Honda CB250 Superdream - what engine can i transplant in it?

mw9835 · L Plate Warrior Joined: 01 May 2010 Karma :

Hi, I want to replace my Honda CB 250 Superdream engine with a larger, more powerful engine. Does anyone know which (if any) engines can be slotted directly in?

Ant132 · World Chat Champion Joined: 18 Nov 2007 Karma :

CB400N Superdream engine goes straight in. Thumbs Up

stroker · L Plate Warrior Joined: 29 Mar 2010 Karma :

more powerful than a 250 superdream??? not difficult...... how about a singer sewing machine??? Laughing

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Rowey · World Chat Champion Joined: 07 Oct 2007 Karma :

Just so you know. Replacing the 250 engine with a 400 engine will require new carbs (or new needles and jets if you can get them seperately) and it'll need the 400 CDI. Think that's all.

It's not as simple as a strait swap. And tbh having riden both. There's not a huge amount of difference. The 400 is a little bit more grunty.
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Acemastr · World Chat Champion Joined: 01 Oct 2008 Karma :

why the hell is this in Biking News?!?!
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hondapartsman · Renault 5 Driver Joined: 13 May 2010 Karma :

Yes, really ought to be in workshop I'd have though but a genuine question. Have you thought about the CB450, made in Brazil, again you'd need the proper CDI and carbs though to make it work, 250 one just will not work with 400/450 engine and carbs are a different size.
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2wheelsteve · Spanner Monkey Joined: 05 Feb 2010 Karma :

markjay50 · L Plate Warrior Joined: 16 Jul 2010 Karma :

Yes, i've known about the CB450 and this is made from brazil and you need to proper CDI and carps, thanks.....!!!!
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TQ · Trackday Trickster Joined: 17 Dec 2009 Karma :

Digit · Scooby Slapper Joined: 22 Aug 2010 Karma :

I'm new to the forum mw so I'm late coming onto this, but I can answer your questions in detail if you still need the info.
First the 400 engine will bolt straight in, the exhausts will fit. You need the 400 carbs, the airbox to carb rubbers, CDI and the 400 harness unless you are happy to change a number of connectors.
Hope that helps.

Roy.
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daveuprite · Derestricted Danger Joined: 03 Aug 2010 Karma :

Hi - I kind of went down this route about 25 years ago, trying to get more power out of my wet dream. First a LEDAR kit, rejetting and new airfilters - which pepped it up a bit. Then fitting the 400 superdream engine, carbs etc which obviously made a difference too.

But eventually, having wasted money trying to polish a turd, I went out and bought an RD400 - which actually had some go in it.

Nowadays, gven the stuff available on the secondhand market, I would really reconsider trying to improve a superdream. They are heavy and slow, whatever you do to them. Much better off starting with a decent base bike. If you like 80s jap bikes, what about a VFR500 or an XJ600 or a GS550/750 or a CB750 etc etc. All can be had for between £500 and £1000 depending on condition. Or get a proper more modern performance bike like a 99 5eb R6 for £1500, which will make the wet dream feel like a penny farthing.

Sorry to sound negative, but I've learnt the hard way over many years that there are some 'projects' not worth pursuing into which you pour good money after bad. And you hopefully avoid having to spend hours in a cold garage pissing about just to make a slow bike slightly less slow. But good luck with it, whatever you decide to do...

Dave R