Who runs their Commando between 7998 and 8022 rpm?
- Thread starter beng
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I don't even fantasise about doing that. It fills me with dread. I didn't even race my Seeley 850 for many years after I built it, because I knew what was in the motor, and I'm still amazed it hasn't gone bang in recent times, even with the revs kept well down.
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Once way back when fitting a single Mikuni Carb. was a brand new idea. 70 S model. The throttle jammed or the cable on WOT. as I was a teenager and wanted to test it but good. Thank god I was in first at 5 mph. Pulled in the clutch instantly realizing the imminent danger and watched the tach hit that range.Reached over with left hand turning off sidecover switch then panic dropped her. Heart beat like a hit of crack like I would know . The terror. No damage .
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Rohan
'How is the son of sir eddy's dommie coming along, that reportedly revs/ will rev to 11,000 (or was it 12,000) rpm ?'
My 500cc Triumph engine revved reliably t o 10,500. The stroke was 63mm and the valve gear was very modified. If anyone thinks they can do that with an 89mm stroke motor, they are kidding themselves . 82mm stroke Triumph 650 motors will cop 8,000 revs for a long time. The only reason I persevered with my 500cc Triumph for 12 years was that it was almost impossible to destroy the bottom end. Apart from that it was a pain in the backside to race it. I don't need that sort of anxiety. I suggest we should look at the strenghths of the commando engine design, and use them to the max, and I personally don't believe it is at the top end of the rev range. Alternatively simply buy a nice big Nourish Weslake engine, it would be cheaper.
'How is the son of sir eddy's dommie coming along, that reportedly revs/ will rev to 11,000 (or was it 12,000) rpm ?'
My 500cc Triumph engine revved reliably t o 10,500. The stroke was 63mm and the valve gear was very modified. If anyone thinks they can do that with an 89mm stroke motor, they are kidding themselves . 82mm stroke Triumph 650 motors will cop 8,000 revs for a long time. The only reason I persevered with my 500cc Triumph for 12 years was that it was almost impossible to destroy the bottom end. Apart from that it was a pain in the backside to race it. I don't need that sort of anxiety. I suggest we should look at the strenghths of the commando engine design, and use them to the max, and I personally don't believe it is at the top end of the rev range. Alternatively simply buy a nice big Nourish Weslake engine, it would be cheaper.
Rohan said:
Really? The Atlas 750 was a Dommie, with an engine identical to the first Commando except for the balance factor and intake manifolds. The 650 was functionally the same as the 750 except for a smaller bore size. Lots of Dommies had the same cam and valvetrain as Commandos.
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That is a bit mean. Rohan was simply being perverse as ever. My feeling is that even the commando engine is the same old rubbish as the early dominator. There is obviously a developmental progression. Wishing won't make a commando into a Japanese four cylinder superbike, and would anyone really want that ? Love them for what they are, however please don't fantasize about them. I love my commando engined bike, however I don't kid myself that it hasn't got limitations.
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I wonder if it would be practicable to fit a 5mm chrome-moly plate and centre bearing, between the crankcase halves of a commando engine, and use a roller crank out of an XS2 Yamaha, and separate barrels with Norton head and a construction to hold barrels, followers and pushrod tubes ? That would be able to be revved to 8000 RPM reliably.
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