CB750 K2 Carb balancing -
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- เผยแพร่เมื่อ 22 ส.ค. 2024
- After all the wsork completed on this Classic Honda CB750 K2 it's finally in a condition that we can balance the carbs. Poor starting & irrattic running were the owner's complaints when the bike came in some 14 months ago, the carb sync is the final stage in getting this old girl back to running how she should...
Enjoy
Andy
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Thanks for all your support, until next time...
Andy
Those are great results, a good valve adjustment before the synchronization would be the answer to perfection . Good job 👏 👍
Thanks so much Andy trying to help a friend you made it vary simple
Thank you for a great video I have a 1980 cb750 DOHC and I’m new to bikes and have a high idle issue I’ve watched a few videos on carb sync. But it seemed like those videos the carbs were fine to start. Your video really helped me . I already bought a Digi sync and I was having a problem with it moving around I like how you mounted yours thank you so much for this video
Thank u Andy i hope u and Mrs Mechanic have a great Christmas🎄
Many thanks George, you too Matey, enjoy the break...
Cheers Andy
That was a great video. Been looking forward to the carb balancing for a long time. Used a few different Raytech testing tools during my time in engine rooms. Very accurate and durable equipment. Cheers Andy.
Thanks Connor, yes, it seemed to fo a great job. The bike now starts & runs really well. I'm very happy with the end result....its taken a bit of work!
Wishing you a great Christmas & a relaxing time over the holidays.
Cheers for now
Andy
Sounds like mine a bag of spanners, think my timing chain needs adjustments.. thanks for sharing.
Mine came from Japan so an electric fan was fitted...
Merry Christmas Andy to you and family and all reading this.
Thanks Pete, you too. Cheers Andy
Andy seasons greetings sir ! I'm only part way into the video .. on my vacuum adapters I dremmel cut a slot in the tops and use a long flat head screwdriver to install them . I've also used soft rubber vacuum pipe as wider o rings to make up the space on the long threads... as I don't have a lathe ...
Peace and love brother 👍🏻☮♥️
Great video. Syncing my 1975 CB750 carbs is such a pain the butt. I’m not very good at it. Seems like every little adjustment effects the other carbs, as we saw in this video. I bought the bike 3 years ago as a first bike and I’ve been learning to do all of this stuff myself. Last year I picked up a 64 Triumph TR6 as a second bike. It has one carb, which is so nice. Now I only want single carb bikes for ease of tuning and maintenance. : ) I’ll never get rid of the CB750 though. Hopefully I won’t have to sync those carbs very often.
Excellent tutorial Andy. More reason for me to stick with thumpers. Glad more videos being posted. Have a great holiday.
Cheers Mike, will do. You too Matey. Big Thank You for all your help & support, it really is very much appreciated. Enjoy the holidays...oh & the bottles from your cabinet! Lol
All the best
Andy, Mrs Mechanic & Tool Girl Holley
Andy.merry Christmas to both of you.keep up the good work.
Thanks Kevin, lots to get done at this end in preparation for the bike trip. Enjoy your break. Cheers for now Andy
It's Christmas in the future for you and your family already and hope you have a good one.
Good Morning Jim, Thank You :-)
Wishing you an awesome Christmas & prosperous New Year. See you on Sunday. All the best Andy
i see in some videos that the air cleaner are removed.
Are You sure You understand this? When vacuum goes up - gets a higher value, the pressure goes down.
Yes, the basis of carb balancing is to balance the vacuum in all 4 of the intakes.
@@AndyMechanic 160 mmHg is less than 240 - so the vaccum pressure is lowest at 240. Zero vacuum is higher pressure than 240, but less vacuum pressure.than 240. The manual is correct.
merry Christmas . watching thing its making me think if ways to do it with a scope in a very accurate way. pressure pulse sensors . say you want an rpm of 1000rmp divided by 4 that makes 250 rpm per cylinder. so 250 pressure pulses a cylinder . i may be mikes out with this idea tho
Merry Christmas to you & your family Simon. Thank you for all your help & advice, it is very much appreciated.
The scope would certainly give an accurate RPM for sure plus super accurate vacuum readings if I had enough pressure transducers! Probably a bit of overkill on this old girl! The RayTech SynchroKing did a great job & I'm super grateful to have it in my tools inventory now :-)
Stay safe & enjoy the break - right video editing time....
Cheers for now
Andy
Merry Xmas Andy & family 👍🇬🇧
Thanks Richard, you too. Enjoy the Christmas break. All the best. Andy
Hello, revs ideally but idle is not the way it should be....
Check idle jet & circuit on each carb. Once you are sure they are all clear do a carb balance.
Cheers Andy
Yes, l find the heat build up affects the readings, l usually have to take a tea break when half way through syncing my 4 cyl bike. Then go back when its cooled and make the final tweeks. Is that the typically slappy/clacky primary chain l can hear? which may sound worse when not under load.
Sure is, got a lot better once idle smoothed out :-)
Yes, I was very concious od engine temp, was a hot day too which doesn't help! Had to take a couple of breaks then start filming again. Wasn't too bad a result in the end & way better than it was previously.
The carbs really need a full stripdown & ultrasonic clean. Then rebuilt with an overhaul kit to get it 100% but that will have to wait until next year...
Cheers Andy
@@AndyMechanic Well done, how did you know which way to go with the air screws when it wouldnt settle properly when revved?? Also you did PROMISE me an on board ride video didnt you......promised.....
Ah...clockwise to richen mixture, anticlockwise to lean off. The revs were slow to come down which is usually an indication of a lean mixture...
Test ride.....yes, I did & unfortunately I just ran out of time. It would have been awesome & it may still happen in the New Year....have a video planned with the owner Alan for the hand back.....so maybe, just maybe I'll redeem myself with this one! Lol
@@AndyMechanic I see, thanks for replies and ta-ra for now.
@@bananabrooks3836 make sure you know the diffrence between an air screw and a mixture screw ,a air screw is between the airbox and throttle slide and operates tge way andy states, a mixture screw is between the throttle slide and intake and operates the oppisite way in leans out richens
first bike was a 750-ss greight bike . when synchronizing do you doit without the air filter on the carbs?
Nop, do it with the air filters attached
hi andy . im just having simular carby issues atm im all go on all 4 . phew. 1 problem is either 3 or 4 has a pop when taking off of on the throttle when around 2k revs , have any ideas please .
james . in tauranga .
What is that god-awful sound - it’s like the primary chain /cam chain was slapping around like crazy.
I’ve heard the same on other videos of these engines.
Yep....that's exactly what it is.....not great! Cheers Andy
I think honda is just screwing with u andy lol