I know how its mounted on engines that already come with a knock sensor. It obviously is mounted in its bung that came cast from the factory.

I was asking how can i fit it on an engine that did not come with one, was seeing if anyone did it before and so where did they mount it. 

I also said i dont want it to control timing as im not going to overcomplicate things and f*ck about just to make something cool. I only need it to indicate knock presence.

So if anyone has done this before and can share some wisdome!

 

Cheers 

From what you're describing that you want from it, time on a rolling road would be cheaper, easier, quicker and provide far more useful info.

The main issue with using a knock sensor to tune the engine will be logging the data and filtering out all the other stuff which will provide a signal completely unrelated to ignition. 

[george 1100]

On 8/13/2022 at 11:44 PM, HWB said:

Has anyone here added a knock sensor to their bike ?

Im thinking of a way to install one on my high comp build. Also wondering how it would cope with the rattling of the flatslides. 

Is this even possible to do ? Im not saying i wanr to relay it to the ignition or anything (tho that would be cool) just need it to tell me if knock is occuring.

Flatslides rattle is confusing me and i dont want to damage the newly built motor.

 

Cheers

How much comp are we talking and type of fuel?

[HWB]

D.ot head ported and skimmed ever so slightly to remove scratches about 0.4mm on 1127, cometic mls gasket cams set at 105°\105°. Did not calculate compression ratio but cylinder compression test is as follows : 175psi 180 psi 180 psi 180 psi, i guess it has more to do with cam timing more than static compression.

Fuel is 95, adding 125 ml of Wynn's on a full tank.

Cant hear kock but it might be occuring at high rpm, also flatslides rattle is confusing me.

The thing is engine is heating up quite alot, and that right there is a telling sign if knock isnt happening now it will happen eventually. Trying to save the engine. Im tgrowing an afr from AEM on it and taking her out later this week, maybe if its a bit lean( which i doubt) i can make the engine cooler by adding fuel, will also put cooler spark plugs to reduce heat, im also installing a head cooler. All of this to reduce heat but i want to know if knock is occurring or not.

 

 

[Gixer1460]

Most of the time if you 'hear' knock, damage is already done! Is this the stuff you are dosing with - Wynns Lead Substitute, 250 ml ? If so, you are massively overdosing as 1ml doses 1 Litre of fuel ! And @ £10 a bottle it'd be loads cheaper to fill up with ESSO Super which is ethanol free and 98 octane. BTW - lead isn't needed in any Jap bike since the 70's.

Is the DOT head on a Blandit or GSXR type bottom end as at a guess, you maybe over 12:1 CR without much overlap to mitigate it.

Heating up an engine can be caused by lots of things - CR is one, jetting is another, low cooling and ambient temps won't help nor will over advanced Ignition etc. Putting 'cool' plugs in won't help cool the engine - they run cooler themselves by dumping temp into the head, so they may reduce 'pinking' but will also foul easier as they can't burn off the contaminants as easily! 

You have all the ingredients to produce knock, so why not minimise those first as you'll likely have to address some if not all of them anyway? Usual tuning position is Start Safe then move towards limits - you sound like you may or may not be at the limits without knowing where safety actually is.

My approach may be cautious but it works and I've never needed / used a knock sensor yet. BTW, are you using electronic, mapped  fuelling / ignition control or Carbs and 2D Ignition?

[HWB]

Gsxr 1127 block, 748 d.ot head cams (same as 1100) 05 octane fuel. Wynns says 1 bottle treats 60 liters of fuel adds 2 octane points. Did the rule of 3, poured the result in the tank. (Full reservoire) stock ignition, carbs are 38 flatslides with velocity stacks (50mm) if cr is 12.1 it should not ping on 95 octane right ? Even less with octane booster 

Edited August 15, 2022 by HWB

[george 1100]

Tune it slightly fat, run a curved OEM cooler and head cooler and enjoy it. If it was knocking, you would've noticed. The sound is completely different to rattling flatslides. I had a cbr1000 with and open pipe and sometimes it would knock when I would labour the motor. Could hear it very clearly

Edited August 16, 2022 by george 1100

[dupersunc]

Would a 2t detonation counter do the job?

https://www.Eblag.co.uk/itm/192438540664