By RoSy
If any one has fitted a Booster Plug as suppled by Hs to a Euro 4 C5, how did/do you find it? I fitted one to a Versys 650 I had and it made a whole lot of difference for the good, but the Versys is a completely different bike so I wonder if its worth the money spent on a C5.
By Squadron
Yes I did fit one to my 2019 Euro IV C5. Did it make a difference? I’m saying yes but only because I hate to feel ripped off. Honestly I don’t think it did make any difference at all but that’s is just my experience. Others might have a more positive take on this.
By RoSy
Thanks for the reply, I think for what it cost and the low out put of the engine it is not going to make a lot of difference, unlike a more powerful machine, and going by what you have said it sort of confirms my suspicion that its probably 125quid not very well spent.
By Rattlebattle
Whilst I’ve no experience of Booster Plug on a Euro IV bike I have tried two on other (Euro III) bikes. In my experience all they seem to do is richen the mixture throughout the range. In doing this the flat spot off idle (ie where the ECU transitions from open loop to closed loop, the usual reason for trying one) is improved but overall in my view it’s not a proper resolution of the issue. All it really seems to do is to replace the input from the temperature sensor with its own input value, which is affected by where you place the supplied sensor - it should be in the airstream.
It seems to me to be a very expensive way of achieving what can be done just as well by disconnecting the O2 sensor and plugging a cheap resistor into the socket. I don’t know about Euro IV ECUs but it works ok on my Euro III C5, fooling the ECU into accepting that there is a live input from the O2 sensor and hence not showing a MIL light. (It wouldn’t anyway on my C5 now because I put a carb on it three years ago and disconnected the MIL light as it no longer serves any useful purpose ).
I do wonder whether in fact all Booster Plugs are the same anyway, apart from perhaps the value of a resistor. I doubt that they really are bike- specific to any other degree, but I could be wrong. I still have one kicking around from when I tried it on my Triumph Thruxton 865. It didn’t do much for that and certainly was nowhere near as beneficial as uploading the right map for the changes to inlet and exhaust I have made. Really a decent Euro IV ECU these days should fuel accurately and self-trim for such changes. Certainly my Honda does.
By Squadron
Unfortunately the O2 sensor can’t be disconnected or jumped out with a resistor on the EuroIV. The ECU is virtually tamper proof. I might try a different place for the Booster Plug sensor. Currently it at the rear of the bike just behind the rear shock top mount - don’t know if the airstream is the best there?
By RoSy
Is it long enough to take it through to the front by the headstock? anywhere behind the engine is going to be warmer than infront.
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By trophyvase
Why would it need to be put anywhere else than where the instructions suggest - under the seat. I'd guess it needs to be out of an air flow that is potentially too warm (behind the engine) or too cool (in front of the engine).

Or am I missing something very obvious? :?
By RoSy
When I fitted one to my 650 Versy it said to fit at the front in constant air flow by the headstock. Thats all I know, I assume because its cooler air.
By Squadron
It isn’t long enough to go directly to the headstock. However, on their website the manufacturer states it’s OK to cut the lead to the sensor and solder extra length in. They also nominate the headstock as the best place to put it in the general instructions.
By PeteF
Having run a Euro 4 for a couple of thousand miles now I suspect the way to free up the power is a less restrictive exhaust system. Anyone done this and with what result?
A suspect this booster plug is a crude method of just bunging more fuel into the engine by fooling the ecu about ambient air temperature. It can't be subtle enough to do a decent job. A proper remap might do it but even then I suspect the restrictive exhaust would be the bottleneck.

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