BBK for the 244cc? By Guitarman (Read 1,494 times)

[Guitarman]

Is there a big bore kit for the 244cc water cooled engine? I want to add more power if possible.

[kz1000st]

Are we good, or what?

www.partsforscooters.com/169-394-Hoca-CN250-Big-Bore-Kit

[Guitarman]

Thanks! Do you know what that will boost it up to?
I don't see any real specs listed.

[Alleyoop]

From what it says, it is a 75mm piston and yours is 72mm
Alleyoop

[bobf]

Can we divide 244 cc by 72 mm and then multiply by 75 mm to get 254.17 cc? Or is this way too simplified and likely stupid? Just wondering.

Maybe area is a better deal. A=PiX(RxR)

We have 3.14X(36X36) or 3.14X1296=4,069.44 for 72 mm

or have 3.14X(37.5X37.5) or 3.14X1406.25=4415.62 for 75 mm

then 244/4069.44=0.06x4415.62=264.76 cc?

Surely there is someone on this forum that knows how to calculate the improved horse power, if any.
.

[Guitarman]

I think you mean 254cc Bob. And thats how I would do it, but I'm no expert and like you, I wonder if that's just too simple of an answer. And if it is correct, I'm not sure 10cc is worth it. I was hoping to push it up to a 300 or better if possible.

[Alleyoop]

The 244cc has a 60mm stroke so here are some displacement figures:
Alleyoop

Cylinder Bore Displacement
(with stock 60 mm stroke) 73mm 251cc 75mm 265cc 77mm 279cc
78mm 286cc 80mm 302cc

[Guitarman]

I would need an 80mm BBK to get where I want. Hmmm.... Will my crankcase even mod to that size? That sounds like quite a large adjustment to make in it. Bore it out an extra 8mm? Would that weaken the walls too much?

[Alleyoop]

To answer that question you would have to take the head off and look at the case to see if the stud holes and the chain valley would have enough meat left to not bust through it with the vibrations.
Alleyoop

[Guitarman]

Do you have to drill it out the entire length into the crankcase, or just where the piston head moves?

[Alleyoop]

Enough so that the JUG goes down and the head flush with the gasket on the case.
Alleyoop

[vansmack2]

That bore kit will get you to 265cc. You can calculate the cc here.
www.bgsoflex.com/displacement.html

Be sure you set measurements to millimeters.

[Guitarman]

vansmack,
Thanx! what a handy tool.

Do you have one that does watts to Horses?

[vansmack2]

For watts to horsepower try one of these I found with a quick Google search.

www.rapidtables.com/convert/power/watt-to-hp.htm

www.unitconversion.org/power/watts-to-horsepowers-conversion.html

www.convertunits.com/from/watt/to/horsepower+%5Bmetric%5D

[Bashan]

Mike at Buggy Parts NW deals exclusively with the 244 cc vertical engine. He is mainly a buggy guy but he sells a lot of scooter parts also. He's told me that after one of his BBKs the scooter can smoke the rear tire. He ain't cheap but he sells good stuff. Mike is a very nice guy and if you call there he'll talk to you. Here's a couple of the BBKs on his website.