Speedo replacement question

[Norton1]

My 82 has an 85 MPH speedo on it - whoever thought that up ought to be introduced to reality TV - and in the search for a 150 mph replacement I've noticed several that came on the smaller cc models. Will they work? Is the drive from the front wheel the same?

Not that I would ever exceed 85 mph (cough cough cough) but one never knows for sure -

[EMS]

If you replace the speedo on your '82 with any 150mph unit, you will lose the rear suspension warning light. The best unit to replace it with is a speedo from a '79 CBX. These can get really pricey, because everybody wants them. Some other model speedos do not have the odometer in the instrument, have different colors and, of course, may have different ratios.
To my knowledge, there is no other mph speedo that can be used in a Prolink CBX that will work right without a significant compromise.

[Norton1]

Hmmm - well I might have to go another route entirely then. I will check on the price to get one rebuilt but the 150 unit I have is trashed also. And I'd rather not lose any of the warning lights. Maybe I'll have to go with an electronic one. Set it up on the dash for easy reference. And retain the original gauge but lose the cable for it.

Thanks EMS -

[Don]

I would think that the original one would be much preferable to either of your proposed solutions . . . . it will serve you well 99% of the time. Most CBX's get to be a handful at speeds faster than that so likely you wouldn't be spending much time looking at your aftermarket speedo anyway. Having a functioning (and somewhat accurate) odometer is a really handy thing to have too

A good used 150 mile CBX speedo is probably going to run you $500 to $600 and you do occasionally run across brand new NOS ones for about double that . . . . for that sort of money I could learn to LOVE looking at the stock 85 mile one

Don

[Norton1]

I suspect you are correct about the 85 mph one being OK. I typically ride at 65 or so with my wife and I. The other guys I ride with tend to cruise at 85 or 90 so it'll be a guestimate at times for the stock unit. I would think this bike should be stable at 85 or 90 am I mistaken?

[ericfreeman]

Probably the easiest way to judge speeds over 85 will be to figure out what mph correlates to a certain rpm. Depending on your sprocket sizes, you can come up with a simple multiplier using one of the internet's gearing calculators. For example, my '79 with a 32 rear sprocket runs about 16 mph per 1000 rpm. At 4k revs, I'm doing about 64, 5k is about 80, 6k about 96. Pretty easy to come up with a number that will get you in the ballpark.

Eric