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@christopher_55934 avatar
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Ossessionato
2007 Stella 225
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Ossessionato
@christopher_55934 avatar
2007 Stella 225
Joined: UTC
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Location: Rochester, Minnesota
UTC quote
Could a person bore out a 1958, 125 piston port cylinder to a 150? How about to a 160 or one of the other piston port motors? Just curious which always gets me in trouble.
@rowdyc avatar
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Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
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@rowdyc avatar
GL, PK, PE200 with hack, Sears Rust Badge
Joined: UTC
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Location: Deep in the heart of Texas
UTC quote
From my limited understanding, there's not much someone can do with the current setup to see significant gain.
.....but if someone buy a few pieces and know what there doing, you can see great improvement. https://www.sip-scootershop.com/en/wishlist/2a398a6d-b674-48bb-8ec9-029c964605c9
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@christopher_55934 avatar
UTC

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2007 Stella 225
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Ossessionato
@christopher_55934 avatar
2007 Stella 225
Joined: UTC
Posts: 3547
Location: Rochester, Minnesota
UTC quote
rowdyc wrote:
From my limited understanding, there's not much someone can do with the current setup to see significant gain.
.....but if someone buy a few pieces and know what there doing, you can see great improvement. https://www.sip-scootershop.com/en/wishlist/2a398a6d-b674-48bb-8ec9-029c964605c9
Oh boy, I don't plan on going down that road with this scooter. Going for the kiss method and enjoy rides around town at less than 30 mph. Just curious if I have to go to an oversized piston if I can go to a 150 or bigger one. I'd put my reed valve LML motor in before going down that route.
@birdsnest avatar
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Not So Moderator
VNB VSC VMA VSX - o9c vbc vmb
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@birdsnest avatar
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UTC quote
You would probably have to change the whole jug to bump up to 150.

Also, I think maybe Gickspeed would be the guy to ask.




The Electronic Ignition options may also be worth looking at if you have some spare change.
⚠️ Last edited by Birdsnest on UTC; edited 2 times
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@christopher_55934 avatar
UTC

Ossessionato
2007 Stella 225
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@christopher_55934 avatar
2007 Stella 225
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Location: Rochester, Minnesota
UTC quote
Birdsnest wrote:
You would probably have to change the whole jug to bump up to 150.

Also, I think maybe Gickspeed would be the guy to ask.

The Electronic Ignition options may also be worth looking at if you have some spare change.
I saw where Jonathan had bored a factory cast iron P200 cylinder to fit an aluminum P225 piston. Also saw on hear where a 160 or 180 piston port motor had been bored to fit a P200 piston that had been welded up. It may not be a good idea, curiosity also seems to get me in trouble. I found several oversized piston options was just curious if one of the other larger was an option.

Nerd emoticon
@birdsnest avatar
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@birdsnest avatar
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UTC quote
Alos... this...
Quote:
the calculation is quite simple for anything to figure out cc or cubic inches of any engine, it is just a matter of first geting the square # from a round diameter measurement then multiplying in the stroke. the equasion is Y x Y=R x .7854 x STROKE= total cc, for instance on the 125cc were talking about say the bore is 54mm the stroke is 54.5. first to remember is we are tryng to figure cubic centimeter so we have to convert from mm, and in bore/stroke we are dealing with millimeter measurment so the cm bore is 5.4 (54mm) so 5.4 x 5.4=29.16 this times .7854=22.90cm(2290mm), this is the square cm/mm of the cylinder now simply multiply that by the stroke 5.45cm (54.5mm) and we get our cc --124.805 or 125cc
@v_oodoo avatar
UTC

Style Maven
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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UTC quote
Small world, I was wondering the same thing.
Hopefully Jon Gick will see this and help us out.
I got my old motor split, the ruined 125 piston out and the crank is toast along with the con rod, but the cylinder isn't too bad and can be bored. I'd kinda like to get it working now after giving up years ago. I have a rare useable 150 piston, Who has a spare rare crank?
GickSpeed wrote:
I really love those unique VNA engines.

