Tips for closing cases in bike
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Enthusiast
61 VBB and 79 P200
Joined: 01 Jan 2018
Posts: 52
Location: Folsom CA
Thu Oct 15, 2020 6:37 pm quote
I had some work to do on the flyside of an engine so I thought it was a good opportunity to experience pulling it without taking the motor out of the scooter.

Everything went swimmingly. It’s a really great way to work on things… But before I reattach the cases or is there any advice that I should pay attention to that’s different in this situation? My normal practice is to freeze the crankshaft bearing and heat the fly side case. Anything I might also want to do?
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Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8047
Location: The state of insanity, SoCal
Sat Oct 17, 2020 2:23 am quote
should slip right on. make sure that your gearbox rod/selector is all the way in 4th (like sticking out) so you can wiggle waggle the axle if need be to snake it into the bearing. a dab of sticky grease on the kickstart gear spring (if you have one), don't forget the kickstart gear, either. lube up all the seals and seal surfaces. sometimes depressing the kickstart lever will allow the cases to come together a little easier. light taps with a soft mallet if needed. don't pinch the conrod between the cases.

other than that, bob's your uncle!

-g
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Old douglas ..smallie with polini 115..super with nasco 177
Joined: 07 Nov 2013
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Location: New Zealand
Sun Oct 18, 2020 11:53 am quote
..and
a few hours before closing I put the entire engine in the deep freeze just to cool the fly side bearing which is now on the crank ....ie complete engine ready to close goes in the freezer for an hour

then heat the empty flyside bearing hole with a hand held propane torch..till you cant touch the metal....quickly install the fly side seal...and offer up the cases

Nice cool bearing slips into nice hot hole....with a wee wiggle of the kick start
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1963 Vespa VBB, 1965 Allstate Cruisaire, 1974 Vespa Super, 2003 Stella 2T
Joined: 31 Jan 2016
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Location: Kansas City
Sun Oct 18, 2020 1:37 pm quote
So I have been researching this. Most say put the bearings on the crank. Heat the cases and put it together..

Some say put the bearings in the case and then heat the bearing and use the tool to pull the crank in on the clutch side. Heat the bearing on the fly side and just put it together.

http://www.scootermercato.com/Garage/Tech-Tips/Engine-Assembly-Part-1-Large-Frame
Starts about half way down the page.

Not sure exactly how I would do it.
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Old douglas ..smallie with polini 115..super with nasco 177
Joined: 07 Nov 2013
Posts: 620
Location: New Zealand
Sun Oct 18, 2020 4:47 pm quote
Ive done both ways
I must have done this over 20 to 30 times in 25 years.

Start with just the crank on the bench and get a bearing on the flyside by tap tap taping it on with long reach socket....or pushing bearing on with threaded rod and washers

then big half of cases......heat bearing hole and put the clutch seal in and tap it down with a big socket.....then the bearing on top of that while case still hot

Now draw the crank in with a puller

so now you have both bearings on the crank...clutch side hidden in cases with the crank sticking out of it..fly side bearing looking at you.

Here is the main trick

Heat the fly side hole and install the seal...then quickly offer up the cases...to aid this i put the engine in the freezer an hour before
9 times out of ten you need to manipulate the kick start at the last cm of closure.

sooooooooooo beasrings on crank.......any other method and you will cook the seal when trying to heat the bearing prior to closing

Ya cant heat a bearing hot enough when the seal is already installed below it....
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Sun Oct 25, 2020 7:52 am quote
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