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just wondering if its at all possible to fit a cb250 superdream engine into my 1983 honda cb125T superdream.
if not anyone have any ideas of other engines bigger than 125cc that would fit in place?cheers[
]Hiya,welcome to TBF, interesting project, keep us updated with phots etc!
I’d be supprised if it would fit tbh but if you can do engineering and welding etc ANYTHING can be made to fit, its just a case of how much work you want to do. The superdream 250 is just a sleeved down 400 iirc so I’d not bother with the 250, just go straight for the 400. It will need the whole wiring loom, battery, upgraded brakes and suspension plus the fram would need bracing. You’d prob end up with a bike that weighed just as much as the doner bike so I could only see the point in doing it if you were after building something unique for shows etc. As an everyday bike it would not be that great as the frame would wrap itself in knots unless it was strengthened significantly
The CB200/CD200 engine would probably fit straight in, but I don’t think they offer much more power. As Pete says it is possible to fit pretty much anything into anything if you are determined enough, but I agree that the benefit would be slight
cheers guys!
id be able to weld up some brackets and braces easy enough.
i think the cb200 engines put out around 14BHP and i think the 125 produced around 12BHP.
so looking further into it im seeing theres not going to be much difference [xx(]
i was also considering boring the cylinders out but i dont honestly think theres enough room to do it.
ive looked at attempting to up the power of my 125 engine but the only things i can really think of is replace the air filter and attempt to find a way of getting a better exhaust on it which could prove difficult as the only exhausts made were a full piece arrangement with no way to swap cans[]
any other ideas on upping the power of the original engine?
cheers!Rather than increase power, tricky and expensive relative to the gain on your bike, I would investgate reducing weight of the machine. Single seat, ligther mud guards, remove rear footrests etc. Again the benefits would be slight, but it could be fun trying. Another possibility is gearing, maybe trade off top speed for acceleration.
Overall my honest advice would be put up with the level of go on tap until you are ready to get a bigger bike
are you on “L” plates still?
A different engine is a LOT of work and if you still on a restricted licence it will be blatently obvious to even a non bikeing policeman that you’d put in a bigger engine.
It will also cost (even if you do it all yourself quite a lot of money and time to convert the bike.
If you have a full licence and want more go it really makes more sense to sell the 125 and buy a bigger bike. You can pick up a Superdream or similar pretty cheap these days (my old man got a 250SD for £200 a few years back and it had only done 3,500miles! So bargains are out there if your budget isn’t huge. You could then sell your 125 and probably end up with a full size bike for less than it would cost to convert this one and you’d have it there and then rather than having to spend all winter with an angle-grinder and welder in ya garage!
Whats your situation if you don’t mind me asking? How much you got to spend etc and what licence do you have?
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Originally posted by Pete247are you on “L” plates still?
A different engine is a LOT of work and if you still on a restricted licence it will be blatently obvious to even a non bikeing policeman that you’d put in a bigger engine.
It will also cost (even if you do it all yourself quite a lot of money and time to convert the bike.
If you have a full licence and want more go it really makes more sense to sell the 125 and buy a bigger bike. You can pick up a Superdream or similar pretty cheap these days (my old man got a 250SD for £200 a few years back and it had only done 3,500miles! So bargains are out there if your budget isn’t huge. You could then sell your 125 and probably end up with a full size bike for less than it would cost to convert this one and you’d have it there and then rather than having to spend all winter with an angle-grinder and welder in ya garage!
Whats your situation if you don’t mind me asking? How much you got to spend etc and what licence do you have?
Sound advice there 247
Nooo im on a full licence with my cbr400 NC23 sat in the garage too.
ive kept hold of my 125 as just a bit of fun plus its so much easier riding through ice and snow to get to and from work in the winter on my 125 than it is on the cbrs battlaxes haha.
but now ive decided as i love all things out of the ordinary to make my 125 dream a bit better than the rest.
my main goal is to just get my old dream to beat my friends cbr125 which would mean attempting to get around another 10 to 15mph out of it.
which i know will be difficult as my dream has the aerodynamics of a brick and is a bigger physically sized bike than the cbr125.
although with mine being a twin and the cbr being a single cylinder idv thought i had the edge on him with power anyways :Sahh, cool. Hope I didn’t come across as patronising, wern’t my intent
If you got the time and willing to put the effort and cash into it, how about finding a sneaky 2stroke engine, maybe off an old crosser, sort the sprockets out and you’ll have a beast!
the dirtbike engines ore generally tiny and if you get an enduro version it’ll have basic electrics too! and PLEASE if you do this step by step pics! [
]not at all
well i reacently lost my job so ive got the time and a bit of cash to fix it up
il have a look at two stroke dirt bike motors and get some pricing!
if i manage to get the parts to do it il get as many pics as possiblewicked
Just a thought too, the KTM EXC250 f (fourstroke) produces about 33bhp but will weight about the same as your std 125 engine. Don’t know if it’ll fit easily as its taller than the equivelant stroke. Very simple to work on (go LC4 engine rather than the latest version) has bags of torque and would have electrics too. Only trouble with the proper enduro engines is they require lots of servicing but like said they simple to work on and if you do it all yourself the most expensive servicing thing would be the high quality engine oil every 20hrs run time. A bit more reliable than a 2smoke. The 125cc EXC 2stroke also produces around 30bhp so with either of these or another manufacturers equivelant you’d be over doubling your power and not really adding much to the weight of the bike
ive had a look and cant seem to find any of the exc250 engines for sale!
any ideas on how good the old honda CM250 engines are?From the Used Bike Guide:
“Custom twin that didn’t inspire but mild state of tune meant engine lasted well (early ones had piston problems), while chassis was better finished than the SuperDream. Electrics react badly to British winters, with a lot of cutting out, and the rectifier can burn out. Usual front disc brake seizure becomes so bad with age that alternative front ends are often fitted. Lacks the comfort and general usability of the SuperDream but lasts for over 50,000 miles. Good ones rare.”
Can’t seem to find any 2 sites that state the same power specs as each other but roughly 17bhp and in the rebel frame its weight is around 144kgs. If you were uping the brakes on your bike as well I’d not bother with the brakes off this bike after reading the above.
The CM was basically a custom Superdream, bit uninsiring tbh, I know…I have owned 3 Superdreams in the past
ive had another thought and checked into RD250 engines!
according to the good old (usually not very reliable) internet these engines pump out between 30 and 35 BHP
which would easily be enough of power increase being a 2 stroke too but i cant see the engine fitting going well and as is always the case all the engines i see that are reasonable are living 300 miles away!
would it be worth getting an rd engine because it would also need a watercooling system fitting to my bike too?
or did they do air cooled RD250s at all?
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