Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: alexdecker on July 27, 2021, 09:40:19 AM
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Hey all
I just found out that I can take the entire motor out of my Honda 550F in one fell swoop, without taking anything apart. That was nice. Now, I am wondering - I restored the top end of my motor, but I would like to replace my primary chain. I don't wanna take the entire top end apart piece by piece again. Is it possible to detach the entire top end in one go, or do I have to separate it piece by piece?
- Alex
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You are going to have to take the cam out and disconnect all the con rods as you have to thread the chain over the crank. Its better to replace the 8 dampers in the primary drive at same time. Kawasaki chain is same but cheaper
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Rods can stay on.
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Rods can stay on.
No they can't, else you'd have to withdraw the pistons with the crank to get it out. Don't know if you can even get the piston to pass through upper crank case opening.
Splitting the cases has undone the main bearings, but you'll still have to split the rods as Bryan indicated.
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Halfords advanced 1/4 drive sockets go up to 14mm size if that's any help, unsure what size those are.
Also Bahco 1/4 drive up to 13mm and really useful little set
https://www.screwfix.com/p/bahco-sl25-1-4-drive-socket-set-25-pcs/21134?tc=DX3&ds_kid=92700055262507126&ds_rl=1244066&gclid=EAIaIQobChMInorQ2NaD8gIVje7tCh0ZnwDtEAQYAyABEgKDWfD_BwE&gclsrc=aw.ds
Excellent quality and really tough.
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I've got the Halfords set of 1/4 drives sockets and the wall is too thick - I had to carefully grind a socket down when I did my 500
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I've got the Halfords set of 1/4 drives sockets and the wall is too thick - I had to carefully grind a socket down when I did my 500
Just checked the halfords against bahco and they are within .05mm from each other for OD so neither will work then.
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Eh…though we had split the cases? In which case the primary chain comes o with rods on. Either that or I have achieved the impossible…which is unlikely. ;D
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Just reread the original post…pretty sure the pistons will come though the cases? It might even be easier to reinsert them given the generous barrel chamfer.
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Possibly we are mixing visualization here.
If you flip the engine upside down and remove the bottom case (leaving the top end still assembled) then you'd either have to withdraw the pistons with the rods, which may not be possible, or detach the rods from the crankshaft to lift it out and leave the pistons still in the bores.
Or are you saying that you'd remove the top end first, in which case by undoing the main studs you've effectively separated the head and base gaskets.
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I think the confusion is what degree of 'I don't wanna take the entire top end apart piece by piece again' - does Alex want to leave head/barrel/pistons together or just head/barrels? I personally think the former would be best and just taking cam out so that crank can be withdrawn to facilitate primary chain withdrawal?
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Correct Ken
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Just checked my dismantled engine. You are correct, rods off as the pistons will not pass the webbing.
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Just for info later 500 you can fit 550 cylinders on but early ones the crankcase holes are too small
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Apologies for straying of topic, but did I read recently that if using the Vesrah gasket set not to use the 2 x O rings provided for the cylinder head oil control valve?. Do I just purchase two Honda items instead?
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Apologies for straying of topic, but did I read recently that if using the Vesrah gasket set not to use the 2 x O rings provided for the cylinder head oil control valve?. Do I just purchase two Honda items instead?
Honda 0'rings are only for original Honda gaskets.
The problem is that all aftermarket gaskets are thicker than the original Honda one and the gasket manufactures just took the Honda information size O'rings and put there packs.
I up grade all engine 0'rings when building a engine. I keep trying to find time to maker up kits of upgraded 0'rings but, never found the time yet and also some aftermarket head gaskets are different thickness to another manufacture ;)
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Thanks Trigger. I’m about to reassemble my 550 using a Vesrah kit and now I have doubts. I don’t suppose you could advise on where I might get some suitable O rings?
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Same problem with Honda gaskets. It happened after asbestos was outlawed as gaskets had to be thicker to retain strength
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If you PM Julie with the size of the hole in the gasket and the thickness of the gasket, she should sort you out ;)
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Sound, will do. Thanks.
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Bought a few years ago ken, would you like one?
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I did just that in the 80's for my 836, worked fine, and am busy making one for my 54mm "big bore" :D 400f, I have never seen them for sale, where do you get them?
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Related but not specifically gaskets. I looked at some components in both brass and copper that someone had made from sheet into old large format camera components, they'd been lazer cut to his design and were absolutely immaculate in technical execution with stunning accuracy and no distortion in the finished item.
No idea about supplier but probably worth enquiries to see if someone offers that facility on a one off basis as scan / layout is so easy with kit available now.
Anealling for copper is red heat then cold water quenching to get soft properties and best sealing.
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Thanks all for the replies!
In regards to the sealings - I just redid the top engine with the Vesrah gasket kit, and proceeded to drive around 1000 km. within the next week. No leak. So can totally vouch for the usability of the Vesrah kit (I got the complete one).
As to separating top from bottom, I guess it will still be somewhat of a major disassembly again. So with that in mind - as long as Im in there, what would you guys recommend fixing in the bottom end besides primary chain?
- Alex
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Primary dampers, camchain, all the seals
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And check cam train rubberware
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In respect to the Vesrah kit, did you use the o rings that came with the kit? I’m advised to use a 3mm thick o ring for the cylinder head oil valves rather than the standard 2.5mm item?
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Pm sent Ken
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In respect to the Vesrah kit, did you use the o rings that came with the kit? I’m advised to use a 3mm thick o ring for the cylinder head oil valves rather than the standard 2.5mm item?
Yes, I only used sealers and O-rings from the Vesrah kit…
- Alex
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Cheers Alex.
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Hi guys, further to this topic on o ring sizes for cylinder head oil way seals I’ve measured this morning as I was going to fit cylinder head. The machined recess in the surface of barrels is 1mm and my vesrah gasket is 1.65mm I dont see a 2.5mm o ring being a lot of benefit here. I actualy found a 2.65mm o ring in a set I had but even this is not going to cut it. Am I right in thinking this has going to have to be 3mm thick rings?
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Won’t the gasket get compressed?
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Steve, i did wonder about that, but how much is a 1.65mm head gasket liable to compress under full torque? I have not a clue.
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Well if it’s compressed from 1.65 to 1.00, then a 2.5 o-ring would be fine.
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Absolutely Steve. This is exactly what I need to know!
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Absolutely Steve. This is exactly what I need to know!
Did you end up on a 2.5 or 3 O-ring?
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I ended up with 2.65mm because that’s all I had. Fingers crossed they do the trick.
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I ended up with 2.65mm because that’s all I had. Fingers crossed they do the trick.
So - following up on this - did the 2.65 o-rings do the trick? :)