I think it’s reasonable to say that Aprilia got it right when they chose Rotax and the rock-solid V990 motor for their range of bikes in the late 90’s. Bullet-proof doesn’t quite do it justice, especially in the de-tuned Caponord variant. But even this wonderful piece of Bavarian engineering has it’s weak points, and probably the one most obvious from a service-by-service aspect is that damn annoying magnetic plug in the crankcase.
Yes, little old AP0241782 can be easy to install, but a stress-breeding mega-monster when it comes to it’s removal. Stubborn is just too understated for how this little sucker can behave! Even with a brand new, high quality hex-key you feel the fear rise in your throat as you apply more and more torque – until finally with a loud ‘crack’ it gives way while your knuckles accelerate toward the floor at light speed. Or as has happened on the odd occasion, the head sheers off!
Over the years I’ve tried removing it with the engine hot, cold and in-between …. with prayer, witchcraft by a full moon and plain old cursing. In the end the best remedy I stumbled upon was a bag full of the little suckers donated by a friend. Spoiled as I was, I could afford to be decadent and change the plug for a new one every three services. By that time the fit between the screw and hex-key was getting a little stretched. But then one day, the bag ran dry …. oh my!
A little online digging threw up a bit more info regarding Aprilia numbers and options. It turns out that the magnetic plug AP0241782 has now been superseded by 2R000498 AND there is an optional washer offered if you want to use one. The 07-09 RSVR and 07-10 Tuono used the same plug AND also had the crush washer AP0250640 fitted. This washer is now sold listed as a usable option on all engines that use this plug. Does it make a difference? I’ve no idea as I’ve not tried one, but I guess it moves the mating surfaces from the taper to the screw head/crankcase and washer. In the end I went a different route used by many others over the years.
Following the recent footsteps of my old mate Beasthonda, I dipped into my pocket and purchased a KTM mag plug – 58030021100 for the princely sum of just under £9 compared with the Aprilia part retailing at £32. This saving alone is worth moving away from the Aprilia part! Now the eagle-eyed among you may have noted that the magnet on the KTM plug is longer than on the Aprilia one and be concerned that this could cause a possible oil restriction – fear not. The 10mm magnet (versus 8mm) fits into a cavern …… the space inside the crankcase behind the magnet goes back at least 50mm, so there’s tons of room around for oil to flow by. So, job done ….time to move on with the rest of the lockdown service.
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 another 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! 😀
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!
You may (or may not!) have read the post a couple of months ago – Fixing a few Capo niggles. That was where between Continental trips, the original air-box molded connection for the crank-case vent was drilled out and a new 90° bulkhead coupling and pipe fitted to drain any oil into the front of the airbox, well away from the throttle body and IACV (Idle Air Control Valve).
Now with the Caponord seriously (+1,000 miles) overdue a service, I got stuck in and removed the tank ready for plugs/air filter. I admit to being really pleased to see no oil what so ever in the upper part of the airbox and only a tell-tale smear in the front section. A syringe sucked what oil there was from the drain tube – approx. 5cc @ 3,000 miles WITH the oil tank filled to the HIGH mark.
Previously it didn’t seem to matter where the oil tank level was, oil kept getting thrown into the airbox and sucked down into the throttle body. Look closely at the design of the airbox and you see the ‘fenced’ in area (red) around the velocity stacks – and of course, the two slots in the stacks (arrows) for excess oil to drain through.
It’s pretty obvious then that Aprilia/Rotax EXPECTED regurgitated oil – and tried to ensure it was fed back to the engine and burnt. Unfortunately that isn’t always the case and when some bikes are left on the side-stand oil manages to get over the ‘fence’ and muck up places it shouldn’t!
Of course a little hot oil can spread a long way and look far worse than it really is ….. I guess it just niggled the hell out of me each time I lifted the airbox lid. In hindsight it’s one of those quick jobs I wish I’d done years ago.
One niggle that has wound me up more than anything about the Capo over the years, is its unerring ability to regurgitate oil into the airbox – apparently no matter how much or little I fill the oil tank. In the end, enough is enough, time to do something about it.
So this is it, remove the molded spigot/structure into the airbox and replace with a new low-profile 90° coupling and pipe to dump regurgitated oil into the front section of the airbox, from where it can be drained off via the extended drain-line down by the oil filter. Hopefully no more lumpy idle and intermittent ‘cough’ coming off idle after extended (12Hrs+) runs at motorway speeds from the vented oil draining down into the throttle bodies. A better fix of course would be to build a trap before the airbox that would allow oil to drain back the way it came while still passing vapour into the airbox. That’ll wait until winter, for now I’m hoping this will work good enough.
Secondly, and I don’t mind admitting when a change to the Capo doesn’t work – I’ve gone back to the #60 clutch oil jet from the #40. Why? Simply because the benefits were outweighed by the losses …… yes the #40 jet made the initial 1st gear selection go from ‘CLONK’ to ‘clonk’ but it also buggered up all subsequent gear changes, gone was the silky smooth shift that I’d had with the #60 jet. In the end I would say that if your Capo shifts gears smoothly and doesn’t have an issue selecting Neutral, then leave well alone. I’m sure for those with no jet, a blocked jet or a nasty gear shift this may well be a worthwhile modification, for me I’m glad to have the old slick-shift gearbox back again.