Messing with my Aprilia Cup

I hate Phillips head screws. The ones in the cylinders laugh at my impact driver and there's only so hard I'm going to hit it. At the same time, I knew I couldn't show my face here if I didn't replace the seals for the powervalve shaft. This slightly sketchy arrangement with my hydraulic press got it done. Basically just enough pressure that the bit couldn't lever out.

RS250-cup-screw-extraction.jpg

I found this while pulling powervalve hardware from the old cylinders. The left/top cylinder is really nasty inside while the right/lower is very clean. I didn't take a picture of the mess before I took it apart because I was expecting the other cylinder to look the same. Everything coated with a layer of black oil, even the external hardware (pulley, etc).

RS250-cup-oily-cylinder.jpg
 
Please tell me that with all that equipment you do have a 3/8" air impact?? The butterflies are hard to find these days, but there was a time when a line mechanic could work easier without his eyes than his butterfly.
 
ahrma_581 said:
Please tell me that with all that equipment you do have a 3/8" air impact?? The butterflies are hard to find these days, but there was a time when a line mechanic could work easier without his eyes than his butterfly.
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I have a little 3/8" electric impact that's not particularly useful and 1/2" air and electric. What would a butterfly impact do other than make perfectly conical holes where there used to be phillips?
 
3/8" pneumatic has just enough torque to bump them loose: 1/2" impact is for overtightened lug nuts. FWIW I must've loosened and installed a bazillion 6x1 mm pot metal screws with one. Very few conical holes.
 
dave3593 said:
I have one of those old school things you put a screwdriver bit in and hit it with a hammer. That thing will take out a buggered up Philips when nothing else will.
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Mike Fennell said:
The ones in the cylinders laugh at my impact driver and there's only so hard I'm going to hit it.
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:D

It worked fine for removing the countershaft seal cover but the cylinder heads are much less substantial. I couldn't bring myself to hit it hard enough.
 
Sharath helpfully pointed out that I'm stupid (he was nice about it) and that the screws on my Japanese engine are not Phillips but rather JIS. I even knew that somewhere deep in my brain but it just didn't occur to me.
 
Mike Fennell said:
Sharath helpfully pointed out that I'm stupid (he was nice about it) and that the screws on my Japanese engine are not Phillips but rather JIS. I even knew that somewhere deep in my brain but it just didn't occur to me.
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I never learned about JIS until this forum. I learned after we quit racing. So I still have never purchased any, but should look into that, just to see what i've been missing out on.
 
Boman Forklift said:
I never learned about JIS until this forum. I learned after we quit racing. So I still have never purchased any, but should look into that, just to see what i've been missing out on.
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Go here. Buy at least a P2 and P3 JIS Megadora of your choice length. Then spend another hour or two looking at all the other neat stuff. Probably should pick up a set of JIS impact bits too.
 
Found something interesting yesterday while staring at stuff (rather than assembling it...).

I was checking out the spare clutch pack to pick the best basket and noticed it has a different style of clutch. 8 frictions vs 7 and the steels are smooth.

rs250-cup-clutches.jpg

Assume the clutch on the left is some kind of period upgrade and the one on the right is stock. Unfortunately, the steels have surface rust.

In other news, I got an order in with Sean at TTW just before he went on break. Expect it today. Another Zeeltronic, wheel bearings, plugs, other random stuff. Updated my spreadsheet - I'm in this about $7500 but the bleeding is mostly over. Chain/sprockets/tires left. Maybe some powdercoating and/or paint.

Checked ring end gap the other day and installed some powervalves. Now it's just me being lame that's holding things up.
 
Mike Fennell said:
Found something interesting yesterday while staring at stuff (rather than assembling it...).

I was checking out the spare clutch pack to pick the best basket and noticed it has a different style of clutch. 8 frictions vs 7 and the steels are smooth.

View attachment 227190

Assume the clutch on the left is some kind of period upgrade and the one on the right is stock. Unfortunately, the steels have surface rust.

In other news, I got an order in with Sean at TTW just before he went on break. Expect it today. Another Zeeltronic, wheel bearings, plugs, other random stuff. Updated my spreadsheet - I'm in this about $7500 but the bleeding is mostly over. Chain/sprockets/tires left. Maybe some powdercoating and/or paint.

Checked ring end gap the other day and installed some powervalves. Now it's just me being lame that's holding things up.
Click to expand...
The clutch on the right looks like a modern clutch. I'd be much more inclined to use it instead of the "period correct" looking clutch on the left.
 
Mocked a cylinder up yesterday. 0.6mm base and a used head gasket resulted in 1.65mm squish. In my mind, I was thinking I'd aim for 1.0 and I don't think there's a straightforward path to get there w/o machining. Then I realized I was just parroting what I've read. Do I really care with this stock(ish) build or should I just assemble and ride? IIRC, 1.9 is stock. I want this thing to be reliable on track. Steve and company will be tuning it for me.

Also, I have a 0.3mm metal base 'gasket' in my pile of stuff from Cometic. Is that really a gasket (assemble with a smear of sealant?) or a shim? That would give me 1.35.

Hmm...I just read that the 'kit' base gasket was 1.4mm to raise the ports. That explains the thick Cometic gasket I have. I'm getting the feeling there's a lot more to this than just 'setting squish' in a vacuum and maybe I should just assemble this thing as-is and get it off my bench so I can work on my Ducatis.

* To review, the build is a new stock crank, Wiesco pistons, Cougar powervalves. I picked up another Zeeltronic for it too.

rs250-cup-squish-sm.jpg
 
I check out AF1 every so often as they occasionally get rid of some RS250 stuff cheap. Today brought me:
  • Ferodo CP911 pads - $20
  • OEM 13T front sprocket (-1) - $4
  • OEM 41T rear sprocket (-2) - $7
  • OEM clutch pressure plate - $10
  • DID VX3 chain - $110 (~$30 under RevZilla)
I'm not sure what my gearing should be at NJMP Thunderbolt. Stock is 14/43. Bike came with 13/43. 13/41 might be tall with a 160/60-17 on the back (I think that's what it runs) but ... $7... I didn't need a pressure plate either.

Mocked up the front cylinder. Same 1.6x mm squish. Gonna put the rest together and make some noise.


I discovered I have a decent source for AvGas. Is that a good choice? @SpeedWerks Racing will be doing the tuning so no risk of dumb Fennell things. The PO was running T4, which is way more expensive and a big PITA to secure (although I called the Delaware distributor and they're happy to load a 54 gallon drum on my open trailer and wish me luck).
 
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