Installing Barrels & Head on my SOHC CB750 Cafe Racer Project Bike Engine | 19

Installing Barrels & Head on my SOHC CB750 Cafe Racer Project Bike Engine | 19
At last I have started to put the engine together for my Honda CB750 Cafe Racer project. It seems to have taken forever!
Here's what I used:
Honda Bond 4 Sealant: ebay.us/iWIEhV
Torque Wrench ½”: ebay.us/N3DaQS
Torque Wrench 3/8”: ebay.us/kJRsSF
Torque Wrench ¼”: ebay.us/AUgpRz
BLACK E-Tech 400ML Extremely High Temperature Paint : ebay.us/DrPPSA
After getting the barrels I had bought bored to suit the Yoshimura pistons, I realised that the head that came with the bike wouldn’t be suitable to match with them. So that lead to a delay while finding and refurbing another head. I decided on the 392 generation of head as that works with the barrels and pistons that I have.
Now is the time to get the barrels on followed by the head. I had a multi layer steel gasket that came with the original parts with the bike. But when I started to look into what implications there might be with this I decided not to use it, so bought a standard type gasket instead. Apparently the MLS gaskets need to have a very good surface finish on the block and head to work well. Although I have had the block resurfaced I hadn’t had this done with the head. As the head is straight and in good condition I didn’t want to add extra cost and time into getting it machined.
The most difficult part with putting the barrels on is getting the piston rings compressed and into the barrels. Because there are 4 cylinders and they go into the barrels all together it can be a fiddle. I did think of trying to sort out some kind of ring compressor to help me fit them, but in the end I just went with the compress one ring at a time method that you see most other people doing. Fiddly but it works.
I used the Honda pattern for torquing up the head bolts. I have seen various forum posts saying to go beyond the 15 ft/lb in the Honda manual, but only to 17 ft/lb. This works out to 23 n/m. I tightened them in stages, first snug, then to 15 n/m, then to 20, finally to 23. I left them for well over 24 hours then went back and rechecked them. I really don’t want to have to pull the engine to re torque them after 500 miles like some people recommend, so I am going full belt and braces on them.
Overall the job went quite smoothly, I used Honda bond in the appropriate places it seems that it should work well.
As I am writing this I know what happens next. You will have to wait an see, worth subscribing for!
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[@brokenspokes6731]

I am enjoying your build series. A few tips when putting on the barrels on the pistons - first I use a long screw driver to hold my cam chain on the top of the barrels. Next I use a clamp to hold my piston rings in line. I usually do the inside pistons first then the two outside pistons. I always use oil in the barrels while inserting the pistons. I did pick up a few good tips from your series. I didn't know too much about the various honda heads numbers. so thanks for that..

[@SPANNERRASH]

Will definitely try that next time. It was interesting to see how Honda had changed things over the years, I bet there is a lot more too, but I only had the three different head and barrells to look at.

[@DocJonesGarage]

The bird is calling you! Looks good

[@SPANNERRASH]

It's still calling :(

[@kevinsmith1044]

Always entertaining Need to go back and study up on this whole series.... won't be long before I get started on one.

[@SPANNERRASH]

Thanks for the encouragement. Time and patience is all that is required :)

[@williamwintemberg]

Les made lowering the barrels on to the block look relatively easy. I can assure anyone, it is not an easy process. It takes time and a ton of patience to get it past all the piston rings without damaging a ring. It can be a real "Oh No" moment once a ring is broken and the broken piece of ring is in the crankcase not to mention the infamous scratch in the cylinder left behind among other things. Don't ask me how I know this. Good job Les!

[@SPANNERRASH]

So far so good. I have mostly done this on twins in the past, adding the extra two pistons made it more of a challenge. Sorry to hear of your "Oh No" moment, I have plenty of those. Car guys don't know how easy they have it when it comes to putting the pistons in :)

[@williamwintemberg]

@@SPANNERRASH Again, Great Job! Beautiful video. Yes, less cylinders do make things easier but extreme care and patience is still key. Imagine doing a CBX! OMG!!!

[@davidallen3050]

LOOKING FORWARD TO THE NEXT VID ,,THANK YOU !

[@SPANNERRASH]

Thanks, I really do need to pick up the pace. It will be Winter and it won't be finished at this rate.

