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Discussion Starter #1
Hi!

I have a 76 cb360 that starts fine and rides great, but recently I've noticed a problem about a mile or so into each ride and it isn't so great. When I disengage the clutch to switch gears, the rpms go way up yet the bike severely slows down, until I reengage, at which point everything feels normal. I'm afraid it isn't just a problem with the clutch though, because when I pull over and put it in neutral, I'm not able to roll it back or forth. Everything just kind of gets all locked up for a while whether the clutch is in or the bike is in neutral. Just doesn't go anywhere. The problem eventually goes away and it doesn't happen again until a mile or so into the next ride.

I haven't done anything to fix it yet, other than read up and try to figure out the problem, but I'm new to this and haven't worked on the bike a whole lot, so I'm completely stumped. I want to check a few things off a list that I can do myself before I bring it in to a mechanic. Any ideas on what the problem could be/how I can fix it?

Thank you!
 

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That sure does sound like a riddle. Just to be clear, you roll off the throttle when squeezing the clutch and the RPM's still go up? How much is "way up"? Also, the bike slows down with a lurch as though you downshifted, or just sort of winds down? When you pull over in neutral and can't roll the bike, do you have your left hand on the clutch lever? It almost sounds like when you squeeze the clutch the clutch plates aren't actually disengaging and the transmission shifts down a gear. That's the only way I can make sense of it. If the clutch really disengaged, you'd just be coasting, so there'd be no sudden change of speed (and you would be able to roll it easily in neutral). The revs increasing and the bike slowing down sounds like engine braking due to dropping a gear. I'm a beginner myself, but I'm trying to diagnose the problem with a little detective work and engineering knowledge. My guess is a bad spring or something in the gearshift linkage assembly. The gear might be being held in place by friction from the engine drive, and when you disengage the engine drive the shift drum stopper arm pops and the transmission drops a gear. Add a spotty clutch to that and it might cause the symptoms you're seeing. I'm hoping someone more expert will chime in here, but that's what the clues sound like to me...
 

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More likely the front brake master cylinder is causing the brakes to remove engaged. The RPM is more likely a stuck/binding throttle cable or linkage, or a vacuum leak. you can have more than one problem.

The master cylinder has a small pinhole in the reservoir, closest tot he where the hose connects. this is a bleed to let pressure off the line and allow the pad to retract. they often get blocked and cause the brake caliper to drag. Another possibility is the wheel cylinder is corroded, not allowing the pad to retract.

I suspect that you have so much throttle on to overcome the brake drag, that you don't reduce the throttle as much as you should ( I may be wrong). You also may have a vacuum leak. Cold, my bike ran well, after 15-20 minutes, I had hanging idles and stalls, and difficulty starting. My Carburetor manifolds (rubber mount on the engine/carb) were cracked. Cold they did not leak, warm, they leaked badly.


For the brakes, get the bike on the center stand. Use a 3/4 in board under the stand to get the rear wheel way up. See if the rear spinfns freely in neutral. Than have someone sit on the bike and lean back, raising the front wheel off the ground, see if it spins freely. that should narrow down the problem.
 
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