Topic: CB250F ??? what the heck!

[aesache]

So I was at a motorcycle swap meet yesterday looking for a tank for my 350f cafe project (looking for a "toaster" style tank) and came accrossed a gentleman who was selling what looked to me like a 350f engine that was mostly complete except for carbs and a points cover. me thinking hey i could use some spare parts, as the cylinders on my engine have a few broken fins, asked him how much. He said $275 for it. I said are you joking and offered him 150 for it and after some persuading he finally agreed.






      CB250F-1000081

[aesache]

ooops dont know what happened there must have clicked post anyway long story short thats the serial # on the case but after disasemble the cylinders and the head (combustion chamber) are way smaller than the 350f's

can i use any parts off this engine or is it a boat anchor that i spent way to much on?

[Caminokid]

Never heard of one. You may have ran up on something. dont scrap it.

[bender01]

Is it one of the rare rc 166S or something. Honda did make a race bike 250 that redlined at 22K or something nuts. Im off to you tube.

Edit
  Ist this? dohc
  http://en.wikipedia.org/wiki/Honda_CB250F
 

[736cc]

  Me thinks you stepped-on a 1975 Benneli 250 Quatro, it was the smallest production four cylinder ever made. All Benneli 4 motors 's were basic knock-offs of Honda's.
[/URL][/img]
http://www.motorcyclespecs.co.za/model/beneli/benelli_250_quatro%2075.htm
  Or the Moto Guzz1 254 which had same motor as the Benneli
[/URL][/img]

[Hush]

Check the gears, if the Wickapedia is correct you should have 6 gears, if only 5 probably the Benelli.
I always liked the Benelli, they had a very limited run here in NZ but the one's I got to ride were awesome.
The 125 twin was as fast as the Yamaha RD350 surprisingly!
I was offered for free a 6 cylinder in-line Benelli by a work mate but as I didn't have the shed space at the time I turned it down......duh!!!

[Alan F.]

 CB250F-1000081

Whatever it turns out to be... it's a very low serial number.
Where are you located? Maybe it's a Japan only bike?

[aesache]

very low serial number? look higher to me? its not a benelli unless benelli has honda stamped on there covers if so then maybe? and there is only one cam shaft in it and i count only 5 gears anyway i dont know what i am going to do with it (it looks identical and i mean IDENTICAL to my 73 cb350f)  and i took the clutch cover off and it fits both my engines?  the guy i bought it from was asian so maybe it was a Japan only bike?

also the carbs off my 350f fit perfectly on it  this motor looks like it has never been run maybe i will see if it fits in my frame and use it in my cafe? do you think it will be really under powered if i do


i will try to get some pics up of it this week

[fmctm1sw]

I thought I read somewhere Honda intended to make a 250 four but found losses too great to overcome in such a small displacement.  I can't remember where I read it but I don't think any ever made it into production...

[Alan F.]

Well there is the posibility that it may be a very special engine, you'll know for sure when you let the clutch out for the first time.

I wonder if you'll find anything in the honda museum  http://www.hondamuseum.com/

or maybe at Honda's own collection?  http://world.honda.com/collection-hall/


fmctm1sw, I remember reading that too.

[Hush]

Hmm an enigma, I just love a mystery........

[tomkimberly]

So I was at a motorcycle swap meet yesterday looking for a tank for my 350f cafe project (looking for a "toaster" style tank) and came accrossed a gentleman who was selling what looked to me like a 350f engine that was mostly complete except for carbs and a points cover. me thinking hey i could use some spare parts, as the cylinders on my engine have a few broken fins, asked him how much. He said $275 for it. I said are you joking and offered him 150 for it and after some persuading he finally agreed.






      CB250F-1000081

Honda Engine serial numbers have and "E", ie: CB250FE-1000081 would be what I expect if it is a true Honda product.


Tom

[Pinhead]

I definitely wouldn't start pulling parts off of it until you know exactly what it is, though...