If soaking them overtime abs hitting the pistons with a piece of wood does not prevail:

Option 1:
That being said, set the cylinder up in a press and use oxy-acetylene to heat up the cylinder. Then press out the piston.

Option 2:

Break out most of the piston and then use a boring bar to remove piston to wall. You are going 1st or 2nd over, so this part is fairly easy.

Option 3: but a good used VNA cylinder and a new piston. It may need bores, but the piston is not stuck either.
I started with this:

External inline image provided by member with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
You can see how close to rotary valve they were, it's already blanked out in the mold tooling.
You can see how close to rotary valve they were, it's already blanked out in the mold tooling.
@geeklion avatar
UTC

The Dude
Too Many piles of Junk that need too much work and too much money
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Posts: 1724
Location: PNW from LBC
 
The Dude
@geeklion avatar
Too Many piles of Junk that need too much work and too much money
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Location: PNW from LBC
UTC quote
Working on a 125 VNA, so I'm interested in this possiblity as well. My understanding is that the 125 is so limited as far as tuning, but that is also what makes it so unique!
@gickspeed avatar
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Location: Racing Capital of the World
 
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@gickspeed avatar
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Location: Racing Capital of the World
UTC quote
rowdyc wrote:
From my limited understanding, there's not much someone can do with the current setup to see significant gain.
.....but if someone buy a few pieces and know what there doing, you can see great improvement. https://www.sip-scootershop.com/en/wishlist/2a398a6d-b674-48bb-8ec9-029c964605c9
No. Those items are for a Widebody engine; will not work.
⚠️ Last edited by GickSpeed on UTC; edited 1 time
@gickspeed avatar
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UTC quote
V oodoo wrote:
Small world, I was wondering the same thing.
Hopefully Jon Gick will see this and help us out.
I got my old motor split, the ruined 125 piston out and the crank is toast along with the con rod, but the cylinder isn't too bad and can be bored. I'd kinda like to get it working now after giving up years ago. I have a rare useable 150 piston, Who has a spare rare crank?
GickSpeed wrote:
I really love those unique VNA engines.

If soaking them overtime abs hitting the pistons with a piece of wood does not prevail:

Option 1:
That being said, set the cylinder up in a press and use oxy-acetylene to heat up the cylinder. Then press out the piston.

Option 2:

Break out most of the piston and then use a boring bar to remove piston to wall. You are going 1st or 2nd over, so this part is fairly easy.

Option 3: but a good used VNA cylinder and a new piston. It may need bores, but the piston is not stuck either.
I started with this:

External inline image provided by member with no explanatory text
I honestly do not know where you would start with a 57 mm deflector piston, never thought about it. It's not like you are dealing with a domed piston. Frankly, I would just rebuild the engine with a fresh bore and standard 54mm VNA piston and leave it like that. Surely something can be done but the minimal gain would far exceed money & time thrown at it.
@neil_edgar avatar
UTC

Hooked
'81 50 special,'57 GS150 VS3,'59 152L2,'60 SII Li150
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Posts: 213
Location: The garden of England
 
Hooked
@neil_edgar avatar
'81 50 special,'57 GS150 VS3,'59 152L2,'60 SII Li150
Joined: UTC
Posts: 213
Location: The garden of England
UTC quote
I believe the 57mm piston can be used. With the shorter stroke you end up with 139cc. I don't have both pistons to hand at the moment to compare. There are plenty of oversize VNA pistons available up to 55.2, which gives 130cc.
@neil_edgar avatar
UTC

Hooked
'81 50 special,'57 GS150 VS3,'59 152L2,'60 SII Li150
Joined: UTC
Posts: 213
Location: The garden of England
 
Hooked
@neil_edgar avatar
'81 50 special,'57 GS150 VS3,'59 152L2,'60 SII Li150
Joined: UTC
Posts: 213
Location: The garden of England
UTC quote
It's also worth pointing out that good used cylinders for these motors are like Venus's arms, especially the 125's. And given the short time they were in production, I doubt they will ever be re popped.
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