Low compression CB750 engine teardown. Found the problem.
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- เผยแพร่เมื่อ 23 ต.ค. 2020
- Hope you guys enjoyed this one. Let me know what you think in the comments.
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"Im not going to do a 'How to...' video, this is more of an overview"
...Proceeds to do an overview video 10 times better than 99% of 'How to's!' Lol. Watched every bit of it and I dont even have a 750, great vid as ever! Excellent job mate.
Thanks Alan
Just a few quibbles with the terminology used in your commentary:
The "top" ring is properly called the compression ring
The "second" ring is properly called the scraper ring
Yes, the "third" "ring" is called the oil control ring and consists of an expander in the middle with rails above and below it.
As well, after honing the cylinders you MUST use clean white rags, preferably something soft like cotton (old clean white tee shirt material that's 100% cotton without silk screened stuff on it works great) to clean the cylinder bores of all the grit from the hone stones AND the cast iron powder from the liner surface itself. Wipe the bore with a cotton rag dampened with mineral spirits (NO WD40 or similar lubricants) and then toss the dirty rag. Repeat this process until your last rag will not show any black stuff at all. You'll be surprised at how much rag material you can use just to ckean ONE cylinder bore. Your whole engine will thank you for taking this extra step of getting rid of all that abrasive crap.
As to installing the block and coaxing the pistons/rings into the bores: you really should thoroughly bathe the rings with engine oil before trying to get them into the bores. You'll find that things go much easier.
It would also be a great idea to lube ALL the cam bearing surfaces AND the lobes with engine oil or "startup lube" before installation.
Just finished the top end rebuild on my 78’ 750 following this video. Thank you Taylor for the information and wisdom. This is the single best video on TH-cam covering this imo
I wish I had this video to watch 30 years ago! Nicely done.
Thanks, very nice to watch.
Having already disassembled the cylinder head, you could have taken the opportunity to grind the valves too...
I really have to complement your skill at methodically explaining each procedure as you moved along during the whole top end rebuilding process. You have a real gift for teaching and making things crystal clear from start to finish! This video is definitely valuable content. Subscribed! Keep them coming’
Wow, thank you!
@@ClassicOctane I agree, really well done, and even though mine is a Kawasaki all the same principles apply. Just one thing, would you recommend engine-in or engine-out? I was originally thinking engine-in but after watching this I might be investing in an engine stand. Cheers.
Great call choosing to do the top end rather than just engine swapping. This is much more interesting and helpful.
Glad you liked it
1
I'm
@@ClassicOctane taught me a bit about engine timing! Thanks!
Mate. I've been watching you for a while now, and I must commend you on your entire approach to your content. I've considered trying it myself, but the whole 'talking to camera, explaining stuff, then editing and publishing these videos, along with actually fixing a real life motorbike, is a bit of a handful!' So you, my friend, are something else. Just thought I'd say something positive (and truthful), cuz we all need that shit now don't we.
Lazy Bones well said!!!👍
Agreed!
Thanks! I really appreciate the kind words.
always a good idea to remove the valves and lap them in by hand.Particles of rust can sit on the surface of the seats and hold the valves open slightly.Its just peace of mind,and saves having to strip the engine down again.cheers Graeme from New Zealand,enjoy your programmes
Someone already said it, but it bears repeating,....you are an excellent teacher. Very complete presentation in understandable terms. Well done!
I'm in the midst of a top end rebuild on my bike. This vid gives me hope. lol.
When removing Piston Rings you should place small rags around the 4 Con Rods so any mishap and you dont end up with foreign objects drop into the bottom of the motor..
Not only that but connecting rods can be damaged if they come in contact with crankcase resulting in stress riser crack and rod to fail in service
You stole my comment. When he snapped ring a piece could have dropped into engine.
You do a great job with these videos, very comprehensive without being boring and educational as well.
My ADHD has now got me binge watching all your videos. And now you have a huge fan up here in Everett, WA. And this all started with your video of the most awesome explanation of rebuilding the carbs on the CB550. Absolutely great videos. Very good editing. There's no unnecessary waste of words or time. Thank you sir.
I had the pleasure of attending and graduating (youngest to grad age 16) from American Honda Midwest Service school back in 1970 right after the Daytona win. The class was held in Bob Hanson’s Race shop in Racine Wisconsin. My instructor was Bob Jamison who prepped the winning 750. He was a real stickler for detail and this is what I learned from his philosophy. You did a great straight forward job however what you missed was...the troubled cyl probably had rusted (at least) the intake valve. If you’re not intending on inspecting the valves, do a leak down by pouring solvent in the intake and ex to see if it’s getting past the valves. The cam tension rollers get brittle and under all circumstances be changed. The rubber compound on the knockoffs are not near the original Honda part.