[@davidallen3050]

IT'S WINTER HERE IN NZ ,,BUT WE'VE HAD SOME SUNNY DAYS MY OLD 1200 SPORTY GOING REALLY WELL !

[@mulliedog1]

Great Video!! Nice watching your progress!!

[@SPANNERRASH]

Thanks Mulliedog, glad you enjoyed it.

[@richbeal3048]

I may have missed the part where the valve seals and guides were checked or replaced, but that should always be done especially when oil leaks into exhaust has been a possible issue . This way the entire valve train and springs are checked before reassembly, sometimes even a leak down test just to check the valve/ head seal so that a compression test can be made to be sure that all 4 have equal compression and that none has been lost to ring issues . Otherwise , looking good.

[@SPANNERRASH]

Thanks, good advice which I had taken in kzbin.info/www/bejne/n167iXZnqZuraJY :) I ended up getting 2 sets of seals and changing them as I changed my mind about the original head I was using, so went through a second one between the two videos. This has become such a long playlist that some repetative parts haven't been included. Take care.

[@martino4414]

Les, enjoy your videos. I will be attempting this shortly on a K6. One point, there is a bolt on the front centre of the cylinder head. I think there may be a similar bolt at the rear, but not sure about that. I didn't see you put that in. It is not possible to put it in once the valve covers are on. I know this because mine has broken and I'm nor able to pull it out and replace. Engine out to fix it!

[@SPANNERRASH]

Thanks for the info. I know that there are these fasteners as well, and I will put them in before I move on.

[@H-M-78]

Engine looks great, good job! I,m using aluminium paste/grease on steel bolts to aluminium

[@SPANNERRASH]

Thanks. Good idea to use something on steel into aluminium, they can have some strange corrosion because of the different metals. I always try to use something.

[@H-M-78]

@SPANNERRASH The idea is not using copper grease and end up with three different metals. I'm no expert but especially stainless into aluminium can have issues from what I understand

[@CB750K]

I noticed the cam chain tensioner, but seeing one detail in a project I've never tried or even witness before didn't make me feel superior. ;) I'm just glad to be able to see something like this up close. Oh, and is it standard practice to color a rebuilt motor black? Seems like I see that often.

[@SPANNERRASH]

Well done, I wish I'd noticed it earlier :) It is really useful to be able to see things dismantled to get a better understanding of how they work. As for black, I assume it is because it hides oil and dirt more than anything. On an aircooled engine the fins get hot, so it might help with cooling, but I suspect that isn't really true.

[@1234567marks]

The tensioner was in plain view for us Les, I wanted to shout at the screen “Les!, tensioner!!!” 😂

[@SPANNERRASH]

Too late the Prophets cried, the island is sinking. Bet you kow this lyric. It was extremely annoying when I realised! Next time, time travel, and shout louder :)

[@1234567marks]

@@SPANNERRASH Ha, well time travel would be useful to head off all the mistakes I’ve made on bikes over the years!!, I had to Google those lyrics, and then listen to fools overture on KZbin, it reminded me that I don’t like supertramp!, led Zep every time for me 🙂👍

[@codyjarrett9685]

Yet another great vid. Where did you get your gasket set from

[@SPANNERRASH]

I have had a set in the cupboard for a few years. No idea where I got it from. The head gasket is a Cometic on which I bought off eBay.

[@smithtracing]

Don't forget to add more honda bond!!!!

[@SPANNERRASH]

Super sealant, just what the doctor ordered.

[@smithtracing]

@@SPANNERRASH I love this series of videos! Just got me a CB750 as well - I'm kind of doing the same thing. Keep up the good work!!

[@stephencroft6481]

Thanks for vid very interesting

[@SPANNERRASH]

Thanks Stephen.

[@49er16]

And advice for getting the cylinder head detached from the barrel? I've been soaking the gasket in penetrating fluid but they still won't separate. Thanks for any advice.

[@SPANNERRASH]

First, do make sure that you have all fasteners out. It is easy to miss something. With the CB there are the headbolts, and the 6mm ones as well. If you are absolutely sure they are all out then you could try applying heat and then cooling. Alternate between the head and the barrels, with a little patience it will come off. Don't hit it too hard, but if you put a wooden block against the fins and give it a few taps, it might shock loose. Let me know how you get on. Good luck.

[@mikeford5106]

Good build,......... bloody awful "music" !

[@SPANNERRASH]

Cheers Mike, its tough to find music that's royalty free, but noted.