RB20 long stroke

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Grumpy225
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Posts: 650
Joined: Sat Nov 24, 2012 7:59 am
Main scooter: Gori200, rt195, ld150,rb20
Location: Bakersfield, CA
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I have a 62mm crank on the shelf and just happened to kill the one in my RB20. Is it possible to stroke this kit (with the correct 116 rod of course)? I'd think it should be okay but just haven't seen anyone do it yet.
cartmel808
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Joined: Tue Feb 04, 2014 10:35 am
Main scooter: 1975 Vespa Rally 200 Femsa
Location: Durham, England
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I run a 62/116 crank in my RB200.
Its ported to 130 trans / 190 exhaust, with a Franspeed race pipe, 30mm flat slide Delly, af close ratio 4speed box and 17 degrees static ignition.
It was dyno’d earlier this year at 28bhp and I think 21 ft/lb torque with this set-up - had a 34mm delly on initially & dyno’d slightly higher peak power @ just under 29.5 bhp - but it rides nicer with the 30mm carb & with greatly reduced spit back.
Great engine & very rideable.
Grumpy225
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Posts: 650
Joined: Sat Nov 24, 2012 7:59 am
Main scooter: Gori200, rt195, ld150,rb20
Location: Bakersfield, CA
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cartmel808 wrote: Wed Sep 18, 2019 11:08 pm I run a 62/116 crank in my RB200.
Its ported to 130 trans / 190 exhaust, with a Franspeed race pipe, 30mm flat slide Delly, af close ratio 4speed box and 17 degrees static ignition.
It was dyno’d earlier this year at 28bhp and I think 21 ft/lb torque with this set-up - had a 34mm delly on initially & dyno’d slightly higher peak power @ just under 29.5 bhp - but it rides nicer with the 30mm carb & with greatly reduced spit back.
Great engine & very rideable.
That answers that, thank you. I just need to source a rod for this maz crank and see about fixing the rest of it (misshift caused the motor to over rev and the big end came apart).
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garry inglis
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Main scooter: ts1 230 and rb200
Location: darlington
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hi cartmell 808 did you use the 39mm crown piston if so how big was the base packer or did you use a 30mm crown height im just thinking from 58x116 to 62x116
holty
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Main scooter: lambretta gp
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ive done one of these, I think it ended up with a packer top and bottom as the piston came out of the top of the barrel, used a mammoth head and doweled it to the barrel, did a bit of alteration to the ports as well.
cartmel808
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Posts: 467
Joined: Tue Feb 04, 2014 10:35 am
Main scooter: 1975 Vespa Rally 200 Femsa
Location: Durham, England
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garry inglis wrote:hi cartmell 808 did you use the 39mm crown piston if so how big was the base packer or did you use a 30mm crown height im just thinking from 58x116 to 62x116
Dan Clare built the engine for me Garry & I’m not sure on the size of base packer used, or piston crown height - but would assume that it’s running the standard piston that comes with the kit.


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