Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: s7paul on April 20, 2011, 09:17:56 PM
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Hi all. I've just removed the head from my CB500 and would like to remove the cylinder block too. However, it seems totally stuck. I've tried using the two pry points but this just results in bending my biggest screwdriver. There's not really anywhere else I'd be happy to apply too much pressure, as I know how delicate the fins are. So, does anyone have any useful tips for shifting a stuck block?
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I've seen but never used this way before, you'll have to reason it out for yourself as to risk.
Plumbing maintenance pipe blockers, basically two metal discs with a bolt through center sandwiching a rubber doughnut. When you tighten the bolt the rubber doughnut squashes out to seal a pipe, if you put it in the bore with a piece of wood on piston top and rotate the crank with a spanner it can be used to lift the block at alternate ends to break free the gasket or if pistons and crank removed you can put it in the bore and gently tap with a dowel from the bottom end.
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Gentle but firm taps with a hide or rubber mallett onto the finsgenrally gets things moving. there are heavyer bits where bolts go though and with perseverence things genrally come free
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If it's bending a large screwdriver I'd look for hidden bolts that are still in place.
Cheers
Den
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I agree somethings not right. If the heads off though there are no bolts. Hmm weird..how big a screwdriver.....?
It should be BIG BIG. Too big to do up your house door hinges and imposible to bend without serious force.
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I had this trouble with my 550. the studs are tappered and get a load of crap down the holes then the thicker screw tread will not go through the hole I cut the tread of the studs then the thin bit went through the hole and of it came. The down side to this is, you have to get new studs and they don't make them. All they are are is a bit of steel with an 8mm tread on each end. Simple to do.
Paul
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The studs are usually made like that so the solid core has the same dimension along the entire length of the stud to ensure an even loading when stretched under torque. The threads are bigger as they are an addition to the core diameter and don't contribute much to the designed load spec.
They are made like this to get the max load vs wheight / space balance to best performance.
You often get gear shafts with this same basic pattern as well, for the same reasons.
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Thanks for all the suggestions. Just to close this off, I tried all the usual stuff - big screwdrivers, hide mallet, etc., and there were no other bolts holding it down that I hadn't already removed. Eventually I used a steel wedge, which I managed to tap into the joint such that it was actually splitting the gasket material (rather than bearing directly onto the metal). A few careful taps each side and it finally started to move. I didn't like having to resort to such methods but there's no damage, so it looks like I've got away with it.
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Good to hear a "happy" ending, I forgot to mention that my head and barrels were stuck together by a rusty dowel !
Chers
Den