Topic: Project 40 - CB750 K1

[CrankyOldGuy]

Oil Tank and Hoses

Today I removed the Oil Tank and Hoses A and B.

I found the 3 bolts (90141-300-000) and rubber washers (55106-300-000) need to be replaced.  The rubber washers have deteriorated over time while the threads on the bolts have been damaged where they appear to be vibrating in the nut.

Hoses A and B came off quite easily.  I found one different bolt attaching Hose B to the crankcase; it has a combined hex head and phillips screw head.  This must be the special bolt (6x25 90040-300-000) referred to in the parts list. The other 3 bolts have hex heads (6x25 92000-06025). Perhaps it is different for installation purposes but I was able to remove it with a socket.   I have already ordered new o-rings (15x2.5). The corded portion of both hoses has a faded gray-white colour appearance  I will try the black marker approach to see if I can blacken the corded portion.  I washed the hoses in varsol; just minor washing required until the fluid in the hoses ran clear.

The oil tank is in good shape, especially the oil tank cap (dipstick).  The fuel filler cap packing (strange name) (cork washer 17631-253-000) is also in good shape.  Rinsed out the inside of the tank with varsol several times until the liquid ran clear.  Once the varsol evaporates I will coat the inside of the tank with oil.  The breather tube (15761-300-020) and the oil tank breather pipe (55107-300-000) may be serviceable but most likely should be replaced.

Harry O.

[CrankyOldGuy]

A couple of useful aids that I have found and thought I would pass along.

1.  Nitrile disposable gloves  - I read about these the other day on the forum for those of us who are allergic to latex.  They work well and my hands are actually clean after working on the motorcycle.

2.  Aluminum trays - I picked up a package of aluminum trays the other day - about 50 to the pack.  They are probably a couple of quarts/litres in capacity.  Great for keeping a small group of parts together, such as an oil pump, or for washing parts, such as oil hoses and tank.

Harry O.

[CrankyOldGuy]

Spark Advancer Shaft and Spark Advancer

While waiting for parts to arrive for the oil pump I decided to work on the spark advancer shaft and the spark advancer.

I always thought after the encounter with the German Shepherd that the spark advancer shaft was not  straight.  I had ordered a new shaft c/w o-ring from DSS last winter for a planned replacement.  A good set of vise grips was required to remove the shaft (see pic below).  It was good to have the replacement shaft on hand to ensure that the existing shaft had to be turned counterclockwise to remove it.  The first couple of tries the engine turned over but on the third attempt the shaft turned.  I have included below a picture of the new shaft (left) and the existing shaft (right) side-by-side.  I do not know if it is clear in the picture but the existing o-ring is a greyish-black colour and is swelled in size compared to the new one. For this reason alone it was a good idea to remove the o-ring; possibly eliminating a future oil leak. 

The spark advancer was easy to remove.  I disassembled the assembly  so that I could clean it, and remove the grit and dirt that had accumulated over time.  I have included below a picture of the disassembled spark advancer.  It feels like the advancer was greased, but I am not sure, maybe only oiled.  I could find no reference in the shop manual.  Anyone have any experience with respect to the lubrication of the assembly?  I will also inquire about this on the main forum.

One lesson that I have learned is that rubber has a shelf lift and it is not 40 years.

Harry O.

[CrankyOldGuy]

Contact Breaker Assembly

Today I also removed and replaced the contact breaker assembly.  A picture of the existing assembly is attached below.  The assembly was dirty, the points were old, and the cable was frayed in a couple of locations.  Hard to say what condition the condensers are in.

I had purchased a Daiichi contact breaker assembly last winter from DSS plus a set of Honda points.  A picture of the new assembly with the Honda points is shown below.  Since the picture was taken I have replaced the Daiichi points with the Honda points.

I also purchased a new points cover c/w screws from DSS last winter (see pic below).  The cover has the cork gasket and a desiccant coating on the inside .

Harry O.

[CrankyOldGuy]

Oil Pump Screen - Good and Bad News

Just a quick plug - HondaMan's book "My CB750 book" (Chapter II) is an excellent resource for understanding and servicing the oil pump.

I received my parts order from the local Honda dealer (the same one I purchased the K1 from in 71) that included the new oil pump screen (see pic below).  That is the good news!

