I'm rebuilding an engine on my project cb750 dohc for the first time with no real experience or clue what I'm doing. I've found so many sohc videos but very few on the duals so you are now my hero. Thank you so much for these helpful videos.
I’d bet a dollar that the low compression is due to valve issues and not ring issues. The rings on these bikes are solid but more times than not, people disregard checking the valves and then they run into problems, like bent and or burned valves. If you run the clearances by the book, you’ll end up with burned valves. Run a clearance of .13mm with a range of .11mm to .15mm. My bike was showing between 100 and 130 psi across all cylinders and after swapping burned/bent valves, valve stem seals and new shims, the pressure went up to 160psi. The metal shavings, that’s another animal. Good luck and am looking forward to see the progress.
Interesting call, the shims are definitely too tight which makes me think the valves won't have enough room to rest, but the oil increasing it makes me want to change the rings, just for peace of mind too for the price.
MAN! I'm having so much fun watching this series! I am new to bike building and your videos are AMAZINGLY DETAILED and easy to follow . Thank you! SUBSCRIBED!
What a massive project this is. Good luck, I keep my fingers crossed you'll figure this baby out in the end. I'll continue watching with much intrigue. BTW: your cinematography skills are growing in lockstep with your engineering skills. I'll stay tuned.
Yeah it's going to be a fun one. It's a pity I don't get much time to refine the cinematography as it is part of my proper job, it's just the limited timescale of creating these videos that inhibit better productions.
You may also have a problem replacing the cracked cam clamp, I had a similar issue on a CB900 many moons ago with a broken rev counter drive cam clamp. I was informed at the time that whole head would need to be replaced as these clamps are machined in situ during manufacture so are unique to that particular head & not replaceable individually. Ended up giving the whole lot away to a friend of a friend.......if I knew then what I know now!
I'm having a similar issue on mine, the camshaft hodler is having a damaged thread... not possible to replace then? a friend told me about a fixing using Helicoil thread, as we already tried to remanufacture the thread with a thread tap...
Great to see a in depth vid on breaking down the engine, I'll be doing the same to my CM400 just so I know it's fresh and ready when it goes back in. Keep the awesome videos coming 👍
Thanks for the tips on this. I've just started rebuilding my '79 CB650 and even though the 750 is a bit different, the basics are pretty much the same. I do have 1 request though; looking at the engine, it has a lot of oxidation on the aluminum. If you clean and polish that yourself, could you devote an entire (hopefully very detailed) video to it? Can't wait to hear the 750 and CX500 running again.
if you're in a hurry, youtube search " how to polish a motorcycle engine" theres a guy with an old suzuki (im pretty sure suzuki anyways) that does a very in depth video of it! takes some time and attention to detail but its worth every minute when its done!
Are those pressures in the manual for a cold compression check? Always assumed they were on a warm engine. But loving the videos looking forward to the next.
What book are you using? Is it at specific book for honda cb750? Any books you'll recommend for honda motors? Im going through my cb750 at the moment and want to work a bit on the engine :)
Could be a good thing if you got to strip it down to the bear bones it will give e you a good chance to sort out all the engine cases. Enjoying this one big time keep up the good work
Hello from Australia. I’m a new subscriber and currently binging my way through your videos! Love what you do. I will be starting my first cafe racer project soon (ish) I’m tossing up between a cx500 and a bmw k100/1100. Just wondering what your thoughts are? Any pros & cons etc.
For The Bold - dreegez yeah, thanks. I’m leaning towards the bmw anyway. I laughed when you said the cx front end at £700 cost more than the bike- in Australia they start at $5000 and the k100 you can pick up for $2000 ish, so beemer it is! I guess I need to learn how to weld first. Thank heaven fo the University of TH-cam and fellows such as yourself!
The good thing about Honda's are that they are dishwasher safe. You should be able to throw it on the bottom rack and it will be good as new. The wife will be happy that you are finally putting your stuff in the dishwasher instead of leaving it lying around on the counters as well. Basically a win, win.
I need to test the compression of my project 1980 cb650 chopper I bought, I've never heard it run and the front end was removed so throttle and electric start are no longer connected, could I just connect the battery to the starter like this and get an idea on the engines health by doing a test like This? I'm an absolute newbie to bike mechanics so sorry if it's a dumb question.
That engine is toast sadly. That is one hell of a lot of swarf-gunk that has been manufactured there. Probably gonna be cheaper to find another powerplant. Measure the bearing shells man!
