Topic: sohc3: cams

[carsholduptraffic]

i have been going through my parts box, and i have a 750 cam that has been radically modified by persons unknown. side by side with the 'stock' cam i have pulled out of the bike, it has had its 'base circle ground so that it looks to give about 3-4mm more lift but the lobes don't look to have been altered. this is from my calibrated eyeball gauge though......
i have read that the 750 (836 actually) likes more duration over more lift to make the most of itself. i have stock carbs. any 750 wizards out there have an opinion on cams for a daily (spirited) 750 commuter??? more power is always nice, but it's kick only, and reliability is an issue. (my bosses words- but he drives a jeep- how would he know)
i have another head, ported to the max, but no valve seal provision on the exhaust side. looks like new guides in it, and it was once destined for a drag setup, as was the hot cam.
so is more lift worth it, and will running a head with 1/2 the valve seals missing be a bithch to live with?
nick in canberra
(i hope to post pics of the head tomorrow)

[MRieck]

Oh boy...I can answer your questions but not now. I'll post tomorrow.

[MRieck]

A stock CB head likes more duration because it has crappy ports and requires alot of time to fill. Unfortunately this has a somewhat negative effect on acceleration but a positive effect on top speed. A Megacycle 125-65 cam is good cam with an 836 kit and some port cleanup. (.375IN/.350EX I forget exact duration). You need a decent port to take advantage of the quick fill offered by any high lift cam. The exhaust guides without the seals is stinks....period. If you change the guides out you will need a valve job too as the new guides will not center up with the existing 45 degree cut on the seat. That race head has probably been milled too- I wonder how much? You can measure the base circle on a stock cam and compare it to the regrind to see how much extra lift there is. I'd doubt if it is much over 2mm.

[carsholduptraffic]

thanks for the info MRieck....
any day now for me working out how to make the pictures appear on the internet!!!
my k2 has far less compatibility issues than my computer.
the sohc3 is at cold bare matt black frame stage. lopped the pillion mounts, extended steering stops to suit cb900 triple clamps, tapered rollers go in tomorrow when the paint dries on the triples.
should roll on saturday. then its motor time.