[Shenanigans]

Taaaaaaake a pictuuuure already

[HondaMan]

Check the gears, if the Wickapedia is correct you should have 6 gears, if only 5 probably the Benelli.
I always liked the Benelli, they had a very limited run here in NZ but the one's I got to ride were awesome.
The 125 twin was as fast as the Yamaha RD350 surprisingly!
I was offered for free a 6 cylinder in-line Benelli by a work mate but as I didn't have the shed space at the time I turned it down......duh!!!

That would have been their 750, based on the CB500 engine, but with 2 more cylinders outboard. It otherwise appeared to be a CB500 engine, so complete was the cloning. I always wondered if Honda made their engines, because they looked SO much alike.

I remember those! I wanted one, but they didn't come to the States in 1974.

This CB250F: I'd love to build a bike around this engine...

[AshimotoK0]

I remember that someone in the UK used to sell a 250cc conversion kit for CB400/4 to make the bike legally rideable on a learner licence. Then they changed the learner laws and they disappeared but they were definitely available in the late 70's May have been Mocheck who did the 'Harrier' cafe racer version of the 400/4. Not sure though.

[aesache]

I FOUND OUT WHAT IT IS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I was talking to a guy at my local honda dealer and he had a very old service manual for a 1973 honda CB250F. (aparently only availiable that year). Honda sent the CB350F to California in stock form and a third party company (he was unsure of the name and it was mentioned no where in the manual) machined new pistons cylinders and modified the stock head. this was then assembled with a very agressive cam to make a cb250F which was MUCH cheaper for insurance. these were very limited production

as for the very odd serial number on the case its a plate that is riveted on over the factory number aparently the one on the frame of these bikes was changed as well

So why do you ask would they stop producing these conversions? well i figure it was because the manual sais it has a WHOPPING 19hp at 10,800rpm and that the bike would top out at 71 mph

i asked the guy if he would part with the manual he said no way but he did agree to let me photocopy any pages that i needed. i am going to go back and take my laptop and scanner and see if he will let me scan it (its only about 20 pages long)


I would like to reasemble this motor and maybe put it in somthing (eventually anyway have to finish current projects first) but there is probably a les that zero chance of me finding a head gasket for it i think the rest is stock gaskets but where will i get or make a head gasket

[razor02097]

Hmm.... 19hp?..... at the crank?.... I guess it was the "special" engine 

[Sam Green Racing]

I FOUND OUT WHAT IT IS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I was talking to a guy at my local honda dealer and he had a very old service manual for a 1973 honda CB250F. (aparently only availiable that year). Honda sent the CB350F to California in stock form and a third party company (he was unsure of the name and it was mentioned no where in the manual) machined new pistons cylinders and modified the stock head. this was then assembled with a very agressive cam to make a cb250F which was MUCH cheaper for insurance. these were very limited production

as for the very odd serial number on the case its a plate that is riveted on over the factory number aparently the one on the frame of these bikes was changed as well

So why do you ask would they stop producing these conversions? well i figure it was because the manual sais it has a WHOPPING 19hp at 10,800rpm and that the bike would top out at 71 mph

i asked the guy if he would part with the manual he said no way but he did agree to let me photocopy any pages that i needed. i am going to go back and take my laptop and scanner and see if he will let me scan it (its only about 20 pages long)


I would like to reasemble this motor and maybe put it in somthing (eventually anyway have to finish current projects first) but there is probably a les that zero chance of me finding a head gasket for it i think the rest is stock gaskets but where will i get or make a head gasket

If you still have the old one, send it to Cometic, they will make one offs I beleive.

Sam.

[Duck]

Might be easier to use your digital camera to copy the manual. 10 megapixel does a very good job. 2 is usable. Congrats on a great addition to a motorcycle petting zoo.
-Duck

[Alan F.]

I'm with Hondaman on this one, I'd love the chance to build a bike around that engine.  Maybe a custom alloy mini Egli frame and lighten everything to the max!
Now that sounds like a challenge.
-Alan

[bender01]

Wow! Im guessing that insurance was oughtta sight in the early 70s?
 Those must have been changed cosmetically too or How would the insurance Co. know. This has too be a California thing. It could of been just named and tagged that way, and still of been a stock 350f?? It was done on 427  chevrolets for insurance reasons. The L-88 suposedly had 450 or so HP but was nearer 550. Before my time but so ive heard. More research into this is a must.

