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Discussion Starter #1 (Edited)
I want to raise the rear and slim the seat. They say I'm tall over 6.2 and I want install a more minimal seat. So I'm hoping raising the rear a lil will make up for seat height loss.

If you have a raised rear and a slim seat please show me the pics.

Thank you!
 

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Misread your post..

Just converting to an 18 inch wheel will make only the very slightest difference. I don't think it will give you enough height to get the effect your looking for. I have a 78 with a slim seat and the stock 18 wheels and its still way lower than a stock bike. Making rear sets helped with comfort on mine but I am only 5 ft 10.

The 18inch wheels have a narrower and smaller tire than the shorter rims.
 

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Discussion Starter #3
I thought that adding the larger rear tire wouldn't change the shaft angle at all, it would simply change the height by about an inch and a little slower off the line because of slightly less RPMs required to rotate the wheels.

It'd make sense that handling would change to some degree.

Regardless I'd love to see some raised rear ends ;)

I wonder that happens with both front and back bigger tires!?
 

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Honda originally specified a 130/90-16 (theoretical diameter = 25.2") for the rear wheel of your bike (& all others in this family with 16" wheels. They specified a 3.75-18 (theoretical diameter = 25.5") for the rear of the CX500 models with 18" wheels. The difference is about 1.2%. In other words, the rolling diameter of a 16" wheel with the stock tire is almost exactly the same as the rolling diameter of a 18" wheel with the stock tire.

If you change from a 130/90-16 to a 120/90-18 (theoretical diameter = 26.5") the 18 should have 5% larger rolling diameter with the subsequent 5% reduction in engine RPM (6500RPM becomes 6190 RPM) and a slightly smaller improvement in fuel economy.

If a 130/90-18 (theoretical diameter 27.2") will fit between the swingarm (some brands might) it would be 8% larger than the 130/90-16 with 8% reduction in RPM (6500 RPM becomes 6020 RPM) &c.

I usually recommend a 120/90-18 because most brands should fit and the handling should be a bit sharper than with the 130/90-18. As well, if you check the tire manufacturer's recommendation you will probably find that a CX500 wheel's rim is too narrow for a 130 tire. In your case, changing from a 130/90-16 to a 130/90-18 wouldn't affect the handling much and would give you a little more height but I don't think it would be as good a solution as using a thicker seat.



Note: The only tire dimension that is consistent from one model of tire to another is the inside diameter of the bead. Everything else is nominal in the first place and can change depending on rim width. For example, if the same tire was mounted on a 2.5" rim and a 3.5" rim it would probably be narrower and taller on the 2.5".
 

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If anything, my bike ended up a little bit higher than I intended. A 6'2" fellow would be quite at home. (I'm 5'9+/-)
 

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Yeah, it does really hang em out there for the world to see. They make it look good, and they make it go even better!
 

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Except for 2 things:
1) I'm surprised Murray hasn't commented about the angle between the swingarm and the engine and its effect on u-joint life.
2) With the front end of the tank lower than the rear any water that gets into the tank will pool there instead of being drawn out through the petcock. Given time it will find its own way out.....
 

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Swing arm angle is good. The frame is raised independently of the engine so the angle is only +/-1° from stock. Gas tank is a very valid concern. No defense for that except that I use nonoxygenated gas and empty it completely every 6 months thanks to our fairly short prime riding season.

As I look at this photo, the angle of the driveshaft does look off, but when it's stood up and the angle is measured, it comes out really close to my unmodified bikes. Murray did bring it up to me privately during the build and I double and triple checked it.
 
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Reactions: Sidecar Bob

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Good day everyone, I'm new here and had a quick question if someone could please help me?

I have a 1979 CX 500 Deluxe, the rear tire thats currently on the bike is a 120 90 16 can I possibly fit a 120 90 18 tire on that rime?

Thanks and stay blessed
Silverline.mb
 

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No. To fit an 18" tire you need an 18" rim.
 

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IIRC, the factory recommended rear tire for the Deluxe is 130/90-16.

In case you don't know, the numbers in the tire size are tread width/aspect ratio-rim diameter so a 130/90-16 is approx. 130mm wide, 117mm tall (0.9 x 130) and fits a 16" rim.

As Mike said, you can't put a 18" tire on a 16" rim BUT the 18" wheel used on the original CX500 (not Custom, Deluxe or Eurosport) will fit your Deluxe and you can use a 120/90-18 tire on that. In the process you will lower your engine RPM slightly while making it handle slightly better (narrower tires are easier to lean).
 
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