1983 VF750F Interceptor Clutch Slave Question

Last year, I was given an old 1983 Honda VF750F Interceptor V45 for free. The engine was broken down to the valve covers and the parts were given to me in a box. The owner said if you can put it together and get it running again, you can have it. Luckily he had the full OEM service manual and gave me that as well. I have tons of questions but, long story short, my father and I spent the winter rebuilding the carburetors, brakes, did all fluid changes, rebuilt the forks, new tires, and fixed some electrical wiring glitches and we got the bike on the road (although she is far from a perfect runner but that is for another day). I was fine with her being road worthy and I wasn't looking for perfection. Point is, I drove it all summer of 2022 before I lost clutch lever pressure at the beginning of October. After struggling to get it the clutch to bleed I put it away for the winter. But, I want to try and get it back on the road this spring.

I have one main question with my clutch bleeding issue. When I first experienced loss of clutch pressure I bled the clutch and got it to come back for me but slowly started to feel it weaken as I would drive it to and from work every day and take it for the occasional country stroll. Finally one day while I was driving home from work during the first week of October I could feel the clutch was giving me almost no resistance at all. I got her home but I didn't want to drive it again until I could feel the clutch was working good. I noticed a small hole under the slave cylinder casing that had some liquid underneath it and thought maybe the casing had blown out or something. Because finding parts is difficult for this thing and I am mostly just an at home mechanic with no major or professional experience, I thought I would just go for the old JB weld strategy because, well, I just want her on the road. I know this is basically sacrilegious to "fix" anything with JB weld but like I said I was desperate and confused. Now after doing more research online I am wondering does the slave cylinder housing on these bikes have a "weep hole" for when the slave cylinder gaskets go bad? If so, I'm an idiot and JB welded over something that I clearly shouldn't have. It is not mentioned in the service manual so I didn't even realize it could be a thing since I am not an experienced mechanic. If anyone has any knowledge on the subject I would greatly appreciate it. I am getting DOT 4 coming out of the bleeder on the slave cylinder but it is not building pressure no matter how long I try. Should I try replacing/rebuilding the slave? Does it have a "weep hole" and am I an idiot for JB welding it thinking it was an actual leak? Does anyone have experience with this issue on these old bikes? Anything would be useful at this point.

 

Time to man up and rebuild your clutch system.

You should probably bleed your brakes too.

 

Get your slave off and apart. Might need just a seal (usually), but the piston could be toast from moisture in the fluid.

"Casting blowouts" usually don't result in a nice round hole.

 

Thanks for the quick response. I will take the slave apart tomorrow and see what it looks like. Since you said I should rebuild the system do you recommend I do the master as well? Are there are any other tips or suggestions about the clutch system you might have or parts you think I should go ahead and rebuild/replace in regards to it?

 

I would vote for replacing the seals in both the slave and the master. The slave cylinder might be scored or corroded, so pay attention to the state of the bore, and make sure to clean all the bits up nicely. Also pay attention to which way round the seal sits. The weephole that you sealed exists to prevent any leaking fluid from making its way under pressure into the engine; probably a good idea to open up the weep hole again.

I suspect your problem is more likely in the master cylinder with a dodgy piston seal and/or corrosion of the bore. In addition, make sure the body of the cylinder is spotless and especially the very tiny compensation port in the floor of the reservoir; if that gums up, your clutch can't release line pressure and eventually the pressure builds until it overcomes the clutch springs and drive stops.

Honda used similar hydraulic clutch master and slaves on heaps of bikes; if you have to replace any parts and can't find an exact model match, something similar is likely to do the job.

 

Just want to update and say the bike is back on the road! I rebuilt the clutch master and slave and she's engaging again. Took me a minute to get her to bleed all the way but I had a hand vacuum pump and it was a life saver. Want to say thanks boys. Oh, I also got rid of the JB weld too. Things are looking up. The next little thing on my list is the flasher relay. It sometimes works and sometimes doesn't. Seems very inconsistent. Other than the obvious conclusion that I need a new relay are there any other reasons you guys might know that would cause it to be intermittently working or not working that I need to check or look out for? I thought it wouldn't hurt to ask before I hunted down another relay and bought it right away. Also, if I have a hard time finding one is there another model bike that the relay would work for the '83 VF750F? Appreciate any and all help.

 

Does your front running light go out when you hit the blinker, and then not blink?

I would still spray some WD-40 in the slot of the turn signal switch button. And the high/low, horn, starter button and kill switch. And ignition switch while you have the WD-40 out.

Also, you might pull your signal bulbs and check for any corrosion in the sockets. It can increase resistance and affect how your relay operates.

EDIT: good job on your clutch!!