I like the challenge of the rebuild and then knowing that everything is new, whereas with another engine you never know when that next thing will go, rather do it all now and leave the engine in the frame once its in.
I've been doing all this last weekend on my 82 gsx400f. If you're not careful, it's easy to drop one of those stud nuts down into the crankcase, but I wouldn't be so careless....Oh no, not me...ahem.
I'm rebuilding an engine on my project cb750 dohc for the first time with no real experience or clue what I'm doing. I've found so many sohc videos but very few on the duals so you are now my hero. Thank you so much for these helpful videos.
Amazing, best of luck with yours, I'll be measuring the crank and ports in next week's video so more coming.
My favourite build on TH-cam at the moment!
Amazing, I'm glad you like it.
I’d bet a dollar that the low compression is due to valve issues and not ring issues. The rings on these bikes are solid but more times than not, people disregard checking the valves and then they run into problems, like bent and or burned valves.
If you run the clearances by the book, you’ll end up with burned valves. Run a clearance of .13mm with a range of .11mm to .15mm.
My bike was showing between 100 and 130 psi across all cylinders and after swapping burned/bent valves, valve stem seals and new shims, the pressure went up to 160psi.
The metal shavings, that’s another animal.
Good luck and am looking forward to see the progress.
Interesting call, the shims are definitely too tight which makes me think the valves won't have enough room to rest, but the oil increasing it makes me want to change the rings, just for peace of mind too for the price.
For The Bold - dreegez,
Since you’re going to be in there, might as well change the rings then. Good luck and looking forward to the next video
MAN! I'm having so much fun watching this series! I am new to bike building and your videos are AMAZINGLY DETAILED and easy to follow . Thank you! SUBSCRIBED!
Excellent. Glad you’re enjoying he series. Thanks for subscribing
I love the engine builds! I learn so much from them. I hope this one's not too much trouble :)
I think it should get easier the lower down I get,.
What a massive project this is. Good luck, I keep my fingers crossed you'll figure this baby out in the end. I'll continue watching with much intrigue. BTW: your cinematography skills are growing in lockstep with your engineering skills. I'll stay tuned.
Yeah it's going to be a fun one. It's a pity I don't get much time to refine the cinematography as it is part of my proper job, it's just the limited timescale of creating these videos that inhibit better productions.
You may also have a problem replacing the cracked cam clamp, I had a similar issue on a CB900 many moons ago with a broken rev counter drive cam clamp. I was informed at the time that whole head would need to be replaced as these clamps are machined in situ during manufacture so are unique to that particular head & not replaceable individually. Ended up giving the whole lot away to a friend of a friend.......if I knew then what I know now!
Going to look into it, might end up being a fix it job.
I'm having a similar issue on mine, the camshaft hodler is having a damaged thread... not possible to replace then? a friend told me about a fixing using Helicoil thread, as we already tried to remanufacture the thread with a thread tap...
Looks like you will have your hands full here. Looking forward to part 2!
It's going to be fun.
Great to see a in depth vid on breaking down the engine, I'll be doing the same to my CM400 just so I know it's fresh and ready when it goes back in. Keep the awesome videos coming 👍
It's the best way, if you do everything can 'could' go wrong in the future then you know that engine won't have to come out for a long time again.
What manuel are you using for the bike? Also, thanks for these videos. I'm currently tearing apart my engine now
Glad you enjoy them. It’s the Honda factory manual.
Thanks for the tips on this. I've just started rebuilding my '79 CB650 and even though the 750 is a bit different, the basics are pretty much the same. I do have 1 request though; looking at the engine, it has a lot of oxidation on the aluminum. If you clean and polish that yourself, could you devote an entire (hopefully very detailed) video to it?
Can't wait to hear the 750 and CX500 running again.
Very easy to polish up the aluminium, and yeah I can make a video on it.
if you're in a hurry, youtube search " how to polish a motorcycle engine" theres a guy with an old suzuki (im pretty sure suzuki anyways) that does a very in depth video of it! takes some time and attention to detail but its worth every minute when its done!
Can we get a link to cody’s channel
th-cam.com/channels/mpL0CxrbzbsD6G0GE0P_DQ.htmlfeatured
Can you put a link to the service manual you're using? It looks better than the clymer one that I have.
Try this link
www.cb750.com/threads/828-79-83-CB750-Service-Manual-in-PDF-Format
Can you please tell me if it was oil in the pulsar pick up case many thanks
I honestly can't remember
Are those pressures in the manual for a cold compression check? Always assumed they were on a warm engine. But loving the videos looking forward to the next.
