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BIKE TECH–Making a faster Caponord

September 28, 2012


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CONTINUED FROM: FUBAR My Caponord is dead

Well, the problem started with a flashing EFI warning light.  The diagnostic computer indicated it was a front cylinder coil.  So I started taking the bike apart.


And I found a three bedroom mouse condo…..


So, I evicted the mice and continued removing parts until I got to the front coils. The fuel tank must be removed as does the air box cover and the air box base. 

IMG_1229 IMG_1231

Of course nothing is as easy as it sounds.  Updated Aprilia Caponords have metal fuel quick disconnects.  Apparently the fuel stop mechanism fell apart over time and immediately began draining fuel all over the bike, me and the ground.  I managed to get a fuel container but it took almost an hour to get the tank empty.  Luckily my brother had an extra set of brand new fuel QD’s so the replacement went quickly.  No further fuel issues.  One thing -  remember to lubricate the O rings as they can rip apart when making the connection again (don’t ask me how I learned that……)


I replaced the stock air filter with a DNA Performance Filter.  DNA claims they are superior to K&N and I’ve had some crappy results with K&N filters in the past.  I got mine here. No matter, the stock filter is restrictive and the air box “snorkel” is seriously restrictive.


This is the infamous “snorkel”.  Installed, the capo gets a very restricted shot of air from under the frame.  Removing it is a simple matter of just pulling it off. 


With the air box removed, and the intake stacks covered I went after the front two ignition coils.


The front ignition coils are located at the front of the engine and are a bit fiddly to remove.   The picture below shows a critical detail – the coil sender wires are secured with a small zip tie.  These are important to re-install as they keep the connection from vibrating loose.

NOTE – factory replacement ignition coils are horribly expensive (Aprilia coils run $200.00 each!) Some folks on the Aprilia forum have used automotive coils and modified them to fit but the results are pretty ugly and there is a bunch of dremel and connector hacks involved.  A better solution was found on e-bay for significantly less.  They are OEM spec and exact replacements. I got mine  here


Replacement coils in place – the rubber mounting boots are re-used. Don’t forget to reconnect the air box drain/vent tube (marked here with blue tape).


Don’t forget to zip tie the connectors.


Re-installing the new coils. 


The spark plug wires were shot so I ordered a custom set of Magnecor 8.5 mm wires.  They are fantastic.


Fantastic quality and guaranteed for life. I got mine here.  I replaced the spark plugs at the same time.  I chose iridium tipped spark plugs for long life and efficient spark.  AF1 Racing sells a complete set (NGK DCPR9EIX Iridium Spark Plugs 4pk. (PU21030065x4). It’s important to remember that you DO NOT GAP these plugs as the tips can be easily damaged. The previous owner (QuicksilverCapo) was an absolute perfectionist.  Of course, when I pulled the plugs – an identical pair of iridium plugs was already installed……..  Well, new plugs are new plugs.

NGK DCPR9EIX Iridium Spark Plugs 4pk.


A shot of the newly de-snorkeled air box.  Better air flow = better power and hopefully more MPG.


Air box cover reinstalled.


The next replacement was the starter relay.  I had a bit of terror (see my last post) then the bike started to crank over by itself.  The replacement is a 100amp Yamaha part that is a direct fit.  Again OEM Aprilia is $150 – aftermarket is $50 – Yamaha is under $20.00 – and its better quality. I got mine here


New starter relay installed. The entire unit is plug and play – you don’t have to swap any parts.


I got the bike back together and despite a small fire……..

Ok, I’ll tell you.  This was stupidity in the making.  The bike would not start after re-assembly.  I used a metal fuel quick disconnect from my Aprilia Futura figuring it would work in a pinch.  I don’t think that when it was connected the bike got any fuel.  So in trying to figure out why it would not light up (pun intended) I stopped thinking and reached for the starter fluid…………. You can guess the rest.  I hit the starter button and WHOOOOM!  A mini-explosion followed by a fire deep in the bike.  To put it mildly, I freaked out.  Blue flames were coming out from the air box area.  Also, to make things worse, I had been working with gas and more than likely had some residue on my hands and clothing, also, there was a 5 gallon can of the drained fuel a foot or so away. 


I knew I could immediately get to the fire by pulling the tank off. That meant hitting two quick disconnects which would most likely drip some or perhaps a lot of fuel. Not a choice. I blew most of the flames out but where were a few persistently licking out from near the air box. Fire extinguisher? Are you kidding? If I could find it it would take too long and I had only seconds to get the fire out before it did some serious damage. 

What I did have immediately at hand was a can of Diet Coke – and that’s what I used to get the fire completely out. On disassembly only a few wires were charred – I was lucky.  Any longer and I really believe I’d have lost the bike.  I fixed the wires, replaced the quick disconnects with the ones from my brother and the Caponord started immediately on re-assembly. 

Lesson learned.  Leave that starter fluid for old 69 Camaros and lawn mowers – not high compression Rotax V90 engines. 

The bike is running fantastically.  The starter relay is much, much better – the bike starts immediately.  The air filter and de-snorkling made a huge difference.  I immediately noticed a much crisper throttle response and hope to see improved mileage.  Heck, it HAS to be better with the removal of the mouse condo!  If you store your bike it pays to look under the hidden bits for mouse nests, etc. 

Finally, the cost of replacing all the parts (two coils, spark plugs, BMA filter, starter relay, air filter and spark plug wires) was less than the price of an OEM relay and coil.

NEXT:  More stories from the road


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2 Comments leave one →
  1. September 28, 2012 11:22 pm

    Well put good read. Cheers Roffy. N>Z>


  1. FUBAR!–My Caponord is dead….. | Singlesided Swingarm

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