QuestionHi Bill I have a 1984 Honda nighthawk 650 and when I put it in gear it lurches forward when I pull the clutch in all the way when its cold or first started it feels as if there is no clutch at all after I ride it a few blocks the clutch begins to work I am not sure how to bleed the system as its told in the owners manual is this something that a dealer has to adjust thanks Jim
AnswerJim, there is no adjustment on a hydraulic clutch 650, assuming that this is a CB650SC model.
First gear lurch is normal on almost all motorcycles during the morning wake-up routine. The clutch plates have been compressed overnight squeezing all of the oil out between the plates, but leaving a bit of a suction on the facing surfaces. With cold oil and this temporarily "sticking" clutch plate scenario, the first disengagement of the clutch, to select low gear invariably leads to a big CLUNK for the first shift or two.
The master/slave system of clutch release is no different than that of the brake system. You have a master cylinder which pressurized the brake fluid and pushes it down the hydraulic line to move the slave cylinder piston forward, pressing on the clutch release pushrod. You should just have a 1/4" of free play at the lever, then feel pressure build-up quickly as the fluid pressure builds.
If the master cylinder and slave cylinder have not been serviced in the last 26 years, you will see a loss of fluid pressure in the master cylinder and a tendency for the slave cylinder piston to hang up on the seal and/or the seal ring will begin to leak enough to bleed off pressure and start a fluid drip down the side cover area.
http://www.cmsnl.com/honda-cb650sc-84-nighthawk-650-us_model7227/partslist/E++08... for illustration details. There is a bleed nut on the slave cylinder to facilitate bleeding air out of the system, if that is the problem. If air has gotten into the system, it really indicates that there is deterioration in the fluid system that needs attention.
Bill Silver
