Ok. here goes.
An exploded diagram of it is below as well. And a photo of the puller.
Here we go.. by numbers then:
1, Bike on rear stand, LHS faring removed, drain oil.
2, Disconnect the 3 oil lines and remove dry sump tank.
3, Undo the 10mm bolt (top of housing) retaining the crank sensor and remove.
4, Place oil drain container under crankcase. Loosen all cap screws on housing. Break seal and allow to drain.
5, Separate the gasket from both surfaces. Remove outer housing (this will require a firm pull due to magnetism).
6, Tie housing up out of the way.
7, Position 3 screwdrivers thru the holes in the flywheel (FW) and gears to lock slipper clutch.
8, Loosen 6 counter weight retaining cap screws by 1-2 revolutions.
9, 14mm allen in a breaker bar to remove the FW bolt. This will be tight. Standard thread.
10, CRC inner FW thread and M22 bolt. Grease end of bolt.
11, Insert and tighten M22 bolt.
12, Have gloves or rags available for hot parts. Also soft landing spot for FW.
13, Apply heat to centre of FW only (rough cast surfaces) for approx 1 minute.
14, 1/4 turn of bolt should displace FW.
15, Use screw drivers to handle/remove hot FW. Leave on flame proof surface and allow to cool for 30 min. DO NOT USE FLUID TO COOL FW.
OK, that was the hard part!
16, Lift gear out from rear of counter weight.
17, Remove 6 cap screws and lift counter weight away.
18, Clean old loctite from cap screws.
19, Fit new M8 nuts with loctite. Rotate capscrews only (not the nuts) due to clearance issues.
20, Clean off any excess loctite. Refit gear to the rear of the FW.
21, Remove old loctite from the end of the crankshaft and inner FW tapers (Scotch Brite recommended).
22, Put locktite on both tapers and key way. Be sure to keep it away from the bearing.
23, Position FW on it's key way. Align gears to allow FW to push fully into position.
24, Insert screwdrivers to lock clutch. Insert bolt and torque to 94 ft/lbs.
Easy as!
25, Untie housing. Refit gasket to outer housing using a couple of cap screws to hold it in place.
26, Refit housing and crank position sensor.
27, Refit dry sump tank and lines. Check drain bolt is closed.
28, Fill with oil.
29, Wipe engine surfaces/ dry sump tank dry of oil.
29, Vent work area. Place handy towels under bike to indicate any leaks.
30, Start bike and bring up to running temp. Admire throttle response.
31, Allow engine casings to cool. Check handy towels for evidence of oil leaks.
32, If no leaks evident, refit LHS faring and enjoy.
The Aprilias have a metal dry sump tank that must be removed to get to the outer housing. This tank has lightweight brackets that are easily bent. Make sure they are ok because during a test run by a friend who did this his engine torqued in it's rubber mounts towards the tank. The result was that the head of one of the cap screws pierced the oil tank releasing its contents. First inspections gave the false impression that the housing gasket has failed causing the leak, this was not the case. After repairing the tank he had to reposition/ re-bend the brackets. He also spaced the tank out further by using a panel washer on the mounting points. Clearance remains at 2-3mm.
It is definitely something to be aware of when undertaking this mod, but wasn’t a problem for me.
Now... some general info with a bit more detail....
So… a wee overview.
It is easier to do when you do an oil change, just take the oil tank off, flywheel cover off and you are good to go. just watch you dont catch the gasket on the flywheel or it will tear
you basically just crack it open and unbolt the weight :biggrin
drain oil, alternator cover off, flywheel off, HEAT with propane torch, weight off, super stud locktight on, nuts on, alternator cover on, oil in and
Use a M22 steel bolt instead of the puller. M22 x 1.5. Needs to be a HARD metal. (M22 means the threaded portion is 22mm in diameter.) Needs to be at least 30mm length of bolt shaft too
BE CAREFULL>>>>> You may need an alternator cover gasket depending on how careful you are taking the cover of, 90% you can get it off in one piece but because of the magnets in the flywheel and the stator there is some resistance.
Only use super strong loctite on short nuts you are putting on for lighter flywheel. Medium loctite is fine for when putting flywheel bolt back on, just make sure you put on tight.
Lastly, whether you find the bolt or get the Aprilia puller, make sure to lubricate the threads, of both puller and flywheel, and the end that contacts the crank. The best thing to use is molybdenum disulfide assembly lube. This is what is commonly used on new cams and engine rod and main bearings. If this is not available use a good grease or engine oil.
If you look at the end (threaded end) of most any bolt you will see that it is not machined square and flat. In the old days bolts were turned and threaded on a lathe so the end was machined flat. Today, bolts are cut to length with a shear and the threads are then rolled onto the shaft. This leaves the end uneven. If you look at the picture of the aprilia puller you will see that there is a shoulder at the end of the threads. This is what contacts the crankshaft, not the end of the smaller diameter pin. So to make a long story short, if you find a m22x1.5 bolt make sure the end is flat. If not, have a machinist face off the end on a lathe. Better yet just get the aprilia tool. If the end is uneven it will not apply even pressure to the crank. At best it will bind and make it even more difficult to get the flywheel off. At worst it could damage the end of the crank. The one I bought wasn’t flat so I got a file and tapered the end 1mm slightly.
The flywheel puller screws into the flywheel till it contacts the end of the crank. Tightening it forces the flywheel off the tapered shaft. You want to apply heat to the central hub portion of the flywheel, not the tool. Be sure to lubricate the threads of both puller and flywheel, and the shoulder that contacts the crank. The best thing to use is molybdenum disulfide assembly lube. This is what is commonly used on new cams and engine rod and main bearings. If this is not available use a good grease or engine oil. This reduces friction and increases the pulling force while reducing stress on the threads.
When reassembling, the manual specifies applying Loctite 648 green to the taper and to the bolt. Be sure it does not get inside the bushing of the sprag clutch gear. The flywheel bolt is torqued to 94 ftlb (130 Nm). The crankshaft holding tool comes in handy here.
When you Unbolt the big 2lb weight (item #11 in the dia, they even call it a 'weight' in the parts manual ) off the back of the flywheel, you can just replace it with 6 steel, low profile nuts. is you want something more secure you can replace the sprag clutch housing with one from a 99-03 engine which has 3 threaded holes in it.
remember this is actually 'simulated' hp which can be measured with an accelerometer (Dynojet dyno) but in steady state the hp is the same. kinda like going from a heavy tire to a light tire, the bike will accelerate a lot quicker due to the lower rotational mass. What is cool is that there is less engine braking with the lighter flywheel (which is good as the slipper clutch doesnt quite slip enough stock), and the corner will definitely get out of corners a lot quicker which is the key to a faster lap time.
It is easier to do this job when you do an oil change, just take the oil tank off, flywheel cover off and you are good to go. just watch you dont catch the gasket on the flywheel or it will tear.
The ones I've removed so far, looked like they used Loctite to secure it to the tapered shaft.
Also, there are two types of Aprilia pullers, the old puller was made of soft steel and stripped out when you applied the force required. The new puller is not only much harder but also has a new shape that works much better. But… just buy a bolt from an engineering workshop. Cheap as chips.
I used a small gas torch to heat the flywheel and soften the Loctite. Then use a big breaker bar to generate enough leverage, haven't tried using an impact wrench yet, I'd hate to strip out the threads on the end of the crank or flywheel. But mate used one and it came off piece of piss.
