1982 Honda CB900F “Holly”

CALfeRacer

Fat man on a little bike
Well, after having an itch to ride after my SV getting stolen I made the questionable decision to purchase an 82 CB900F. The PO replaced basically everything, and it made cool noises so I couldn’t resist.
The original plan was to dial the carbs, replace the chopped tail, and ride it to work semi-frequently. But, it looks like she’s gonna need a little more work so I might as well dive in and put up a thread.
 

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CALfeRacer

Fat man on a little bike
As I said before, the PO did a ton of stuff to this bike. Apparently he got it from a coworker ~6 years ago and has been tinkering ever since. It has new tires, wheel bearings, brake pads, stainless brake lines, new front brake master, rebuilt rear brake master, new chain and sprockets, barnett clutch, motogadget m-unit, motoscope, m-lock RFID key, electronic ignition (spacing on the brand rn, but he did mention the guy does mainly Harley stuff), the taillight is off a Ducati Monster w/ integrated signals, Renthal bars with two-button controls on each side, Keihin CR carbs w/ K&N filters, and Vance & Hines exhaust. Phew.
Some quick pros and cons for the bike:
Pros:
-New consumables are obviously nice.
-CR carbs are cool, and it rips on the mains (~6k and up)
-V&H pipe sounds AWESOME
-Motogadget gauge is pretty slick, and very easy to read for how small it is
-RFID key is pretty cool
-Came with extra parts like stock & fiberglass fenders, the leftover paint he used for the body, all paperwork/tuning docs he had
Cons:
-CR carbs are not 100% dialed, need work below 1/2 throttle.
-She's definitely cold blooded, maybe I'm just too used to FI
-V&H pipe drags at very mild lean angles going right
-RFID key drains the battery, so it lives on the tender (more to follow)
-Seat fits weird and is an uncomfortable shape
 

CALfeRacer

Fat man on a little bike
So the problems came last night, rode out to visit some family after work (~1 hour) and had no issues. When I headed home 3 hours later, it started up quick but the battery was dead after getting gas. Bump started easily, but completely died 1/3 of the way across a bridge heading home. Bump started again, but then died again on the bridge. Very loud popping out of the exhaust, no acceleration, and then lights and gauges off. One last bump, made it to the toll plaza on the far side and parked it. Glad I opted for roadside assistance on my insurance, except apparently nobody is available to tow a motorcycle at 10:30pm. So I left it with the toll employees in their parking lot, took a Lyft home, and picked it up today once trucks were available.
Last night I was pretty frustrated, and considered selling off the bike out of spite. I also came up with the name 'Holly'. But then I buckled down and realized I need to put some work in and address the problems. I know it's somewhere in the wiring, but not sure if the RFID is actually THAT big of a drain, or if the battery isn't getting charged while riding. My plan this weekend is to test if the battery is getting charged while running then go from there. After that the carbs need some work to run smoother at less than WOT, unless I'm hosed since the CR's are race carbs. Cruising at 70-75 can lead to some weird dead spots and almost surging. Not ideal since half of my commute is exactly that.
Then come fun things! Like getting a fairing, moving the headlight down/in, and painting/installing the tail section I got (thanks @pidjones!!!). Or maybe the wiring stumps me, I get mad, then put it up for sale and spend the extra coin to get something new and FI that'll just work. But where's the fun in that?
 

pidjones

Well-Known Member
There is a very helpful F bike forum. http://www.cb1100f.net and CB DOHC forum http://www.cb750c.com but, there are a ton of DOHC masters (and slaves) here on DTT. I rescued the '79 CB750F from a fencerow it had been parked in since 1999. It had NOT enjoyed primo upgrades, but seriously shady hacks. Still, turned out to be a great running bike. But, not my style of riding (I'm an old phart GoldWing-type), so I sold it not long after finishing it. They are cold-shouldered. Get used to that. See if the PO has a diagram of how he wired it. Otherwise you'll need to do a hand-over-hand of the system and sketch it out so troubleshooting can be done. One of the forums should have the Honda manual and troubleshooting sections.
 

Jimbonaut

Well-Known Member
DTT SUPPORTER
Congrats on the new ride man, I love these bikes - really hope you get over the sell/don't sell hump and make this bike a keeper. I was also going to suggest cb1100f.net as another great resource of info and help on these bikes. I'm working on an '82 750F and both forums have been invaluable.

Dig that exhaust - is it really that low that it scrapes? I wondered about that - a lot of the aftermarket 4 into 1 set-ups for these bikes do look like they hang a little low beneath the bike. And that V&H muffler isn't baffled, right? I bet it absolutely screams! I really like the rear shocks on these 900's too - if you're ever thinking of switching them out let me know ok?

