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Post by farmerjohn on Jul 18, 2020 21:23:21 GMT
I bought 1980 CB400 2 yrs ago general refurb followed & still not running ok. Starts ok & runs up to approx 3000 revs, open throttle & it just dies. Checked compression & valve clearances, carbs cleaned & refurbed, stator rewound, new coil, plug caps & plugs. Could problem be CDI box ??
Any suggestions much appreciated.
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Post by na44superdream on Jul 18, 2020 21:35:25 GMT
After all that work you would think it would run like a watch !
It couldn't be the inside of the fuel tank has debris that has clogged the tap mesh gauze and when the throttle is opened up, the fuel flow rate cannot keep up?
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carlthebandit
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Post by carlthebandit on Jul 19, 2020 6:59:28 GMT
I would go through the carbs again, they are difficult to clean out properly.
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Post by bojer on Jul 19, 2020 7:26:35 GMT
As CTB says sounds like another carb clean needed , very common especially if sat for a few years , even with an ultrasonic clean and full dismantle mine took a couple of goes before they were ok and even then they improved with use .
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Post by Dennismenace on Jul 19, 2020 12:27:30 GMT
Even with a clean out of the tank I found the gauze mesh on the petrol tap clogged up. Also, it is almost impossible to get the gauze out in one piece if there has been any rusting in the tank. Fortunately, a new fuel tap with new gauze filter is less than £20.
If the bike ran for a while I doubt it is the coil or CDI. Could be a carb blockage. Also check the fuel transfer pipe between the carbs. Are the plugs wet if you turn the bike over with the ignition off (kill switch on)?
When you ran it "for a while" did both exhausts get hot?
If you had the stator off did you check the ignition timing with a strobe when you put the stator back on?
Let us know how you get on.
Dennis
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Post by farmerjohn on Jul 19, 2020 15:54:12 GMT
Hi Guys & thanks for your input
Fuel tank cleaned out (loads of crap) I bought Rustbuster kit & relined tank, also new fuel tap & filter so fuel flows ok
Stator had full rewind, there was problem with ignition coil, now bench test says all ok
Shall check plugs with kill switch on, in fact RH exhaust was much hotter than LH when running
SO carbs off again & check. I've had carbs off 3 times during lockdown so getting pretty efficient at removing !!
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Post by buster on Jul 19, 2020 16:11:02 GMT
just out of interest what colour are the plugs? rh might be lean? could be worth checking where the left hand mixture screw is and setting the right one to the same (only a starting point) and see if that helps. the other thing I'd suspect, as someone already mentioned, is fuel struggling to get to the right hand carb. mine was like that after a long period standing (crappy modern fuel  ) |
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Post by marktrower on Jul 19, 2020 18:23:32 GMT
i have the same problem with mine lack of power with the superdream so i have this to feed my needs  |
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Post by Graeme on Jul 19, 2020 18:52:33 GMT
i have the same problem with mine lack of power with the superdream so i have this to feed my needs Are they as good as they are meant to be Mark, superb handling and pretty quick? Gee. |
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Post by marktrower on Jul 19, 2020 21:04:26 GMT
They are a unique bike no practically what so ever if you not climbing about no comfort what so ever you need a strong grip for the clutch your left hand will be numb with pain in heavy traffic you soon learn to filter were a fly would not get they viabrate like a old steam engine not fast but very quick one of the best handling bikes you can buy on the road i have now had the bike 15 years now I have not found a bike to replace it.the new bikes are fantastic but technology makes them easy to ride the bull is old school muscle bike there is not meney bikes that give me that deep tingle in my stomach a big engine red rocket my old ypvs engined lc and my xb12s it will not be sold it will be past down
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Deleted
Deleted Member
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Post by Deleted on Jul 19, 2020 23:13:45 GMT
I would go through the carbs again, they are difficult to clean out properly. And easy to leave bits out of... I'll get my coat.  |
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