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Author Topic: Good report, but where to begin...  (Read 2491 times)

Offline 88SS

  • Posts: 78
Good report, but where to begin...
« on: Apr 15, 2017, 22:57:29 »
I recently purchased a 1980 cb750f super sport for a very good price. It started and ran ok for a few days, then as I started tinkering it started running lean. The baffles were rotted out so pulled them, then the exhaust, and then replaced it with 4 into 1 exhaust. I tuned up the carbs and it ran ok, but still a touch lean. Condition became worse. Then I changed the plugs, coils, and wires. Replaced the carb boots and did a rejet to 68 and 105. Still lean. Changed the inline filter. Lean. Then my battery starts going dead on me. Changed all the charging parts. The r/r, stator, and rotor.... and the battery cables. I did an oil change, and replaced the k&n filter (in the stock air box) with a stock paper one. Fixed the shift shaft oil seal leak by replacement, and switched to iridium plugs, and replaced the petcock. This is where it gets interesting.

Immediate changes with the new petcock. I'm assuming it was causing most if not all the lean condition. The carbs start pissing gas immediately out of 2 and 4, so I pull them. When I get the bowls off, I notice the ones leaking are adjustable, and the ones not are non adjustable and stock. Long story short, I adjusted them, put them on the bike, and no leakage. Took the bike for a spin and it was like new money. Rode like a dream. No issues for the first time in months.

I talked to the p/o about the carbs, and apparently they are off an 83 model bike and he replaced a couple floats with adjustable. Hopefully my issues with be resolved for a bit, but what should I look into next? I've got a faint tick, so I'm going to tighten the cam chain in the morning. I'm thinking a valve shim wouldn't hurt, but I'm really just looking forward to riding. Anyone ever taken one on a long ride? Any info is good info, and thanks in advance.


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Offline Cookie

  • Posts: 595
  • God help the child who grows out of everything
Re: Good report, but where to begin...
« Reply #1 on: Apr 15, 2017, 23:15:31 »
- Check and adjust valve clearances to .005".
- Fresh oil/filter can't hurt.
- May require new valve stem seals.
- Adjust your timing chain. There's a guy on the cb110f forum called 605brent; his company in New Zealand has developed the perfect replacement chain/guides.
- Clean and tighten all the connectors - No sense wasting electrical power through corrosion.
- Consider doing the ignition coil relay mod. It's on here somewhere.
- Ride the hell out of it!

Welcome to DTT, 88SS
* Insert something witty here *

81 CB750C
84 Tempter - well, most of it...

Offline Cookie

  • Posts: 595
  • God help the child who grows out of everything
Re: Good report, but where to begin...
« Reply #2 on: Apr 15, 2017, 23:22:28 »
Also, post up some pics
* Insert something witty here *

81 CB750C
84 Tempter - well, most of it...

Offline 88SS

  • Posts: 78
Re: Good report, but where to begin...
« Reply #3 on: Apr 15, 2017, 23:26:40 »
I did go through all the connections and cleaned the shit out of them. I replaced the oil filter when I changed the oil. Timing is dead on, so I'm not sure if there's any issues with the timing chain. Pretty sure there's a tiny bit of slack in the cam chains, per the faint clicking at idle. I'll tighten it tomorrow. My electrical connectors are dry rotted in a lot of places however.

The plan is to ride as much as possible this summer, and take it down to the frame over the winter. I need to paint the frame, motor, and tank. Really looking to restore the bike, so I'm hesitant to mess with the paint too much. I do have rust however. When I get it to the frame, I'll replace the wire harness.

It seems like valves are pretty important on this bike, so I'll probably give them some love sooner before laterally


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Offline 88SS

  • Posts: 78
Re: Good report, but where to begin...
« Reply #4 on: Apr 15, 2017, 23:27:14 »
*later

....autocorrect.... worthless


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Offline 88SS

  • Posts: 78
Re: Good report, but where to begin...
« Reply #5 on: Apr 15, 2017, 23:36:25 »



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Offline 88SS

  • Posts: 78
Re: Good report, but where to begin...
« Reply #6 on: Apr 15, 2017, 23:38:18 »
These were taken when I first got the bike. I'll get some fresh ones next weekend. I would love to get a Corbin seat for it


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Offline 88SS

  • Posts: 78
Re: Good report, but where to begin...
« Reply #7 on: Apr 16, 2017, 16:18:18 »
Well..... while tightening the cam chain, I totally broke the bolt off. Will this still be ok to ride with until I can replace it?


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Offline Cookie

  • Posts: 595
  • God help the child who grows out of everything
Re: Good report, but where to begin...
« Reply #8 on: Apr 17, 2017, 10:04:59 »
I would choose to error on the side of caution and park it until your replacement tensioner bolt comes in. You can't know for sure if it's doing what you want on the inside, or if it'll stay in.
* Insert something witty here *

81 CB750C
84 Tempter - well, most of it...

Offline 88SS

  • Posts: 78
Re: Good report, but where to begin...
« Reply #9 on: Apr 17, 2017, 21:05:10 »
Sounds like solid advice to me. Luckily I'm out of town this week. The bolt should be in by the time I return home. I honestly didn't think I would ever find one. It took me all day. Also, it's going to be tough getting the broke bolt out


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