Upon receiving said oil screen to ensure that it actually exists ( we are lucky that Honda actually carries them again), I decided to take the oil screen off the oil pump.  It came off quite easily using a very small flat blade screwdriver and prying at a few spots around the perimeter to loosen it up (found this method using the search function).  The rubber around the perimeter of the screen is not as pliable as the rubber on the new screen. The existing screen is covered with black bits and the bad news is they are predominant on the pump side (see pic below).

I have also included a pic of the oil pump with the screen removed.  They may not show up clearly but there are black bits inside the pump body.  I don't know if the black bits got inside the pump body while I was removing the screen or when I was trying to brush the black bits off the screen a few days ago, or they were already there.
 
To be on the cautious side I am going to do is disassemble the oil pump body and clean out the black bits.  There are two 46x2 o-rings plus the 11x15x3 oil seal inside the main pump body which I will replace.  From my experience so far, o-rings tend to have changed colour to greyish-black and are swollen.   

I also cleaned an reassembled the spark advancer.  It moves more freely now.  It was a good idea to do this due to the buildup of grime.

To appease my grief on having to disassemble the oil pump I bought myself a 25-250 in./lb. pro-lock torque control torque wrench 

Harry O.

[Danno]

hey bud hit those nasty bits with carb clean if they dissolve they are just gunk but if they don't run them through your fingers if they are hard bits they may be pieces of your timing chain tensioner so check it
 they are known to fall apart over time which seems to be harder on them than use

[Danno]

they could also be cork bits from your clutch if someone replaced the friction discs with barnett but since you are the only owner of the bike you would know that

[CrankyOldGuy]

Danno,

Thanks for the input.  I will give the carb cleaner a try. 

Harry O.

[CrankyOldGuy]

Six months have gone by since my last post.

I disassembled the pump and the 46x2 o-rings were squished flat, not round anymore.  There were scratches in one of the pump chambers which seemed to make the pump bind a bit.

The little 11x15x3 oil seal between the two pump chambers gave me a nightmare of a time in trying to remove it!!!   The rubber was brittle and came out in bits.  The knurled metal retainer portion of seal would not budge.  Here I was fetched up with no relief in site.  What do I do ... of course .... e-mail the Colorado Caped Crusader (aka Hondaman) for help  .. off goes the pump to Colorado for a winter vacation. 

I opened the box today ... all I can say is wow!!!  The pump looks like new and turns real smooth.  I have attached a few pics ... but they really don't do justice to Hondaman's work.

As a favour to Hondaman  ... and because of my work commitments ... I have sent him my carbs to play with this time.

Harry O.

[Tews19]

Subscribed! Please post more frequently!!!!! I have a K1 as well and admire the look of yours.

[toomaas]

Hi - not sure how active this topic still is, but I've come across it while dealing with the same issues on an oil pump.

I've stripped mine down to replace all and anything rubber - including the very pesky 11x15x3 oil seal. When I manage to get it out it'll need a replacement. Any advice on how to get it out and where to find a replacement would be most welcome!

I'm also thinking that I'll need to replace the (possibly collapsed) oil hoses and found some with a supplier in Japan (yamiya750)

But at around $330.00 I'm wondering how easy it is just to use the old attachments on new hose...?

[CrankyOldGuy]

Hi toomass,

I purchased both the 46x2mm o-rings and the 11x3x15mm oil seal from my local Honda dealer.  The oil seal is part number 91208-300-003 or #912080MN1-771; the GL1000 Gold Wing oil pump uses the same seal (courtesy of HM).

I had extreme difficulty in removing the oil seal.  I ended up sending it to Hondaman for his help.  If you PM Mark he may be able to tell you some tips in its removal.

Harry O.

[Garystratos201]

Great thread, please dont let it die. I`m in the middle of an extensive K1 rebuild and need all the inspiration I can get.........Gary

[toomaas]

Thanks for that - good to know that the seal is shared with the Goldwing - should make the search a bit easier.

I put the pump assembly in the freezer last night in the hope the seal will contract enough to pop out - though 'pop' is probably being optimistic...

If that fails I'll follow up your suggestion.

Cheers,

Tom.

[Garystratos201]

I had the same approach you when I started my K1 project. Its amazing how  soon it becomes an obsession. What was once just a get it running approach to a frantic search for correct parts. I`ll watch you thread with interest...........Gary

[toomaas]

Success!

Got the seal out - and thanks to all advice. I've been jumping between threads on this one...

There's more info on the oil pump pages 101-102 here:

http://forums.sohc4.net/index.php?topic=36459.2525