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Discussion Starter · #1 ·
as title suggest. Main concern is difference in revs per cylinder size .

Rather I high rev higher top end wear 125 over slower more torque bottom end gearbox blowing 160 ETC..

Is the 140 better balanced and so on ?
 

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If your talking out of the box stock. The 140 might be the in between motor i'm to sure though. Because most of these aftermarket motors were built for pitbikes. Most offroaders prefer low to mid power motors. But when i got my 150cc it seemed to have been well balanced.
The smaller motors can rev and scream all they want. They will always be out powered by the bigger motors on the tracks.
My 165cc with the v2 race head and takegawa s35 race cam revs like crazy! And keeps pulling it makes all the hp on the topend. It is a true road race cam for sure so i sorta have to ride like a 2stroker.
I'll throw this in also,with the smaller motors if you want more power. Then it's gonna cost alot more than they are worth and you'll reach the limits fast. With the bigger motors you have a little bit more to play with and get more bang for the buck.
Down side to the big motors is, if your trackbike suspension and brakes not up to par You will find out real fast! The bike will seemed to take more work out of the rider to ride.
 

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Discussion Starter · #3 ·
cheers, I'll build this from scratch and will want to go all out......brakes, suspension will be taken care of.

My main concern is , I have a few of these 110&125 engines from dirtbikes and the gearbox has gone on all of them .

Do you blokes now of "underbone" racing class that's popular in asia ?

I am hearing cbr125 or a cr80 gears are going in or someone is making a kit to put these in what is original a honda Ct110/125 3 speed semi auto step trough Scooter that this " underbone" class is based off .









?
 

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First time i've heard of it. Definitely sounds interesting though. I've been screaming for 5spd trans for years. The only bolt in ones i know of is the takegawa ones. And i heard people complaining about them breaking just from kick starting the motor.lol I'll have to look into this.
 

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Discussion Starter · #5 ·
yea, google underbone as I first heard about it by word of mouth not long ago , turns out philippines , macau etc even have street races , clips on youtube.

I think the name comes from the single steel rail chassis with engine mounted Underneath off it ala the Ct110/125.

These things were & are used by our postal service for 30+ years. As kids you could get a crate of 5 of them all wrecked for $50 and manage to scrape one working bike together.
 

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Yes I've looked then up and saw some vids with some great racing! Although i wasn't able to find anything on the 5speed trans conversion though. I did find tons on the 4speed conversion though. I suspect that the 5 speed conversion will take some trickery. Cuase i know the takegawa 5speed conversion has really narrow gears. This is what led to them breaking or not holding up. I would love to see the conversion or how they even made them fit. The cr80 or cb125 gears to fit that is. I think the gear stacks would be to long and they must have cut down the gears. In order to make the fit in the 110cc's.
 

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Discussion Starter · #7 ·
give me a couple of days and I will find out name of site/company

The 5 speed shouldn't be hard to find as the Ct125 were released with them.
 

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Yes but the honda ct125 had a vertical motor in it if my memory serves correct. And most if not all the vert motors had wider lower engine cases. Which ment the gear stacks was longer for beefier gears. Otherwise the xr80 gears would fit in these horizontal style motors. That's what i was looking at using years back when i wanted a 5spd trans for my motor.
 

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Discussion Starter · #9 ·
ah I see, wikipedia set me straight.

Here goes , we had 2 Ct125's . The "trail" version , yes based off xl. Our other version is like your dax 70/90 but bigger all round. If you google image search 'Ct125 postiebike' you will see the australian only released model . We never got the dax down here. Z50 or our bigger version of dax that ranged from 90/110/125 semi auto 3-5 speed.

Basically if we wanted the xl based model we needed to specify the 'trail' version .








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