Planet Minis

kball · 12-01-2009, 03:51 PM

I have a bunch of decent ct70 parts. I did a search and found all kinds of threads about mixing and matching parts. Couldn't you take a complete top end from a ct70 engine and stick it onto a crf50 bottom end? I have a pretty fresh piston from one my cr70s but the trans is shot. So I was thinking about trying to put the whole ct70 top end-piston, cylinder and head onto my 50 for a ghetto big bore conversion since it'd be all free and I have all the gaskets here. I just want to see if anyones done it before I tear it all down.

dirtbkr188 · 12-01-2009, 04:55 PM

Only if you're using a top end from a '91-'94 CT70, all the other years are 6V short rod engines. A short rod piston on the 12V long rod engine will hit the head or a valve.

XRshfifty · 12-02-2009, 02:19 AM

Thats how my bike is set up.

everything here.

POWROLL PRODUCTS FOR THE CRF50 & XR50

kball · 12-02-2009, 11:24 AM

Seems like i'm better off to just get an 88 kit for the crf and stick the complete ct70 engine into my 78 z50

hammer_213 · 12-02-2009, 04:16 PM

i put a ct70 top end on my 50 once.. made a spacer that goes under the head and used two lower head gaskets.... it actualy ran awesome ( as a matter of fact its still in my buddys 50(70) today)...

so it can be done!!!!!!!!

12-01-2009, 03:51 PM	#1 (permalink)
kball PM Newbie Join Date: Jun 2008 Posts: 63	ct70 head, cylinder and piston onto crf50 bottom? I have a bunch of decent ct70 parts. I did a search and found all kinds of threads about mixing and matching parts. Couldn't you take a complete top end from a ct70 engine and stick it onto a crf50 bottom end? I have a pretty fresh piston from one my cr70s but the trans is shot. So I was thinking about trying to put the whole ct70 top end-piston, cylinder and head onto my 50 for a ghetto big bore conversion since it'd be all free and I have all the gaskets here. I just want to see if anyones done it before I tear it all down.

12-01-2009, 04:55 PM	#2 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 3,105	Re: ct70 head, cylinder and piston onto crf50 bottom? Only if you're using a top end from a '91-'94 CT70, all the other years are 6V short rod engines. A short rod piston on the 12V long rod engine will hit the head or a valve.

12-02-2009, 02:19 AM	#3 (permalink)
XRshfifty PM Newbie Join Date: Dec 2009 Location: Portland, OR Posts: 11	Re: ct70 head, cylinder and piston onto crf50 bottom? Thats how my bike is set up. everything here. POWROLL PRODUCTS FOR THE CRF50 & XR50

12-02-2009, 11:24 AM	#4 (permalink)
kball PM Newbie Join Date: Jun 2008 Posts: 63	Re: ct70 head, cylinder and piston onto crf50 bottom? Seems like i'm better off to just get an 88 kit for the crf and stick the complete ct70 engine into my 78 z50

12-02-2009, 04:16 PM	#5 (permalink)
hammer_213 PM Newbie Join Date: Sep 2009 Location: Denver Posts: 82 My Mood:	Re: ct70 head, cylinder and piston onto crf50 bottom? i put a ct70 top end on my 50 once.. made a spacer that goes under the head and used two lower head gaskets.... it actualy ran awesome ( as a matter of fact its still in my buddys 50(70) today)... so it can be done!!!!!!!!

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