The valve seals also get hard, and while you’re in there, it’s an evening job to pull the valves, lap them in and put new seals in. Make sure u check and lube the stems.
Sure you did
Jamison grad 69
Definitely made me get the confidence to rebuild my top end! Awesome content!
I have 3 CB750's and a CB550, all of which I would consider yard bikes with extensive exposure and neglect, but, I am hopeful I can get one or two of them running. You have the most comprehensive classic bike repair channel I have ever seen on TH-cam, thank you for publishing these videos. BTW, where is the vid of this engine running?
I'm actually looking at doing my own cb750 project, also in Austin! I had to watch this video just to mentally prepare myself. Great explanations and video!
Awesome video! Helps a lot to visualize what I need to do when it's my first rebuild. Keep up the videos on the cb750. Can't wait to see the next ones!
Thanks, will do!
I appreciate your videos. Enjoyable and informative. This one, like so many of your others, gives me confidence to take on new challenges. Thank you.
Very methodical, low key presentation. Well done.
I'm glad you bought the pliers, spiraling on rings is not a preferred method.
Absolutely love your content on the Honda cb’s. Trying to find a 70’s one right now to build one, absolutely love the sound and how much you can customize the look of this bike 🙌🏼😌
A - Im a strong believer in cleaning up the engine prior to removal and conducting a leakdown test on it at that time as well . In addition if it wasnt a runner I'd be tearing down the bottom end and checking bearing condition and clearances . Also the bore & pistons should have all been measured . Minimum piston - wall 0.001 - 0.002 clearance . Ring end gap top 2 = 0.007 - 0.016 . Oil ring = 0.012 - 0.035. little tip ... you can increase the taper prior to boring / honing ... makes installing the pistons a snap. Cam timing . I always check again AFTER cam chain tension has been set . Use assy lube cam bearing surfaces .Your videos are well done.
Pistons with jammed rings can make the bore go oval so measuring is a must before deciding what's needed.
Love your vids. This is like ASMR for motorcycle nerds.
Glad you like them!
I see you start all four pistons in the cylinders at once... I start the middle two first then the outer ones and that seems to work well for me. good job on the video and it looks like you do good work. great to watch ...you are a natural teacher.
I just might be buying an old CB 750, your info is wonderful. Keep up the good work!
Congrats Taylor once again for another well done job & explanation. I got 2 toys both cbs to restore, a cb750c & a cb1100f sports. I will get there. Thanks for sharing ur clear videos helping everyone. Keep it up!
Will do. Thanks!
I had planned on doing this work on my K2 during the downtime this winter. This will be an invaluable help along with the various sacred texts I've collected.
Good luck!
love those large , air-cooled fours
Got rid of a 750 4 years ago. Wish I still had that thing.
what beautiful work. outstanding job.
Awesome vid man! Wish we could have seen the vid of it getting pulled and what you did for that. Good job on stressing the head bolt removal and installation process. Could have used a little lube for the cams and pistons, but when I saw you adding oil at the end, definitely shows you know what's up. Keep up the good work!
Yes. I picked that up too.
I know it takes energy to explain wuch is highly appreciated because of my inexperience thnks
Nice one Ty, you make me think that I could rebuild a Honda CB750 engine, you make it look soooo easy. Great video man. 😎👍👍👍🇬🇧
You can do it!
Thank you so much for this video. It makes me feel like I can take on a similar project. Keep up the great work you are doing. Big fan!
That's always my goal. I hope to give everyone the confidence to tackle a project they otherwise wouldn't have attempted.
‘71 cb350 twin setting up & have watched & rewatched most of your content. I was going in anyway, but with quite a bit of weight off the shoulders that the bite doesn’t seem as big. Gives us, who are beginning to finally scratch an itch a another facilitating resource to the tasks being undertaken. Thank you sincerely for your efforts in documenting to share your love/work. Hats off to you sir.
Absolute awesome video from me,.. so glad you decided to keep the original engine to the frame,. Surely the rebuild will be more worthy in original state as engine plus chassis,..once again excellent video from me, take care,..
Thanks!
