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Discussion Starter · #1 · (Edited)
I have searched and read a few threads though I have only owned the bike 19hrs.
1981 CM400c was running when I went to pick it up. Has been sitting for a few years. Drove around the driveway and loaded it up.

When I came home I put 'some' Lucas additive and a fresh can of unleaded in and the thing wont stop leaking all over my floor. Threads said my floats were stuck or bad seals. Didn't make since considering it was fine before but okay. I pulled the carb cleaned it out wiped it down and its back in and still leaking like a baby in a crib. Petcock it good. It is leaking from the drain tubes on the bottom of each bowl plus what looks like 2 other hoses I have not traced yet. (spent the last hours trying to load video)

Anyway. The bike is starting to scare me a little. I'm not very mechanically inclined but I make due. Any thoughts? I will keep working on pictures/video.

Oh yeah, first time Honda owner. Looks like a great group here and I am looking forward to any links or advice. Thank you.
 

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Welcome to the forum. Great to see another 400 series here. It sounds like your float needles aren't sealing, or your float level it too high, or your overflow tubes in the bows are cracked and leaking. There is a sticky for the carbs in the cm/cb sohc section. Do you have a Honda Service Manual? PM sent for Manual.
 

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Perhaps the "Lucas additive" did NOT "play well" with the rubber tips of the shut-off needles or the plastic floats.... I have no idea as I never use additives for that reason.....

Petcock MAY be good, BUT is it turned OFF?
 

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Discussion Starter · #4 ·
Perhaps the "Lucas additive" did NOT "play well" with the rubber tips of the shut-off needles or the plastic floats.... I have no idea as I never use additives for that reason.....

Petcock MAY be good, BUT is it turned OFF?
I am am more used to old Toyotas so the additive was a gimme but who knows. I may have opened a can of worms instead.
As for the Petcock, when its off no leak, when I turn it on it leaks. This would leave me to believe the PC is good. J
Just got back from a nice ride (KL250) and stopped by the P.O.s house to chat, he had the Original owners manual but no service manuals. Ill have to snag one in town like I said I have only had the bike less than a day.
I like the bike for sure going to head back out there and do some more tinkering. Thank you.
 

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Discussion Starter · #5 ·
Okay, I have done nothing but switch to Reserve and there is no fuel leaking anymore. I am assuming everything settled back into place? I have been letting the bike run with the Choke out and its fine 1K rpm. it has been running @15min and whether I push the choke or pull the throttle it tried to die. I have the manuals now so I am going to do some reading.

I hope everyone out there is having a wonderful day.
 

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Idle speed is 1200, it might idle at 1K or die. Sounds like a piece of dirt was stuck in the float needle causing the overflow.
 

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Discussion Starter · #7 ·
I was thinking along the same lines. I know the tank has at least a little rust in it. Now to figure out the throttle issue. I am moving forward with the assumption that i have a stuck or clogged jet. I pulled everything out previously and sprayed it down, hit it with a tooth brush but maybe I have missed something.
 

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I was thinking along the same lines. I know the tank has at least a little rust in it. Now to figure out the throttle issue. I am moving forward with the assumption that i have a stuck or clogged jet. I pulled everything out previously and sprayed it down, hit it with a tooth brush but maybe I have missed something.
Read through the VB carb rebuilding sticky in this section, it'll help even though it's tedious
 

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Discussion Starter · #9 ·
Been on the road so started back at it again today. I have glanced through the carb write-up. Tedious is right. I will get to it. We stripped the carb down again found a pinhole in the 'float level indicator' we soddered it up and put it all back together. she now will start and Rev but if you hold that it will loose power and die. Will no longer idle. Haha. Appriciate your thoughts and such. I will be out of town again for a bit so I'll jump on it again when I am back
 
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