Cm400a Issues AND CB750a Issues-- Lucky me!

EmilyRose750a

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Aug 13, 2020
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Location
BOSTON, MA, USA
Hello all!
Having issues with BOTH of my Hondamatics!
I'll try to keep my rambling down.

1979 CM400a- A history
-I've had this bike about three years.
-Bought it not running. Towed it to the shop I use. (Specializes in vintage bikes...)
-Tires, carbs, oil, little things and up and running! Yay!
*Fast forward 2.5 years, no issues.*
--Winter storage in my garage in upstate NY, no issues. Swapped out the fuse box over winter, that was it.
--Rode it home 300 miles back to Boston in mid March. Could feel the brakes a little tight/stuck.
--Went into the shop in April for a pre-season check up & planning to sell soon so a just a good once over so I could advertise honestly.
--Replaced horn, oil change and replaced front brake master cylinder.
**Fast forward to May**
---Trying to leave for a long day of riding 12+ hours.
---Started up, warmed up, saddled up, click it into 1st/low and as soon as give throttle just *clicked* off.
---Same a few more times between home and the gas station, but it did have gas.
---Got on the road and couldn't get it over 45 for the first 20+ minutes, which really felt like forever!
---After that was good all day. No issues. I figured it was just from sitting during early C-19 times.
---Bad weather, a raging plague and back to work left little time to ride the rest of the month.
**Fast forward to June**
----Same issue. Started up, warmed up, saddled up, click it into 1st/low and as soon as give throttle just *clicked* off.
----Sometimes more of a sputter, less of a *click*.
----Got about three miles from home and she quit on me. Switched from fuel to reserve to be sure. Had spark. A passerby named Carlos gave it mouth to mouth.
----AAA towed home :( I had to walk!! Not allowed to ride in the truck cause of Covid.

A friend/fellow rider/mechanic came up for a wrenching session.
Figured we'd clean carbs, replace spark plugs and see if that helped.
Discovered choke cable very loose. Throttle cable also had a decent amount of slack.
Lastly a black plastic part connecting piece was split nearly in half.
I've been looking high and low for what its called and keep coming up with the wrong words for it... attaching photo of that. Its now duct taped...
Perhaps called 'airbox to carb manifold?'
thumbnail



****What the shop says****
Shop is suggesting the Torque Converter is to blame for conking out at 3ish miles.
Quoted nearly $500 for parts and labor to diagnose and replace. Another $175 for the manifold and choke cable.




NEXT BIKE


1978 CB750a-

(Posted in the Other Bikes section as per Admin)


So here I sit on my deck, sans bikes. Beautiful weather here!
Going moto camping this weekend in my Geo Tracker so I can at least get some wind therapy, even if I'm on four wheels...
 
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I'm not seeing the picture of the broken part but sounds like the air box boot as we call it. It only came with the entire air box, if so then it's common part for all the CM400's.
I've sent a PM to oldtimer, Bill H, asking him to give his thoughts on this. He's got the most experience with the A model.
Do you have the Honda FSM and A model supplement? If not the visit our library in General Topics> Technical
 
After several notifications with EmilyRose I think she is talking about the carb insulator. I tried to send a photo but was unable too . She tried to send a photo but it didnt come thru. Could LDR or ancientdad send her a photo of the insulator ? I dont think the problem is the converter but fuel. I would hate to see her spend about $ 500.00 she doesnt need to. I also asked her to have an OHM test on the stator but dont know if its been done.
We cant do any thing for her as long as the bike is in the shop.

Bill
 
OK, for definition of the part you're having trouble with, in this picture from the left side of the bike is it the rubber piece on the left or the right of the carb?
201_4097.JPG
Message from Bill, oldtimer, tells me the bike is still in the shop and your work space is nonexistent. Bill is leaning towards a fuel issue and I'm thinking it's more and electrical, one or both of us is right but there's testing tha has to happen before a solution is found.
Here's the library link https://www.vintagehondatwins.com/forums/index.php?threads/76 which will get you to the Drive storage for all of the FSM's and other important documentation.
 
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