Yeah, I still have my piston ring pliers from 20 years ago for the one time I needed them and do not regret buying. And the ring compressors.
Thank you, always enjoy your videos.
Love your channel and all your hard work and effort you put into this videos and I discovered you from Ronald fingers fingerprint workshop
The best man! Go Classic Octane!
Well done Taylor, you've saved another engine and it was good to see what was wrong with it, the video made good content .....👍🏴🇬🇧
Thanks
Very good in explaining everything step by step ! That is very clever of fasting the engine to the engine stand
Can you show how the engine is mount to the stand and fabricate the frame to the engine . That would be helpful for us . I have a engine stand and trying to figure on how to attach a cb550 engine to the stand .thanks and keep up the good work !
Very good instruction video ! Thank you !!! Greets from Belgium (Europe) 👍
Awesome video! Very informative and explained well! Great job👍
such a great vid, thanks for taking the time to share!
My pleasure!
Just a perfect explanation which we owners of cb's thank you a lot. Thankyou master
Created one of these engine rebuild video series myself... it took me a while to setup cams, etc ... so I really appreciate the fresh content Taylor. Hope all is well.
The sonic cleaner (that I purchased after seeing yours) did wonders for my pistons... 50% simple green, 50% water. I noticed you didn't add Hondabond on the pucks?
Was wondering why no assembly lube on install?
Great job man, but, I would add i always clean out the ring grooves on the pistons with a piece of old piston ring in case there is slight carbon build up under the rings. Here in the UK we call the top ring with the chamfer a ridge dodger , It's there in case you have a slight lip on a bore to stop the ring hitting it (Which you probably know already )
This is very helpful since I'm planning to eventually do a top end rebuild on my 78 CB750K!👌🏽
Go for it!
Nice video once again. I have always tought that you hone the cylinders to have something in the cylinder walls where the oil would stick better
thaks a lot for all the info. i think the ring gap not being at the forward or rear of the pistion is because there's some force fore and aft as the pistion mooves up and down which makes the bore oval/oblong over time.
Thanks very much Taylor. Very good informative video. I learned a lot. It won't be as intimidating as it would have been. As you say, slow and methodical is the key. Cheers, 👍🇨🇦
Glad it was helpful!
Your correct in ascertaining the trepidation most folks place on a refresher with engine teardowns, associating it with marked levels of terror that things will be thrown out of kilter from small missteps taken along the way. A hundred diversions probably accounts for most unsuccessful repair procedures more than misdirections that take place. Great synopsis of one's route to travel when putting these plants back together. Best of luck with your frame and suspension refit and upgrades. Warmest regards.
thanks for the walkthrough man!!
GREAT VIDEO, LEARNED A LOT, THANKS FOR SHARING
Fantastic vid. Love it. Interested though why go to all this trouble and not do the valves. ?
Excellent video. I may have to do all this to my K6 one day. Also, I noticed I've got the same boxer t-shirt that you're wearing. So I'll remember to wear that when I do the work....for good luck 😌👍
Great video as always but, damn, I get huge workshop envy :-)
fantastic vid. I put a big bore/big cam kit on my Grom clone a few months ago and it was nice seeing it's pretty much the same process for this give or take 3 cylinders 😂
Very good video/info on top end rebuild. Thx, new subscriber.
very interesting video. It seems so easy watching you do it. Can't wait for the next one. Hi.
Thanks for watching
CB750 problem SOLVED! ....Convert it to electric. haha
Love the video, brother. You know your stuff and always a pleasure seeing good dudes wrenching.
Great technical lesson.
Cool...you made it look easy..thanks for posting
Great info out there! Keep going strong!
Appreciate it!
Great job and the video surely will assist with my head removal
Had a 1978 Honda 750 Four F2 got rid of it when the tappet noise went bad that was back in 1983 and have regretted it ever since wish I had your knowledge back in the day.
Really like your videos. Very informative. thanks and very much appreciate it.
Thanks for watching!
Sweet project dude!
Just my two cents as a small engines mechanic, you should try soaking your combustion chambers and piston tops in wd-40 and a brass brush, been doing this the last four years and it works wonders.
Again awesome content and great work!
I do the same but using Marvel Mystery Top Cylinder oil.
Good video. Thanks for making it. CanI suggest next time add a comment on how to test now well the valves are sealing. Such as using a flash light to see a gap. Or gasoline/kerosine in the valve to look for drips. Not that hard to lap the valves since you are in there.
I really enjoy your Videos. Nice Shop, and you make it all look so easy!
