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| charge on the fly man |
I noticed 20mi in, my cylinder was running a little hot - AGAIN. I had already upjetted by 6 sizes at Inverness because my plug looked a little lean and it ran great. Not a four stroke sound in any range... this had me concerned. I couldn't find an airleak anywhere except a small one at the carb and I attributed this to the crappy SHA shim. I'd been running the pre-Inverness jetting since last fall and all winter. Well, it was running lean again yesterday so I decided to pull over and upjet to be safe and look harder for an airleak when I got home.
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| Somehow the vespa did all of Inverness doubled up no problem despite this huge growing airleak. |
Had to get my girlfriend to come pick me up in Brownie and she got grease on her shorts putting the rack on... bummer :/ Hope that comes out with GoJo.
I have some round stock coming from McMaster and I'm going to try to build up the cases with my spool gun setup, file it flat and make a bolt on intake like on the polini speed cases. I don't really want to just get another case and have this happen again. I thought about taking this bike on pinball and I can't be having the intake break off in the middle of the country.
I decided I wasn't going to let that day be a total loss, so I decided I'd reassemble the Derbi PP engine sitting all over the living room of my apartment. I seized this thing at Inverness because of poor jetting. I put a new exhaust on my 84 Volvo the day before we went to inverness and I ran out of time to jet the Derbi (which is what I intended my girl to ride). Was out riding it Friday night at inverness and I seized it... UGH. No before shots of the cylinder, but check out the piston and the shots of the cylinder AFTER clean up:
My girlfriend's dad says the measure of a good woodworker is not his ability to not make mistakes, but hide, undo, work with and around them WHEN he does. I don't think this applies as directly to mopeds, but I told myself this when I got the cylinder cleaned up haha.
The only residual stuff is some scoring down below the exhaust port, so it should be fine. It's had a hone run over it so it should be smooth. HCl took off the aluminum smeared above and around the ports, then a fresh 38mm dingleberry hone erased all evidence of any damage ever being there around and above the ports. I was very lucky. The dykes ring shattered (which is why the bottom end came apart) and I got away with little damage to the cylinder.
While I had the bottom end apart, I noticed that the bearings were super crunchy, so $30 was allocated to new crank bearings and seals. The transmission bearings were in good shape and hopefully the seals continue to seal once I've got fluid in it after the rebuild. Cross that bridge when I get there I guess.
The magic temperature for engine assembly is 300*F. Bake all cases at 300*F for 20 minutes to obtain butter like assembly and dis assembly! I've reused seals I've baked and they're just fine. In an ideal world, you'd replace the seals after you baked them, but I think it's better to risk damaging $30 worth of seals than a rareish crank and transmission.
Everything installed in the left hand crankcase and the right hand one is in the oven! Install crank seals after of course ya dummy.
Impact driver bits make for good final torque bits too. I always tighten everything down to 6ft-lbs and then bump it up to 7.
When I take things apart, I leave the shims and washers on the shafts they go on where they go and use zip ties to hold everything on while it's on the shelf. Somehow, I got the pedal shaft bushing/shim for the left hand crankcase on the output shaft. I realized this when I noticed raw steel threads riding against the aluminum case lol. A quick visit to Biery's blog and an FB message and I was assured I had properly corrected everything. Gear alignment looked good.
I also snagged a new set of 3 sets of 107mm clutch springs from eBay for $8. They're sold on scooter websites for 107mm clutches and the reviews are good for hobbits running the 107mm clutch clutch springs, so I figured I'd give it a go. The stiffest ones are missing and the medium and lower tension ones are what I got. I don't plan on kitting the TT though, so that should do me just fine. Maybe I can trade the ones I don't use for beer to someone with a hobbit. White is medium and black is the lowest tension. They were difficult to get on and the black springs are definitely higher tension than stock. The stock ones barely disengage though so that's not saying much.
I have a NOS piston from Steve Brown to go in the cleaned up cylinder and two more sets of rings! I've wondered if maybe I couldn't clean up the other piston and go crazy cutting the skirt. The bottom ringlands are trashed but the top dykes ringlands are TOTALLY salvageable.... hmmm... it's pretty gnarly though.
Then, today, some TREATS came. 22t sprocket and a new petcock for the ZA70 maxi and a 26t rear tomos sprocket for the derbi. Woot. Can't wait for this week to end. So much wrenching to do next week.