Hope you stick with the bike mate, you'll be glad you did if you do :cool:
 

Jimbonaut

Well-Known Member
DTT SUPPORTER
By the way, how's the front brake feel? I bought the exact same Nissin front brake master cylinder for mine (yet to install) with steel brake lines and rebuilt calipers. I read it's great, and a looker too.
 

CALfeRacer

Fat man on a little bike
Thanks for the responses guys! I'll try my best to respond:
There is a very helpful F bike forum. http://www.cb1100f.net and CB DOHC forum http://www.cb750c.com but, there are a ton of DOHC masters (and slaves) here on DTT. ...They are cold-shouldered. Get used to that. See if the PO has a diagram of how he wired it...
I'll have to check those out, admittedly I do think I stumbled on some threads there when I was doing a little background digging before buying the bike. Good to know they're cold blooded, I can get used to that (my old Katana was a little bit too). He did give me a wiring diagram, as well as the FSM on a zip drive.
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most dohc carb problems are ignition and charging system related so get them right before fiddling much with your carbs IMO
I'll start with charging and ignition, I really need to check what ignition module he put on. I do know that it has a dial with 11 different maps to choose from. Thanks for the link!
By the way, how's the front brake feel? I bought the exact same Nissin front brake master cylinder for mine (yet to install) with steel brake lines and rebuilt calipers. I read it's great, and a looker too.
Front brake feels good, tbh I think it feels better than the factory front brake did on my SV1000 (probably a little less stopping power, haven't had to really test yet though).
 

CALfeRacer

Fat man on a little bike
Congrats on the new ride man, I love these bikes - really hope you get over the sell/don't sell hump and make this bike a keeper. I was also going to suggest cb1100f.net as another great resource of info and help on these bikes. I'm working on an '82 750F and both forums have been invaluable.

Dig that exhaust - is it really that low that it scrapes? I wondered about that - a lot of the aftermarket 4 into 1 set-ups for these bikes do look like they hang a little low beneath the bike. And that V&H muffler isn't baffled, right? I bet it absolutely screams! I really like the rear shocks on these 900's too - if you're ever thinking of switching them out let me know ok?

Hope you stick with the bike mate, you'll be glad you did if you do :cool:
Yup, and I have pictures to prove it
It does have a baffle, but it isn’t much so definitely still a screamer. Will do, I’ve thought about updating suspension since it’s very bouncy, going to start with race tech emulators and springs on the front if I do. Then we’ll see how I feel about the rears, I like the look of them and definitely do not want to spring for Ohlins.
 

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cxman

Active Member
DTT SUPPORTER
I'll start with charging and ignition, I really need to check what ignition module he put on. I do know that it has a dial with 11 different maps to choose from. Thanks for the link!

make sure you pic one suitable to your bike the cb900 has very conservative timing advance way less than the cb750
 

CALfeRacer

Fat man on a little bike
Ok so it's a Dyna 2000 ignition, I think he bought the kit with triggers and coils too. I found ignition curves, but need to confirm where the static timing is set.
I saw a note about the charging system needing to be good, so I'll start there.
 
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SquidHunter

Active Member
Don’t do anything until the charging system is good. If it’s still using the stock charging system, I believe the regulator was attached (inconspicuously) on the stock harness.
I switched to the cycle x charging system. It’s based off of a triumph system I believe. It’s less weight on the crank too. Since switching I’ve been loving it. Quick revs, and haven’t used a tender all winter.


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CALfeRacer

Fat man on a little bike
Don’t do anything until the charging system is good. If it’s still using the stock charging system, I believe the regulator was attached (inconspicuously) on the stock harness.
I switched to the cycle x charging system. It’s based off of a triumph system I believe. It’s less weight on the crank too. Since switching I’ve been loving it. Quick revs, and haven’t used a tender all winter.
Yeah, the regulator is just under the left side cover, easy enough to get to. Are you talking about the exposed system w/ the oil pressure gauge? Looks cool but I'd like to retain the cover, and don't necessarily want to switch back to a lead-acid battery (believe it has an agm currently). What battery are you running?
 

Maritime

Well-Known Member
AGM and lead acid are the same tech, just one is a gel acid vs a liquid acid. If you are talking lead acid - (AGM or not) vs a Lithium Iron or Lithium ion then those are different beasts.
 

CALfeRacer

Fat man on a little bike
AGM and lead acid are the same tech, just one is a gel acid vs a liquid acid. If you are talking lead acid - (AGM or not) vs a Lithium Iron or Lithium ion then those are different beasts.
Gotcha, that's good to know. Once I test my charging system (busy weekend, wasn't able to get around to it) I'll make a decision. Looks like cycle x used to do one without the exposed components, I'll have to ring them and see if they still offer that if I decide to go down that path.
 

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