Topic: CB250F ??? what the heck!

[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.