Crankshaft interchangeability for the CA95

[Steverinomeiste]

Hi Everyone;
After spending months trying to find a crankshaft assembly for my bike I changed strategy and did some part number comparison. I learned something a lot of you probably already knew. A 125 CB92 crankshaft assembly fits a CA95. I found one, and it does actually fit. It looks good visually and the bearings feel smooth. Following the advice I read here I've flushed it throughly and I now have it sitting in a bucket of fresh motor oil. Tonight I am going to study the section on crankshaft installation in the service manual and start putting my engine back together. Exciting Stuff!
Also, I've found an expert on these crankshafts. He disassembled my old crank and confirmed that contaminated oil had ruined it.
Steve

[Jetblackchemist]

The interesting part is the CB92's claimed top speed is 75 MPH, 5 MPH more than the CA95's claimed top speed of 70 and it's 25cc's or so less in displacement and [email protected] rpm's no less; it makes me curious as how the crank will change that end of things. I know CB92's were popular to race; and CA95's not as much, so it makes sense that they probably put more time balancing that thing out on the CB92.

Sam has raced them, and Smither's know's a guy that modded the CA95 engines pretty heavily so maybe they can shed some light on benefits and differences between the two motors...

[Sam Green]

I just found this while looking for an old thread and looking at the date it was posted it was done when I was away racing in Finland for a few weeks.
The crankshaft has no bearing on the performance of any of the various models.
In fact, the C92, Cb92, CA95 and CB95 all share the same crankshaft.
The difference in power between the C92/C95 tourers and the CB92/CB95 sports models was basically due to a higher state of tune, (pistons, cam and carb) that being coupled to a lighter rolling chassis also made them faster.
You Americans were lucky in that Honda deceided to put the CB95 sports motor into a touring frame to produce the CA95.
The only downside for C92/CA95 owners when needing a crankshaft is, because they fit the CB92 as well, it pushes the price up.

Sam.

[Sam Green]

Originally Posted by Jetblackchemist

The interesting part is the CB92's claimed top speed is 75 MPH, 5 MPH more than the CA95's claimed top speed of 70 and it's 25cc's or so less in displacement and [email protected] rpm's no less; it makes me curious as how the crank will change that end of things. I know CB92's were popular to race; and CA95's not as much, so it makes sense that they probably put more time balancing that thing out on the CB92.

Sam has raced them, and Smither's know's a guy that modded the CA95 engines pretty heavily so maybe they can shed some light on benefits and differences between the two motors...

Jet, if you were to put the slightly more powerfull CA95 motor into a CB92 chassis, you would think it would be faster...wrong
Although the bigger pistons give it that bit more power and torque, the extra weight of the pistons will not allow it to rev quite as high, resulting in a similar top end speed.

Sam.

[Jetblackchemist]

Done.

[Sam Green]

In that case then, it's the weight plus the areodynamics that are slowing the CA down, plus the lack of 500rpm.

Sam.

[Steverinomeiste]

Sam, that is interesting. I bought my crankshaft from a fellow in England that I think does some racing of CB92's. I did pay quite a bit, I think around 150.00 dollars including the shipping cost. But I was having no luck finding one in the USA. Fortunately everything has turned out great. My CA95 runs great. I am now trying to get of the self discipline to quit riding it for a few days and sort out lighting issues. I know I just need to take my time with my test light and continuity tester and pretty soon things that should light up will. I had no lights before I took it apart either.