Airbox crankcase vent – Mk2

Aprilia Caponord ETV1000 Rally-Raid engine crankcase vent pipe to airbox and throttle body

With the velocity stacks and snorkel measured up and squirreled away in CAD, it was time to rebuild the airbox …… except billy-butter-fingers here, went and knocked the airbox base off a chair onto the floor – not far – but enough for it to land awkward and break the spigot for the crankcase vent. Unfortunately the spare I’d made, I gave away to a friend last year! So there I am trying to remember where I’d bought the bits to make Aprilia Caponord ETV1000 Rally-Raid engine crankcase vent flow analysisanother one, when I had a “Stop the bus!” moment …… don’t waste time and fuel going into town, sit down, draw something in CAD and print that puppy! 😀 

Here’s the finished article …. it has a slightly larger inlet/outlet cross-section, although the previous one worked just fine and this time the fit for the grey pipe is better. internally there is a chamber to help reduce gas flow and (hopefully) convince some of the oil to condense and run back down into the crankcase, not out into the airbox. That’s the theory anyway, but it’ll probably turn out to be complete bollocks! Either way, it looks neater so that’s a positive step forward ……. now, what else can I break today! 😀

Aprilia Caponord ETV1000 Rallyb-Raid engine crankcase airbox vent 3D print

The MK1 vent did well and lasted almost  2 years (37K miles) and in that time I never had a moments issue with oil in the airbox going where it shouldn’t. Let’s hope this one does as well!


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Hybrid velocity stacks

Aprilia Caponord ETV1000 Rally-Raid 47mm and hybrid 51mm velocity stacksIf all goes to plan, later this year the second Rally-Raid that’s currently being rebuilt, will finally get a motor installed. The plan is to use a big-bore motor …. an 1,103cc in place of the standard 998cc. The compression and valve timing will remain bog-standard Caponord (10.5/1  Inlet timing – 25°BTDC/37°ABDC and Exhaust timing – 57°BBDC/5°ATDC). However to accommodate the increase in air-flow, I’ve decided to use Futura 51mm throttle bodies instead of the Caponord 47mm items.

Meanwhile on top of this chunky aluminium marvel sits a pair of velocity stacks. These stacks vary in height (and diameter) depending on the intended tune of the engine. The RSV Mille of course is designed as a race-rep and as such wants high horsepower at high RPM – hence 57mm throttle bodies and very short velocity stacks. On the other hand the Caponord was tuned for improved low-end grunt and so has small throttle bodies (47mm) and tall velocity stacks to maintain good gas flow speed at low RPM. The Futura seems to sit firmly between the two!

Now of course I could simply use the medium height velocity stacks straight off a Futura, but I decided to go a different route and print a new pair of hybrid stacks – Caponord height BUT 51mm diameter to fit the Futura throttle bodies. Unlike ABS, Colorfabb Ngen (Co-Polyester) can’t be vapour polished with Acetone, so I’ll have to sand the venturi down with a variety of grades of wet-and-dry up to 2,000 grit and maybe finish it off with something like Quixx plastic polish – if it works on this stuff! Here’s a couple of pics comparing the original and new version – straight out of the printer!

Unfortunately 3D parts (unless made on high-end machines) don’t typically have the same strength as injection molded or machined parts – but they do make great ‘proof-of-concept’ parts! If these stacks prove to be a positive step forward, but not durable enough for the working environment, I can at least get the drawings to the machine shop and have them made in aluminium … but that’ll be a tad more expensive than 85p each off the printer! 🙁 


Just had a spare half-hour to rub some 100/400 & 1200 grit paper down one of the stacks and all I can say is – WOW! This material rubs up lovely and probably a couple more sessions will see it through. All the print-ridges have gone and I can’t feel anything but a nice smooth surface that retains a print pattern that makes it look quite distinctive.  🙂

Aprilia Caponord ETV1000 RST1000 Futura Rally-Raid hybrid velocity stack



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A little unhinged

The day before the awful January weather hit, I managed to get a nice afternoon ride-out on the Capo. Stopping part way along for a coffee break, I paused for a moment to put helmet and gloves in the top-box – forgetting I had a bungee-cord still attached between the lid and side cases. With my mind wandering away on other things, I flicked the latches and began lifting with finger and thumb. In a heartbeat the cord snatched the lid out of my hand, slamming it hard against the hinge-stops bending the hinges and shearing two rivets. Oh well, after 10 years I guess it could do with a bit of TLC, now it definitely needs it!

Aprilia Caponord ETV1000 Rally-Raid Hepco Becker top box 3D printed spacersA couple of weeks later, after the snow had finished having its wicked way, I managed to get around to doing a complete strip of the top-box in an uncomfortably cold and damp barn, first straightening the hinges then rebuilding it all with new 4mm stainless steel rivets instead of the feeble aluminium 3mm ones. While I had it stripped down I remembered that I’d had a little 3D printer idea regarding the top-box and now was the perfect time to do it.

Aprilia Caponord ETV1000 Hepco Becker 45L top box alignment spacersSomething that’s always bugged me with the Hepco-Becker top-box is the lateral play in the mount which allows the box to be fitted off-center – around a half-inch or more (>12.5mm) either way. To take this slop out two plastic blocks modelled on the shape of the existing mount have been added using the same size self-tapping screws as on the main support. These blocks don’t take any load, that’s still handled 100% by the original support, their only job is to ensure the box lines up perfectly every time it’s refitted ….. no bumping, shuffling or tweaking it into place, and this most certainly pleases my mild OCD!

Aprilia Caponord ETV1000 Rally-Raid Hepco Becker top box support plateWhile doing all this, the bottom galvanised steel support plate was measured and a larger improved design drawn up. The original 1.5mm thick plate has too much flex for my liking (built to a budget) so the idea is to fit a slightly thicker 2mm stainless steel one for improved support, looks and weather resistance. After all this, the top-box should be good for another 10 years + …….as long as I don’t screw up the hinges again that is! 😀

Aprilia Caponord ETV1000 Rally-Raid 3D printed speedo sensor Honeywell 1GP7001And finally, the January backlog of post and parcels are starting to trickle through and with the first batch came the 8mm OD stainless steel sleeves and a couple of Honeywell 1GP7001 speed sensors. So the sensor and case are now assembled and tested. Only the cable strain relief sleeve is missing before I can fit it permanently to the bike. Fingers crossed they’ll be in the next batch of post!

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More bunged up …… or spoke too soon!

Aprilia Caponord ETV1000 Rally-Raid spare spokes in the front wheel spindle - AP8108784, AP8108787, AP8108805I’ve been carrying six spare spokes around in the front wheel spindle for years ….. however the whole thing was a bit of a mash-up and not worthy of a post on here unless I desperately wanted some serious ridicule. Until now that is! Out with the hand-cut foam and insulating tape and in with the nice new 3D printed parts – two spacers to hold the spokes all nice and even and two new symmetrical end caps. All this held together with a length of 8mm aluminium tube, two ‘O’ rings and two M6 stainless fasteners topped off with a pair of decorative washers I had left over from my old Honda Blackbird days. All works pretty well, even if I say so myself! 😀 

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Feeling a little bunged up

The Capo now has 3D printed bungs in the swing arm pivot and the ends of the crash-bar mounts. They’re held in by 43-39-2, 14-10-2 and BS011 ‘O’-rings. And yes, the BS011 rings are the very same as those used on the fuel lines. So one day if the old girl springs a leak and needs a new fuel line ‘O’-ring by the roadside – no problem, whip out a crash-bar bung and pinch the ring!  Next ….. front and rear axles then the engine mounts above the swing-arm pivot .

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