[Hush]

Alrighty who in the world has a genuine SOHC4 250f we can see pictures of?
I bet the Japs kept one for their museum, but you would think that someone would have a whole bike sitting in the back of their shed somewhere eh!
Suprisingly no one up to this point has tripped over a complete rolling frame.

[Laminar]

Hmm.... 19hp?..... at the crank?.... I guess it was the "special" engine  

The '74 CB200 had 17hp at the crank out of an inline 2. I could get mine up to around 70 on a good day.

[HondaMan]

Hmm.... 19hp?..... at the crank?.... I guess it was the "special" engine 

The '74 CB200 had 17hp at the crank out of an inline 2. I could get mine up to around 70 on a good day.

That's sad. 
The CB175 twin could do 82-85 if you tucked in real good! The old CB160 could do 78, at least the one my Frat father had (same tuck-in, though!).

[Pinhead]

Wow, my SL175 topped out at around 60! I think it was geared a little slower, though, being more of a trail bike...

[Laminar]

That's sad. 
The CB175 twin could do 82-85 if you tucked in real good! The old CB160 could do 78, at least the one my Frat father had (same tuck-in, though!).

I think Honda rated its top speed at 77 or 78, but when I had it the engine was 34 years old and it had pods, open exhaust, and big tires on it. And 70mph was 7000rpm.

[mlinder]

The built 160's and 175's are hitting 95mph out here at PIR.
Built correctly, I'm sure that little 250 could do that... probably at a los of low end, but...

[razor02097]

Either way it would be something cool for sure  .  Did you have serious plans for the motor?  Build up a bike or something?

[Laminar]

The CB175 twin could do 82-85 if you tucked in real good!

Well the CB175 did have 20hp compared to the CB200's 17. I think the CB200 was built for monster low-end torque, while the CB175 was built for screaming high-end horsepower.

[Sam Green Racing]

Hmm.... 19hp?..... at the crank?.... I guess it was the "special" engine 

The '74 CB200 had 17hp at the crank out of an inline 2. I could get mine up to around 70 on a good day.

That's sad. 
The CB175 twin could do 82-85 if you tucked in real good! The old CB160 could do 78, at least the one my Frat father had (same tuck-in, though!).

Hey Mark, my 150 Benly did 87mph (electronic) back in the day, seems the smaller you go ,the faster.

Sam.

[Sam Green Racing]

I FOUND OUT WHAT IT IS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I was talking to a guy at my local honda dealer and he had a very old service manual for a 1973 honda CB250F. (aparently only availiable that year). Honda sent the CB350F to California in stock form and a third party company (he was unsure of the name and it was mentioned no where in the manual) machined new pistons cylinders and modified the stock head. this was then assembled with a very agressive cam to make a cb250F which was MUCH cheaper for insurance. these were very limited production

as for the very odd serial number on the case its a plate that is riveted on over the factory number aparently the one on the frame of these bikes was changed as well

So why do you ask would they stop producing these conversions? well i figure it was because the manual sais it has a WHOPPING 19hp at 10,800rpm and that the bike would top out at 71 mph

i asked the guy if he would part with the manual he said no way but he did agree to let me photocopy any pages that i needed. i am going to go back and take my laptop and scanner and see if he will let me scan it (its only about 20 pages long)


I would like to reasemble this motor and maybe put it in somthing (eventually anyway have to finish current projects first) but there is probably a les that zero chance of me finding a head gasket for it i think the rest is stock gaskets but where will i get or make a head gasket

It would be intresting to see some pics of the head and how they blanked off the squish (3.625mm).
To convert it to 250 they would have to use 39.75mm pistons (stock 47mm) and on a stroke of 50mm would have been miles under square.
The extra thick liners (7.25mm, 3.625 overall) might have caused it to run a tad on the hot side unless they built a custom block.


Sam.