D.O.H.C. ? I want one of these
- Thread starter dobba99
- Start date
- Status
lcrken
VIP MEMBER
- Joined
- Mar 15, 2009
- Messages
- 5,022
kommando said:
Do you have any more info on Les being involved with the Merlin design? I remember him taking over the Piper 8-valve pushrod head project, doing some more development, and racing a bike with it for a while. But I've never seen any reference to him taking over the Merlin DOHC design.
I believe he later sold the pushrod 8-valve head rights to Andy Molnar.
Ken
Chris
VIP MEMBER
- Joined
- Jan 21, 2008
- Messages
- 1,691
Hi
Les developed the piper head. We had quite a bit of info in an earlier thread.
The twin cam Merlin is a much rarer beast. Never seen one in the flesh but remember reading about them & being told that the engine was raced hard in a wasp sidecar.
Chris
Les developed the piper head. We had quite a bit of info in an earlier thread.
The twin cam Merlin is a much rarer beast. Never seen one in the flesh but remember reading about them & being told that the engine was raced hard in a wasp sidecar.
Chris
lcrken
VIP MEMBER
- Joined
- Mar 15, 2009
- Messages
- 5,022
Pete, thanks for posting the articles. I recall seeing articles about the Merlin conversion back in the day, but didn't save any of them. On one of my business trips to England in the '80s I saw a complete Merlin engine for sale in the classifieds in MCN, and had fantasies of buying it and shipping it back, but couldn't quite make it happen.
The only other info I have is this clip from Roy Bacon's book.
Ken
The only other info I have is this clip from Roy Bacon's book.
Ken
Someone locally has something similar to that on a late 60s or 70s Triumph 650 twin, done a few years after,
although the drive to the cams was on the timing side.
Apparently it ran very well on the road, he'd ridden it to the show where it was on display.
Can't recall that all-out performance came into the conversation though.
When the dohc can go faster than the motor it sits on top of, bit of a mismatch ?
Thanks for posting article...
although the drive to the cams was on the timing side.
Apparently it ran very well on the road, he'd ridden it to the show where it was on display.
Can't recall that all-out performance came into the conversation though.
When the dohc can go faster than the motor it sits on top of, bit of a mismatch ?
Thanks for posting article...
- Joined
- Dec 10, 2008
- Messages
- 7,253
The advantage of four valves is not necessarily the added rpm or horsepower capability as it is the ability to have a wider powerband along with the good horsepower. When using two valves you can get good horsepower but it comes with a narrow powerband.
The double overhead cams were likely adopted as an easy way to operate all them valves. Jim
The double overhead cams were likely adopted as an easy way to operate all them valves. Jim
Nater_Potater
VIP MEMBER
- Joined
- Apr 7, 2013
- Messages
- 1,342
While the DOHC is cool, I'd be more interested in the four-valve-per-cylinder head for the reasons Jim points out. Does anyone make a pushrod variant?
Nater_Potater said:
There was mention above, and alsewhere of the Piper 8 valve head - that Andy Molnar acuired eventually. (?).
It wasn't really viable though, and it didn't get into production.
It also made a Commando look like an (ugly) CB250 clone on steroids ....
- Joined
- Jun 30, 2012
- Messages
- 13,901
Rohan said:
Would you personally attempt to ride it ? I would never stroke a big twin down to less than 75mm. It would probably cop 12,000 RPM if the valve gear kept up. You wouldn't have the case and bearings problem in the bottom end. DO IT ! - A 750cc Paton ?
The way to go might be to look at the Nourish Weslake Triumph head and work out how large you can make the bores , then stroke the commando motor to get 750cc, and make barrels and crank to suit. If the Weslake combustion chamber is too narrow, you might end up with a good squish band. There is an 80s Triumph thunderbird which has a steel one-piece 75mm stroke crank.
http://www.motorcyclespecs.co.za/model/ ... 20tr65.htm
- Status
Similar threads
