Hi from North Wilts

[Multiman]

Hi and thanks for letting me join the forum.
It looks like a great place to learn and get help from what I have already seen whilst browsing over the last week or so.

I'm a proud new owner of a 1975 400/4 which runs, but is a bit tatty so I will be sprucing it up over time.
The previous owner had it from 2009 and I was told doted on it but has sadly passed away.
It came with a spare engine, a 1.5 Motad exhaust systems which are still in their packaging and a couple of crates of old bits n bobs. So whilst it has a high mileage of 50k Think I got a good deal, well we all hope that don't we?

So first question. If I change the current short megaphone silencer for the DS pattern part will I have to change the carb settings?

[taysidedragon]

Hi, welcome to the forum from another 400f owner. Lots of us on here so plenty of help and advice available.
If you change the silencer you might have to change carb jets or settings,  depends if the previous owner changed the jets from standard.

[Yetanotherbike]

Welcome to the forum, from another CB400F owner. I've not long joined myself and I've picked up a lot of useful information and contacts in a very short space of time.

[McCabe-Thiele (Ted)]

Welcome to the forum - lots of help on here from folk who know their stuff.

Sounds like you have a good starting point from it's history. Be great to see the pictures when you can post them

[philward]

Welcome to the forum. I would imagine that unless the PO re-jetted for the short mega, the DS replica would be made to work with the standard jetting. I'm sure that someone who has fitted the DS silencer will be along to advise shortly.
Enjoy the forum

[Laverda Dave]

Welcome to the 400/4 forum 😁.
I have a DSS replica system and it runs fine with the standard jets. Are your headers original?
Is the bike running, if not you may find the carbs flood due to standing idle. If this is the case you will likely need to strip and clean the carbs but whilst you are in there you can check the jet sizes.

[JezzaPeach]

Hi, if it starts and runs ok, I’d say fit the exhaust you want, do some decent length runs to heat up properly, then check the colour of the plugs. If a nice mushroom brown and the fuel consumption seems right, then no need to fiddle more!

[Yetanotherbike]

These days I'm not so sure that plug colour is such a reliable guide. Since we now have to run on rubbish fuels, that have different qualities from back in the day. However It's easy enough so get the bike on an exhaust gas analyser, which will soon tell you how your carbs are performing

[Multiman]

Thanks for the welcomes and suggestions everyone.
Look out for newbie questions the 350/400 forum sometime soon.

[Nurse Julie]

Welcome to the forum.

[Moorey]

Welcome to the forum and have fun.