In my shop, I forget where I put the wrench, can't find the right socket, look in the tool box, all wrenches are there but the one I need etc. etc. etc.
I hate getting the engine out of the frame. All the wiring, cables, tank and more, all come off and then the motor is removed. For me, the motor is the fun, and the easier part. Then putting it all back into the frame, and re-hooking everything up, correctly of course.
I DO have the thought go through my head, What are you going through this much effort for? I try to keep those thoughts locked up in their own padded room in my head.
Great video. Makes me want to build one just for the experience
You should!
Hi friend, thanks for the video, I need to do this job to a cb550f, now I'm not in a panic,
550s are even easier because you can do it in the frame.
I've used Easy-Off Oven cleaner (it is carbon after all) on piston faces and valve bowls, then a parts washer.
Great video, One thing I'm sure you do anyway is I spend at least half an hour on each cylinder scrubbing after the honing process as that fine stone and metal paste sits in the honed cross-hatch and takes alot of work to get out, I use paper towel and lacquer thinner until after a wet scrub the towel comes out white with no signs of grey, without doing this engine life is severely shortened, I have race motors going around that I built in the 90s smoke free with great compression.
Great workshop.
Great job on the video and the rebuild .. I have experience with that myself.. The only part I didn't understand is why you separated the cam sprocket from the shaft. But I watched the whole video and it is very good....not easy to do that. You are helping a lot of people to do it right.
the answer is obvious to rotate it and set chain timing correctly.
Great video....very informative, I like the way you work. Just one niggle for me......I think whilst the head was off I might have been inclined to check the valve seats and re-grind them to know the that whole head was good.
and measure bores for oval
Excellent, loads of respect and support Rodge David Kidderminster UK
Excellent. Great video. Enjoyed it.
Many thanks!
I had this excact scenario with a 750 Honda, i managed to free up the rings by carefully heatcycling the piston,and managed to loosen all of the stuck piston rings
Curious as to why you would go all that way and not bother with a new cam chain or even look at the crank. Great video, love this stuff be thankful it's a single cam.
great episode Taylor
Thanks
Nice work as always
Appreciate that
Awesome video 😊
For a video that is not how-to, there is a lot of how-to. This is a great look at the process, and thank you for sharing.
Hey, I bet it would be a REAL bummer to get the cylinder block and head on, look at the assembly bench and notice the cylinder base O-rings you forgot to put in. :P
The reason the head gasket goes on dry is because any sealer used could possibly block the tiny high pressure oil way holes in the cylinder head and that would be very bad news indeed. One thing I noticed is that the head gasket was not laid flat over the oil rings and you just pushed/dropped the head gently into place and kinda hoped that nothing gets pinched. Hope it works out and no oil leaks.
You can score the bore if you have gaps front and rear, not over the gudgeon pin either or you could theoretically snap the end off.
Classic stuck rings!
Pretty easy fix. Good call replacing all the rings!
Thanks 👍
Great videos keep the good work 👍
Thanks, will do!
Taylor you do great work and then present it well. Couple things I’ve learned to do. Permatex or something under the pucks or they leak. Torque cam towers and caps or risk screwing up threads. Red loctite on cam gear sprocket. Big problem if they loosen up. Torque head bolts and do it again in 24 hours and again in 24 hours until it holds a constant torque. You can put a weldless frame kit in allowing you to do a top end job w/o removing the engine. You can always weld the frame back together. Keep up the good work.
Yes would defo agree with the use of loctite and re-torqueing the head after a setting period
Good suggestions. Thanks!
Love your work. Very easy to watch. Regards Woz from Oz. ps 900 f supersport/bold'or engine rebuild next what do you think .haha.
Excellent job..learned a lot..tks
Nice work Tyler 👍
Thanks 👍
Love this video, thank you. I have a dohc I'm planning on doing this on. Quick (probably dumb) question, how do you know the bores are within spec for the rings? Could it be that I buy a rebuild kit and actually still have bad compression due to the bore being worn?
Wow...beautifully done..
Thanks Tyler!!!
The beauty about SOHC Hondas (and Z1 Z900/1000 Kawasaki's also H1 H2 triples) is that there is so much after market stuff for decent prices. Their continuing popularity and sheer numbers sold, especially in the U.S means its commercially viable to mass produce parts. I'm into 80s Japanese stuff, but the 2 year product cycle, often with complete redesign, means finding parts for some bikes a nightmare.