Update: Remote GPS receiver and DR650 carburettors.

Regular readers of this blog will recall that I have written about a number of experimental developments I have tried with my DR650’s, yes I have two now…

Carburetors first, last autumn I purchased a cheap-ish Chinese slide-accelerator pump copy of a Keihin FCR 39 for my 2020 grey DR. It wasn’t that I was unhappy with the performance of the factory Mikuni BST40. I had made a number of alterations and modifications in the usual manner and with a combination of jets and needles from at least two jet kits I had got the constant vacuum carburettor running well. I was curious though about how much better a “pumper” slide carb could be.

As it turned out, once all the necessary non-Chinese parts had been bought and the bare carb had been refinished for use the purchase price had effectively doubled. I needed to replace the accelerator pump diaphragm and spring, purchase a cnc machined airbox adaptor, finish-machine the inlet stub on a lathe and make external plumbing fittings to close off passageways that would have been otherwise used to join two or more of these carbs together for multi cylinder engines.

The end result has been a very useable carburettor with the expected trade off with increased fuel consumption.

Now you might also be aware that I have bought a second, new DR… the white one.

Two much of a good thing?

This new DR cam from the dealership having had a “jet kit” fitted by the dealers. Even after having had “uprated parts” fitted, the carburation was horrible! In the apparently usual Suzuki DR way.

Breathless in the midrange and most worrying/annoying/dangerous, when warm and from idle, for example at traffic lights or a Stop line, go to open the throttle (just a little or a big handful -it made no difference) the engine would stall and stop. The only way to avoid this was to raise the idle speed to something that could be described as a “fast idle”. Only then there was no engine braking.

I had carefully stored and kept the BST40 from the grey bike and in an afternoon I retrofitted the older carb onto the new bike. With the exception of a emissions capture pipe that I blanked off with a bolt, the old carb was a direct fit and needed no adjustment to get the engine running correctly.

The “old” BST worked as well on the new bike as it did on the older bike - and a heck of a lot better than the new BST. I haven’t checked what the jets in the poorly-performing new carb are but I guess they are leaner than those in the old carb. Gone is the off-idle stall, lots of low to midrange “go”, slow idle for backcountry engine braking.

So then I had an idea to do a back to back comparison between the pumper-slide carb on the grey bike (39mm) and the jetted and needled CV carb on the white bike (40mm).

Seat of the pants, purely subjective, no scientifically measurable data.

I am not so sure there is any discernible difference between a well-sorted BST40 cv carb and a FCR39 (copy). Granted it was easier to get the FCR performing satisfactorily, probably by dint of the extra petrol squirted by the a-pump, but the amount of work I needed to put into the FCR to get it to fit was probably greater than fiddling around with jets and needles.

The take-home message though is the factory settings on the factory carb are horrible! If you do not have to pass a technical inspection every year that involves emission testing, fix your carburettor!!

Which brings me on to the remote GPS receiver thing…

Dual SkyPro XGPS160 GPS Receiver, to give it it’s proper name…

I have previously written at length about the trials and tribulations of using non-surveying instrumentation in a rallyraid-type setting. In a nutshell, it’s not always as good as you hope it to be for a number of unavoidable reasons.

Enter the remote GPS antenna-receiver. While not up to centimetre precision, the performance of the 160 is an order of magnitude better than the GPS chip in your smartphone.

As you can see from the photo above, I was able to make a miniature dashboard that mounted to the handlebar clamps and provided a horizontal surface on which the device could be placed such that it points straight up.

I gave it a little go.

It easily pairs by Bluetooth, I hooked it up to three iPhones.

It works while being charged.

The iPhone I use to display the pdf roadbook took Bluetooth input from both the 160 and the remote scroller-controller, also while being charged.

The phones running Gaia and Richta also took the GPS data from the 160 at the same time.

To keep the rain out, the 160 can be wrapped in a plastic sandwich bag and have the charging lead fed through a small hole in the bag.

I can only assume that the GPS detection performance will be better than with the smartphone antenna alone - I have no easy way to test this

But

This is the technology many other people in “our line of work” use to boost the GPS performance of their smartphones when participating in amateur motorsports.

Such devices introduce a level of smartphone GPS performance without requiring the event to adopt a more complex methodology.

Perhaps I will see a few more of these intriguing-looking devices sprouting on rally bikes next year…?

JDB