Honda-SOHC

Quote from: AshimotoK0 on August 13, 2020, 08:40:16 AM

These are the two Service Bulletins you need ..they came originally from BryanJ.....  Why Honda never ammended the main Shop Manual with this information beats me. My original '69 diecast crank had the Japanese chracaters stamped on the con-rods but yours are something different.

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Hey. Been away a while I'm now back on the rebuild. So I'm still stuck with identifying the con rod bearings. I've got the journal ones worked out but for the con rods that came out if the engine I don't know how to find the shell colour as the rods are not marked as per the manuals. e.g the rods all have '2/29 (or 28)' marked on one side and nothing on the other side. All rods are marked 'S30F' and looking at the bullitins look like the 'new' type with the numbers on.

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I have used Surfex HD from Bilt Hamber in my ultrasonic cleaner for a few years now the parts need to be free from most of the usual crap that accumulates over the years.  I use the same product in my parts washer to soak the bad stuff away.  In the ultrasonic I set the temp at 60 and clean for 30 mins.  If things are really grotty I sometimes take them out after the first 30 mins and use a scriber or small screwdriver to loosen stubborn bits in the crevices and then do them again.  5% Surfex by volume has been good for me so far.

Ian

Quote from: K2-K6 on April 05, 2021, 02:01:03 PM

Oops, just read that's the manual spec you've quoted (I thought it was measured amount  ) are yours far away from spec?

It's just as important if it has any surface pickup that would be poor for continued running.

Any detailed pictures of lobe peaks?

I'll check again tomorrow and take some pics. Thanks.

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CB750 head gaskets are a minefield, at least 3 different types fitted between 1969 and 1979 

For a 750K1 you need a Vesrah VG156 or you can use a VG157 and upgrade it with O'rings but not the ones in Ash's link ( they are only for Honda orginal head gaskets ) . With any after market gasket set, you can't use the O'rings supplied with the gasket set on the head or base gasket as they will not seal.

One of the hardest things is to get all the oil ways to seal up on any early CB750. If you need any upgraded O'rings to do this job, i hold stock of them 

Quote from: WestYorkshireBiker on August 29, 2020, 04:16:52 PM

Quote from: Trigger on August 28, 2020, 07:15:53 PM

It can be a very expensive hobby trying to remove these. Stud A is still available at about £15 each and there are 12 of those. Stud B has not been available for many years. Add in the cost of spark eroding at £25 a pop and you are looking at a shed load of money, just to replace something that with a good clean could be good to go     

Thanks. Another question! I'm struggling to remove the front engine mount bolt. All the others came out no probs. It's just a straight through bolt right? Can't turn the head after heat and brute force. Don't want to get the big hammer out either just yet!

Edit: nevermind. Bolt sheared off despite my heat cycling and gentle persuasion.... Thanks.

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Successful day. Finally got the K6 lump out. Onwards and upwards..

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Some confusion there. The one you have marked "OFF K1 ENGINE " is a later set of barrels K3 to K6
And the one you have marked "K6" is a K1 or K2 set of barrels. You can tell if they are K1 or K2 by the front of the barrels, K1 has a flat area and a K2 is rounded in the same area as, in the pictures.

Also i have put a picture showing the different liners. 1) is a early liner and 2) is a later liner. You can tell by the 2 cut aways on the number 2 liners


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