Topic: Honda CB750 Brake Lines/Hoses - more discovery?

[Stev-o]

I am not the right person for the job.

That is your decision to make, thought I read in your other thread that you have a good relationship with a shop that works on your other bike?  Is that an option for the CB750?

Your bike is a fairly basic bike to work on, I'd say any competent modern bike mechanic would be able able to handle everything needed to get the bike safely back on the road [brakes, tires, etc].  We can help you source the necessary parts that will be needed, that is sometimes a stumbling block for shops, they just cant go to a Honda dealer and order everything that is needed.

[kyle750]

I am not the right person for the job.

 We can help you source the necessary parts that will be needed, that is sometimes a stumbling block for shops, they just cant go to a Honda dealer and order everything that is needed.

Many thanks for the offer of assistance with parts. This will be extremely helpful going forward.  Thank You!  I have a lot of experience with vintage watches and have been very successful in sourcing very hard to find parts. With my watchmaker here in Thailand I source and buy all the necessary parts and he does all the work. His skills as a watchmaker are superb!   I direct the entire watch project from start to finish and the end results are almost always excellent. 

I imagine the CB750 project working the same.  Working closely with a (yet to be identified) mechanic specializing in vintage Hondas we diagnose problems and determine what needs to be fixed or replaced.  I source and buy the parts and he does the work.

[Rookster]

Just to add this for anyone looking for more information on how to pump the piston out with the grease gun.  if you get an extra bleeder screw and cut the bottom off it you can use this as your grease nipple.  screw it into the brake line side.  Any standard grease gun should connect to the ball end of the bleeder.  Make sure the real bleeder screw is in tight and pump.  This is safer than trying to grab a few threads with the possibility of stripping the brake line side of the caliper.



Scott

[Stev-o]

Just to add this for anyone looking for more information on how to pump the piston out with the grease gun.  if you get an extra bleeder screw...

Good info Scott.  Although I have successfully used the grease gun method, I was always leery of stripping the threads.

[PeWe]

Good to know.
I have a caliper looking almost like new with stock pads with little wear in need of getting the piston out.
I did not try the grease gun that much when the threads differed.
Caliper has M10 fine threads.

Will try again with a modified bleeder.

The old dried brake fluid has been tricky to get out from the bleeder threads and brake line connection.
Like old glue.

[BenelliSEI]

Just to add this for anyone looking for more information on how to pump the piston out with the grease gun.  if you get an extra bleeder screw...

Good info Scott.  Although I have successfully used the grease gun method, I was always leery of stripping the threads.

Steve…. The adapter I use is an old end from a steel line I scrapped. Cut it free, then drilled and tapped it for a standard grease fitting. Took a few minutes, but it fits perfectly and is risk free. I’ll post a picture later.

[kyle750]

I've taken the brake caliper to 2 different local shops.  First shop specializes in larger bikes and he sprayed the caliper well with WD40  and slammed the inner flat face firmly against a hard block to try to loosen the piston.  Sealed off the end with a fine thread bolt and used compressed air with a rubber cone shaped nozzle - seemed to be a firm fit as I did not hear any escaping air.  It did not work.

2nd shop was a car repair shop and they had a grease gun and once again sealed of the end with a bolt.  Mounted the grease gun to a vise and pressed hard. Piston did not come out.  After a while  a metal seam in the grease gun blew out - probably a cheap or older gun.

Having the right tools is essential for any job but I am not prepared to buy each and every tool needed to repair the bike.  I need to find a mechanic who is well equpped with the right tools and specializes in repairing Old Hondas.  I have not actively started the search yet but I have put out feelers that I am looking.
 
I've taken a break on the brake caliper and am now working on transferring the title to the bike.  As a foreigner living in Thailand I am required to provide additional documentation for title transfer including more bureaucratic paperwork from Immigration.

