SOHC.co.uk Forums > CB500/550
sluggish 550
mickwinf:
z1100r i agree, if you want a job doing.....
z1100r:
Get yourself a nice evening with an early start and get the head off again. Turn it upside down and pour petrol into the combustion chambers, the level will go down fairly quick on the bad ones and fuel will be in the inlet or exhaust tracts of the dodgy valves. 50psi is awful and definately signifies a major problem, I'm not going to speculate what the problem is anymore, firstly you need to satisfy yourself that the base engine is sound.
Personally I would get all the valves out and roll them on something flat - surface plate, kitchen worktop. Once satisfied they were al straight I would put them back in 1 at a time turning them and watching the head for wobble. Then give them a light lapping in with paste just until i could see complete grey rings on valve and seat. I would then be happy with the head.
So moving on, this previous engine builder bloke sounds like he aint got a clue. I would definately at this stage whip off the barrel and make sure I had a full complement of rings and that their end gaps were roughly correct.
Its upto you how far you go but I think you need to get certain things straight like...RIGHT THE BASIC BLOODY ENGINE IS NOW OK.......!!!! Thats the bores the pistons, the rings , the valves, the head gasket, the cam timing.
mickwinf:
well... good news and bad, i had a spare hour this am so rechecked the compressions, i had not screwed the tester in properly!! now all 4 cyls are showing 140-150 psi.hmm take rocker cover off and check cam timing,it is spot on.So i am sure basic engine is ok. plan now is to re-assemble and check and recheck clearances clean and check carbs.I am thinking which jets would be operating at 5000 rpm, could it be wrong size main jet or needles set wrong?? will keep trying!
z1100r:
well if your happy thats good. To get the lack of revs/power that your getting something has to be not working, not be just out of tune. You've swapped too much stuff for 2 sets of everything to be that wrong and have the same thing wrong it. I'm lost, willing you to find the problem quickly.
mickwinf:
i am stumped also,but i checked pistons etc when i replaced valve so am sure its not a big mechanical problem, but what the hell is it?!!
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