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Discussion Starter · #1 ·
I saw a video where a friendly guy was talking about his Honda PC800.



My parents neighbor got one and there was one for sale at the local dealer for what seemed like a great deal but i wasn't sure it was for me.



Looked too much like a scooter but now i sort of want one thus i'm just checking them out on youtube.....ANYWAY



So this guy mentioned in the comments section he used a VT1100 Final drive or differential assembly or something i forget to quiet the rev's down.



This got me to thinking, if one could find a final drive to mesh with the pinion gear and the tire was thin enough would this be possible on CX's?

I realize this kills the power and torque greatly depending on the set up but lets be honest, these bikes aren't rockets.
 

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Anything is possible with tools. I don't think there is a direct bolt up but I would think that with a cutting tool, welder and measuring tape it would be possible to make a mount for the new final drive, cut the swing arm to a certain lenght, weld on the new bracket aligned correctly and adapting the drive shaft. Possibly needing the drive shaft from what ever bikes final drive you need.





Or you could do the cx650 clutch mod. And if you need more put on the wheel of a 78 cx.
 

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As stich has said, nothing is immpossible with some imagination and a hammer. The bigger question would be does it make sense to swap a final drive out. That could end up being a great deal of work, and some risk of winding up with a poor performing/handling bike.
 

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FYI: Most shaft drive bikes drive the wheel from the left side. The CX/GL, Gold Wing, BMW, and Moto Guzzi are the only exceptions I'm aware of.
 

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As Blindstich said, anything is possible given enough machining and cubic dollars. As far as I know there were only two rear ratios used on the CX's, a 3.09 ratio and a 3.40 on the 650 turbo. Don't switch to the 3.40, that will lower your top speed not raise it. The turbo also uses a different gearbox and a different primary ratio. Probably your cheapest swap to lower your engine speed is to change the primary. I think there are five ratios that CX's used and I think the lowest (highest top speed) would be the 1.70 used on the 650 turbo. Some of the other 650's used one in that range or 1.75. I would suggest that you find your primary ratio in your manual and look at one a bit higher. If yours has a 2.45 ratio, then you could look at a 2.24 or a 2.11. If you have a 2.11 you can switch to a 1.725. The warning to all of this is that it will slow your acceleration and you may not have the horsepower to pull a higher gear. I don't suggest a 1.725 unless you have a 650 or a turbo.



Gearbox swaps are another option. There is a wide selection of gears available from the CX400 to the 650 turbo. The swap can be done, it just depends on how much money and time you want to invest. Even then 650 turbo gearing may not be very useful in a 50 hp bike.



A wheel swap might also help, but be sure to use a high aspect or tall tire. If you switch from a 120/90-17 to a 130/70-18, your tire height would be virtually the same. You would want to stay with a 90 tire to keep the most height. Look at the tire's specs on the manufacturers website for height information.



Regarding the primary swap, there are plenty of good stories on that swap on this and other forums.



Please keep the forum posted on any mods you make and your results.



I have a spreadsheet I use for playing with CX gearing. It is on Excel. I have no idea how to post that, but will gladly PM it to anyone who wants it, or who knows how they can post it.



Ed
 

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Depending on how carried away you may get I suggest that if you do go about this that you check out the ratios. The cx650 clutch primary gear swap is like having 5 1/2 gears. Cruising at 60mph at 5,000 rpms. But I believe that the power gets goofy. Usually I shift around 5000-5500 and when I shift out of 4th into 5th it drops the rpm down to 4,000 which is ok on flat roads but otherwise it takes a while to get up to rpm. I find myself riding the slower back roads in 4th gear since doing 45mph in 5 gear is a waste at around 3,500 rpms.



I think my bike runs best on the highway around 6,500-7,000 rpm's but with the 650 clutch that's 75-80mph and I don't need to go that fast.
 

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Discussion Starter · #7 ·
i wasn't aware these bikes had either of those lol.



I didn't know there was 5 setups. If i'm doing 70ish, i'm about at 6500 and i would think a few revs less would be fine. Its not like these are interstate badass bikes. For city or country roads this bike is the stuff, but when your doing 70 and up it makes a lot of noise but really no power. I don't really go more than 70 anyway so for me the change to something lower would be fine.



Hopefully if i ever get a raise by the end of the year or graduate like i'm planning i'll pick up a VTX1300 and probably keep the CX just for town riding.
 

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Isn't the ST1100 Pan European on the same side as the CX? If so a rebuild with more modern running gear could be an option.. I wasn't thinking with my current CX but i could always find another..
 
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