Topic: 1975 CB750F - my wife is going to kill me soon

[Mainer4]

Ok, second bike post today.  I bought a kinda nice 1975 CB750F two years ago to replace our 1976K.  But the new bike needs a new muffler and they are scarce as hen's teeth.  I need a muffler from someone for this bike - any leads on an aftermarket supplier - MAC? Whatever?  My only requirement is that it allow me to continue using the centerstand. 

Then there is the darn rear mastercylinder which is locked up and no parts available or so it seems.  What to do with that thing, I am told that '76 an '77 are different.  The front calipers are also stuck so the bike has no brakes at all.  I am sure I can deal with the front ones, I rebuilt my '76K and my '75 CB400f with no problems.

Howard in Maine

[Jerry Rxman Griffin aka MuthaF'er]

Mac USED to make a slip on muffler. USED to. No direct replacements that I've seen in a few years. You could always get a complete Mac or Kerker exhaust.

75/76 rear master IS different than 77/78. Rebuild kit IS available but you will not find it stocked and it will have to be ordered. 75/76 Goldwing master will work. You shouldn't have any problem with the front.

[BeSeeingYou]

My rear MC was frozen too but I did get it apart.  I shot some seafoam into the bore, pushed the piston further in to compress the spring and then heated the whole thing up with a heat gun. Nothing happened so I set it down on the workbench and turned away to go upstairs and it all popped apart.  You can try and find a 75/6F used one but they are hard to come by.  Someone was just parting out a 76 here so check the for sale section.  The Gold Wing option was one I had been looking into before I was able to salvage mine.  The only difference I was able to detect was the absence of the small tab on the casting where the outlet hose is connected to keep the banjo orientated at the right angle.  On the GL the fitting at this location is also a threaded in fitting and not a banjo like the F so you would need to clean off the paint and make sure it is smooth for a good seal.  Minor mods IMO.  I had no problem getting the rebuild kit for the rear from www.Babbittsonline.
A member here DonR had made a stainless steel muffler for his F and was talking about making more if there was a demand.  Maybe check with him.

[greasy j]

this new place is pretty awesome, they have great deals on really useful stuff.

and a few different types of mufflers for cb's! most under $50!

http://www.dimecitycycles.com/

and what is it with you guys and your fascist wives? buy her a bike and hopefully she will catch your moto-disease

and I just read another post with a resource for rear mc's, look around it's here somewhere. not much help, I know...

[Don R]

I made one and never followed up with more, but it is a 2 1/2" inlet 3 1/2" outlet the only hard part is welding the stainless bracket to the pipe. The baffle is from patriot. the one in the picture has a pint glue can for a baffle it looks gold because it is stainless. not as noticeable normally. One could also be made in chrome for a better match.

[bjb87gta]

If the metal pieces for the rear cylinder are reusable, the internal rubber parts for the front and rear cylinders are the same, so parts from a front kit will work as a substute. Use compressed air or a grease gun to remove the pistons from their bores if they are stuck like on a caliper, just make sure you clean the grease from everything right away to prevent any swelling of the rubber parts. You might get lucky and be able to clean everything up and reuse it if it is in good condition. Sometimes the brake fluid is in a semi-jelled state, and just needs to be flushed out to work again. Just remember how important your brakes are when you make this decision, since front and rear are both hydraulic on the F.