Pretty sure any year CB250 will swap.

 

Awesome thankyou Flite 🙏, found a couple of contenders on Ebay, one was a CB250N from a Superdream which I wasn't sure of. But if any year cb250 fits then that's going to make my life so much easier going forward as well.

250 parts are everywhere, there's very little choice/availability for the 125 sadly.

 

With the 249cc engine (advertised at 26-30HP), compared to the CMX250s 234cc (21HP 1985-87), you should have lots of fun!

 

Yeah I noticed they are a bit beefier thing is the CB250 30hp engines don't seem very common probably due to age now I think 74 is the latest year for the stated 30hp, they were a little slower after that I believe still better than 11 hp lol think that's how many raging horses the 125 puts out.

 

The Rebel 250 engine will fit the 125 frame. The 125 is just a sleeved down 250 engine. The CB250 Nighthawk will likely fit, but it is a dual carb engine, so you might run into problems there. The Rebel 125 intake manifold might fit the 250 engine, but you might need a Rebel 250 manifold. I've heard of people converting the Rebel 250 to dual carbs, but they likely used pod air filters.

 

Hey Bob, yeah I had the guy that sold me it said you could just bore it out and put a 250 head on it, and I thought for all that effort I may as well just swap it for a cmx250 engine.

Must admit I'm probably gonna want the easiest option by the time I get to sourcing carbs, i was indeed hoping the 2 to 1 carb intake would fit and to keep a single carb, and get a 250 rebel one, only 1 to tune then! and use the standard air filter.

Pod filters look cool, but if i went that direction id definitely go the whole hog and dual carb it. I'd need to find out what the air intake and filter is like on the cb250 models.

 

If you go with pod filters, that eliminates the airbox, which eliminates the crankcase ventilation tube that vents in the airbox, which requires a pod filter on the crankcase tube, which, if it isn't cleaned regularly, gets gummed up internally, which results in the left side oil seal blowing out by crankcase pressure. But golly, it looks cool until oil sprays all over your leg!

 

😅 ahh. Ok that's far more issues than I anticipated, I thought I could maybe make a set up that incorporated a breather tube, this is all extra hassle though when yeah, I could just you the standard airbox. Thanks Flite 🙏

 

A member did several fantastic mods on his Rebel. Retained the vent tube in an unusual way IIRC. Here's a thread on his mod. 1 in Vermillion | Honda Rebel 250 & 450 Forum

 

I bought a 2002 nighthawk cb250 years ago as a parts bike- it had the 234cc engine that had a single carb, just like the rebel. They may have offered the bike with dual carbs like the Asian rebels- not sure.

 

Yeah they are identical to the CMX250 engines definitely a contender. Literally gonna look for the best condition one I can find as long as it fits and I don't have to do too much to it I'll be happy. Know I need to get the engine mounts don't think my 125 ones will fit.

 

If you find the 249cc & it fits, many of us might like the extra power too.

But I think that the HP that was advertised was actually bHP, meaning power at high revs directly off the flywheel & not actual power at the wheel.

You've piqued my interest in it for sure.

 

Measure the mounts on the replacement engine. Could be the same.

 

Ok cool thankyou, must admit although I've found a few engines the reasonably priced ones are CB250N's from a superdream but theybare pretty old. Still don't know if that engine will fit and what I'd need. Preferably I'd like to need as little as possible and I'm anticipating I may need the wiring loom as well for that engine. There's a CMX250 on offer that looks in amazing condition! but the guy has split the engine up and is charging ridiculous money for the individual parts.

Just realised also we didn't get the 250 nighthawk in the UK 😩

So at the moment the 125 isn't ruled out yet 😅as far as I can see it's just that 1 guide I posted a photo of that needs replacing, at least I think that's the guide?? Or is that just the seal? Dont know if anyone can confirm??

Got myself excited about a 250 now though lol, just finding something may be a bigger task, and more money, than refurbing the 125.