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Messing with my Aprilia Cup

Discussion in '2-Stroke Machines' started by Mike Fennell, Apr 19, 2024.

  1. Robin172

    Robin172 Well-Known Member

    I either use my finger or a small paintbrush.
     
  2. Boman Forklift

    Boman Forklift Well-Known Member

    I've used my finger. Didn't know about the finger/acetone trick. Also like the syringe and rubber band ideas.
     
  3. dave3593

    dave3593 What I know about opera I learned from Bugs Bunny

    Shouldn't that be in the cologuard thread.

    Sorry, I've been drinking beer and working on a crankshaft. It's the perfect combination.
     
  4. Robin172

    Robin172 Well-Known Member

    :crackup:
     
  5. Mike Fennell

    Mike Fennell Never Was

    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
     
  6. ahrma_581

    ahrma_581 Well-Known Member

    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.
     
  7. Mike Fennell

    Mike Fennell Never Was

    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?
     
  8. ahrma_581

    ahrma_581 Well-Known Member

    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.
     
  9. Mike Fennell

    Mike Fennell Never Was

    No kidding? I never would have thought of trying that.
     
  10. dave3593

    dave3593 What I know about opera I learned from Bugs Bunny

    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.
     
    SuddenBraking and Boman Forklift like this.
  11. Mike Fennell

    Mike Fennell Never Was

    :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.
     
    dave3593 likes this.
  12. Mike Fennell

    Mike Fennell Never Was

    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.
     
    motosapien likes this.
  13. Mechdziner714

    Mechdziner714 More Gas Less Brakes

  14. Boman Forklift

    Boman Forklift Well-Known Member

    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.
     
    Mike Fennell likes this.
  15. YoshiHNS

    YoshiHNS Mr. Slowly

    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.
     
  16. motosapien

    motosapien Well-Known Member

    happy to help Mike jis+blowtorch for the win!

    sorry I don't come here often.

    Sharath
     
    Mike Fennell likes this.
  17. Mike Fennell

    Mike Fennell Never Was

    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.
     
    onesixsix, freedomgli and PatricksDad like this.
  18. Martin Lewis

    Martin Lewis Can we go back to the track already?

    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.
     
    Mike Fennell likes this.
  19. Mike Fennell

    Mike Fennell Never Was

    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
     
    IL8APEX likes this.
  20. Mike Fennell

    Mike Fennell Never Was

    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).
     
    onesixsix likes this.

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