They're from warm but no way of warming this up. I am allowing for a little expansion for the heat.
For The Bold - dreegez yeah makes sense.
What book are you using? Is it at specific book for honda cb750? Any books you'll recommend for honda motors? Im going through my cb750 at the moment and want to work a bit on the engine :)
Yeah it's the factory manual
What’s your thoughts on doing a cafe racer build on a 83 Kawasaki kz1100
why not, I think any bike would be a good challenge.
Thx for the input love the build series 👍🏻
cant wait for part 2!!
Hopefully this Friday.
Could be a good thing if you got to strip it down to the bear bones it will give e you a good chance to sort out all the engine cases.
Enjoying this one big time keep up the good work
Absolutely, a mix of painted and polished.
Hello from Australia. I’m a new subscriber and currently binging my way through your videos! Love what you do. I will be starting my first cafe racer project soon (ish) I’m tossing up between a cx500 and a bmw k100/1100.
Just wondering what your thoughts are? Any pros & cons etc.
I like both, the K engine is lovely, probably the better of the 2, the frame on the K100 though might be a little trickier than the CX500
For The Bold - dreegez yeah, thanks. I’m leaning towards the bmw anyway. I laughed when you said the cx front end at £700 cost more than the bike- in Australia they start at $5000 and the k100 you can pick up for $2000 ish, so beemer it is! I guess I need to learn how to weld first. Thank heaven fo the University of TH-cam and fellows such as yourself!
That's a lot compared to what I paid, but I have to say since I got mine the prices of CX500 have rocketed in the UK.
looks like you have you work cut out for you, look forward to the progress.
Yeah it's going to be a good one.
The good thing about Honda's are that they are dishwasher safe. You should be able to throw it on the bottom rack and it will be good as new. The wife will be happy that you are finally putting your stuff in the dishwasher instead of leaving it lying around on the counters as well. Basically a win, win.
True, if I'm not on TH-cam next week you'll know it didn't go well.
For The Bold - dreegez lol...
There are Some big Bore kits so somewhat 832cc wich offers good to this completly destroyed engine
Let's see what the customer thinks ;)
how many miles were on that bike?
I think 39,000
This is going to get interesting!
Definitely.
Thanks you are a gentleman,
Thumbs up
What manual are you using? Doing the head gasket on mine
The Honda factory one
@@forthebold how do I obtain one
please educate me. how the heck did you get an engine just sitting there on your workbench to turn over?!?
absolutetuber I'm assuming he's just connecting the battery direct to the starter motor
as i thought about it i realized how dumb my question was haha. probably what he’s doing. but i’m a noob trying to learn is all
absolutetuber hey me too man, all have something to learn :)
Yup, connect the battery direct to the starter motor.
I need to test the compression of my project 1980 cb650 chopper I bought, I've never heard it run and the front end was removed so throttle and electric start are no longer connected, could I just connect the battery to the starter like this and get an idea on the engines health by doing a test like This? I'm an absolute newbie to bike mechanics so sorry if it's a dumb question.
Love the videos but the shakey camera is tough to watch at times.
Too Bear Grills.
That engine is toast sadly. That is one hell of a lot of swarf-gunk that has been manufactured there. Probably gonna be cheaper to find another powerplant. Measure the bearing shells man!
I like the challenge of the rebuild and then knowing that everything is new, whereas with another engine you never know when that next thing will go, rather do it all now and leave the engine in the frame once its in.
As gooey as that sludge was, I doubt it ever had an oil and filter change. You've got your work cut out for you. Those cams still look good though.
True, I don't think it was well looked after.
could be a perfect excuse to get the cylinders machined to a higher cc
Could be, I'll put it to the customer, a slight cost with OS pistons.
I've been doing all this last weekend on my 82 gsx400f. If you're not careful, it's easy to drop one of those stud nuts down into the crankcase, but I wouldn't be so careless....Oh no, not me...ahem.
Easily done ;)
Great video
Thanks.
I want to buy a honda cb450 motor with carb in low price and working in india
Hope you find one
Hey you sound a little better lol
Back to 95% now ;)
Check out classic octane on TH-cam
More metal shavings than Robo cops Dandruff!! That's a Subscribe right! ;0)
It looks like that motor was really abused. Good luck with it.
Wasn't well looked after that's for sure.
you disappoint; instead of food this week, buy ''shop heat & ventilation''
zapatero