c50 to c90

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periklis
Posts: 1
Joined: Fri Jun 16, 2017 9:06 pm
Rides:: honda c50z

c50 to c90

Post by periklis » Fri Jun 16, 2017 9:10 pm

Hello everywhere,
How can i upgrade my c50 to c90. I have already upgraded it to c70 but i need a little more. 90cc or even 100cc would be ok. What is needed and how much does it cost?
Thank you very much

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Alan CF
Posts: 6750
Joined: Mon May 09, 2011 6:10 pm
Rides:: CUB RACING small cc engine rebuilds crank repairs
Location: CHESTERFIELD

Re: c50 to c90

Post by Alan CF » Fri Jun 16, 2017 9:26 pm

is your c50 a 12v model or 6v with points, if its a 6v with points you cant do it,(it can but its to much work and finding parts will be impossible).
Your better off fitting the 12v c90 motor. now if its a 12v c50 then its not that hard to do.

Scrub that... just seen you have put c50z in your profile.

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steveST100
Posts: 1888
Joined: Tue Oct 25, 2011 3:04 pm
Rides:: 1983 C50LAC 1976 ST100 1980 ST70
Location: Clitheroe Lancs

Re: c50 to c90

Post by steveST100 » Fri Jun 16, 2017 11:41 pm

If its the 6v c50 and you have it already up to 70 fit a 88cc 52mm barrel and piston set up.If you have the 6v c70 head on there already this is the best set up for the 88cc maybe fit a r20 cam or a Honda SS50 fast road cam.
Had this set up on a 6v ST70 engine fitted with a ATC125 carb.
You can go up to 54mm barrel(95cc) if you bore the cases out to take it,and if you fit a 50mm stroker crank to the 54mm its 115cc.Yes you can get them with the 6v taper as well as i have one.

steve g

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denner
Posts: 27
Joined: Sun Aug 16, 2015 11:16 am
Rides:: 1991 Super Cub C50G (81cc)

Re: c50 to c90

Post by denner » Fri Jun 16, 2017 11:58 pm

If we are talking about a standard C50, there is no need to bore the cases, you can just use an aluminum 57mm short-throw cylinder and just cut off the cylinder extension that goes to the crankcase. Then all you need to do is to get a short-pin 57mm piston and shave off the skirts around the pin and it will work like a charm, bringing everything to 105cc with an insane revving sequence due to the short throw of the 41.4mm stroke. No need to go crazy on the carburator, on the contrary, from personal experience I have had the best results with the standard 16mm one, especially for low/middle rpm.

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steveST100
Posts: 1888
Joined: Tue Oct 25, 2011 3:04 pm
Rides:: 1983 C50LAC 1976 ST100 1980 ST70
Location: Clitheroe Lancs

Re: c50 to c90

Post by steveST100 » Sat Jun 17, 2017 1:12 am

Scut piston.
Image
Barrel.As you can see skirt cut off.
Image
Sorry but not for me.

steve g

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