Honda CB750 Oil Pump, Primary Chain & Bottom End Check [Cafe Racer Engine Build] 11

[@scheier3]

Great help to me here in California. I have to watch all your videos on this motor as I'm starting a rebuild.

[@SPANNERRASH]

Glad to help, I hope you enjoy the Cafe Racer engine rebuild videos too.

[@CB750K]

It's like seeing the back of your own head for the first time. So foreign, yet familiar. And look how CLEAN that is!

[@SPANNERRASH]

Who's seen the back of their own head, pass me a mirror :) Things were pretty clean better than I expected.

[@10summoners]

Again, quality info. I sincerely appreciate the detail!

[@SPANNERRASH]

Glad it was helpful!

[@hvymax]

I usually shellac them to the cover and grease the engine side so they come off clean and easier to service.

[@SPANNERRASH]

Good tip! Especially if you are keeping a bike for a long time.

[@1234567marks]

I think I’ve got a set of barrels in the shed, K6 I think, I’ll have a look if you think they could be useful?

[@SPANNERRASH]

Thanks Mark, I have a set on the way, but I am not sure of the condition yet, I'll let you know if they aren't up to scratch. I would be really grateful if you could check yours to see if they have good fins, and the liners are sound, if they are good please do let me know how much you want for them. The barrels from the bike are in really great conditon, it is a crying shame that they are out of spec for my pistons. They would be great if I was to go to 836 so that they only needed boring by another few thou but I wasn't even thinking of 812/823 until I stripped the engine and found the Yoshi pistons.

[@1234567marks]

@@SPANNERRASH ok I’ll have a look tomorrow, I’m pretty sure they are good but I haven’t seen them for approx 4 years!.

[@1234567marks]

Hi Les, sorry I’m going to be a let down, I sold the cylinder head and cam’s about 4 years ago, I must’ve given him the barrels as well!, no recollection of doing so but they aren’t there so I must’ve done, hope the one’s you have coming are ok 👍

[@SPANNERRASH]

@@1234567marks No sweat, it was very kind of you to offer anyway. Fingers crossed the ones coming are good

[@matthewsmith1925]

Hi. I’m recommissioning my cb750 k3 and have started the engine just for a few seconds but the oil light is not coming on the dash, I’ve checked the bulb and it’s fine. Do you have any ideas? Could it be the switch? Or would the light stay on if the switch was faulty? Many thank, Matt

[@SPANNERRASH]

It is unlikley that your oil pump has suddenly failed. So I would suspect the switch, assuming you haven't been doing any other engine work. When you switch the ignition on the oil light should come on and stay on until the engine is running. The oil pressure switch switches it off. The switches do go quite often, one of my earlier videos on a CB750 shows me changing it. It is in the middle at the back of the block under the cam chain tensioner and has a wire that goes from it to under the starter cover. If you disconnect it and put power to the wire the light should come on, if it does then it must be the switch, if not then it could still be a wiring issue, or less likely no pressure. To reassure yourself take the top off the oil tank with the engine running and look in with a torch, you should be able to see oil returning to the tank. If you can see it I would suspect all is well and just the switch needs replacing. I hope this helps let me know how you go on.

[@matthewsmith1925]

That’s brilliant, thanks 👍

[@thereve]

Can the primary chain be checked and the oil pump removed with the engine in the frame?

[@SPANNERRASH]

Yes, if you watch this earlier video of mine, kzbin.info/www/bejne/qqrMd36sodCci9E I am checking the primary chain with the engine in the bike. As you have to remove the sump plate to get to the primary chain, you can also remove the oil pump. Obviously you will probably have to remove the exhaust to be able get full access.

[@stephencroft6481]

Have you tried David silver for honda parts ?

[@SPANNERRASH]

Yes, I have had a lot from David Silver. I have used CMSNL as well. They are both good.

[@zzzarybaxz]

Hi, in my engine from k1 I have to replace the Primary Chain is over 73 mm

[@SPANNERRASH]

Looks like you are doing the right thing. 73mm sounds like it is really due. My information comes from the Factory Manual. Its a lot of work and makes replacing the primary on a Harley or Triumph twin look a breeze. Good luck with it.

[@luisvelarde8999]

not a look over the release and pressure valves on the oil pump? Sometimes they are the cause of "malfunctioning". Even more if you mention (actually was a text stamped on the video) saying: definitely wet sump...I would have take a look to them.

[@SPANNERRASH]

Good point. I really should have looked at them. I am not overly worried about the wet sumping, it isn't such an issue on these unlike on Triumphs. I know the pump is giving good pressure and can be removed without having to take the engine out again, so I have put it on my list for another day.

[@bluehazeboy]

Have you tried Sep in derby to re-sleeve your barrels?,

[@SPANNERRASH]

Thanks for commenting, but they were the first that I asked, I was surprised when they said no. I am trying to get a decent set of barrels to have bored now, but all of the ones that are coming up seem to have some issue or other.

[@bluehazeboy]

@@SPANNERRASH wow, that’s surprising, I always thought that would be right up their street,

[@bluehazeboy]

Just watched wheeler dealers from last night (Monday) & another posible lead ,knight’s engine service, they’re in Northampton

[@SPANNERRASH]

Cheers @@bluehazeboy I will look them up!

[@bluehazeboy]

@@SPANNERRASH it’s probably another longshot, but you never know

[@abdullahnadir6581]

They face outside and both rotor markings need to align to each other usually

[@SPANNERRASH]

Thanks.

[@qivarebil2149]

Considering You might end up with a completely new top end, I find it a bit careless to not overhaul or replace the scored parts in the oil pump. You just showed us bits of junk and maybe even metal shavings in the sump, and You're saying You couldn't care less about it. I think You just lowered the value of the bike, quite a bit there.

[@SPANNERRASH]

I hear what you say, but the jury is still out on the oil pump. I have looked at a couple of other pumps at an autojumble and they seemed pretty much the same, and the seller wanted good money for them. Remember though that the bike had good oil pressure when I had it running so I know the pump works. The bits and pieces that were in the mesh wouldn't have been caused by the pump. I am still pretty sure they came from the top end. We'll have to see whether I come across another, better, pump before I have the engine back in the frame.

[@mikeford5106]

Do NOT use a K series cylinder with a F2 [410] cylinder head ..... they are NOT compatible .... you will have massive oil leakage .

[@SPANNERRASH]

Thanks, that was something I didn't originally know, wish somebody had said at that time. But if you follow the playlist you will get to kzbin.info/www/bejne/gKvMfmigf56Xr5I where I try to explain why it doesn't work. Take care.