Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Harold 400/4 on September 27, 2020, 09:49:39 AM
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I’m after some advice on my 400/4 pls.
I have had some top end work done by a local guy I really trust including a rebore, new pistons, rings etc. It’s run in now and on the whole running really well. It pulls well and revs freely. However, it bogs down when pulling away. I have pulled the plugs and to me it looks too rich, generally very black and sooty. End of silencer is sooty as well. I took the air filter out to see if increased air into the carbs would help, but it made no difference.
So having read various threads, I thought I’ll adjust the airscews out a tad to lean it up a bit. Checked them and believe it or not, they are 4 turns out already?! In theory it should be running way too lean?
Nurse Julie, I saw your post on the CB400f site re plugs. What was your thinking behind the D7EA plugs? I’m currently using the D8EA.
Can’t get hold of my pal who did the work, as he lives in Belgium and staying there until things settle down with the virus. Any advice gratefully received.
Cheers. Harold.
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My thinking behind the D7EA's was simple Harold, that was what we had in stock at the time 😁😁😁. But, I have used both the D7's and D8's and to be honest, the bike performed exacy the same and my spark plugs were exactly the same colour when I checked.
As far as your bogging down is concerned, get the air screws back down to about 1 3/4 turns out and go from there.
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Definitely something out of kilter there.
As Julie already indicated, it's more of a trim and preference between an 8 and a 7 plug, so unlikely to be the cause of your issue.
That rich, black plugs, would ordinarily be air fuel ratio. Information on jet sizes and needle position you've got and if they are original fit versus pattern brass components will shed more light on it and allow further appraisal in trying to help you get it more accurately set up.
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If its not fuel / air related Harold, which it probably is, do you know what piston / bore clearance your man re bored to and are the pistons OEM or aftermarket ?
Edit... Also do the plugs smell of fuel?
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Thanks for your comments. As you say, it would make sense to check the current jets, needle positions etc. If it has been changed from standard, it could be that the adjustment screws have been set to 4 turns to compensate for an increased amount of fuel getting through? I will check on plugs Julie and also find out exact spec of what was done.
It’s frustrating as once I get to about 3000 revs, it is fine.
Cheers. Harold