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Discussion Starter · #1 ·
Hello, i have a blata b1 rep and i have seen a couple of videos of People putting a scooter 70cc on it.

I would like to do that, and i am totaly up for the task.
What cylinder from witch scooter or moped would you think is ideal?
It needs to be the same stroke or if the cylinder has a larger stroke it needs to go in the lathe and cut of the extra amount, right?
 

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Discussion Starter · #3 ·
Yes, i have had a lot of scooters with 70cc kits, some of Them still had Stock crank and was still very powerful and reliable.

my stock blata rep cylinder have seen better days and the casting on it is just terrible. I could only find one shop that shipped to Denmark and the price was very high for a Chinese cylinder.

in Denmark you can buy a lot of used scooter parts for cheap, so I would save some money, get more power with a 70cc.

I know this isn’t an easy process.
 

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Sounds cool I have never seen one like that there was a member that took a scooter cylinder and put it on a CAG engine he couldn't get the clutch to hold that much power it was a beast.

He machined an adapter plate to widen the ports to make it bolt up.

You really should consider a engine swap since a lot of the Euro bike engine will fit your frame
 

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Jozy did something like that a while back with his bzm powered scooterino. Slapped a 70cc jug on his bzm bottom end. Chris did that to. Just search bzm 70cc and you should find their posts.
 

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Discussion Starter · #8 ·
One of my friends told me that i could put a longer connecting rod in the crank to have a longer stroke. But wouldn’t that mean that the crankshaft had to be balanced?
 

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You will have to recalculate the balance factor and probably add tungsten to the crank counterweight no matter what you do since the 70cc piston is substantially bigger and heavier.
 

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Discussion Starter · #10 ·
You will have to recalculate the balance factor and probably add tungsten to the crank counterweight no matter what you do since the 70cc piston is substantially bigger and heavier.
Hmm, just didnt see the other ones do it.
But you are probably right.
I just know that on scooters you don’t need to do that, it will run just fine with a 70cc kit on stock crank
 

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What's your poison? Mine is 40:1
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I believe you don't need to rebalance the crank. But I also have never owned one to try. There is always a balance but close is fine on these little 2 strokes IMO.
I haven't balanced one yet with no issues.
 

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Two stroke stuffing on YouTube has videos on both how to calculate the BF and how to add tungsten.

I think it's a two part series but it might be 4 but basically you way everything on a scale do a bunch of math then add tungsten to the crank
counterweight going from 39mm to 49mm is going to need to be balanced or it will shake all the bolts out of everything and a lot of your horse power gains will go into shaking the frame.
 

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Discussion Starter · #14 ·
Two stroke stuffing on YouTube has videos on both how to calculate the BF and how to add tungsten.

I think it's a two part series but it might be 4 but basically you way everything on a scale do a bunch of math then add tungsten to the crank
counterweight going from 39mm to 49mm is going to need to be balanced or it will shake all the bolts out of everything and a lot of your horse power gains will go into shaking the frame.
Okay thanks i Will look into that.
If I add a 2-3mm aluminum plate to enlarge the transfer ports and make a smooth transition, doesn’t the cylinder become too high and then I would need a longer stroke right?
 

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Yea just make your mock up connecting rod out of aluminum flat stock then send it to hot rods to have it made out of tool steal or whatever you think will fit and handle the power
 

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No that's bizeta that will not fit in your rep bikes crankcase

Yours is a Blata copy

I wouldn't even consider thinking about purchasing anything more then the piston and cylinder until you have your adapter plate mocked up and almost in a functional state

And you might have to buy a crankshaft and rod set and press apart the crank and swap rods or find a rod in a Yamaha or something but you won't know until you have your stroke worked out and know the exact length of connecting rod you need you really can't even look at anything...

Ideally you would want to try to work it out so you can get the stock crank and rod to work.
 

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Discussion Starter · #19 · (Edited)
The bzm crank fits blata + replica import, at least that what it says.

and yes you are right.
I messaged 2strokestuffing, and he said I could not use stock crank, then I would lose 3mm of port and won’t make good power, and changing the rod to a different length won’t change the stroke.
 

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Interresting stuff guys. Can't yet help you with this theme, but we have a lot of scooter parts around here, so I will check with one of my mates what he thinks about it.
 
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