Put a 650 Clutch in a 500

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650 Clutch Mod

Replacing the GL500 clutch with the GL650 Clutch (This cuts 300 or so rpms off the engine at highway speed) The other way to do the same without a clutch mod is to put a 78 cx500 18 inch rim on the bike.

Posted by: David () Date: June 24, 2005 11:26AM

I have written up what all transpired while converting my brother's GL500 from the GL500 clutch assembly to the GL650 clutch assembly.

I have seen this conversion talked about on several internet boards, but there were parts not mentioned and steps not mentioned so I wrote this up. I hope it helps people considering the conversion.


Steps required in changing a GL500 clutch to a GL650 clutch

Parts needed: 1. Front engine gasket 2. Clutch cover gasket (Not really needed, but a good idea) 3. O-rings (3) between the front cover and the engine 4. 650 Primary crankshaft gear 5. 650 Clutch housing 6. 650 Clutch plates 7. 650 Clutch Springs 8. 650 Collar 9. 650 Roller bearings 10. 650 Rear washer 11. 650 Oil separator (Oil splash guard) (500 splash guard can be used with some hammer work to make the 650 clutch housing clear the 500 guard and the use of the 500 rear washer rather than the 650 washer. They have a different OD)


1. Seat 2. Tank 3. Fairing 4. Crash guards (if equipped) 5. Radiator 6. Right motor mount 7. Clutch cable 8. Oil pressure sender wire 9. Fan 10. Front engine cover 11. Clutch Assembly 12. Primary gear

When you strip the front of the engine I would recommend you build the tool to take the clutch-retaining nut off the engine. You can make it with a piece of pipe, a hacksaw, and a grinder. I highly recommend that you weld a socket to the other end of the pipe so you can use a breaker bar, or better yet an impact wrench to take the nut off, and it is much easier to torque the nut back on with a torque wrench with the socket in place.

If you don't want to make the tool that is recommended by Honda to hold the primary gear in place to torque the clutch bolt and the primary gear bolt, you can get around that by putting the clutch plates into the clutch housing, putting the springs into place and put a washers over each spring and tighten them all down with the bolts for the throw out bearing. Then put the bike into 1st gear and have someone else apply the rear brake while you torque the clutch bolt. After you have done this you can reapply the brake and torque the primary gear bolt. Then remove the blots from over the clutch springs and put the throw out bearing assembly in place and torque them properly.

You can also torque the bolts by yourself if you have a strap wrench to go around the clutch housing, but be sure to go around the rear part of the housing to make sure you don"t bend the aluminum of the clutch housing.

After stripping the front of the engine you must either put on the Gl650 oil separator or do some firm, but gentle hammer work to make the 650 clutch housing clear on the back side and put grease on the backside of the clutch housing and spin it to see where it is rubbing. Tapping with a ball peen hammer did allow the housing to clear. It did not allow the use of the 650 washer that was too wide and would have rubbed on the oil separator. The GL500 washer seems to be wide enough to do a sufficient job of holding in the roller bearings in place. If the 650 separator was used the 650 washer would have cleared.

While the engine is apart it would indeed be foolish not to replace all the o-rings gaskets and radiator hoses if they have never been replaced. This is also a good time to replace clutch throw arm seal on the side of the cover.

I hope this helps those of you who are considering this project. On everything I read about this job, not one person mentioned the oil separator replacement or the denting of the old one to make the 650 clutch housing fit.

Unfortunately, I didn't take any JPEGs of what I did, but I would be willing to answer any questions you have about the procedure.

Finally, you must question whether it is worth the time, effort and money (about $100 plus the clutch assembly) to gain 400-450 RPM at freeway speeds. My brother, for whom I did the project for, says he is happy with the results, but he was given the clutch assembly for a gift and only had to pay for the other parts. Also, the old GL500 oil separator was used, by denting it, as there wasn't a GL650 separator available at the time. My brother says it changes the RPM enough to take the annoying buzz out of his handlebars that occurred between 65 and 70 MPH.

Now for me to add info to Dave's post as I have collected most of the parts and will be buying the rest from him so I can do the job at the next oil change with his help.

First the oil shields are available for about $23 from honda. Both are the same part but they have different part numbers. Cx650 11365-ME2-000. Gl650 199275-00.

Both just short of $23.

The front shield is the 500 and the rear is the 650


The 500 clutch is on the left and the 650 is on the right.


Parts needed to make up for the lack of the extended rear piece molded into the 500 clutch.


This drawing, Washer Bushing, is one forums members had machined as a solution instead of trying to find CX650 transmission parts. 800x470px

And what the 650 shield looks like in place.


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