SOHC.co.uk Forums > CB750
750 K2 Strip & Rebuild - help please
Lobo:
Whilst I was there a couple of cranks were done Ash, the first whose balls were rather proud 🥹, and mine whose were relatively recessed. The 1st crank, well, they popped out at first strike of the cold chisel, and on mine a couple+ of strikes were necessary, with one re-TIG’ing of a blob - the outcome tho’ was never in doubt.
Be sure to have replacement balls….
Lindsay mentioned the latter grub screws, and also that on any ball-plugged cranks intended for racing he’d tend to modify them to this.
Nige, many discussions wrt Synthetic oils…. do I assume you use it in your SOHCs with no detriment to the clutch? And if so are you increasing the change times?
AshimotoK0:
--- Quote from: Trigger on March 26, 2022, 06:31:38 PM ---You should always remove the balls when cleaning a crank. The later 750 crank has grub screws with are easier to remove ;)
--- End quote ---
What's your recommended method for removing the balls Graham?
Trigger:
--- Quote from: AshimotoK0 on March 27, 2022, 12:50:49 PM ---
--- Quote from: Trigger on March 26, 2022, 06:31:38 PM ---You should always remove the balls when cleaning a crank. The later 750 crank has grub screws with are easier to remove ;)
--- End quote ---
What's your recommended method for removing the balls Graham?
--- End quote ---
Crank in a big vice, lay a penny washer over the ball, weld a rod to the ball, attach the slide hammer to the rod and pull out ;) Never tried a chisel before.
K2-K6:
--- Quote from: Lobo on March 26, 2022, 09:26:43 PM ---Nige, many discussions wrt Synthetic oils…. do I assume you use it in your SOHCs with no detriment to the clutch? And if so are you increasing the change times?
--- End quote ---
yes to using it in sohc engines without clutch problem.
It's as you mention a contentious subject. Routinely I've never ever worn a clutch out on bike or car, and so may have a different view from others. Aware that routinely some riders/drivers get nothing near the clutch life I experience, so a caveat there to start with.
I've looked after bikes that the rider habitually trashed the clutch with not any input from synthetic oil.
It could be turned the other way round for arguement sake. Given the choice of assessment to see if your bike has clutch slip if you use this type of oil, a potential only, to are they willing to compromise the bearings etc from poor oil conditions, which would they rather replace ? Clutch or engine rebuild ?
Many comments about clutch slip come from completely unqualified views. There's many different influences as to how a clutch can slip, but their projection only sees "slippery" oil.
One of the determinants here is that most are completely unaware that synthetic engine oils aren't more slippery than mineral type. It's just a non informed assumption.
The facts here are (even in your own engine) there's been lubrication failure, however that occurred, that compromised the cam in it's history. Also that it has evidence of sludging in the crank passageways. Far from perfect in any unbiased view. These engines, with decent lubrication should easily see 100, 000 miles, in pure engineering materials terms, why many of them don't is more the question I'd ask.
As you mention Simon, it's a densely packed topic and often filled with hearsay along with little phrases used in place of good technical explanation.
Perhaps a dedicated thread worthwhile.
Trigger:
Every customer i have had in with clutch slip problems is that they are still using the old 40 year + plates or a high grade of synthetic oil.
Having gone by the Manual and measured the thickness of the plate and it is within spec. They have not taken in to that the friction plate has gone hard over time and is just slipping due to a hard surface and always say, but it is within spec ;)
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