[kyle750]

On a Positve Note - Lots of parts are now rolling in to my USA shipping service and Thailand. Brake pads (I bought both organic and semi-sintered), brake piston and seal, bleeder screw and front pipe,  master cylinder rebuild kit,  front fork boot covers, front fork seals, used engine starter motor cover (mine is heavily rusted) only $8 from Ebay USA, used engine front sprocket cover (mine is cracked) only $25 from Ebay USA, handlebar and steering stem bolts (my bolts are very rusted).

Also good news is that the parts delivered from Japan I was expecting a 30% import/customs duty on motorcycle parts but it was only 10%.  Maybe a mistake by customs but if 10% is correct that will make a big difference going forward.   

[M 750K6]

I'm happy with my replacement calliper from David Silver. I priced up replacement parts, to refurb my old calliper, which was working, but tatty and sticky. On cost, it was close, so I went for a new calliper, bolt off, bolt on. Was easy.

[MauiK3]

It also feels good to have confidence in new brakes!

[Stev-o]

Having the right tools is essential for any job but I am not prepared to buy each and every tool needed to repair the bike. 

A basic metric tool kit will suffice for 75% of the work you will do on your bike.  At least get a 10mm socket and wrench!

If that caliper is rusted that bad, it may be best to find a replacement.

Just an example...

https://www.ebay.com/itm/361536141592?fits=Year%3A1971%7CModel%3ACB750&_skw=1971+cb750+caliper&itmmeta=01JFD6Z8ABB9MFRJ2G26QTD12G&hash=item542d3bb918:g:OjIAAOSw4PxaMEv0&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKmSwuozfU29bn6SqvnPHOIrQCn59mb5xEKThzyeaWlmBRkjbbq%2BQ38c2VHGvQzzrjUpPVAm13%2B4en1YWYVuvElIoM%2FqKrw%2Ful0vCMvuflQM%2BA%2FaqbSEkmZz1CvPbHJ%2BlDPqPl8jZ2wBtwOJWvMUrLwot4xazjI5kWZlxua6CYWiHxxqSgGXuVmEw980Rphd6Dg1UC%2BwvlNThZeuUByJLbeuoJO20siA%2B3ZNxlk6%2BGKd5tYiv4rbauyhzrjMkbwWjh16vXDylg4VgMZhz%2B1OecoyYoZka8WeBgsqutNUGlAljg%3D%3D%7Ctkp%3ABk9SR6SF_ab7ZA

[kyle750]

Having the right tools is essential for any job but I am not prepared to buy each and every tool needed to repair the bike. 

A basic metric tool kit will suffice for 75% of the work you will do on your bike.  At least get a 10mm socket and wrench!

If that caliper is rusted that bad, it may be best to find a replacement.

Just an example...

https://www.ebay.com/itm/361536141592

Thanks Mate for the link.  Very Much Appreciated.  Thank You! I'm totally with you on this one as I only need the one side - other side of the caliper and bolts are fine.   I purchased the exact caliper last night.  Shipped out yesterday.  I've already bought a few parts from Everett Powersports and I am extremely impressed with their  service, communication,  and shipping - Excellent +++  I have wasted too much time already  on the original caliper.  My German Friend took the original caliper yesterday and told me he can try to remove the piston.  He is now soaking the caliper in a jar filled with diesel fuel with a closed lid.  "Give it time and we will try again"  but I needed to move forward with Plan B. 

I almost bought this caliper from a seller in Thailand as it would have arrived very quickly but the price was more than I was willing to pay. 

https://www.ebay.com/itm/121564277852

Although I am looking forward to a first ride with the CB750 I also realize that 50 year old bikes need time to get back on the road!

[Stev-o]

Having the right tools is essential for any job but I am not prepared to buy each and every tool needed to repair the bike. 

A basic metric tool kit will suffice for 75% of the work you will do on your bike.  At least get a 10mm socket and wrench!

If that caliper is rusted that bad, it may be best to find a replacement.

Just an example...

https://www.ebay.com/itm/361536141592

  I almost bought this caliper from a seller in Thailand as it would have arrived very quickly but the price was more than I was willing to pay. 

https://www.ebay.com/itm/121564277852

Seems to me that listing is just the caliper, you would still need the piston, seal & bleeder. Bad deal!

