Getting the most out of a 125

Anything else ya ride!
davebike
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Rides:: C90G(12v) CB500R FZ6Fazer
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Re: Getting the most out of a 125

Post by davebike » Fri Oct 13, 2017 7:09 am

Odd
I run a tuned (better cam valve springs and inigtion ) 90 (85cc) engine with an ACF70 four speed gearbox and I touched 60 on the flat !
But I got a rev counter and spent some time setting up the gearing to be spot on !

DW

ChesterC90
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Joined: Mon Mar 20, 2017 10:01 pm
Rides:: C90 and Lambretta

Re: Getting the most out of a 125

Post by ChesterC90 » Fri Oct 13, 2017 6:10 pm

I've heard of modding your standard c90 engine, taking it up to 110 using a 70 head? But I've mot done enough research to understand how it works.
Getting on a bit does slow the old noggin. So I come here? For advise and inspiration!

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Diesel Dave
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Joined: Tue Oct 13, 2009 7:25 pm
Rides:: 1965 Enfield Diesel, 2017 Sterling, Modenas Kriss and CT200 - the only Cub left
Location: Brentwood, Essex

Re: Getting the most out of a 125

Post by Diesel Dave » Fri Oct 13, 2017 6:17 pm

Try going for a run at full speed but your only allowed to breathe through a straw.

You will take off like a scalded bat but be unable to reach anything like top speed.

Your carb is waaaay too small for a 125 unless you want a trials bike with loads of torque and bottom end but no rev's

ATC carb and BBR manifold would allow the motor to breathe much better.

ChesterC90
Posts: 38
Joined: Mon Mar 20, 2017 10:01 pm
Rides:: C90 and Lambretta

Re: Getting the most out of a 125

Post by ChesterC90 » Sat Oct 14, 2017 7:54 pm

Update:

Fitted a mikuni 28 carb, which I know is probably too big, but 1st signs are good. Bike starts and runs, but Boggs when either the main jet or needle come into play.
Going to 1st try needle on top and middle, then get into main jets. I'm thinking the pilot I ok, as it runs well when ridden 1/4 throttle.

And the sound.. Well it's like a my neighbours Harley, very loud with some great tick over notes.

I'm hopefull this carb when set up right will do the trick, remains to e seen if it can go over 50, but fingers crossed.

Thanks for the input by other members.

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Diesel Dave
Posts: 10254
Joined: Tue Oct 13, 2009 7:25 pm
Rides:: 1965 Enfield Diesel, 2017 Sterling, Modenas Kriss and CT200 - the only Cub left
Location: Brentwood, Essex

Re: Getting the most out of a 125

Post by Diesel Dave » Sun Oct 15, 2017 8:22 am

Main jet size first - everything else follows.....

ChesterC90
Posts: 38
Joined: Mon Mar 20, 2017 10:01 pm
Rides:: C90 and Lambretta

Re: Getting the most out of a 125

Post by ChesterC90 » Sun Oct 15, 2017 5:48 pm

Have you a link on flea bay where you got your atc 1 Dave?
Cheers

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Diesel Dave
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Joined: Tue Oct 13, 2009 7:25 pm
Rides:: 1965 Enfield Diesel, 2017 Sterling, Modenas Kriss and CT200 - the only Cub left
Location: Brentwood, Essex

Re: Getting the most out of a 125

Post by Diesel Dave » Mon Oct 16, 2017 11:01 am


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gtd65
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Re: Getting the most out of a 125

Post by gtd65 » Mon Oct 23, 2017 11:54 pm

Strange, my Rider's Super Cub goes a lot faster than that and it's totally standard.

I've had (an indicated ) >100km/h on the speedo.

Nips along very happily at 85~90 km/h on the flat too.

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