Modern Vespa

I've purposely kept the title vague, as in not mentioned a model, as I'm struggling to get any info at all on pretty much anything Piaggio//Vespa, so even if I can get the answer to my question for a Vespa, it'll perhaps bring me closer to a result.

I am trying to find out the distance the ASR sensor should be from the wheel plate on a BV350. I've searched the internet and found nothing, and I don't have a manual.

I have found a post on the X10 forum saying 1-1.85mm, that's all.

The back story here is I have a fault on my BV350; the ASR and ABS lights are on and it won't recalibrate. Now I suspect the distance is fine, but I want to rule everything out before I buy replacement(s) sensors.

Both the front and rear sensors are both about .75mm from the plate. Which you'd think are too close, but it all worked fine, until it didn't.

Between it working and it not working neither wheels were removed. Although I did hit a particularly nasty speed bump, which I was thinking might have cause a wheel to shift on it's bearings. But, they are both the same (.75mm) and it's pretty much impossible that they both shifted. So, I suspect the distance isn't an issue at all. However, I'd still like to know the distance it should be, so I can rule it out.

Anyone know?

Does the workshop manual not give the spec. ? https://manuals.wotmeworry.org.uk/Beverley/BV350/

I've never found that link before. Thanks.

I'll get AI to check for me in the morning.

I've worked out in the manuals it's called the speed sensor. Not to be confused with engine speed sensor. But there is no mention at all of distance from the wheel plate.

I have found a general reference to Vespa and the speed sensor, and a statement saying that while there are no specific measurements published, anocdotal evidence says it needs to at at most 1mm from the plate, and not so close as to rub. This makes more sense to me than the 1-1.85mm comment I found on the X10 forum. I can't really see a sensor, which I'm assuming is little more than a magnet, having such precise requirements. The max 1.85mm bit could be correct, but I can't see why there would be a min distance specified, other than "not so close it rubs".

So, I'm going to put this one to bed and assume that the issue I'm facing isn't one of sensor distance. Afterall, both are at almost exactly.75mm. So the fact they are both the same says to be it's correct.

A mechanic is calling to the house to fix something else on monday, he's said he'll bring his OBD scanner and if he's got the right connector, he'll hook it up and see if there are any error codes.

Failing that, I'm just going to have to start replacing parts and hope. The first will be the sensors themselves.