[PeWe]

There are others selling this too.
I have ordered from DSS to my K2
https://www.davidsilverspares.co.uk/CB750K1-FOUR-1971/part_223210

[kyle750]

While waiting for brake parts to arrive we started fiddling with the bike.  A little harder to start up this time but finally started up.   Idling a little low and kept stalling out so we increased the idle to around 2,000.  Quick clean out of the carbs with lots of tiny gunk removed but the carbs are not leaking gasoline. A little smoke coming from the exhaust pipe from cylinder 1 on startup but smoke stopped after about one  minute.  Checked the spark plugs and both the plugs and wires look good.     Adjusted the rear brake and it is good.  Quick electircal test and everything seems to be in working order -   both turn signals (front and back), headlight, and even the horn still works. I thought there was supposed to be a beeping sound whenever a turn signal was switched on?  No beeping?

After a while the bike idled very smoothly.  The thunderous roar of the exhaust is AMAZING! I can't safely ride the bike yet but I can listen to it . . .  and dream!

Quick question.  I turn the fuel cock to the off position after shutting off the engine and when I start the engine I turn it to on and let it sit for about a minute before hitting the start button.  Is this the correct procedure and should I try to drain the fuel in the carbs before shutting the engine off. Thanks!

My good friend Tony from Germany.  He cleaned the carbs and set the idle and bike is running much better now but there is still room for improvement. 

[bryanj]

Turn off when stopped and on before starting, with 750 oil can leak past the oil pump into the sump when engine stood for a time, never fill up before starting after a lay up without draining engine

[MauiK3]

Tip about the stock exhaust
Try not to start it and not run it long enough to get it really hot, moisture collects at the low point and corrodes the inner pipes. Check the little hole at the low point and make sure it's open. The hole is a drain and needs to let the moisture out.
Bike looks great.

[Stev-o]

While waiting for brake parts to arrive we started fiddling with the bike.  A little harder to start up this time but finally started up.   Idling a little low and kept stalling out so we increased the idle to around 2,000. 

Each bike is slightly different but here is my starting procedure for a cold start:

- Turn on ignition and fuel petcock
- Put choke on full position
- Hit start button with no throttle until she fires [or 5 sec], then give gas and reduce choke to half.

As far as idle, 2000 is too high, be sure to adjust it when engine is fully warmed up.  I like it around 1500.
This is not a modern vehicle with fuel injection, expect to use the throttle for at least a minute to keep it running when start it cold.  When starting it warm, it should fire immediately and settle to a nice even idle or it needs to be tuned.

I can sense your passion for the old girl, isn't it great!

[BenelliSEI]

Did your friend put in fresh gas? Sounds like you have a sweet machine!

[kyle750]

Thanks for all the encouraging replies. It is thrilling to hear the engine breathe and the pipes rumble and small victories are needed as this bike will be a long and winding road.  My good friend Tony strongly  believes I should have never bought the bike.  He says the bike is too old, too outdated, too expensive, too much work, and I don't have the skills and tools to fix it, and I will not ride it enough to justify all the time and expense. 

Of course Tony is 100% right.  It makes no economic sense to buy a 50 year old bike but my whole life I have been rational with sensible, safe,  and prudent purchases.  An old Honda CB that needs a lot of work  is not rational but it speaks to my heart. Tony thinks it was a Big Mistake!

[bryanj]

If our bikes had to make economic sense this forum would not exist plus tell your freind that when properly seviced it can be as reliable as when new and back then reliability was phenominaly good

[kyle750]

 should I try to drain the fuel in the carbs before shutting the engine off.

I did not phrase this question correctly so decided to rephrase and ask again.

when shutting down the engine should I turn the fuel cock to off and continue running the engine to drain the remaining fuel in the carbs and let the engine automatically shut off. Thanks!

[bryanj]

Not normally

[kyle750]

Not normally

Thank You

[M 750K6]

I would drain them if your fuel has ethanol AND you are going to leave it for a long time, say 6 months. That, or regularly turn on the fuel tap for 30 seconds to stop the fuel evaporating and floats sticking.