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74-77 GT 750 cylinders..how to tell
Posted: Tue Jun 24, 2014 10:29 am
by T350guy
When looking for cylinders how can you tell the difference between say the 74 and later 75-77 cylinders.
My later 77 GT 750 cylinder has seen better days and maybe cheaper to buy another than repair.
Ian
Re: 74-77 GT 750 cylinders..how to tell
Posted: Tue Jun 24, 2014 1:20 pm
by jeff kushner
Offtopic but are you the same "Ian" that is building the H1 turbo that I've been talking to off and on over the past year?
jeff
Re: 74-77 GT 750 cylinders..how to tell
Posted: Tue Jun 24, 2014 2:55 pm
by tz375
Fortunately that's really easy if you have the barrels in front of you.
Externally there is no significant differences between an L and M-A-B cylinders.
The ports are very different though. L has the same ports as a J or K. Exhaust roof 42.5mm down and inlet floor 101mm down.
M-A-B have exhaust roof 40mm down and inlet floor 106mm down.
Best street barrel IMHO is a J-K-L and best performance barrel is the later one. The issue is intake height on later motors hurts low to midrange performance. So for a mild street bike get an L block and raise the exhaust port slightly for the best of both worlds.
Re: 74-77 GT 750 cylinders..how to tell
Posted: Tue Jun 24, 2014 10:29 pm
by T350guy
jeff kushner wrote:Offtopic but are you the same "Ian" that is building the H1 turbo that I've been talking to off and on over the past year?
jeff
Sorry not me Jeff But I do have a H1...H1B that is
Thanks for the info on the cylinders.
I'll keep that in mind when I'm looking .
Ian