1982 Honda CB900F Barn Find Restoration - Episode 4 - Carb Rebuild part 1
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- เผยแพร่เมื่อ 21 พ.ย. 2024
- Part 1 of the Carb rebuild for the 1982 CB900F. In this video I disassemble and Clean the carbs.
In Part 2 I'll rebuild them with new parts and hardware.
Note that this is a very detailed video, It may not be for everyone especially those with a short attention span and lack of appetite for detail.
Thanks for taking the time to do this video, the best one I've seen for rebuilding these carbs - saved the day!
Thank you!, there are 2 added videos on these carbs here on my channel, there are a few tricks I missed the first time through. Thanks for the comment.
If your bike is pre 82 Be sure to watch part 3 where I drill and tap /pull out the slow speed jets. Terrifying but necessary.
Thank you very much for your very helpful video. I am hoping to buy a 1981 CB750F bike in a couple weeks and will be glad to have the information you generously provide. Thank you and all the best to you!
Glad I could help! Check out the follow up vids on these carbs also on my channel. Depending on the year there are some slow speed jets that have to be drilled and tapped to get them out . Pre 1982 are this way. Post 82 you can remove them easily
@@true-moto-resto Thank you!
For Those Viewing: An impact screwdriver is critical in removing many of those screws. And you can get a nice replacement set of almost all the outer screws on those carbs.
The 1981 Honda CB650 has very similar carbs to those. Not many bikes have those exact carbs, known a Keihin VB44 on the '81 CB650.
A paperclip with bent tip is handy for removing the tiny o-ring inside the fuel screw cavity.
Rebuild kit can be found online pretty much anywhere, like eBay & Amazon (imported kits). Just make sure the new kits has the size jets you need (in advance.)
I just worked on similar set of carbs. Been there - Done that. 👌
900f was a really nice motorcycle. The rubber mounted engine was a treat.
hopefully I can do her justice with this resto
I started with the mixture screws 2 turn out but the bike did not run good so turned them out 2.5-2.75 and it runs desant but i need to synk them aswell. It is not running 100% i belive the mixture screws is set at factory and is not always the same for every carb. I wish I culd some how measure the mixture to know it is right. I did the trick to set as low idle as possible and adjusted them but ended up changing it later because the bike did not rev out .But a good starting point to have the same settings. Thanx for the detailed video you are puting out on the web for all of us to lern 👍😊
I’m sure I’ll have to play with these once they’re back on the bike too
Im working on the same carb bank right now out of a cb900c, wish i had the f for the sporty styling lol
If it’s a pre 82, you’ll have to watch my final video on the cb900f, I removed the carbs (again) and had to drill and tap the pilot jets to remove them for cleaning (82 and newer they just screw out). Also make sure those accelerator pumps are working , took a bit of cleaning to get all the jet nozzles working on mine
The throttle shaft seals can deteriorate leading to lean condition so might b worth doing
Thanks Karl, I recorded this a few weeks ago, so that ship has sailed. I didn’t change the seals, none in the kit, but on the chance that they are felt seals like the VFR’s I’ve done, I did oil the shafts at the seal point sufficiently to lube the felt and help the seals. I guess we will see. Cheers !
I did not see you remove the Idle Slow Jet, from under the rubber plug. The only way to clear the tiny opening is to remove/extract the jet and use a single bristle from a wire brush, to free up the jet hole. it is tiny. This is why I believe, the bike does not idle well or it sounds like it's "Missing".
You are correct. Unfortunately on these carbs there is no slot to remove / unscrew that Jet. So I had to use a wire while they were still in place . No idea why there is no screw drive slot in them, they look permanent ….very odd
Mel, thanks for the link to the removal of that low speed jet ! jeez that looks terrifying. Ill have to give that a go.
Great video. Was there an issue before rebuilding the carbs? I have a 1982 cb900c and only cylinders 3 and 4 are firing. I just bought it so not sure what was done before. Thanks
The bike had sat in a barn for many many yrs. This was just one video of many showing the full restoration of the bike. Carbs are just one part of the process (2 videos on carb rebuild , this was part 1)
For your bike, start with the basics. Does it have spark on 3 and 4? Does it have good compression on 3&4?
Does is come alive on 3 and 4 if you squirt some fuel down the carbs throats ?
These carbs are quite complex, 3 jets per carb and on some model years you have to drill and tap one of the jets to remove it.
There are accelerator pumps and air cut valves etc
But, start simple and track the problem down to spark, compression or fuel first
@true-moto-resto thanks for your reply. All have spark and compression. 3 and 4 works great. I will directly inject starter fluid to 1 and 2 to see if is a carb issue of no sending fuel to the cylinders. Thanks again. Regards
I’m trying to bring an 81 cb900c back to life and after cleaning the carbs I found a tiny ball bearing, tightly wound spring, and what seems to be a brass square with a circular nub on one end in the bottom of my ultrasonic cleaner. I have no idea where it came from and was hoping it was something from the accelerator pump but the little brass square is still in the carb body for the accelerator pump. Any idea where this might have come from?
It’s been so long since I cleaned the carbs on the CB900. I’ve done so many carbs, they all become a blurt.
On some carbs , the small springs and balls are from the choke assembly. The rod that actuates the choke plungers is held in place by a detention ball and spring so it stays out and doesn’t go back in (choke off) unless you push the rod in.
These are usually on the carbs that have the choke actuator rod right on the carbs and not in the handle bars. Mikuni flat slides are like this
On the CB900 carbs, I honestly don’t recall. But I will say there are 3 videos on these carbs here on my channel
It took me 3 attempts to get them properly sorted out
On the pre 82 carbs, there is a slow speed jet that you have to drill and tap to extract it in order to properly clean it.
I can only suggest watching all 3 videos and hope that you see what your looking for
Thanks for watching as commenting
The text doesn’t stay up long enough to read 😂
Hit pause , lol
Where did you get the carb kit?
KM Carburetors. I found him via the CB1100 forum