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Quote from: Nurse Julie on September 10, 2019, 01:50:50 PMOh dear Paul....you have done well so far retaining your sanity over this problem 😀 Did you back off the tappets fully and hold the tappets up with elastic bands when you fitted the rocker cover?Hi JulieYes this is doing my head in !!!Thinking back when I put the cover back on it was a struggle to get on, I backed off the tappets but no lazzy bands. Cover seemed to be offering some "push" resistance. I am now thinking this is what caused the problem but I guess will only know when I get the head off AGAIN and get the valves checked out. Head is off to my local machine shop with valves in for them to check it all out (they are very good)
Oh dear Paul....you have done well so far retaining your sanity over this problem 😀 Did you back off the tappets fully and hold the tappets up with elastic bands when you fitted the rocker cover?
Not in the 750 manual Nursey, separate rocker cover, the tappets/rockers are mounted on the cam carriers.
The 750 has the rockers etc fully installed prior to cam cover being fitted so the scenario doesn't occur on that, just the smaller capacity fours which are all the same. Out of interest, what do the rockers catch on if you leave them unelasticated? I understand the process of fitting them but not the precise layout that would give some sort of interference. It's highly unlikely that you bend a valve stem like this I'd guess. They are just very tough to bend at the top end of valve.But, if you left the engine at TDC for number one cylinder for example, could you then get a situation in which you pushed the valve down into the top of the piston from "snagging" the rocker arm as you close the rocker cover gasket. Ie, exactly what you are trying to avoid by using elastic to keep the rockers up.If you can do that, then it's more likely to bend the valve using the head as leverage against the piston.If that's a viable scenario, then it would most likely be #1 cylinder in all probability if you've just checked cam timing is correct before you install cover. And I'd have a guess at exhaust on that cylinder.
Quote from: K2-K6 on September 10, 2019, 02:54:30 PMThe 750 has the rockers etc fully installed prior to cam cover being fitted so the scenario doesn't occur on that, just the smaller capacity fours which are all the same. Out of interest, what do the rockers catch on if you leave them unelasticated? I understand the process of fitting them but not the precise layout that would give some sort of interference. It's highly unlikely that you bend a valve stem like this I'd guess. They are just very tough to bend at the top end of valve.But, if you left the engine at TDC for number one cylinder for example, could you then get a situation in which you pushed the valve down into the top of the piston from "snagging" the rocker arm as you close the rocker cover gasket. Ie, exactly what you are trying to avoid by using elastic to keep the rockers up.If you can do that, then it's more likely to bend the valve using the head as leverage against the piston.If that's a viable scenario, then it would most likely be #1 cylinder in all probability if you've just checked cam timing is correct before you install cover. And I'd have a guess at exhaust on that cylinder.Here is the picture from the Honda manual, I think I can see that if you end up with a rocker in that sort of position its not hard to bend a valve maybe (Attachment Link)
Is that what I think it is? A plate screwed to the top of a piston? I have seen it before but what a bodge. Kind of thing some of my mates used to attempt. Amazing how long an engines will last with sutch ' repairs' I had a dumper engine once that had obviously run some considerable time with a piston top knocking around in the combustion chamber, long enough for the exhaust port to be chocked with carbon build up til the ports were pencil sized holes. Other cylinder was fine, it would probably still have run.....