C90 into st70
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- Posts: 8
- Joined: Tue May 14, 2019 5:27 pm
- Rides:: St70
C90 into st70
Hi all,
Anyone advise on any problems doing the above, its a 6v c90 engine.
Many thanks.
Anyone advise on any problems doing the above, its a 6v c90 engine.
Many thanks.
- wightegi
- Posts: 9719
- Joined: Tue Sep 01, 2009 7:23 pm
- Rides:: 12v 1988 e start C90,Royal Enfield Interceptor 650
- Location: Isle of Wight
Re: C90 into st70
50 and 70 engines are the sane size as the 12 volt 90 , the 6 volt 90 will not fit in these frames , the big valve C70 bike is faster than the 6 volt 90 one
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- Posts: 8
- Joined: Tue May 14, 2019 5:27 pm
- Rides:: St70
Re: C90 into st70
Thanks, next question is where can i get a big valve head, anyone know?
Thanks again.
Thanks again.
- steveST100
- Posts: 1889
- Joined: Tue Oct 25, 2011 3:04 pm
- Rides:: 1983 C50LAC 1976 ST100 1980 ST70
- Location: Clitheroe Lancs
Re: C90 into st70
Yes it can be done.
Lot of work and some cutting of the frame to fit it.
Will be a pain to do the wiring.
Stick to the 6v 50/70 and 12v 50/70/90/110/125 for it.
steve g
Lot of work and some cutting of the frame to fit it.
Will be a pain to do the wiring.
Stick to the 6v 50/70 and 12v 50/70/90/110/125 for it.
steve g
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- Posts: 8
- Joined: Tue May 14, 2019 5:27 pm
- Rides:: St70
Re: C90 into st70
Thanks for that info, i want to keep my bike as original as possible so i really dont want to cut the frame, i will hunt for a c70 head, i understand its pre 79 bikes that had them, any pointers towards one would be gratefully received.
- steveST100
- Posts: 1889
- Joined: Tue Oct 25, 2011 3:04 pm
- Rides:: 1983 C50LAC 1976 ST100 1980 ST70
- Location: Clitheroe Lancs
- Barnsey
- Posts: 187
- Joined: Fri Aug 11, 2017 12:31 pm
- Rides:: Honda C50 BMW R100
- Location: Portsmouth, Hampshire
Re: C90 into st70
Check this out:
Ebay part number 322387613092 .
I ordered one of these, and I was relieved that it bolted straight onto my 1973 C50 engine. I just can't say how well it runs as I haven't started it yet.
Regards,
Ian
Ebay part number 322387613092 .
I ordered one of these, and I was relieved that it bolted straight onto my 1973 C50 engine. I just can't say how well it runs as I haven't started it yet.
Regards,
Ian
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- Posts: 8
- Joined: Tue May 14, 2019 5:27 pm
- Rides:: St70
Re: C90 into st70
Steve g, thanks for the big valve link, can you tell me if all big valve heads are bi metal, its just i looked at my spare c70 motor, its an early one with a downdraught carb, the head is not bi metal but the valves are marked with 7's not 7's in circles, the top of the inlet valve measures 26.45mm, thats accross the top in situ, so is it a big valve one?
Many thanks.
Many thanks.
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- Posts: 8
- Joined: Tue May 14, 2019 5:27 pm
- Rides:: St70
Re: C90 into st70
Apologies, they are 25 and 22mm not as i said before.
- steveST100
- Posts: 1889
- Joined: Tue Oct 25, 2011 3:04 pm
- Rides:: 1983 C50LAC 1976 ST100 1980 ST70
- Location: Clitheroe Lancs
Re: C90 into st70
Most but not all the bi-metal big valve 70 heads i have had were from the early downdraft carb models. Think some may have been swapped for later 6v heads or ones from the ATC70 engines. Have had a lot of good fast engine builds using the smaller of the 2 big valve heads,work best with a good fast road cam. One non bi-metal head i had that took the bigger valves was from a CT70H engine.
steve g
steve g