Motoscrubs.com

I have read somewhere that the carb body is the same and the internal venturi is what determines the size. Does it seem likely I can find the part? My carb is too big for efficient airflow and I am also looking for a better cam for traffic riding.

Hi Bob, there comes a time to us all when high performance machine is no longer enjoyable. I am no expert but would a plate under barrel bring compression down or a low compression piston to give better low speed handling. Gotta keep on keeping on.

The bike was once a racer and has been converted back to road trim, but the engine is still in race tune. Too much hassle by far.

Bob ....different bike but same story.....In the late 1970s I bought a BSA 650 super rocket.....great bike but in too high a state of tune and a pig to ride slow or gentle, spitfire camshaft, high comp pistons big valve alloy head, I think a 32mm carb, and a pair of goldie silencers, was good for about 105mph and did 60 mpg. so I stripped the engine gave it a rebore (which it needed) fitted concave top 6.5 to 1 pistons, fitted a std. gold flash camshaft, fitted a small valve iron cylinder head, a 26mm carb, and a 2 to 1 sidecar exhaust system. Result.....the nicest bike to ride you could ask for (I kept it for seven years as everyday transport) it now did 90mph, and 90 mpg, so it lost 15ish mph in top speed but gained about 30 more mpg and you could have ridden it at 15mph in top gear........I am quite tempted to detune my 74 350 mk3 down to 350 sebring engine spec.....................
Cheers,
George

I am quite tempted to detune my 74 350 mk3 down to 350 sebring engine spec.....................

OH! Really George?

Not sure about Sebring spec? But, certainly not going to use a lumpy piston, or big valves in my late '75 350 MKIII (Spanish motor!) rebuild.

Good health, Bill

The 1976 350 road recent restoration included new first oversize piston from Nigel, standard size valves and new 30 Amal carb.
Still running in but so far easy to ride with good pulling power and relaxed 50 /55 mph cruising at about 4000rpm.
Even better now I have the knack of kick start thanks to other George's tips.

Bill,......well maybe.......possibly......I might...... I'm 70 next year but its hard to let go of the 21 year old hooligan that still craves the drug of that light, noisy, fast, super handling, and now properly rare Ducati single
Cheers,
George

Aye George (BMS), snap on all those points, including the '54 burpday!

Aye other George, thank you for the info on your rebuild. I have a cracked cylinder liner, knackered piston and umteen other horrors to deal with, so plenty to keep me entertained and to empty the piggy bank!

Good health, Bill

My main problem will be the 40mm inlet valve and 36 mm exhaust. the rest is easy to deal with. A swap with the early Mark3 head would be the simple solution.