Motorcycle Repair: 1979 honda cm400, honda cm400t, clutch lever

Question
hello, My question pertains to the clutch.I have recently bought my bike and have done an oil change. I used the rec. honda 10-40 oil. After the oil change my bike wont shift at higher speeds ex.55mph When I try to pull the clutch lever to downshift it wont even budge which at times can be kinda scary. It feels like the lever is welded in place on the handlebar till I manually slow to like 35-40 mph. What could cause this?    thanks.

Answer
Kevin, The clutch system starts with the lever and goes all the way down to the right side case.

http://www.cmsnl.com/honda-cm400t-79-us_model1049/partslist/ shows a lot of the parts involved.

Changing the oil shouldn't make your clutch suddenly fail, especially using Honda M/C oil products.

First do the easy stuff...  Loosen the clutch adjustment up, so you can remove the clutch lever and cable. Clean and lubricate the lever pivot hole and pivot bolt with a light grease, Check the cable for sticking and drizzle some light weight motor oil down the inner cable until it starts to run out the bottom end. Push-pull the cable inside and see if if it feels smooth in those motions.

Replace the cable and the clutch lever/adjusters again. With the cable adjuster on the handlebars turned all the way in, adjust the clutch cable at the bottom connection, so that you have a very small amount of freeplay at the lever. If you have excessive freeplay at the clutch lever, the clutch will not release all the way and there will be drag on the engine/transmission during shifting.

You should be able to hold the clutch lever in with the bike in gear, until about half-way out, before it starts to engage. With the lever pulled all the way in, the bike should not feel like it wants to move forward.

If lubricating the clutch lever and cable, plus adjustment doesn't fix the problem, you will have to buy a clutch cover gasket and plan on draining the oil and removing the clutch cover for inspection of the release arm inside. Might be a good time to inspect the clutch plates for wear or warpage, too.

You didn't mention the mileage on the engine, so I don't know if the parts are wearing out or it is more a case of misadjustment.

Bill Silver